2. Water, Electrolyte & Prof. Mehdi Hasan Mumtaz Acid-Base Balance

3. BALANCE Water Balance Electrolyte Balance. Acid Base Balance. Nutritional Balance.

4. TOTAL BODY WATER 42L IVS ISS ICS 5L 14L 23L

5. FLUID THERAPY CELL CAPILLARY EG OSMOLALITY Na + COP INTRACELLULARINTERSTITIAL VASCULAR

6. FLUIDS IVSISSICS 1L 5% Dextros 5/42 X 1000 = 120ml 14/42 X 1000 = 333ml 23/42 X 1000 = 547ml 1L Nacl 0.9% 5/19 X 1000 = 263ml 14/19 X 1000 = 737ml - 1L Colloid containing solution 5/5 X 1000 = 1000ml --

7. ACID-BASE BALANCE Terminology. Physiologic Compensation By Body. Pathophysiologic Disturbances. Practical Approach To Assessment. Biochemical Reports & Case Histories.

8. DEFINITION OF TERMINOLOGY ACID- STANDARD BICARBONATE. BASE- BUFFER BASE & BASE DEFICIT. ALKALI BUFFERING & BUFFER. PH. 24 x PCO 2 (mmHg) H + (nmol/L)=- ----------------------------- HCO 3 (meq/L) (40nmol/L)

9. PRODUCT OF METABOLISM H ++ - Anaerobic Metabolism. CO 2 - Aerobic Metabolism.

10. PHYSIOLOGIC COMPENSATION HYDROGEN IONS.  Incoporation in water. H + +HCO 3  H 2 C 3 O  CO 2 + H 2 O.  Loss from body. Kidney – regeneration of HCO 3.  Intestine. CO 2.  Chemoreceptors in hypothalamus. HCO 3.  HCO 3 generation by erythrocytes.  HCO 3 re-absorption in renal tubules.  HCO 3 generation in renal tubules.

11. BICARBONATE GENERATION BY ERYTHROCYTES Cl — HCO - 3 CO 2 Cl — - HCO 3 +H + CO 2 +H 2 O HHB Hb

12. BICARBONATE REABSORPTION BY KIDNEY RENAL T. LUMEN STIMULATED BY  HCO3 - M. ACIDOSIS HCO 3 - Na + HCO 3 - H 2 CO 3 CO 2 + H 2 O HCO 3 - CELL CD H2O HCO 3 - H+H+ H2CO 3 CO 2

13. BICARBONATE GENERATION IN KIDNEY STIMULATED  PCO 2 (BY RESP ACIDOSIS) &  - HCO3 (M. ACIDOSIS) B-B- Na+ CELL H2O HCO 3 - H+H+ H2O CO 3 B-B- HB HCO 3 -

14. PATHOPHYSIOLOGIC DISTURBANCES Lungs Disturbances of CO 2 = R. Centre Disturbance of H + +HCO 3 = Metabolic

15. Henderson - Hosselbalch EQUATION Proton Acceptor (Base) PH=PK+Log = -------------------------------- Proton Donor (Acid) - HCO 3 (Metabolic) PH=PK+Log = ---------------------------------- H 2 CO 3 or PCO 2 x 0.03 (Respiratory)

16. ACID-BASE DISTURBANCE  - HCO 3 PCO 2 x 0.03  MEATBOLICRESPIRATORY ACIDOSISALKALOSIS ACIDOSISALKALOSIS HCO 3  ---------------- PCO 2 x0.03 HCO 3  ---------------- PCO 2 x0.03 RATIO  HCO 3 ---------------- PCO 2 x0.03  HCO 3 ---------------- PCO 2 x0.03  

17. Metabolic acidosis = Respiratory acidosis = Metabolic alkalosis = Respiratory alkalosis = Defect HCO 3  ---------- PCO 2 HCO 3 ---------- PCO 2  HCO 3  ---------- PCO 2 HCO 3 ---------- PCO 2  Correction HCO 3  ---------- PCO 2  HCO 3  ---------- PCO 2  HCO 3  ---------- PCO 2  HCO 3  ---------- PCO 2 

18. CAUSES OF M. ACIDOSIS 1.Glomeralar failure. 2.Keto-acidosis. 3.Lactic acidosis. 4.Intestinal loss. 5.R. Tubular failure. 6.Actazolamide therapy. 7.R. Tubular acidosis. 8.Ureteric transplantation. 9.NH 4 Cl el therapy. Hyperkalamic M. Acidosis Variable Hyppkalamic Acidosis Hyperchloraemic Acidosis

19. SCREENING TESTS METABOLIC ACIDOSIS BLOOD GLUCOSE. URINE/ BLOOD KETONES. SERUM CHLORIDE. SERUM POTASSIUM

20. RESPIRATORY ACIDOSIS Acute Respiratory Failure.  Erythrocyte Chronic Respiratory Failure.  Renal Generation.

21. METABOLIC ALKALOSIS Administration of HCO 3. K+ depletion – Generation by kidney. Pyloric Stenosis.

22. RESPIRATORY ALKALOSIS Hysterical Over-breathing.  ICP. Brain Stem Injury. Hypoxia. Pulmonary Oedema. Lobar Pneumonia. Pulmonary Collapse. Excessive Artificial Ventilation.

