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Electrolytes, Fluids, Acid Base Balance and Shock

Electrolytes, Fluids, Acid Base Balance and Shock. Gwynne Jones Critical Care. Electrolytes, Fluids, Acid Base Balance and Shock. Correct Fluid Management faqcilitatescrucial Homeostasis. This permits: Optimum Cardio-vascular perfusion Optimum Organ Function Optimum Cellular Function.

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Electrolytes, Fluids, Acid Base Balance and Shock

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  1. Electrolytes, Fluids, Acid Base Balance and Shock Gwynne Jones Critical Care

  2. Electrolytes, Fluids, Acid Base Balance and Shock Correct Fluid Management faqcilitatescrucial Homeostasis. This permits: Optimum Cardio-vascular perfusion Optimum Organ Function Optimum Cellular Function

  3. Electrolytes, Fluids, Acid Base Balance and Shock Knowledge of the Compartmentalisation of Body Fluids forms the basis for: Understanding the Pathological Shifts in these Fluid Spaces in Varying Disease States Quantifying Deficiencies or Excesses in these Spaces Informs Choice of Fluid Type and Quantity

  4. Electrolytes, Fluids, Acid Base Balance and Shock Knowledge of the Compartmentalisation of Body Fluids forms the basis for: Understanding the Effects of Sodium Concentration on Interstitial and Cellular Volume and Function Understanding Acid-Base Homeostasis Understanding specific Patient Needs in Renal Failure, Brain Disease, Liver, Heart and Lung Diseases.

  5. Electrolytes, Fluids, Acid Base Balance and Shock Body Fluid Compartments: Water Contributes 50-70% of Body Weight. Fat has Little Water, thus Lean People have greater Body Water as % weight Water is distributed EVENLY throughout all body compartments but will follow Osmotic Gradients

  6. Electrolytes, Fluids, Acid Base Balance and Shock Body Fluid Compartments: Total Cations Must Equal Total Cations Sodium is Predominently Extracellular and determines Extracellular Fluid Volume. Cell Volume is Controlled mainly by Cell Membrane Ion Pumps

  7. Electrolytes, Fluids, Acid Base Balance and Shock Electrolyte Concentration is usually expressed in terms of chemical combining activity, or equivalents. Equivalent = Atomic Wt (g)/valence

  8. Electrolytes, Fluids, Acid Base Balance and Shock Body Fluid Compartments: Total Cations Must Equal Total Cations The Physiological Activity of Electrolytes in Solution depends on the Number of Particles per Unit Volume (milli-mols/Liter, mMol/L The Number of Electric Charges per Unit Volume (milli-equivalents per Liter, mEq/L The Number of Osmotically Active Ions per unit Volume (milli-osmoles per Liter, mOsm/L)

  9. Electrolytes, Fluids, Acid Base Balance and Shock Body Fluid Compartments: Total Cations Must Equal Total Cations Sodium is predominently Extracellular and determines Extracellular Fluid Volume. Cell Volume is Controlled mainly by Cell Membrane Ion Pumps

  10. Electrolytes, Fluids and Shock

  11. Electrolytes, Fluids and Shock 50% Total body Water 80% Total Body Water

  12. Electrolytes, Fluids and Shock

  13. Electrolytes, Fluids and Shock Two Thirds of the body Water is in the cells. This is between 30L to 40 L. Is has an Electrolyte composition very different from the Extra-cellular water. What is this difference?

  14. Electrolytes, Fluids and Shock • Two Thirds of the body Water is in the cells. • Electrolyte composition: • Cations: • Potassium: 150 mMol/L • Sodium: 10 mMol/L • Magnesium: 40 mMol/L. • Calcium and Hydrogen: nanoMols/L • Anions: • Phosphate and Sulphate ± 150 mMol/L. • Proteinate ± 40 mMol/L • Bicarbonate ± 10 mMol/L

  15. Electrolytes, Fluids and Shock Two Thirds of the body Water is in the cells. This is between 30L to 40 L. Is has an Electrolyte composition very different from the Extra-cellular water. How is it maintained?

  16. Electrolytes, Fluids and Shock These differences are maintained by various cell membrane ion pumps. Na/K ATPase driven exchangers are most important • Two Thirds of the body Water is in the cells. • Electrolyte composition: • Cations: • Potassium: 150 mMol/L • Sodium: 10 mMol/L • Magnesium: 40 mMol/L. • Calcium and Hydrogen: nanoMols/L • Anions: • Phosphate and Sulphate ± 150 mMol/L. • Proteinate ± 40 mMol/L • Bicarbonate ± 10 mMol/L

  17. Electrolytes, Fluids and Shock These differences are maintained by various ion pumps. Na/K ATPase driven exchangers are most important After Severe Shock 20% of Oxygen/fuel consumption is used just to pump the Sodium out of the cells. • Two Thirds of the body Water is in the cells. • Electrolyte composition: • Cations: • Potassium: 150 mMol/L • Sodium: 10 mMol/L • Magnesium: 40 mMol/L. • Calcium and Hydrogen: nanoMols/L • Anions: • Phosphate and Sulphate ± 150 mMol/L. • Proteinate ± 40 mMol/L • Bicarbonate ± 10 mMol/L

