Water-electrolyte  and acid-basic disorders

9.1 The importance of the water to the organism.

Life on earth was born in the water environment. Water is an universal solvent for all the biochemical processes of the organism. Only in case of stable quantitative and qualitative composition of both intracellular and extra cellular fluids homoeostasis is remained.

The body of an adult human contains 60% of water. Intracellular water makes 40% of the body weight, the water of intercellular space makes 15% of body weight and 5% of body weight are made by the water in the vessels. It is considered that due to unlimited diffusion of water between vessels and extra vascular space the volume of extracellular fluid is 20% of body weight (15%+5%).

Physiologically insignificant amounts of water are distributed beyond the tissues in the body cavities: gastrointestinal tract, cerebral ventricles, joint capsules (nearly 1% of the body weight). However during different pathologic conditions this “third space” can cumulate large amounts of fluid: for example in case of ascites caused by chronic cardiac insufficiency or cirrhosis abdominal cavity contains up to 10 litters of fluid. Peritonitis and intestinal obstructions remove the fluid part of blood from the vessels into the intestinal cavity.

Severe dehydration is extremely dangerous for the patient. Water gets to the body with food and drinks, being absorbed by the mucous membranes of gastro-intestinal tract in total amount of 2-3 liters per day. Additionally in different metabolic transformations of lipids, carbohydrates and proteins nearly 300 of endogenous water are created. Water is evacuated from the body with urine (1,5-2 liters), stool (300 ml), perspiration and breathing (those two reasons are combined as “perspiration loss” and make from 300 to 1000 ml per day).

Water balance is regulated through complicated, but reliable mechanisms. Control over water and electrolytes excretion is realized by osmotic receptors of posterior hypothalamus, volume receptors of the atrial walls, baroreceptors of carotid sinus, juxtaglomerular apparatus of the kidneys and adrenal cortical cells.

When there is a water deficiency or electrolytes excess (sodium, chlorine) thirst appears and this makes us drink water. At the same time posterior pituitary produces antidiuretic hormone, which decreases urine output. Adrenals reveal into the blood flow aldosterone, which stimulates reabsorption of sodium ions in the tubules and thus also decreases diuresis (due to osmosis laws water will move to the more concentrated solution). This way organism can keep precious water.

On the contrary, in case of water excess endocrine activity of glands is inhibited and water is actively removed from the body through the kidneys.

9.2 Importance of osmolarity for homoeostasis.

Water sections of the organism (intracellular and extracellular) are divided with semipermeable membrane – cell wall. Water easily penetrates through it according to the laws of osmosis. Osmosis is a movement of water through a partially permeable membrane from the solution with lower concentration to a solution with higher concentration.

Osmotic concentration (osmolarity) is the concentration of active parts in one liter of solution (water). It is defined as a number of miliosmoles per liter (mOsm/l). Normally osmotic concentration of plasma, intracellular and extracellular fluids is equal and varies between 285mOsm/l. This value is one of the most important constants of the organism, because if it changes in one sector the whole fluid of the body will be redistributed (water will move to the environment with higher concentration). Over hydration of one sector will bring dehydration of another. For example, when there is a tissue damage concentration of active osmotic parts increases and water diffuses to this compartment, causing oedema. On the contrary plasma osmolarity decreases, when there is a loss of electrolytes and osmotic concentration of the cellular fluid stays on the previous level. This brings cellular oedema, because water moves through the intracellular space to the cells due to their higher osmotic concentration.

Cerebral oedema appears when the plasma osmolarity is lower than 270 mOsm/l. Activity of central nervous system is violated and hypoosmolar coma occurs. Hyperosmolar coma appears when the plasma osmolarity is over 320 mOsm/l: water leaves the cells and fills the vascular bed and this leads to cellular dehydration. The sensitive to cellular dehydration are the cells of the brain.

Plasma osmolarity is measured with osmometer. The principle of measurement is based on difference in freezing temperature between distillated water and plasma. The higher is the osmolarity (quantity of molecules) the lower is freezing temperature.

Plasma osmotic concentration can be calculated according to the formula:

Osmotic concentration= 1,86*Na+glucose+urea+10,

Plasma osmolarity (osmotic concentration) – mOsm/l

Na- sodium concentration of plasma, mmol/l

Glucose- glucose concentration of the plasma, mmol/l

Urea- urea concentration of the plasma, mmol/l

According to this formula sodium concentration is the main factor influencing plasma osmolarity. Normally sodium concentration is 136-144 mmol/l. Water and electrolytes balance can be violated with external fluid and electrolytes loss, their excessive inflow or wrong distribution.

9.3 Fluid imbalance and principles of its intensive treatment.

Water imbalance is divided into dehydration and overhydration.

Dehydration is caused by:

-         excessive perspiration in conditions of high temperature;

-         rapid breathing (dyspnea, tachypnea) or artificial ventilation without humidification of the air;

-         vomiting, diarrhoea, fistulas;

-         blood loss, burns;

-         diuretics overdose;

-         excessive urine output;

-         inadequate enteral and parenteral nutrition or infusion therapy (comatose patients, postoperative care);

-         pathological water distribution (“third space” in case of inflammation or injury).

Dehydration signs: weight loss, decrease of skin turgor and eyeballs tone, dry skin and mucous membranes; low central venous pressure, cardiac output and blood pressure (collapse is possible); decreased urine output and peripheral veins tone; capillary refill over 2 seconds (microcirculation disorders) and low skin temperature; intracellular dehydration is characterized with thirst and consciousness disorders. Laboratory tests show blood concentration: hematocrit, hemoglobin concentration, protein level and red blood cells concentration increase.

Overhydration appears in case of:

-         excessive water consumption, inadequate infusion therapy;

-         acute and chronic renal failure, hepatic and cardiac insufficiency;

-         disorders of fluid balance regulation;

-         low protein edema.

Clinical findings in case of overhydration are: weight gain, peripheral oedema, transudation of the plasma into the body cavities (pleural, abdominal), high blood pressure and central venous pressure. In case of intracellular overhydration appear additional symptoms: nausea, vomiting, signs of cerebral edema (spoor, coma). Laboratory tests prove hemodilution.

According to the osmotic concentration of plasma dehydration and overhydration are divided into hypotonic, isotonic and hypertonic.

Isotonic dehydration is caused by equal loss of electrolytes and fluid from the extracellular space (without cellular disorders).Blood tests show hemoconcentration; sodium level and osmotic concentration are normal.

To treat this type of water imbalance use normal saline solution, Ringer solution, glucose-saline solutions, etc.. The volumes of infusions can be calculated according to the formula:

VH₂O= 0,2*BW* (Ht_p-0,4)/0,4 ,

VH₂O – volume of infusion, l

Ht_{p –} patient’s hematocrit, l/l,

BW – body weight, 0,2*BW – volume of extracellular fluid,

0,4- normal hematocrit, l/l,

Hypertonic dehydration is caused by mostly water loss: first it appears in the vascular bed, than in the cells. Laboratory tests show hemoconcentration: elevated levels of proteins, red blood cells, hematocrit. Plasma sodium is over 155 mmol/l and osmotic concentration increases over 310 mOsm/l.

Intensive treatment: if there is no vomiting allow patients to drink. Intravenously give 0,45% saline solution and 2,5 % glucose solution, mixed with insulin. The volume of infusions is calculated according to the formula:

VH₂O=0,6*BW (Na_p -140)/140,

VH₂O – water deficiency, l

Na_{p –} plasma sodium, mmol/l

BW – body weight, 0,6*BW volume of general body fluid

140 – physiological plasma sodium concentration

Hypotonic dehydration is characterized with clinical features of extracellular dehydration. Laboratory tests show decrease of sodium and chlorine ions. Those changes cause intracellular movement of the water (intracellular overhydration). Hemoglobin, hematocrit and protein levels are increased. Sodium is lower than 136 mmol/l, osmolarity is lower than 280 mOsm/l.

To treat this type of water imbalance use normal or hypertonic saline and sodium bicarbonate solution (depends on blood pH). Do not use glucose solutions!

The deficiency of electrolytes is calculated according to the formula:

Na_d = (140-Na_p)*0,2 BW,

Na_d – sodium deficiency, mmol

Na_p – plasma sodium, mmol/l

BW – body weight, 0,2 BW – volume of extracellular fluid

Isotonic overhydration is caused by excess of the water in the vascular bed and extracellular space; however intracellular homoeostasis is not violated. Hemoglobin is less than 120 g/l, protein level is less than 60 g/l, plasma sodium is 136-144 mmol/l, osmotic concentration is 285-310 mOsm/l.

Treat the reason of imbalance: cardiac failure, liver insufficiency, etc. Prescribe cardiac glycosides, limit salt and water consumption. Give osmotic diuretics (mannitol solution 1,5 g/kg), saluretics (furosemide solution 2 mg/kg), aldosterone antagonists (triamterene – 200 mg), steroids (prednisolone solution 1-2 mg/kg) albumin solution if necessary (0,2-0,3 g/kg).

Hypertonic overhydration is a state of extracellular electrolytes and water excess combined with intracellular dehydration. Blood tests show decrease of hemoglobin, hematocrit, protein level, however sodium concentration is increased over 144 mmol/l, osmotic concentration is over 310 mOsm/l.

To treat this condition use solutions without electrolytes: glucose with insulin, albumin solutions and prescribe saluretics (furosemide solution), aldosterone antagonists (spironolactone). If it is necessary perform dialysis and peritoneal dialysis. Do not use crystalloids!

Hypotonic overhydration is a state of extracellular and intracellular water excess. Blood tests show decrease of haemoglobin, hematocrit, proteins, sodium and osmotic concentration. Intensive therapy of this condition includes osmotic diuretics (200-400 ml of 20% mannitol solution), hypertonic solutions (50 ml of 10% saline intravenously), steroids. When it is required use ultrafiltration to remove water excess.