23. BALANCE OF ACID-BASE NORMAL VALUES PCO 2  30-50mmHg or 4-6.6kPa.  >50mmHgrespiratory or 6.6kPaacidosis  <30mmHgrespiratory or 4kPaalkalosis PH  7.30 – 7.50  >7.50 alkalaemia.  <7.30 acidosis

24. BALANCE OF ACID-BASE RELATIONSHIP PCO 2 and PH. PCO 2 & ventilation. PO 2 and normal range. PO 2 and FIO 2. PCO 2, and temperature.

25. TERMINOLOGY ACIDAEMIA- PH<7.30 ALKAEMIA- PH>7.50. ACIDOSIS- Base Deficit Present. ALKALOSIS - Base Excess Present.

26. HOW TO ASSESS BLOOD GASES? STEP-1 Assessment of Acid-Base Balance. STEP-2 Assessment of Hypoxaemic State. STEP-3 Assessment of Tissue Oxygenation State.

27. STEP-1 Assessment of Acid-Base Balance CLASSIFICATION ACIDOSIS ALKALOSIS METABOLICRESPIRATORYMETABOLICRESPIRATORY ACUTE CHRONIC ACUTE CHRONIC ACUTE CHRONIC ACUTE CHRONIC

28. STEP-1 Assessment of Acid-Base Balance Acute- Uncompensated. Chronic- Compensated. -Fully. - Partially. COMPENSATED PH 7.30-7.50 DIAGNOSIS.

29. DIAGNOSIS SEQUENCE. PH. PCO 2. HCO 3. PH Normal 7.4 Compensated 7.3-7.5 PCO 3 Normal 40mmHg (5.3kPa) Compensated 30-50mmHg (4-6.6 kPa)

30. DIAGNOSIS IF PH LOW – acidosis.  Look at PCO 2.  If PCO 3 high - respiratory acidosis  If PH low - acidosis  Look at PCO 2  If it is normal or low.  Look at HCO3. It is low – metabolic acidosis. IF PH HIGH - alkalosis  Look at PCO 2.  If it is low - respiratory alkalosis  If PH high - PCO 2 normal or high.  Look at HCO3. High - metabolic alkalosis. NOW LOOK FOR COMPENSATION

31. Classification PHPCO 2 HCO 3 K+K+ ActualStandard Metabolic Uncompensated Compensated <7.3 7.3-7.4 N 30-40     Except Respiratory Uncompensated Compensated <7.3 7.3-7.4 >50 N  NN  Metabolic Uncompensated Compensated >7.5 7.4-7.5 N 40-50       Respiratory Uncompensated Compensated >7.5 7.4-7.5 <30 N  NN  ACIDOSISACIDOSIS ALKALOSISALKALOSIS Primary change

32. STEP-2 Hypoxaemic State Below 60 years of age:  Normal PO 2 = 97mmHg.  Acceptable range= >80mHg.  Mild hypoxiaemia= <80mmHg.  Moderate hypoxiaemia= <60mmHg.  Severe hypoxiaemia= <40mmHg.

33. STEP-2 Hypoxaemic State Above 60 years of age:  Subtract 1mmHg from minimal 80mmHg for every year over 60; this means acceptable range: 60 years = >80 mmHg. 70 years = >70 mmHg. 80 years = >70 mmHg. 90 years = >50 mmHg. New Born:  Acceptable = 40-70 mmHg.

34. STEP-2 Hypoxaemic State Oxygen Therapy FIO 2 x 5 = Expected PO 2. Uncorrected Hypoxaemia = PO 2 <Room Air Acceptable Limit. Corrected Hypoxaemia = PO 2 > Room Air Acceptable Limit. <100mmHg. Excessively Corrected Hypoxaemia = PO 2 >100mmHg < minimal predicted.

35. STEP-3 Assessment of Tissue Oxygenation 1.Cardiac Status. 2.Peripheral Perfusion Status. 3.Blood Oxygen Transport Mechanism. Depends on:  Vital Signs  Physical Examination.