  18. Electrolytes, Fluids and Shock These differences are maintained by various ion pumps. Na/K ATPase driven exchangers are most important. Cell volume fluctuates a little in shock and has some influence on resuscitation fluid choice. In the presence of shock (the ebb phase) they swell. In more chronic severe illness (after shock/flow phase) they shrink. • Two Thirds of the body Water is in the cells. • Electrolyte composition: • Cations: • Potassium: 150 mMol/L • Sodium: 10 mMol/L • Magnesium: 40 mMol/L. • Calcium and Hydrogen: nanoMols/L • Anions: • Phosphate and Sulphate ± 150 mMol/L. • Proteinate ± 40 mMol/L • Bicarbonate ± 10 mMol/L

  19. Electrolytes, Fluids and Shock These differences are maintained by various ion pumps. Na/K ATPase driven exchangers are most important. Cell volume fluctuates a little in shock and has some influence on resuscitation fluid choice. 1. Smaller cells switch off protein production and thus contribute to nitrogen loss. • Two Thirds of the body Water is in the cells. • Electrolyte composition: • Cations: • Potassium: 150 mMol/L • Sodium: 10 mMol/L • Magnesium: 40 mMol/L. • Calcium and Hydrogen: nanoMols/L • Anions: • Phosphate and Sulphate ± 150 mMol/L. • Proteinate ± 40 mMol/L • Bicarbonate ± 10 mMol/L

  20. Electrolytes, Fluids and Shock These differences are maintained by various ion pumps. Na/K ATPase driven exchangers are most important. Cell volume fluctuates a little in shock. Cells are smaller in recovering shock. 2. Insulin and certain Amino Acids stimulate protein synthesis . The re-feeding syndrome is associated with this. How? • Two Thirds of the body Water is in the cells. • Electrolyte composition: • Cations: • Potassium: 150 mMol/L • Sodium: 10 mMol/L • Magnesium: 40 mMol/L. • Calcium and Hydrogen: nanoMols/L • Anions: • Phosphate and Sulphate ± 150 mMol/L. • Proteinate ± 40 mMol/L • Bicarbonate ± 10 mMol/L

  21. Electrolytes, Fluids and Shock The cell is thus a rich sauce. It is the lean body mass that we survive on. For the rest of the talk/life we leave them in the background. We forget them at our peril. • Two Thirds of the body Water is in the cells. • Electrolyte composition: • Cations: • Potassium: 150 mMol/L • Sodium: 10 mMol/L • Magnesium: 40 mMol/L. • Calcium and Hydrogen: nanoMols/L • Anions: • Phosphate and Sulphate ± 150 mMol/L. • Proteinate ± 40 mMol/L • Bicardonate ± 10 mMol/L

  22. Electrolytes, Fluids and Shock

  23. Electrolytes, Fluids and Shock The extracellular space is ± one third of the total Body Water. Blood plasma is a quarter of this (± 5L in an adult). Interstitial fluid is the other three quarters (± 15L in an adult) How is this difference maintained when the endothelium is fully permeable to salt water?

  24. Electrolytes, Fluids and Shock There is a subtle difference between blood/plasma and interstitial fluid. This is mainly the difference in protein. As Albumin is a small protein (MW66,000kD), it has the greatest number of osmotically active molecules. These are able to exert an osmotic activity across a semi-permeable membranes.

  25. Electrolytes, Fluids and Shock There is a subtle difference between blood/plasma and interstitial fluid. Sodium passively determines the extracellular space volume. Why?

  26. Electrolytes, Fluids and Shock Sodium passively determines the extracellular space volume. Total body sodium is around 3000mMol. (±20L X 140mMol/L). Anyone with edema has a high body sodium (and the water it craves). This, unfortunately, does not mean that the Blood/Plasma volume is low/normal/high!

  27. Electrolytes, Fluids and Shock Whose Law determines the mechanism by which these intravascular /interstitial volumes are maintained?

  28. Electrolytes, Fluids and Shock Whose Law determines the mechanism by which this intravascular /interstitial process is maintained? Starling’s Law. Jv = Ks (Ppl - Pis) - σ (πpl - πis)

  29. Electrolytes, Fluids and Shock Jv = Ks (Ppl - Pis) - σ (πpl - πis)

  30. Electrolytes, Fluids and Shock Jv = Ks (Ppl - Pis) - σ (πpl - πis)

  31. Electrolytes, Fluids, Acid Base Balance and Shock • What isσ and why is it important?

  32. Electrolytes, Fluids, Acid Base Balance and Shock • What isσ and why is it important? • σ is the Protein Reflection Co-efficient • σ is 0.3 in skin (ie very tight endothelium) • σ is 0.6 in the lung and Kidney • σ is 0.9 in the Gut and Liver (ie very Leaky for Protein)