9.4 Electrolytes disorders and their treatment

Potassium is a main intracellular cation. Its normal plasma concentration is 3,8-5,1 mmol/l. Daily required amount of potassium is 1 mmol/kg of body weight.

Potassium level less than 3,8 mmol/l is known as kaliopenia. Potassium deficiency is calculated according to the formula:

K_d= (4,5-K_p)*0,6 BW

K- potassium deficiency, mmol;

K_p – potassium level of the patient mmol/l;

0,6*BW – total body water, l.

To treat this state use 7,5% solution of potassium chloride (1ml of this solution contains 1 mmol of potassium). Give it intravenously slowly with glucose and insulin (20-25 ml/hour). You can also prescribe magnesium preparations. Standard solution for kaliopenia treatment is:

10% glucose solution 400 ml

7,5% potassium chloride solution 20 ml

25% magnesium sulphate solution 3 ml

insulin 12 units

Give it intravenously slowly, during one hour. Forced bolus infusion of potassium solutions (10-15 ml) can bring cardiac arrest.

Potassium level over 5,2 mmol/l is a state called hyperkalemia. To treat this condition use calcium gluconate or calcium chloride solutions (10 ml of 10% solution intravenously), glucose and insulin solution, saluretics, steroids, sodium bicarbonate solution. Hyperkalemia over 7 mmol/l is an absolute indication for dialysis.

Sodium is the main extracellular cation. Its normal plasma concentration is 135-155 mmol/l. Daily required amount of potassium is 2 mmol/kg of body weight.

Sodium concentration which is lower than 135 mmol/l is known as hyponatraemia. This condition is caused by sodium deficiency or water excess. Sodium deficiency is calculated according to the formula:

Na_d= (140-Na_p)*0,2 BW,

Na- sodium deficiency, mmol;

Na_p – sodium concentration of the patient mmol/l;

0,2*BW – extracellular fluid volume, l.

To treat it use normal saline (1000 ml contains 154 Na mmol) or 5,8% solution of sodium chloride – your choice will depend on osmotic concentration.

Sodium concentration over 155 mmol/l is a state called hypernatremia. This condition usually appears in case of hypertonic dehydration or hypertonic overhydration. Treatment was described in the text above.

Chlorine is the main extracellular anion. Its normal plasma concentration is 98-107 mmol/l. Daily requirement of chlorine is 215 mmol.

Hypochloremia is a condition of decreased plasma chlorine concentration (less than 98 mmol/l).

Chlorine deficiency is calculated according to the formula:

Cl_d = (100-Cl_p)*0,2 BW,

Cl_d- chlorine deficiency, mmol

Cl_p – plasma chlorine concentration of the patient, mmol/l

0,2*BW – extracellular fluid volume, l.

To treat hypochloremia use normal saline (1000 ml contains 154 mmol of chlorine) or 5,8% sodium chlorine solution (1 ml contains 1 mmol of chlorine). The choice of solution depends on the osmotic concentration of the plasma.

Hyperchloremia is a condition of increased chlorine concentration (over 107 mmol/l). Intensive therapy of this state includes treatment of the disease, which caused it (decompensated heart failure, hyperchloremic diabetes insipidus, glomerulonephritis). You can also use glucose, albumin solutions and dialysis.

Magnesium is mostly an intracellular cation. Its plasma concentration is 0,8-1,5 mmol/l. Daily requirement of magnesium is 0,3 mmol/kg.

Hypomagnesemia is a state of decreased magnesium concentration: less than 0,8 mmol/l. Magnesium deficiency is calculated according to the formula:

Mg_d =(1,0 - Mg_p)*0,6BW,

Mg_d - magnesium deficiency, mmol

Mg_p – plasma magnesium concentration of the patient, mmol/l

0,6*BW – extracellular fluid volume, l.

Use 25% magnesium sulphate solution to treat this state (1 ml of it contains 0,5 mmol of magnesium).

Hypermagnesemia is a state of increased magnesium concentration (more than 1,5 mmol/l). This condition appears usually in case of hyperkalemia and you should treat it as you treat hyperkalemia.

Calcium is one of the extracellular cations. Its normal concentration is 2,35-2,75 mmol/l. Daily requirement of calcium is 0,5 mmol/kg.

Calcium concentration less than 2,35 mmol/l is called hypocalcemia. Calcium deficiency is calculated according to the formula:

Ca_d = (2,5-Ca_p)*0,2 BW,

Ca_d – calcium deficiency, mmol

Cl_p – plasma calcium concentration of the patient, mmol/l

0,2*BW – extracellular fluid volume, l.

To treat this state use 10% calcium chloride (1 ml of the solution contains 1,1 mmol of calcium), ergocalciferol; in case of convulsions prescribe sedative medicines.

Hypercalcemia is a condition with increased calcium concentration (over 2,75 mmol/l). Treat the disease, which caused it: primary hyperparathyroidism, malignant bone tumors, etc. Additionally use infusion therapy (solutions of glucose with insulin), steroids, dialysis and hemosorbtion.

9.5 Acid-base imbalance and its treatment.

There are 2 main types of acid-base imbalance: acidosis and alkalosis.

pH is a decimal logarithm of the reciprocal of the hydrogen ion activity. It shows acid-base state of the blood.

Normal pH of arterial blood is 7,36-7,44. Acid based imbalance is divided according to the pH level into:

pH 7,35-7,21 – subcompensated acidosis

pH < 7,2 – decompensated acidosis

pH 7,45-7,55 – subcompansated alkalosis

pH > 7,56 – decompensated alkalosis

Respiratory part of the acid-base imbalance is characterized with pCO_2. Normally pCO₂  of arterial blood is 36-44 mm Hg. Hypercapnia (pCO₂ increased over45 mm Hg) is a sign of respiratory acidosis. Hypocapnia (pCO₂ less than 35 mm Hg) is a symptom of respiratory alkalosis.

Basis excess index is also a characteristic of metabolic processes. Normally H+ ions produced during metabolic reactions are neutralized with buffer system. BE of arterial blood is 0±1,5. Positive value of BE (with +) is a sign of base excess or plasma acid deficiency (metabolic alkalosis). Negative value of BE (with -) is a symptom of bases deficiency, which is caused by acid neutralization in case of metabolic acidosis.

Respiratory acidosis (hypercapnia) is a condition caused by insufficient elimination of CO₂ from the body during hypoventilation. Laboratory tests show:

 pH<7,35,

pCO_2a > 46 mm Hg

BE - normal values

However when the respiratory acidosis progresses renal compensation fails to maintain normal values and BE gradually increases. In order to improve this condition you should treat acute and chronic respiratory violations. When pCO₂ is over 60 mm Hg begin artificial lung ventilation (through the mask or tube; when the necessity of ventilation lasts longer than 3 days – perform tracheostomy).

Respiratory alkalosis (hypocapnia) is usually an effect of hyperventilation, caused by excessive stimulation of respiratory centre (injuries, metabolic acidosis, hyperactive metabolism, etc.) or wrong parameters of mechanical ventilation. Gasometry shows:

pH>7,45,

pCO_2a  <33 mm Hg

BE < +1,5 mmol/l.

However prolong alkalosis brings decrease of BE due to compensatory retain of H+ ions. To improve this imbalance treat its reason: normalize ventilation parameters; if patients breathing has rate over 40 per minute – sedate the patient, perform the intubation and begin artificial ventilation with normal parameters.

Metabolic acidosis is characterized with absolute and relative increase of H+ ions concentration due to acid accumulation (metabolic disorders, block of acid elimination, excessive acid consumption in case of poisonings, etc.). Laboratory tests show:

pH<7,35,

pCO_2a < 35 mm Hg

BE  (-3) mmol/l.

Treat the main reason of acid-base disorder: diabetic ketoacidosis, renal insufficiency, poisoning, hyponatremia or hyperchloremia, etc. Normalize pH with 4% sodium bicarbonate solution. Its dose is calculated according to the formula:

V=0,3*BE*BW

V- volume of sodium bicarbonate solution, ml

BE – bases excess with “-”, mmol/l

BW – body weight, kg

Metabolic alkalosis is a condition of absolute and relative decrease of H+ ions concentration. Blood tests show:

pH>7,45,

pCO_2a  normal or insignificantly increased (compensatory reaction)

BE 3,0 mmol/l.

To treat this condition use “acid” solutions, which contain chlorides (saline, potassium chloride). In case of  kaliopenia give potassium solutions.

Respiratory and metabolic imbalances can mix in case of severe decompensated diseases due to failure of compensatory mechanisms. Correct interpretation of these violations is possible only in case of regular and iterative gasometry blood tests.

Control tasks.

Task 1.

Calculate the total body water volume and its extracellular and intracellular volumes of the Patience, the patient of 48 years and body weight 88 kg.

Task 2.

Patience, the patient of 23 with body weight 70 kg has sodium level 152 mmol/l and hematocrit 0,49 l/l. Name the type of water balance disorder.

Task 3.

Patience, the patient of 54 with body weight 76 kg has sodium level 128 mmol/l. Calculate the volume of saline and 7,5% sodium chloride solution necessary for the treatment of this condition.

Task 4.

Patience, the patient of 60 with body weight 60 kg has sodium level 140 mmol/l and hematocrit 0,55 l/l. Name the type of disorder and prescribe infusion therapy.

Task 5.

Patience, the patient of 42 with body weight 80 kg has potassium level 2,6 mmol/l. Calculate the volume of  4% potassium chloride solution necessary for treatment of this condition.

Task 6.

Patience, the patient of 33 with body weight 67 kg and diagnosis “gastric ulcer, complicated with pylorostenosis” has potassium concentration 3 mmol/l, chlorine concentration 88 mmol/l. pH 7,49, pCO_2a 42 mm Hg, BE + 10 mmol/l. Name the type of disorder.

Task 7.

