Clinical Management of Electrolyte Disorders

Serious disturbances of fluid and electrolyte balance are frequently encountered in acutely ill patients; somewhat less often in the chronically sick. There seems to be a trend for such cases to increase, due probably to an increase in major surgical procedures on older patients whose renal function is less than adequate. There are already many publications dealing with the physiology of the homeo stasis of fluid and electrolytes, and others dealing with the clinical aspects of the subject. It is often assumed that a knowledge of the basic principles of physiology will enable the doctor to prescribe suitable intravenous therapy. In practice this is often found not to be so and the evidence for this is the frequency of calls for help with electrolyte problems from well-qualified and experienced doctors who are undoubtedly equipped with adequate or even excellent knowledge of the basic It is not an unusual observation that knowledge of theory and principles involved. principles does not necessarily lead to successful practice in this or any other art or craft. Most doctors already possess knowledge of the physiology of the internal envi ronment, but some are aware of being unable to deal effectively with clinical problems related to fluid and electrolyte disturbances and seek guidance to translate theoretical knowledge into practice.

Inhalt

1. Basic information relating to body fluids.- 1. Volume.- 2. Solutes.- 3. Mole.- 4. Solution.- 5. Equivalent.- 6. Osmosis.- 7. Osmotic pressure.- 8. Osmolarity, osmolality.- 8.1. Osmolarity.- 8.2. Osmolality.- 9. Isotonicity, hypertonicity, hypotonicity.- 10. Oncotic pressure.- 11. Cell membrane pumps.- 12. Role of enzymes.- 13. Acid/base.- 13.1. Acidosis.- 13.2. Alkalosis.- 13.3. Buffers.- 13.4. Anion gap.- 13.5. Regulation of acid/base.- 13.5.1. Regulation of acid/base by the kidneys.- 13.5.2. Regulation of acid/base by the lungs.- 14. Osmotic dieresis.- 15. Free-water clearance.- 15.1 Effect of volume depletion in chronic renal failure.- 15.2. Polyuria.- 16. Antidiuretic hormone.- 17. Aldosterone.- 17.1. Hyperaldosteronism.- 17.2. Hyporeninaemic hypoaldosteronism.- 2. The fluid compartments of the body.- 1. Fluid compartments.- 2. Composition of plasma and intracellular fluid.- 3. Role of the cell membrane pumps.- 3. What can intravenous therapy accomplish?.- 1. Use of intravenous therapy.- 2. Limitations of intravenous therapy.- 2.1. Limitation of volume.- 2.1.1. Amount of fluid loss.- 2.1.2. Age.- 2.1.3. Cardiac and renal function.- 2.1.4. Time.- 2.1.5. Previous intravenous therapy.- 3. Limitation of osmolality.- 4. Limitation of sodium.- 4.1. Sodium space.- 5. Limitation of hydrogen ion concentration.- 5.1. Respiratory acidosis/alkalosis.- 5.2. Metabolic acidosis.- 5.3. Metabolic alkalosis.- 6. Potassium deficiency.- 4. The clinical history.- 1. Deficient intake.- 2. Vomiting or aspiration.- 3. Loss from gastrointestinal fistulae.- 4. Loss of bile.- 5. Diarrhoea.- 6. Excessive urinary loss.- 7. Impaired renal function.- 8. Urinary diversion operations.- 9. Excessive loss of sweat.- 10. Drug-induced electrolyte disturbances.- 11. Electrolyte disturbances associated with intravenous therapy.- 12. Thirst.- 13. Dyspnoea.- 5. Physical examination of the patient.- 1. Weight.- 2. Temperature.- 3. Skin.- 4. Sweating.- 5. Mucous membranes.- 6. Oedema.- 7. Jugular venous pressure.- 8. Blood pressure.- 9. Hypotension.- 10. Hypertension.- 11. Cardiac assessment.- 12. Lungs.- 13. Anaemia.- 14. Abdomen.- 15. Tendon reflexes.- 16. Restless patient.- 17. Fontanelle in infancy.- 6. Fluid balance records and their interpretation.- 1. Fluid balance chart.- 2. Fluid intake.- 3. Fluid output.- 4. Prescription for intravenous fluids.- 7. Laboratory data and useful investigations.- 1. Chemical substances in body fluids.- 2. Chemical substances in serum/plasma.- 3. Enzymes and hormones in serum/plasma.- 4. Acid/base and gaseous components of blood.- 5. Base excess and buffer base.