  33. Electrolytes, Fluids and Shock Jv = Ks (Ppl - Pis) - σ (πpl - πis)

  34. Electrolytes, Fluids and Shock Jv = Ks (Ppl - Pis) - σ (πpl - πis)

  35. Electrolytes, Fluids and Shock Jv = Ks (Ppl - Pis) - σ (πpl - πis) The endothelium is more complex than initially imagined. The endothelium is covered by a glyco-calyx. These two barriers: the Endothelium and the Glycocalyx are co-operative. Damage to either one is not associated with an increase in fluid flux. Damage to both is associated with severe leaky vessels (capillaries)

  36. Electrolytes, Fluids and Shock Jv = Ks (Ppl - Pis) - σ (πpl - πis) The endothelium is more complex than initially imagined. The endothelium is covered by a glyco-calyx. These two barriers are co-operative: The endothelium is damaged particularly by Reactive Oxygen Species (ROS) The glyco-calyx is damaged particularly by proteases.

  37. Electrolytes, Fluids and Shock Jv = Ks (Ppl - Pis) - σ (πpl - πis) The endothelium is more complex than initially imagined. The endothelium is covered by a glyco-calyx. These two barriers are co-operative. They allow a flow of interstitial fluid enriched by sugar and electrolytes. The ¼ Blood/Plasma: ¾ interstitial fluid ratio in health is maintained. Excess is taken up by lymphatics and returned to the blood via the thoracic duct.

  38. Electrolytes, Fluids and Shock Blood Volume is ± 5L in the adult. 45% is RBCs The rest is an aqueous solution of electrolytes and proteins. The proteins are functional: Immunoglobulins Coagulation factors Complement Albumin Hormones Etc.

  39. Electrolytes, Fluids and Shock Blood Volume is ± 5L in the adult. Blood Volume is highly regulated by: What?

  40. Electrolytes, Fluids and Shock Blood Volume is ± 5L in the adult. Blood Volume is highly regulated by: Pressure Sensors. Volume Sensors. Osmo-receptors.

  41. Electrolytes, Fluids and Shock Blood Volume is ± 5L in the adult. Blood Volume is highly regulated by: Pressure Sensors: Carotid Sinus, Renal Vessels. Volume Sensors: Large Veins/Atria. Osmo-receptors: Hypothalamus.

  42. Electrolytes, Fluids and Shock Blood Volume is ± 5L in the adult. Blood Volume is highly regulated by: Pressure Sensors: Carotid Sinus, Renal Vessels. Volume Sensors: Large Vein/Atria. Osmo-receptors: Hypothalamus. These act via the Autonomic Nervous system, the hypothalamic-Pituitary Axis and adrenal glands to stimulate thirst, Sodium and Water Retention, Vaso-constriction etc.

  43. Electrolytes, Fluids and Shock Blood Volume is ± 5L in the adult. Blood Volume is highly regulated by: Pressure Sensors: Carotid Sinus, Renal Vessels. Volume Sensors: Large Vein/Atria. Osmo-receptors: Hypothalamus. These act via the Autonomic Nervous system, the hypothalamic-Pituitary Axis and adrenal glands to stimulate thirst, Water Retention, Vaso-constriction etc. Tell me about the hormones!

  44. Electrolytes, Fluids and Shock ADH CATECHOLAMINES ANGIOTENSIN CORTISOL ALDOSTERONE ATRIAL NATRIURETIC HORMONE ENDOTHELIN

  45. Electrolytes, Fluids and Shock This is going to get Harder!

  46. Electrolytes, Fluids and Shock Acid-Base Balance. Hydrogen is in Nano-Molar quantities

  47. Electrolytes, Fluids and Shock Acid-Base Balance. Hydrogen is in Nano-Molar quantities. It all has to do with the dissociation of water. Most of the water is not dissociated (55mMol/L.) 10-14 nMol/L of water is dissociated into H+and OH- If all is H+ the pH is zero. If all is OH- the pH is 14. The pH scale is zero to 14, neutral is a pH of 7

  48. Electrolytes, Fluids and Shock Acid-Base Balance. Hydrogen is in Nano-Molar quantities. It all has to do with the dissociation of water. Most of the water is not dissociated. 10-14 nMol/L is dissociated into H+and OH- If all is H+ the pH is zero. If all is OH- the pH is 14. The pH scale is zero to 14, neutral is a pH of 7 There are three independent variables that affect pH or H ion concentration: The bicarbonate/carbon dioxide system The dissociation of proteins The Strong Ion difference (SID

  49. Electrolytes, Fluids and Shock Acid-Base Balance. Hydrogen is in Nano-Molar quantities. It all has to do with the dissociation of water. Most of the water is not dissociated. 10-14 nMol/L is dissociated into H+and OH- If all is H+ the pH is zero. If all is OH- the pH is 14. The pH scale is zero to 14, neutral is a pH of 7 The Strong Ion difference (SID). This is the difference between fully dissociated anions and cations. Na + K – Cl + La- = ± 40 in health. This is the bath in which your bicarbonate and proteinate buffers work.

  50. Electrolytes, Fluids and Shock • The Bicarbonate System [CO2] [H2O] [H+] [HCO3]

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