Patience, the patient of 50 with body weight 75 kg, was transported to the admission unit of the hospital with: unconsciousness, cyanotic skin, low blood pressure, shallow breathing. Blood tests show: pH 7,18, pCO_2a 78 mm Hg, pO_2A – 57 mm Hg, BE -4,2 mmol/l. Name the type of acid-base disorder and prescribe treatment.

Task 8.

Patience, the patient with body weight 62 kg and renal insufficiency has: potassium concentration 5,2 mmol/l, sodium concentration 130 mmol/l, calcium concentration 1,5 mmol/l, pH 7,22, pCO_2a 34 mm Hg, BE -9,2 mmol/l. Name the type of disorder.

Violations of homoeostasis and their correction.

9.1 The importance of the water to the organism.

Life on earth was born in the water environment. Water is a universal solvent for all the biochemical processes of the organism. Only in case of stable quantitative and qualitative composition of both intracellular and extra cellular fluids homoeostasis is remained.

The body of an adult human contains 60% of water. Intracellular water makes 40% of the body weight, the water of intercellular space makes 15% of body weight and 5% of body weight are made by the water in the vessels. It is considered that due to unlimited diffusion of water between vessels and extra vascular space the volume of extracellular fluid is 20% of body weight (15%+5%).

Physiologically insignificant amounts of water are distributed beyond the tissues in the body cavities: gastrointestinal tract, cerebral ventricles, joint capsules (nearly 1% of the body weight). However during different pathologic conditions this “third space” can cumulate large amounts of fluid: for example in case of ascites caused by chronic cardiac insufficiency or cirrhosis abdominal cavity contains up to 10 liters of fluid. Peritonitis and intestinal obstructions remove the fluid part of blood from the vessels into the intestinal cavity.

Severe dehydration is extremely dangerous for the patient. Water gets to the body with food and drinks, being absorbed by the mucous membranes of gastro-intestinal tract in total amount of 2-3 liters per day. Additionally in different metabolic transformations of lipids, carbohydrates and proteins nearly 300 of endogenous water are created. Water is evacuated from the body with urine (1,5-2 liters), stool (300 ml), perspiration and breathing (those two reasons are combined as “perspiration loss” and make from 300 to 1000 ml per day).

Water balance is regulated through complicated, but reliable mechanisms. Control over water and electrolytes excretion is realized by osmotic receptors of posterior hypothalamus, volume receptors of the atrial walls, baroreceptors of carotid sinus, juxtaglomerular apparatus of the kidneys and adrenal cortical cells.

When there is a water deficiency or electrolytes excess (sodium, chlorine) thirst appears and this makes us drink water. At the same time posterior pituitary produces antidiuretic hormone, which decreases urine output. Adrenals reveal into the blood flow aldosterone, which stimulates reabsorption of sodium ions in the tubules and thus also decreases diuresis (due to osmosis laws water will move to the more concentrated solution). This way organism can keep precious water.

On the contrary, in case of water excess endocrine activity of glands is inhibited and water is actively removed from the body through the kidneys.

9.2 Importance of osmolarity for homoeostasis.

Water sections of the organism (intracellular and extracellular) are divided with semipermeable membrane – cell wall. Water easily penetrates through it according to the laws of osmosis. Osmosis is a movement of water through a partially permeable membrane from the solution with lower concentration to a solution with higher concentration.

Osmotic concentration (osmolarity) is the concentration of active parts in one liter of solution (water). It is defined as a number of miliosmoles per liter (mOsm/l). Normally osmotic concentration of plasma, intracellular and extracellular fluids is equal and varies between 285mOsm/l. This value is one of the most important constants of the organism, because if it changes in one sector the whole fluid of the body will be redistributed (water will move to the environment with higher concentration). Over hydration of one sector will bring dehydration of another. For example, when there is a tissue damage concentration of active osmotic parts increases and water diffuses to this compartment, causing oedema. On the contrary plasma osmolarity decreases, when there is a loss of electrolytes and osmotic concentration of the cellular fluid stays on the previous level. This brings cellular oedema, because water moves through the intracellular space to the cells due to their higher osmotic concentration.

Cerebral oedema appears when the plasma osmolarity is lower than 270 mOsm/l. Activity of central nervous system is violated and hypoosmolar coma occurs. Hyperosmolar coma appears when the plasma osmolarity is over 320 mOsm/l: water leaves the cells and fills the vascular bed and this leads to cellular dehydration. The sensitive to cellular dehydration are the cells of the brain.

Plasma osmolarity is measured with osmometer. The principle of measurement is based on difference in freezing temperature between distillated water and plasma. The higher is the osmolarity (quantity of molecules) the lower is freezing temperature.

Plasma osmotic concentration can be calculated according to the formula:

Osmotic concentration= 1,86*Na+glucose+urea+10,

Plasma osmolarity (osmotic concentration) – mOsm/l

Na- sodium concentration of plasma, mmol/l

Glucose- glucose concentration of the plasma, mmol/l

Urea- urea concentration of the plasma, mmol/l

According to this formula sodium concentration is the main factor influencing plasma osmolarity. Normally sodium concentration is 136-144 mmol/l. Water and electrolytes balance can be violated with external fluid and electrolytes loss, their excessive inflow or wrong distribution.

9.3 Fluid imbalance and principles of its intensive treatment.

Water imbalance is divided into dehydration and overhydration.

Dehydration is caused by:

-         excessive perspiration in conditions of high temperature;

-         rapid breathing (dyspnea, tachypnea) or artificial ventilation without humidification of the air;

-         vomiting, diarrhoea, fistulas;

-         blood loss, burns;

-         diuretics overdose;

-         excessive urine output;

-         inadequate enteral and parenteral nutrition or infusion therapy (comatose patients, postoperative care);

-         pathological water distribution (“third space” in case of inflammation or injury).

Dehydration signs: weight loss, decrease of skin turgor and eyeballs tone, dry skin and mucous membranes; low central venous pressure, cardiac output and blood pressure (collapse is possible); decreased urine output and peripheral veins tone; capillary refill over 2 seconds (microcirculation disorders) and low skin temperature; intracellular dehydration is characterized with thirst and consciousness disorders. Laboratory tests show blood concentration: hematocrit, hemoglobin concentration, protein level and red blood cells concentration increase.

Overhydration appears in case of:

-         excessive water consumption, inadequate infusion therapy;

-         acute and chronic renal failure, hepatic and cardiac insufficiency;

-         disorders of fluid balance regulation;

-         low protein edema.

Clinical findings in case of overhydration are: weight gain, peripheral oedema, transudation of the plasma into the body cavities (pleural, abdominal), high blood pressure and central venous pressure. In case of intracellular overhydration appear additional symptoms: nausea, vomiting, signs of cerebral edema (spoor, coma). Laboratory tests prove hemodilution.

According to the osmotic concentration of plasma dehydration and overhydration are divided into hypotonic, isotonic and hypertonic.

Isotonic dehydration is caused by equal loss of electrolytes and fluid from the extracellular space (without cellular disorders).Blood tests show hemoconcentration; sodium level and osmotic concentration are normal.

To treat this type of water imbalance use normal saline solution, Ringer solution, glucose-saline solutions, etc.. The volumes of infusions can be calculated according to the formula:

VH₂O= 0,2*BW* (Ht_p-0,4)/0,4 ,

VH₂O – volume of infusion, l

Ht_{p –} patient’s hematocrit, l/l,

BW – body weight, 0,2*BW – volume of extracellular fluid,

0,4- normal hematocrit, l/l,

Hypertonic dehydration is caused by mostly water loss: first it appears in the vascular bed, than in the cells. Laboratory tests show hemoconcentration: elevated levels of proteins, red blood cells, hematocrit. Plasma sodium is over 155 mmol/l and osmotic concentration increases over 310 mOsm/l.

Intensive treatment: if there is no vomiting allow patients to drink. Intravenously give 0,45% saline solution and 2,5 % glucose solution, mixed with insulin. The volume of infusions is calculated according to the formula:

VH₂O=0,6*BW (Na_p -140)/140,

VH₂O – water deficiency, l

Na_{p –} plasma sodium, mmol/l

BW – body weight, 0,6*BW volume of general body fluid

140 – physiological plasma sodium concentration

Hypotonic dehydration is characterized with clinical features of extracellular dehydration. Laboratory tests show decrease of sodium and chlorine ions. Those changes cause intracellular movement of the water (intracellular overhydration). Hemoglobin, hematocrit and protein levels are increased. Sodium is lower than 136 mmol/l, osmolarity is lower than 280 mOsm/l.

To treat this type of water imbalance use normal or hypertonic saline and sodium bicarbonate solution (depends on blood pH). Do not use glucose solutions!

The deficiency of electrolytes is calculated according to the formula:

Na_d = (140-Na_p)*0,2 BW,

Na_d – sodium deficiency, mmol

Na_p – plasma sodium, mmol/l

BW – body weight, 0,2 BW – volume of extracellular fluid

Isotonic overhydration is caused by excess of the water in the vascular bed and extracellular space; however intracellular homoeostasis is not violated. Hemoglobin is less than 120 g/l, protein level is less than 60 g/l, plasma sodium is 136-144 mmol/l, osmotic concentration is 285-310 mOsm/l.

Treat the reason of imbalance: cardiac failure, liver insufficiency, etc. Prescribe cardiac glycosides, limit salt and water consumption. Give osmotic diuretics (mannitol solution 1,5 g/kg), saluretics (furosemide solution 2 mg/kg), aldosterone antagonists (triamterene – 200 mg), steroids (prednisolone solution 1-2 mg/kg) albumin solution if necessary (0,2-0,3 g/kg).

Hypertonic overhydration is a state of extracellular electrolytes and water excess combined with intracellular dehydration. Blood tests show decrease of hemoglobin, hematocrit, protein level, however sodium concentration is increased over 144 mmol/l, osmotic concentration is over 310 mOsm/l.