- 6. Actual and standard bicarbonate.- 7. Plasma total CO2, plasma bicarbonate.- 8. Chemical substances in urine.- 9. Enzymes and hormones in urine.- 10. Renal function tests.- 11. Haematological tests.- 12. Central venous pressure.- 13. Haemodynamic monitoring using the Swan Ganz catheter.- 14. Radiological investigations.- 8. Solutions for intravenous therapy and their uses.- 1. 5% dextrose.- 2. Sodium chloride solutions.- 3. Sodium bicarbonate.- 4. One-sixth molar sodium lactate.- 5. Potassium chloride.- 6. Potassium acetate.- 7. Magnesium sulphate.- 8. Isotonic mixed electrolyte solutions.- 9. Colloidal solutions.- 10. Nutritive solutions.- 11. Ammonium chloride.- 12. Mannitol.- 13. Forced dieresis.- 9. Water loss syndrome.- 1. Pure deprivation of water.- 2. Increased water loss.- 3. Physical signs of water loss.- 4. Laboratory findings of water loss.- 5. Treatment of water loss syndrome.- 6. Amount of water required.- 10. Water excess syndrome.- 1. Water excess caused byintravenous infusion.- 2. Water excess caused by irrigation.- 3. Symptoms and signs of water excess.- 4. Laboratory findings.- 5. Treatment of water excess.- 11. Sodium loss syndrome.- 1. Causes of sodium loss syndrome.- 1.1. Vomiting/aspiration.- 1.1.1. Treatment of electrolyte disturbance due to vomiting/aspiration.- 1.2. Diarrhoeal causes.- 1.2.1. Treatment of diarrhoeal loss.- 1.3. Gastrointestinal and biliary fistulae.- 1.3.1. Treatment of loss via fistulae.- 1.4. Loss through intact skin.- 1.4.1. Treatment of heat exhaustion.- 1.5. Loss through damaged skin.- 1.5.1. Treatment of loss through skin.- 1.6. Sequestration of extracellular fluid.- 1.6.1. Treatment of sequestration of extracellular fluid.- 1.7. Intrinsic renal disease.- 1.7.1. Treatment of renal loss of sodium.- 1.8. Adrenocortical insufficiency.- 1.8.1. Treatment of acute adrenal insufficiency.- 1.9. Diabetic keto-acidosis.- 1.9.1. Treatment of diabetic keto-acidosis.- 1.10. Paracentesis or acupuncture.- 1.11. Drug-induced sodium loss.- 1.12. Bartter's syndrome.- 12. Hyponatraemia without sodium loss.- 1. Dilutional hyponatraemia.- 1.1. Symptoms and signs of dilutional hyponatraemia.- 1.2. Treatment of dilutional hyponatraemia.- 2. Hyponatraemia with hyperlipidaemia.- 3. Hyponatraemia with hyperproteinaemia.- 4. Hyponatraemia with hyperglycaemia.- 13. Sodium excess syndrome.- 1. Causes of oedema.- 1.1. Cardiac oedema.- 1.1.1. Treatment of cardiac oedema.- 1.2. Hypoproteinaemia.- 1.2.1.1. Treatment of the nephrotic syndrome.- 1.3. Cirrhosis.- 1.4. Hormonal oedema.- 1.5. Idiopathic oedema.- 14. Hypernatraemia.- 1. Water deprivation.- 2. Increased water loss.- 3. Inappropriate administration of sodium.- 4. Haemodialysis against concentrated dialysis fluid.- 5. Hyperaldosteronism.- 6. Essentialhypernatraemia.- 7. Treatment of hypernatraemia.- 15. Disturbances of potassium metabolism.- 1. Potassium and neuromuscular transmission.- 2. Potassium disturbances and renal function.- 3. Potassium and acid/base status.- 4. External potassium balance.- 5. Hypokalaemia.- 6. Hyperkalaemia.- 16. Metabolic acidosis.- 1. Metabolic acidosis with normal anion gap.- 2. Metabolic acidosis with increased anion gap.- 3. Symptoms and signs of acidosis.- 4. Treatment of metabolic acidosis.- 17. Metabolic alkalosis.- 1. Causes of metabolic alkalosis.- 2. Symptoms and signs of metabolic alkalosis.- 3. Treatment of metabolic alkalosis.- 18. Respiratory disturbances of acid/base.- 1. Primary respiratory acidosis.- 1.1. Causes of respiratory acidosis.- 1.2. Symptoms and signs of respiratory acidosis.- 1.3. Treatment of respiratory acidosis.- 1.4. Carbon dioxide narcosis.- 2. Primary respiratory alkalosis.- 2.1. Causes of respiratory alkalosis.- 2.2. Symptoms and signs of respiratory alkalosis.- 2.3. Treatment of respiratory alkalosis.- 3. Mixed acid/base disturbances.- 3.1. Respiratory acidosis and compensatory metabolic alkalosis.- 3.2. Metabolic alkalosis and compensatory respiratory acidosis.- 3.3. Respiratory alkalosis and metabolic …