To treat this condition use solutions without electrolytes: glucose with insulin, albumin solutions and prescribe saluretics (furosemide solution), aldosterone antagonists (spironolactone). If it is necessary perform dialysis and peritoneal dialysis. Do not use crystalloids!

Hypotonic overhydration is a state of extracellular and intracellular water excess. Blood tests show decrease of haemoglobin, hematocrit, proteins, sodium and osmotic concentration. Intensive therapy of this condition includes osmotic diuretics (200-400 ml of 20% mannitol solution), hypertonic solutions (50 ml of 10% saline intravenously), steroids. When it is required use ultrafiltration to remove water excess.

9.4 Electrolytes disorders and their treatment

Potassium is a main intracellular cation. Its normal plasma concentration is 3,8-5,1 mmol/l. Daily required amount of potassium is 1 mmol/kg of body weight.

Potassium level less than 3,8 mmol/l is known as kaliopenia. Potassium deficiency is calculated according to the formula:

K_d= (4,5-K_p)*0,6 BW

K- potassium deficiency, mmol;

K_p – potassium level of the patient mmol/l;

0,6*BW – total body water, l.

To treat this state use 7,5% solution of potassium chloride (1ml of this solution contains 1 mmol of potassium). Give it intravenously slowly with glucose and insulin (20-25 ml/hour). You can also prescribe magnesium preparations. Standard solution for kaliopenia treatment is:

10% glucose solution 400 ml

7,5% potassium chloride solution 20 ml

25% magnesium sulphate solution 3 ml

insulin 12 units

Give it intravenously slowly, during one hour. Forced bolus infusion of potassium solutions (10-15 ml) can bring cardiac arrest.

Potassium level over 5,2 mmol/l is a state called hyperkalemia. To treat this condition use calcium gluconate or calcium chloride solutions (10 ml of 10% solution intravenously), glucose and insulin solution, saluretics, steroids, sodium bicarbonate solution. Hyperkalemia over 7 mmol/l is an absolute indication for dialysis.

Sodium is the main extracellular cation. Its normal plasma concentration is 135-155 mmol/l. Daily required amount of potassium is 2 mmol/kg of body weight.

Sodium concentration which is lower than 135 mmol/l is known as hyponatraemia. This condition is caused by sodium deficiency or water excess. Sodium deficiency is calculated according to the formula:

Na_d= (140-Na_p)*0,2 BW,

Na- sodium deficiency, mmol;

Na_p – sodium concentration of the patient mmol/l;

0,2*BW – extracellular fluid volume, l.

To treat it use normal saline (1000 ml contains 154 Na mmol) or 5,8% solution of sodium chloride – your choice will depend on osmotic concentration.

Sodium concentration over 155 mmol/l is a state called hypernatremia. This condition usually appears in case of hypertonic dehydration or hypertonic overhydration. Treatment was described in the text above.

Chlorine is the main extracellular anion. Its normal plasma concentration is 98-107 mmol/l. Daily requirement of chlorine is 215 mmol.

Hypochloremia is a condition of decreased plasma chlorine concentration (less than 98 mmol/l).

Chlorine deficiency is calculated according to the formula:

Cl_d = (100-Cl_p)*0,2 BW,

Cl_d- chlorine deficiency, mmol

Cl_p – plasma chlorine concentration of the patient, mmol/l

0,2*BW – extracellular fluid volume, l.

To treat hypochloremia use normal saline (1000 ml contains 154 mmol of chlorine) or 5,8% sodium chlorine solution (1 ml contains 1 mmol of chlorine). The choice of solution depends on the osmotic concentration of the plasma.

Hyperchloremia is a condition of increased chlorine concentration (over 107 mmol/l). Intensive therapy of this state includes treatment of the disease, which caused it (decompensated heart failure, hyperchloremic diabetes insipidus, glomerulonephritis). You can also use glucose, albumin solutions and dialysis.

Magnesium is mostly an intracellular cation. Its plasma concentration is 0,8-1,5 mmol/l. Daily requirement of magnesium is 0,3 mmol/kg.

Hypomagnesemia is a state of decreased magnesium concentration: less than 0,8 mmol/l. Magnesium deficiency is calculated according to the formula:

Mg_d =(1,0 - Mg_p)*0,6BW,

Mg_d - magnesium deficiency, mmol

Mg_p – plasma magnesium concentration of the patient, mmol/l

0,6*BW – extracellular fluid volume, l.

Use 25% magnesium sulphate solution to treat this state (1 ml of it contains 0,5 mmol of magnesium).

Hypermagnesemia is a state of increased magnesium concentration (more than 1,5 mmol/l). This condition appears usually in case of hyperkalemia and you should treat it as you treat hyperkalemia.

Calcium is one of the extracellular cations. Its normal concentration is 2,35-2,75 mmol/l. Daily requirement of calcium is 0,5 mmol/kg.

Calcium concentration less than 2,35 mmol/l is called hypocalcemia. Calcium deficiency is calculated according to the formula:

Ca_d = (2,5-Ca_p)*0,2 BW,

Ca_d – calcium deficiency, mmol

Cl_p – plasma calcium concentration of the patient, mmol/l

0,2*BW – extracellular fluid volume, l.

To treat this state use 10% calcium chloride (1 ml of the solution contains 1,1 mmol of calcium), ergocalciferol; in case of convulsions prescribe sedative medicines.

Hypercalcemia is a condition with increased calcium concentration (over 2,75 mmol/l). Treat the disease, which caused it: primary hyperparathyroidism, malignant bone tumors, etc. Additionally use infusion therapy (solutions of glucose with insulin), steroids, dialysis and hemosorbtion.

9.5 Acid-base imbalance and its treatment.

There are 2 main types of acid-base imbalance: acidosis and alkalosis.

pH is a decimal logarithm of the reciprocal of the hydrogen ion activity. It shows acid-base state of the blood.

Normal pH of arterial blood is 7,36-7,44. Acid based imbalance is divided according to the pH level into:

pH 7,35-7,21 – subcompensated acidosis

pH < 7,2 – decompensated acidosis

pH 7,45-7,55 – subcompansated alkalosis

pH > 7,56 – decompensated alkalosis

Respiratory part of the acid-base imbalance is characterized with pCO_2. Normally pCO₂  of arterial blood is 36-44 mm Hg. Hypercapnia (pCO₂ increased over45 mm Hg) is a sign of respiratory acidosis. Hypocapnia (pCO₂ less than 35 mm Hg) is a symptom of respiratory alkalosis.

Basis excess index is also a characteristic of metabolic processes. Normally H+ ions produced during metabolic reactions are neutralized with buffer system. BE of arterial blood is 0±1,5. Positive value of BE (with +) is a sign of base excess or plasma acid deficiency (metabolic alkalosis). Negative value of BE (with -) is a symptom of bases deficiency, which is caused by acid neutralization in case of metabolic acidosis.

Respiratory acidosis (hypercapnia) is a condition caused by insufficient elimination of CO₂ from the body during hypoventilation. Laboratory tests show:

 pH<7,35,

pCO_2a > 46 mm Hg

BE - normal values

However when the respiratory acidosis progresses renal compensation fails to maintain normal values and BE gradually increases. In order to improve this condition you should treat acute and chronic respiratory violations. When pCO₂ is over 60 mm Hg begin artificial lung ventilation (through the mask or tube; when the necessity of ventilation lasts longer than 3 days – perform tracheostomy).

Respiratory alkalosis (hypocapnia) is usually an effect of hyperventilation, caused by excessive stimulation of respiratory centre (injuries, metabolic acidosis, hyperactive metabolism, etc.) or wrong parameters of mechanical ventilation. Gasometry shows:

pH>7,45,

pCO_2a  <33 mm Hg

BE < +1,5 mmol/l.

However prolong alkalosis brings decrease of BE due to compensatory retain of H+ ions. To improve this imbalance treat its reason: normalize ventilation parameters; if patients breathing has rate over 40 per minute – sedate the patient, perform the intubation and begin artificial ventilation with normal parameters.

Metabolic acidosis is characterized with absolute and relative increase of H+ ions concentration due to acid accumulation (metabolic disorders, block of acid elimination, excessive acid consumption in case of poisonings, etc.). Laboratory tests show:

pH<7,35,

pCO_2a < 35 mm Hg

BE  (-3) mmol/l.

Treat the main reason of acid-base disorder: diabetic ketoacidosis, renal insufficiency, poisoning, hyponatremia or hyperchloremia, etc. Normalize pH with 4% sodium bicarbonate solution. Its dose is calculated according to the formula:

V=0,3*BE*BW

V- volume of sodium bicarbonate solution, ml

BE – bases excess with “-”, mmol/l

BW – body weight, kg

Metabolic alkalosis is a condition of absolute and relative decrease of H+ ions concentration. Blood tests show:

pH>7,45,

pCO_2a  normal or insignificantly increased (compensatory reaction)

BE 3,0 mmol/l.

To treat this condition use “acid” solutions, which contain chlorides (saline, potassium chloride). In case of  kaliopenia give potassium solutions.

Respiratory and metabolic imbalances can mix in case of severe decompensated diseases due to failure of compensatory mechanisms. Correct interpretation of these violations is possible only in case of regular and iterative gasometry blood tests.

Control tasks.

Task 1.

Calculate the total body water volume and its extracellular and intracellular volumes of the Patience, the patient of 48 years and body weight 88 kg.

Task 2.

Patience, the patient of 23 with body weight 70 kg has sodium level 152 mmol/l and hematocrit 0,49 l/l. Name the type of water balance disorder.

Task 3.

Patience, the patient of 54 with body weight 76 kg has sodium level 128 mmol/l. Calculate the volume of saline and 7,5% sodium chloride solution necessary for the treatment of this condition.

Task 4.

Patience, the patient of 60 with body weight 60 kg has sodium level 140 mmol/l and hematocrit 0,55 l/l. Name the type of disorder and prescribe infusion therapy.

Task 5.

Patience, the patient of 42 with body weight 80 kg has potassium level 2,6 mmol/l. Calculate the volume of  4% potassium chloride solution necessary for treatment of this condition.

Task 6.

Patience, the patient of 33 with body weight 67 kg and diagnosis “gastric ulcer, complicated with pylorostenosis” has potassium concentration 3 mmol/l, chlorine concentration 88 mmol/l. pH 7,49, pCO_2a 42 mm Hg, BE + 10 mmol/l. Name the type of disorder.

Task 7.

Patience, the patient of 50 with body weight 75 kg, was transported to the admission unit of the hospital with: unconsciousness, cyanotic skin, low blood pressure, shallow breathing. Blood tests show: pH 7,18, pCO_2a 78 mm Hg, pO_2A – 57 mm Hg, BE -4,2 mmol/l. Name the type of acid-base disorder and prescribe treatment.

Task 8.

Patience, the patient with body weight 62 kg and renal insufficiency has: potassium concentration 5,2 mmol/l, sodium concentration 130 mmol/l, calcium concentration 1,5 mmol/l, pH 7,22, pCO_2a 34 mm Hg, BE -9,2 mmol/l. Name the type of disorder.

Student should repeat next questions

 Violations of homoeostasis and their correction.

 9.1 The importance of the water to the organism.

Life on earth was born in the water environment. Water is a universal solvent for all the biochemical processes of the organism. Only in case of stable quantitative and qualitative composition of both intracellular and extra cellular fluids homoeostasis is remained.

The body of an adult human contains 60% of water. Intracellular water makes 40% of the body weight, the water of intercellular space makes 15% of body weight and 5% of body weight are made by the water in the vessels. It is considered that due to unlimited diffusion of water between vessels and extra vascular space the volume of extracellular fluid is 20% of body weight (15%+5%).

Physiologically insignificant amounts of water are distributed beyond the tissues in the body cavities: gastrointestinal tract, cerebral ventricles, joint capsules (nearly 1% of the body weight). However during different pathologic conditions this “third space” can cumulate large amounts of fluid: for example in case of ascites caused by chronic cardiac insufficiency or cirrhosis abdominal cavity contains up to 10 liters of fluid. Peritonitis and intestinal obstructions remove the fluid part of blood from the vessels into the intestinal cavity.

Severe dehydration is extremely dangerous for the patient. Water gets to the body with food and drinks, being absorbed by the mucous membranes of gastro-intestinal tract in total amount of 2-3 litters per day. Additionally in different metabolic transformations of lipids, carbohydrates and proteins nearly 300 of endogenous water are created. Water is evacuated from the body with urine (1,5-2 liters), stool (300 ml), perspiration and breathing (those two reasons are combined as “perspiration loss” and make from 300 to 1000 ml per day).

Water balance is regulated through complicated, but reliable mechanisms. Control over water and electrolytes excretion is realized by osmotic receptors of posterior hypothalamus, volume receptors of the aerial walls, bar receptors of carotid sinus, juxtaglomerular apparatus of the kidneys and adrenal cortical cells.

When there is a water deficiency or electrolytes excess (sodium, chlorine) thirst appears and this makes us drink water. At the same time posterior pituitary produces antidiuretic hormone, which decreases urine output. Adrenals reveal into the blood flow aldosterone, which stimulates reabsorption of sodium ions in the tubules and thus also decreases diuresis (due to osmosis laws water will move to the more concentrated solution). This way organism can keep precious water.

On the contrary, in case of water excess endocrine activity of glands is inhibited and water is actively removed from the body through the kidneys.

9.2 Importance of osmolarity for homoeostasis.

Water sections of the organism (intracellular and extracellular) are divided with semipermeable membrane – cell wall. Water easily penetrates through it according to the laws of osmosis. Osmosis is a movement of water through a partially permeable membrane from the solution with lower concentration to a solution with higher concentration.

Osmotic concentration (osmolarity) is the concentration of active parts in one liter of solution (water). It is defined as a number of miliosmoles per liter (mOsm/l). Normally osmotic concentration of plasma, intracellular and extracellular fluids is equal and varies between 285mOsm/l. This value is one of the most important constants of the organism, because if it changes in one sector the whole fluid of the body will be redistributed (water will move to the environment with higher concentration). Over hydration of one sector will bring dehydration of another. For example, when there is a tissue damage concentration of active osmotic parts increases and water diffuses to this compartment, causing oedema. On the contrary plasma osmolarity decreases, when there is a loss of electrolytes and osmotic concentration of the cellular fluid stays on the previous level. This brings cellular oedema, because water moves through the intracellular space to the cells due to their higher osmotic concentration.

Cerebral oedema appears when the plasma osmolarity is lower than 270 mOsm/l. Activity of central nervous system is violated and hypoosmolar coma occurs. Hyperosmolar coma appears when the plasma osmolarity is over 320 mOsm/l: water leaves the cells and fills the vascular bed and this leads to cellular dehydration. The sensitive to cellular dehydration are the cells of the brain.

Plasma osmolarity is measured with osmometer. The principle of measurement is based on difference in freezing temperature between distillated water and plasma. The higher is the osmolarity (quantity of molecules) the lower is freezing temperature.

Plasma osmotic concentration can be calculated according to the formula:

Osmotic concentration= 1,86*Na+glucose+urea+10,

Plasma osmolarity (osmotic concentration) – mOsm/l

Na- sodium concentration of plasma, mmol/l

Glucose- glucose concentration of the plasma, mmol/l

Urea- urea concentration of the plasma, mmol/l

According to this formula sodium concentration is the main factor influencing plasma osmolarity. Normally sodium concentration is 136-144 mmol/l. Water and electrolytes balance can be violated with external fluid and electrolytes loss, their excessive inflow or wrong distribution.

9.3 Fluid imbalance and principles of its intensive treatment.

Water imbalance is divided into dehydration and overhydration.

Dehydration is caused by:

-         excessive perspiration in conditions of high temperature;

-         rapid breathing (dyspnea, tachypnea) or artificial ventilation without humidification of the air;

-         vomiting, diarrhoea, fistulas;

-         blood loss, burns;

-         diuretics overdose;

-         excessive urine output;

-         inadequate enteral and parenteral nutrition or infusion therapy (comatose patients, postoperative care);

-         pathological water distribution (“third space” in case of inflammation or injury).

Dehydration signs: weight loss, decrease of skin turgor and eyeballs tone, dry skin and mucous membranes; low central venous pressure, cardiac output and blood pressure (collapse is possible); decreased urine output and peripheral veins tone; capillary refill over 2 seconds (microcirculation disorders) and low skin temperature; intracellular dehydration is characterized with thirst and consciousness disorders. Laboratory tests show blood concentration: hematocrit, hemoglobin concentration, protein level and red blood cells concentration increase.

Overhydration appears in case of:

-         excessive water consumption, inadequate infusion therapy;

-         acute and chronic renal failure, hepatic and cardiac insufficiency;

-         disorders of fluid balance regulation;

-         low protein edema.

Clinical findings in case of overhydration are: weight gain, peripheral oedema, transudation of the plasma into the body cavities (pleural, abdominal), high blood pressure and central venous pressure. In case of intracellular overhydration appear additional symptoms: nausea, vomiting, signs of cerebral edema (spoor, coma). Laboratory tests prove hemodilution.

According to the osmotic concentration of plasma dehydration and overhydration are divided into hypotonic, isotonic and hypertonic.

Isotonic dehydration is caused by equal loss of electrolytes and fluid from the extracellular space (without cellular disorders).Blood tests show hemoconcentration; sodium level and osmotic concentration are normal.

To treat this type of water imbalance use normal saline solution, Ringer solution, glucose-saline solutions, etc.. The volumes of infusions can be calculated according to the formula:

VH₂O= 0,2*BW* (Ht_p-0,4)/0,4 ,

VH₂O – volume of infusion, l

Ht_{p –} patient’s hematocrit, l/l,

BW – body weight, 0,2*BW – volume of extracellular fluid,

0,4- normal hematocrit, l/l,

Hypertonic dehydration is caused by mostly water loss: first it appears in the vascular bed, than in the cells. Laboratory tests show hemoconcentration: elevated levels of proteins, red blood cells, hematocrit. Plasma sodium is over 155 mmol/l and osmotic concentration increases over 310 mOsm/l.

Intensive treatment: if there is no vomiting allow patients to drink. Intravenously give 0,45% saline solution and 2,5 % glucose solution, mixed with insulin. The volume of infusions is calculated according to the formula:

VH₂O=0,6*BW (Na_p -140)/140,

VH₂O – water deficiency, l

Na_{p –} plasma sodium, mmol/l

BW – body weight, 0,6*BW volume of general body fluid

140 – physiological plasma sodium concentration

Hypotonic dehydration is characterized with clinical features of extracellular dehydration. Laboratory tests show decrease of sodium and chlorine ions. Those changes cause intracellular movement of the water (intracellular overhydration). Hemoglobin, hematocrit and protein levels are increased. Sodium is lower than 136 mmol/l, osmolarity is lower than 280 mOsm/l.

To treat this type of water imbalance use normal or hypertonic saline and sodium bicarbonate solution (depends on blood pH). Do not use glucose solutions!

The deficiency of electrolytes is calculated according to the formula:

Na_d = (140-Na_p)*0,2 BW,

Na_d – sodium deficiency, mmol

Na_p – plasma sodium, mmol/l

BW – body weight, 0,2 BW – volume of extracellular fluid

Isotonic overhydration is caused by excess of the water in the vascular bed and extracellular space; however intracellular homoeostasis is not violated. Hemoglobin is less than 120 g/l, protein level is less than 60 g/l, plasma sodium is 136-144 mmol/l, osmotic concentration is 285-310 mOsm/l.

Treat the reason of imbalance: cardiac failure, liver insufficiency, etc. Prescribe cardiac glycosides, limit salt and water consumption. Give osmotic diuretics (mannitol solution 1,5 g/kg), saluretics (furosemide solution 2 mg/kg), aldosterone antagonists (triamterene – 200 mg), steroids (prednisolone solution 1-2 mg/kg) albumin solution if necessary (0,2-0,3 g/kg).

Hypertonic overhydration is a state of extracellular electrolytes and water excess combined with intracellular dehydration. Blood tests show decrease of hemoglobin, hematocrit, protein level, however sodium concentration is increased over 144 mmol/l, osmotic concentration is over 310 mOsm/l.

To treat this condition use solutions without electrolytes: glucose with insulin, albumin solutions and prescribe saluretics (furosemide solution), aldosterone antagonists (spironolactone). If it is necessary perform dialysis and peritoneal dialysis. Do not use crystalloids!

Hypotonic overhydration is a state of extracellular and intracellular water excess. Blood tests show decrease of haemoglobin, hematocrit, proteins, sodium and osmotic concentration. Intensive therapy of this condition includes osmotic diuretics (200-400 ml of 20% mannitol solution), hypertonic solutions (50 ml of 10% saline intravenously), steroids. When it is required use ultrafiltration to remove water excess.

9.4 Electrolytes disorders and their treatment

Potassium is a main intracellular cation. Its normal plasma concentration is 3,8-5,1 mmol/l. Daily required amount of potassium is 1 mmol/kg of body weight.

Potassium level less than 3,8 mmol/l is known as kaliopenia. Potassium deficiency is calculated according to the formula:

K_d= (4,5-K_p)*0,6 BW

K- potassium deficiency, mmol;

K_p – potassium level of the patient mmol/l;

0,6*BW – total body water, l.

To treat this state use 7,5% solution of potassium chloride (1ml of this solution contains 1 mmol of potassium). Give it intravenously slowly with glucose and insulin (20-25 ml/hour). You can also prescribe magnesium preparations. Standard solution for kaliopenia treatment is:

10% glucose solution 400 ml

7,5% potassium chloride solution 20 ml

25% magnesium sulphate solution 3 ml

insulin 12 units

Give it intravenously slowly, during one hour. Forced bolus infusion of potassium solutions (10-15 ml) can bring cardiac arrest.

Potassium level over 5,2 mmol/l is a state called hyperkalemia. To treat this condition use calcium gluconate or calcium chloride solutions (10 ml of 10% solution intravenously), glucose and insulin solution, saluretics, steroids, sodium bicarbonate solution. Hyperkalemia over 7 mmol/l is an absolute indication for dialysis.

Sodium is the main extracellular cation. Its normal plasma concentration is 135-155 mmol/l. Daily required amount of potassium is 2 mmol/kg of body weight.

Sodium concentration which is lower than 135 mmol/l is known as hyponatraemia. This condition is caused by sodium deficiency or water excess. Sodium deficiency is calculated according to the formula:

Na_d= (140-Na_p)*0,2 BW,

Na- sodium deficiency, mmol;

Na_p – sodium concentration of the patient mmol/l;

0,2*BW – extracellular fluid volume, l.

To treat it use normal saline (1000 ml contains 154 Na mmol) or 5,8% solution of sodium chloride – your choice will depend on osmotic concentration.

Sodium concentration over 155 mmol/l is a state called hypernatremia. This condition usually appears in case of hypertonic dehydration or hypertonic overhydration. Treatment was described in the text above.

Chlorine is the main extracellular anion. Its normal plasma concentration is 98-107 mmol/l. Daily requirement of chlorine is 215 mmol.

Hypochloremia is a condition of decreased plasma chlorine concentration (less than 98 mmol/l).

Chlorine deficiency is calculated according to the formula:

Cl_d = (100-Cl_p)*0,2 BW,

Cl_d- chlorine deficiency, mmol

Cl_p – plasma chlorine concentration of the patient, mmol/l

0,2*BW – extracellular fluid volume, l.

To treat hypochloremia use normal saline (1000 ml contains 154 mmol of chlorine) or 5,8% sodium chlorine solution (1 ml contains 1 mmol of chlorine). The choice of solution depends on the osmotic concentration of the plasma.

Hyperchloremia is a condition of increased chlorine concentration (over 107 mmol/l). Intensive therapy of this state includes treatment of the disease, which caused it (decompensated heart failure, hyperchloremic diabetes insipidus, glomerulonephritis). You can also use glucose, albumin solutions and dialysis.

Magnesium is mostly an intracellular cation. Its plasma concentration is 0,8-1,5 mmol/l. Daily requirement of magnesium is 0,3 mmol/kg.

Hypomagnesemia is a state of decreased magnesium concentration: less than 0,8 mmol/l. Magnesium deficiency is calculated according to the formula:

Mg_d =(1,0 - Mg_p)*0,6BW,

Mg_d - magnesium deficiency, mmol

Mg_p – plasma magnesium concentration of the patient, mmol/l

0,6*BW – extracellular fluid volume, l.

Use 25% magnesium sulphate solution to treat this state (1 ml of it contains 0,5 mmol of magnesium).

Hypermagnesemia is a state of increased magnesium concentration (more than 1,5 mmol/l). This condition appears usually in case of hyperkalemia and you should treat it as you treat hyperkalemia.

Calcium is one of the extracellular cations. Its normal concentration is 2,35-2,75 mmol/l. Daily requirement of calcium is 0,5 mmol/kg.

Calcium concentration less than 2,35 mmol/l is called hypocalcemia. Calcium deficiency is calculated according to the formula:

Ca_d = (2,5-Ca_p)*0,2 BW,

Ca_d – calcium deficiency, mmol

Cl_p – plasma calcium concentration of the patient, mmol/l

0,2*BW – extracellular fluid volume, l.

To treat this state use 10% calcium chloride (1 ml of the solution contains 1,1 mmol of calcium), ergocalciferol; in case of convulsions prescribe sedative medicines.

Hypercalcemia is a condition with increased calcium concentration (over 2,75 mmol/l). Treat the disease, which caused it: primary hyperparathyroidism, malignant bone tumors, etc. Additionally use infusion therapy (solutions of glucose with insulin), steroids, dialysis and hemosorbtion.

9.5 Acid-base imbalance and its treatment.

There are 2 main types of acid-base imbalance: acidosis and alkalosis.

pH is a decimal logarithm of the reciprocal of the hydrogen ion activity. It shows acid-base state of the blood.

Normal pH of arterial blood is 7,36-7,44. Acid based imbalance is divided according to the pH level into:

pH 7,35-7,21 – subcompensated acidosis

pH < 7,2 – decompensated acidosis

pH 7,45-7,55 – subcompansated alkalosis

pH > 7,56 – decompensated alkalosis

Respiratory part of the acid-base imbalance is characterized with pCO_2. Normally pCO₂  of arterial blood is 36-44 mm Hg. Hypercapnia (pCO₂ increased over45 mm Hg) is a sign of respiratory acidosis. Hypocapnia (pCO₂ less than 35 mm Hg) is a symptom of respiratory alkalosis.

Basis excess index is also a characteristic of metabolic processes. Normally H+ ions produced during metabolic reactions are neutralized with buffer system. BE of arterial blood is 0±1,5. Positive value of BE (with +) is a sign of base excess or plasma acid deficiency (metabolic alkalosis). Negative value of BE (with -) is a symptom of bases deficiency, which is caused by acid neutralization in case of metabolic acidosis.

Respiratory acidosis (hypercapnia) is a condition caused by insufficient elimination of CO₂ from the body during hypoventilation. Laboratory tests show:

 pH<7,35,

pCO_2a > 46 mm Hg

BE - normal values

However when the respiratory acidosis progresses renal compensation fails to maintain normal values and BE gradually increases. In order to improve this condition you should treat acute and chronic respiratory violations. When pCO₂ is over 60 mm Hg begin artificial lung ventilation (through the mask or tube; when the necessity of ventilation lasts longer than 3 days – perform tracheostomy).

Respiratory alkalosis (hypocapnia) is usually an effect of hyperventilation, caused by excessive stimulation of respiratory centre (injuries, metabolic acidosis, hyperactive metabolism, etc.) or wrong parameters of mechanical ventilation. Gasometry shows:

pH>7,45,

pCO_2a  <33 mm Hg

BE < +1,5 mmol/l.

However prolong alkalosis brings decrease of BE due to compensatory retain of H+ ions. To improve this imbalance treat its reason: normalize ventilation parameters; if patients breathing has rate over 40 per minute – sedate the patient, perform the intubation and begin artificial ventilation with normal parameters.

Metabolic acidosis is characterized with absolute and relative increase of H+ ions concentration due to acid accumulation (metabolic disorders, block of acid elimination, excessive acid consumption in case of poisonings, etc.). Laboratory tests show:

pH<7,35,

pCO_2a < 35 mm Hg

BE  (-3) mmol/l.

Treat the main reason of acid-base disorder: diabetic ketoacidosis, renal insufficiency, poisoning, hyponatremia or hyperchloremia, etc. Normalize pH with 4% sodium bicarbonate solution. Its dose is calculated according to the formula:

V=0,3*BE*BW

V- volume of sodium bicarbonate solution, ml

BE – bases excess with “-”, mmol/l

BW – body weight, kg

Metabolic alkalosis is a condition of absolute and relative decrease of H+ ions concentration. Blood tests show:

pH>7,45,

pCO_2a  normal or insignificantly increased (compensatory reaction)

BE 3,0 mmol/l.

To treat this condition use “acid” solutions, which contain chlorides (saline, potassium chloride). In case of  kaliopenia give potassium solutions.

Respiratory and metabolic imbalances can mix in case of severe decompensated diseases due to failure of compensatory mechanisms. Correct interpretation of these violations is possible only in case of regular and iterative gasometry blood tests.

Control tasks.

Task 1.

Calculate the total body water volume and its extracellular and intracellular volumes of the Patience, the patient of 48 years and body weight 88 kg.

Task 2.

Patience, the patient of 23 with body weight 70 kg has sodium level 152 mmol/l and hematocrit 0,49 l/l. Name the type of water balance disorder.

Task 3.

Patience, the patient of 54 with body weight 76 kg has sodium level 128 mmol/l. Calculate the volume of saline and 7,5% sodium chloride solution necessary for the treatment of this condition.

Task 4.

Patience, the patient of 60 with body weight 60 kg has sodium level 140 mmol/l and hematocrit 0,55 l/l. Name the type of disorder and prescribe infusion therapy.

Task 5.

Patience, the patient of 42 with body weight 80 kg has potassium level 2,6 mmol/l. Calculate the volume of  4% potassium chloride solution necessary for treatment of this condition.

Task 6.

Patience, the patient of 33 with body weight 67 kg and diagnosis “gastric ulcer, complicated with pylorostenosis” has potassium concentration 3 mmol/l, chlorine concentration 88 mmol/l. pH 7,49, pCO_2a 42 mm Hg, BE + 10 mmol/l. Name the type of disorder.

Task 7.

Patience, the patient of 50 with body weight 75 kg, was transported to the admission unit of the hospital with: unconsciousness, cyanotic skin, low blood pressure, shallow breathing. Blood tests show: pH 7,18, pCO_2a 78 mm Hg, pO_2A – 57 mm Hg, BE -4,2 mmol/l. Name the type of acid-base disorder and prescribe treatment.

Task 8.

Patience, the patient with body weight 62 kg and renal insufficiency has: potassium concentration 5,2 mmol/l, sodium concentration 130 mmol/l, calcium concentration 1,5 mmol/l, pH 7,22, pCO_2a 34 mm Hg, BE -9,2 mmol/l. Name the type of disorder.

Life is provided through a variety of mechanisms, however all of them depend on proper circulation. Circulation itself consists of 2 parts: work of heart (pump of the body) and vessels, through which blood is pumped to the most remote organs and tissues. During every systolic contraction heart pump 70-80 ml of blood 9so called stroke volume). Thus in case of heart rate 70 beats per minute heart pumps nearly 5 liters of blood, what makes more than 7 tones per day.

From the left ventricle blood gets to the arterial system of the systemic circuit. Arteries contain 15% of the whole circulating blood volume; they carry blood from the heart to their distal departments – arterioles (vessels of resistance). Arterioles themselves are defining blood distribution: in condition of constriction (spasm) they make blood supply of the capillaries impossible (ischemia appears). On the contrary, in condition of dilatation they provide maximal oxygenation. When arterioles are blocked due to the spasm blood is flowing through the arterio-venous anastomosis directly to the venous system.

Distribution of blood in the vascular bed (% of CBV).

a. heart cavity 3%

b. arteries 15%

c. capillaries 12%

d. venous system 70%

Among the natural vasoconstrictors (agents, which cause constriction of the blood vessel) are epinephrine, norepinephrine, serotonin, angiotensin II. Stress enhances the secretion of cathecholamines, their blood concentration increases and arterioles constrict. Spasm of the arterioles is the basis of blood flow centralization: peripheral flow is disregarded in order to provide brain with the oxygenated blood as long as possible. To the group of vasodilatators (agents, which provide dilatation of the vessels) belong “acid” metabolites (lactate, pyruvate, adenylic acid, inosinic acid), bradykinin, acetylcholine, different medicines (neuroleptics, α-adrenergic antagonists, peripheral vasodilatators, ganglionic blocking agents, etc.), some exogenous poisons. All of them cause blood flow decentralization: opening of arterioles and distribution of the blood from central vessels to the capillary bed.

Capillaries are the interweaving network of the smallest body vessels with the general length of 90-100 thousands of kilometers. However simultaneously work only 20-25% of them. They provide metabolic exchange bringing oxygen and nutrients to the tissues and take back wastes of metabolism. Periodically, every 30-40 seconds one of them get closed and others open (vasomotion effect). Capillaries contain 12% of the whole circulating blood volume, but different pathological conditions can increase this amount even 3 and more times.

“Used” blood from the capillaries flows to the venous system. Veins are the blood reservoir, which contains 70% of the total circulating blood volume. Unlike arteries they are capable of volume control and thus they influence the amount of blood, which returns to the heart.

The most important haemodynamic index of venous system is central venous pressure. CVP represents the pressure which blood causes to the walls of cava veins and right atrium. This parameter is an integral index of circulating blood volume, systemic vascular resistance and pump function of the heart. It can be measure with a special device called “phlebotonometer” (pic. 4.9) or with a usual infusion set and a ruler. Normally CVP measured from the sternum point is 0-14 cm H₂O and from midaxillary line is 8-15 cm H₂O.

Central venous pressure decreases (sometimes even to negative) in case of:

- blood loss

- excessive water loss (dehydration)

- distributive shock (decrease of peripheral resistance due to venous and arterial dilatation)

In those conditions decreases volume of blood returning to the heart and thus suffers cardiac output. In case of negative CVP cardiac arrest is highly probable.

Central venous pressure increases in case of:

- heart failure (insufficiency of left or right ventricle)

 - hypervolemia (excessive blood infusion, improper infusion therapy)

 - obstructions to blood flow (pulmonary embolism, cardiac tamponade, etc.)

When CVP over 15-16 cm H₂O is combined with left ventricle insufficiency the risk of pulmonary edema is very high.

Blood pressure is an integral index of arterial part of systemic haemodynamics. Talking about blood pressure we may refer to systolic, diastolic, pulse and mean arterial pressure. Systolic (P_syst) and diastolic (P _diast) pressures are measured with the manometer (method with the usage of phonendoscope was invented by M. Korotkoff). Pulse pressure (PP) is a difference between systolic and diastolic blood pressure.

Mean arterial pressure (MAP) is calculated according to the formula:

MAP= P _dias + 1/3 PP                            mm Hg

MAP defines the level of pressure necessary for the metabolic exchange in the tissues. Its measurement allows the evaluation of tissue perfusion level.

Blood pressure depends on different factors, but the most important are cardiac output and vascular resistance (mostly arterioles). This dependence is direct, thus you can increase blood pressure using:

-         infusion of vasoconstrictors - solutions of epinephrine, phenylephrine (mesaton), etc. (they will increase the vascular resistance);

-         infusion of hydroxyethyl starch solutions or saline (they will increase circulating blood volume)

-         infusion of cardiac glycosides or other medicine which stimulate myocardium

General volume of blood in the body of a healthy adult is nearly 7% from the body weight: 70 ml per kilogram for male and 65 mil per kilogram of body weight for female. Of course circulating blood volume is lower, because part of blood is out of metabolic processes as a reserve. CBV can be measured with the infusion of coloring substance to the blood flow (Evans blue, polyglucin) and later evaluation of its dissolution degree.

Therefore measurement of CVP, BP, cardiac output and circulating blood volume allow to evaluate condition of circulation system of the patients and to provide adequate correction.

4.2 Acute heart failure; shock and collapse.

Acute cardiovascular failure is a state of cardiac and vascular inability to provide adequate supply of tissue metabolic needs with oxygenated blood and nutrients. This, earlier or later, causes cellular death.

The reasons of the failure vary greatly: mechanic injuries, blood loss, burns, dehydration, exogenous and endogenous intoxications, immediate hypersensitivity reaction, ischemic heart disease, neural and humoral regulation disorders of vascular tone.

Acute cardiac failure is a disorder of heart pumping action. It develops due to primary heart problems or secondary, under the influence of extracardiac factors such as infection or intoxication. There are two types of heart failure: left-sided and right-sided.

Left-sided heart failure is an inability of left ventricle to pump blood from the pulmonary circuit to the systemic circuit. The most common reasons of it are myocardial infarction, mitral insufficiency, left AV valve stenosis, aortic valve stenosis, aortal insufficiency, hypertonic disease, coronary sclerosis, acute pneumonia.

Coronary circulation is possible only during the diastole and in those conditions every violation of coronary passability decreases cardiac output. This way during the systole part of the blood is not injected into aorta, but stays in the left ventricle. Diastolic pressure in the left ventricle increases and blood is literally forced to stagnate in the left atrium. At the same time right ventricle functions normally and continues to pump usual amounts of blood to the pulmonary circuit. Thus hydrostatic pressure in the vessels of pulmonary circulation increases, fluid part of the blood moves first to the lung tissue and then, through alveolar-capillary membrane, to the alveolar lumen.

Clinically pulmonary edema begins with dyspnea (during physical activity or rest). Later attacks of dyspnea are connected with persistent cough with white or pink blood-tinged phlegm. During the attack patient tries to sit as in this position breathing is easier. This condition is called “heart asthma”. When hydrostatic pressure is over 150-200 mm Hg, fluid part of blood moves to the alveolar lumen causing development of pulmonary edema.

Pulmonary edema is divided into interstitial and alveolar edema.

Interstitial edema is a condition during which serous part of stagnated in the pulmonary circuit blood infiltrates the lung tissue, including peribronchial and perivascular spaces.

During alveolar edema not only the plasma, but also blood components (red and white blood cells, platelets) get out from the vessels. During the respiratory act blood mixes with the air creating large amount of “foam”, which violates gas exchange. This way, in addition to circulatory hypoxia, hypoxic hypoxia appears.

Condition of the patient gets worth quickly. Sitting position is optimal, but not as helping as previously. Respiratory rate is nearly 30-35 breathes per minute, but attacks of breathlessness are constant. Skin is pale with acrocyanosis. Hypoxia of central nervous system usually causes psychomotor agitation. Respiratory acts are noisy; during cough pink blood-tinged phlegm is released. Auscultation allows you to hear different wet rales, sometimes it’s even possible to hear them standing aside the patient without phonendoscope.

Pulmonary edema can be also divided according to the blood pressure level: the one with elevated pressure is caused by a hypertonic disease, aorta valve insufficiency or disorders of cerebral perfusion; another one is caused by total myocardial infarction, acute inflammation of myocardial muscle, terminal valve defects, severe pneumonia and is characterized with normal or low blood pressure.

Immediate aid

-         make sure patient is sitting with his legs down (orthopnea)

-         provide oxygenation through nasal catheter (before placing oil it with glycerin, insert it to the depth of 10-12 cm – distance from the wing of the nose to auricle) or face mask. Do not use Vaseline, because it can burn in atmosphere with high concentration of oxygen.

However if catheter is not deep enough patient will suffer from an unpleasant “burning” feeling, because oxygen flow will dry mucosa layer of the nasal cavity; also in this situation concentration of oxygen will be lower than expected.

-         put venous tourniquets on the limbs in order to reduce amount of blood returning to heart: venous bed of limbs can reserve up to 1,7 liters of blood;

-         constantly control heart and kidney activity (ECG, SaO₂ , and blood pressure are checked automatically trough the monitor; to control diuresis you should insert Foley catheter;

-         catheterize central vein, because amount of infusions should be based on central venous pressure;

-         use  medical “defoamers” if they are available (ethyl alcohol or antiphomsylan solution) combined with oxygen inhalation

Scheme of oxygenation set connected to “defoamer” container

a. oxygen source (cylinder with oxygen)

b. tube with numerous holes sunk into container with defoamer

c. tube for humidified oxygen (its opening should be over the level of fluid);

d. patient

-         medical treatment: 1% morphine solution (decreases intravascular pressure of pulmonary circuit, inhibits respiration center in medulla oblongata preventive dyspnea progress, sedates patient);

-         solutions of diuretics are used to decrease the circulating blood volume ( 6-12 ml of 1% furosemid solution, solution of ethacrynic acid), however be careful with them in case of low blood pressure; diuretic effect will last up to 3 hours after i/v infusion, the expected diuresis is 2-3 liters

-         if blood pressure allows you can try to use nitroglycerin to reduce intravascular pressure of pulmonary circuit (1 or 2 tablets with 10 minutes interval)

-          cardiac glycosides for improvement of heart action (0,025% digoxin solution, 0,05% strophanthin solution, 0,06% corglicon solution);

-         in case of high pressure (over 150 mm Hg) use ganglionic blocking agents (1 ml of 5% pentamin solution diluted in 150 ml of saline, give i/v slowly; diluted with saline 250 mg of trimethaphan solution), because they reduce pressure in pulmonary circuit and lower the amount of blood getting to right half of the heart, however be careful with the dosage and monitor blood pressure level carefully;

-         never use osmotic diuretics in case of pulmonary edema – they will increase blood volume and thus heart load!!!

-         when everything listed above failed and patient is worsening with every second you should intubate him and start artificial ventilation with positive end expiratory pressure (begin with 4-6 cm H₂O)

Right-sided heart failure is an inability of right ventricular to pump blood from systemic circuit to the pulmonary circuit due to its weakness or an obstruction to the blood flow.

It occurs in case of pulmonary embolism, right ventricular infarction, excessive infusion therapy (especially including citrated blood) for patients with heart insufficiency, lung diseases (bronchial asthma, emphysema, pneumosclerosis) which cause increase of right ventricular load.

Patients have acrocyanosis, tachycardia, dyspnea, pronounced neck veins, ankle swelling, enlarged liver, ascytis. Central venous pressure is highly increased (up to 20-25 cm H₂O), however pulmonary edema does not appear.

Intensive treatment is mostly pathogenetic:

-         limit the infusions (give only life-necessary solutions, check the water balance of the patient and reduce drinking water if necessary);

-         in case of citrated blood transfusions use 5-10 ml of 10% calcium gluconate solution per every 500 ml of blood to prevent hypocalcaemia;

-         in case of bronchial spasm use bronchial spasmolytics;

-         to remove excessive fluid from the body use diuretics (furosemide solution for example);

-         metabolic acidosis is corrected with 4% solution of sodium bicarbonate (i/v slowly with acid-base state control);

-         in case of pulmonary embolism anticoagulants are used – fraxiparine 0,6 mg subcutaneously; heparin solution – 5000 IU every 4 hours; fibrinolytic drugs (streptokinase, fibrinolysin, urokinase, etc.)

Shock is a pathological state which can be described as a tissue hypoxia caused by hypoperfusion. Pathogenetic basis of shock depends on its reason (trauma, toxins, thermal injury) and at the same time on reactivity of the organism (level of defense mechanisms mobilization).

Stimulation of sympathetic nervous system - production of catecholamines and other vasoactive substances by hypothalamus and adrenal glands are the universal response of the body to the stress. Those mediators interact with the receptors of peripheral vessels causing their constriction and at the same time they dilatate the vascular bed of life-important organs. This is so called “centralization of the flow”: rational decrease of blood flow in less important tissues (skin, organs of abdominal cavity, kidneys) in case of aggressive external influence for protecting life itself (brain, heart, lungs).

However influence of shock agents (pain, hypovolemia, destroyed cells, toxic metabolites), extended microcirculation violations (vascular spasm, microthrombosis and sludge) and caused by them tissue ischemia lead to hypoxic affection and cellular death of the internal organs. Further it can bring multiple organ dysfunction syndrome.

Collapse is a vascular failure. It occurs when body is not able to provide blood flow according to the new level of its needs (either because reaction is not fast enough or because sympathetic activation fails).Vascular bed volume and circulating blood volume are disproportional: too much blood gets to the microcirculation vascular reserve and the amount, which returns to the heart is not enough for the systemic needs (so called “decentralization” of the blood flow). Cardiac output and blood pressure decrease, that causes hypoperfusion of the central nervous system and thus unconsciousness and life-threatening complications.

Collapse definition is a bit nominal, because if such reaction extends in time the state of shock develops. Shock itself can equally run as a vascular failure or as a sudden clinical death.

Pathogenetic classification of shock (according to P. Marino, 1998):

-         hypovolemic

-         cardiogenic

-         distributive

-         mixed (two and more factors).

Clinical classification of shock:

-         traumatic shock;

-         haemorrhagic shock;

-         dehydration shock;

-         burn shock;

-         septic shock;

-         anaphylactic shock;

-         cardiogenic shock;

-         exotoxic shock.

4 Shock caused by dehydration

It is a type of hypovolemic shock, which occurs during excessive body fluid loss (not blood, because hemorrhagic shock is another shock type).

Its reasons vary greatly:

-         gastrointestinal diseases (profuse vomiting, diarrhea, loss of intestinal fluid through fistula);

-         polyuria (uncontrolled diuretic treatment, diabetes mellitus and insipidus, diuretic phase of acute renal failure);

-         fluid loss through skin and wound surface (burns, high fever);

-         inadequate infusion treatment of postoperative or comatose patients;

-         hyperventilation (rapid breathing, Kussmaul breathing, inadequate artificial ventilation parameters in case of apparatus without air humidification).

However not only the complete fluid loss can be the reason of shock, but also it’s pathological distribution into the extracellular space (intestinal cavity in case of intestinal paralysis, abdominal cavity in case of ascites, pleural cavity in case of pleurisy). This way will can also act prolonged heavy tissue inflammations (peritonitis) or massive injuries (crush-syndrome).

      In cases described above electrolytes are also lost (cations of sodium, potassium, calcium, magnesium; anions of chlorine, hydrocarbonate). It causes complex osmolar, acid-base and electrolytic disorders.

Stage of dehydration shock is evaluated according to the actual fluid loss:

less than 5% of body weight – mild dehydration

5-10% of body weight – moderate dehydration

over 10% of body weight – severe dehydration

Water deficiency brings lowering of cardiac output, blood pressure and central venous pressure (through decrease of blood volume returning to the heart, which leads to compensatory adrenergic vasoconstriction).

Dehydration causes body weight loss, skin and mucosa dryness, decrease of subcutaneous turgor and eyeballs tone, hypothermia, tachycardia, oliguria, thirst. While dehydration progresses compensatory mechanisms weaken and central nervous system suffers: patients become sluggish, confused; hallucinations, cramps and unconsciousness are also possible. Laboratory tests show blood concentration.

One of the most important things in treatment of dehydrated patients is daily balance of fluid: check it carefully trough measuring of daily received and lost fluids (food, infusions, stool and urine output). In case of fever or tachypnea make necessary corrections. Balance should be calculated every 12-24 hours (special paper forms make this easier).

Daily fluid balance is calculated by adding all the received fluids (both enteral and parenteral ways) and deducting urine output, stool, perspiration and breathing water loss.

You should remember, that perspiration depends on body temperature: in case of normal temperature (36,6ºC) patient looses 0,5 ml/kg of water during every hour; 1 degree of temperature elevation adds 0,25 ml/kg to normal value of 0,5 ml/kg.

According to the fluid balance infusion therapy is divided into positive (for dehydrated patients), negative (for overhydrated patients) and “zero” (for patients without balance disorders).

Water deficiency is calculated according to the formula:

W _def = (Ht_p-Ht_n)* 0,2 BW/ Ht_n,

W _{def –} water deficiency, l;

Ht_{p –} hematocrit of the patient, l/l;

Ht_n -  normal hematocrit, l/l;

BW – body weight, kg.

Use crystalloids to treat water deficiency: saline solution, Ringer’s solution, Ringer-lactate solution, electrolytic solutions, 5%, 10, 20% glucose solution. To control potassium concentration (during dehydration this cation is widely lost) prescribe polarizing GIK mixture (pic.9.4), but don’t you ever infuse concentrated potassium solutions quickly – it can cause cardiac arrest (not more than 400 of GIK solution ml per hour).