36. STEP-3 Assessment of Tissue Oxygenation  BP.  Pulse Pressure.  Heart Rate  ECG.  Skin Color & Condition.  Capillary Fill.  Senosrium.  Electrolyte Balance.  Urine Out Put. If Above 1,2 Good Only 3 Interfering.  Arterial Oxygen Tension Po2.  Blood Oxygen Content.  Hb Oxygen Affinity.

37. SUMMARY ASSESS ACID/BASE STATUS. ASSESS HYPOXAEMIC STATE ASSESS TISSUE OXYGENATION. TRY TO FIND OUT THE CAUSE. SEE FOR THE NEED OF HCO 3.

38. SUMMARY Acidosis Metabolic Look at 1. Blood urea If  and K+   G.F. 2. Blood Glucose ket If  and K+  ketoacidosis. 3. PO2 If  K+   Lactic acidosis 4. Serum HCO3. If  only  H/o Therapy 5. If  K+   think of NH4Cl therapy + G. Transplantation 6. If Cl -  K +   Think of actazolamide therapy and R. Tubul Acidosis. 7. If Cl - N K +   Proximal Tubul Failure. OTHERWISE THINK ABOUT GIT INVOLVEMENT

39. SUMMARY Lung Functions will Help Respiratory METABOLIC Look at K+ & Cl- K+  Cl-  H/o vomiting Pyloric stenosis If K+  find cause. H/o bicarb therap. Alkalosis RESPIRATORY - H/o H. Injury - L. Infection - IPPV

40. BASE EXCESS/ DEFICIT “mEq of HCO3 that is excess/ deficit per litre of E. C. Water” PREDICTED RESPIRATORY PH? PCO 2 -- PH RELATIONSHIP  PCO 2 20mmHg =  0.1PH.  PCO 2 10mmHg =  0.1PH

41. BASE EXCESS/ DEFICIT 1.Calculate difference between measured PCO 2 and 40mmHg. Move decimal 2 places to left. 2.If PCO 2 > 40 subtract ½ difference from 7.4. 3.If PCO 2 < 40 add the difference to 7.40. PH 7.21 PCO 2 90  90-40 = 50 = 0.50 = 0.50x ½ = 0.25  7.40-0.25 =7.15 PH 7.47 PCO2 18  40-18 = 22= 0.22  7.40 + 0.22 =7.62 Predicted Resp PH.

42. DETERMINATION OF METABOLIC COMPONENT 10mEq/L variance from buffer base PH change of c-15 units. Move decimal 2 places to right i.e. 15 ratio 15:, 2:3=2/3 Measured PH - Predicted PH (resp) - metabolic PH change.

43. DETERMINATION OF METABOLIC COMPONENT 1.Determine PCO 2 variance. I.e. PCO 2 -40mmHg PCO 2. Move decimal 2 point to left. 2.Determine Predicted Resp. PH. 3.Measured PH – Predicted PH difference move decimal 2 places to rt. X 2/3=base excess/deficit. Base Excess = measured PH> predicted PH. Base Deficit = measured PH> predicted PH.

44. APPROXIMATE Na + & K + CONCENTRATION IN BODY FLUID PlasmaGastricBiliaryPancraticS. Intestine Na + K + 140 4 60 10 40 5 110 5 IlealIleost0myDiarrhoeaSweat 120 5 130 15 60 40 60 10

45. DOES TRADITIONAL BLOOD GAS ANALYSIS SERVES THE PURPOSE? PH PCO 2 PO 2 HCO 3

46. WHAT INFORMATION DOES IT GIVE? OXYGEN UPTAK CO 2 PRODUCTION ACIDITY/ ALKALINITY

47. WHAT INFORMATION IS REQUIRED FOR THERAPY? UPTAKE- O 2 uptake in lungs. TRANSPORT- from lungs to capillaries. RELEASE- from capillaries to tissues. HOW TO WE GET? DEEP PICTURE OF BLOOD GASES

48. O 2 UPTAKE MOUTH TO ALVEOLI “Grahams’ Law” of diffusion

49. O 2 UPTAKE Alveoli to Hb “Henrys’ Law” of diffusion

50. COMBINE BOTH LAWS Mouth to Alveoli Grahams’ Law of diffusion Alveoli to Hb Henrys’ Law of diffusion.

51. TRANSPORT TO CAPILLARIES DO 2 “ 520 - 720ml/min/m 2 ”

52. O 2 RELEASE TO TISSUE VO 2 “ 110 - 160ml/min/m 2 ”

53. WIHAT IS DEEP PICTURE? PCO 2. tHb. oS 2. O 2 Hb. ctO. p50. VO 2.

54. O 2 TRANSPORT AMOUNT OF HB. FRACTION OF OXYGENATED HB. O 2 TENSION.

55. MAJOR CHALLENGES Balancing O 2 Supply and O 2 Demand

56. O 2 CARRYING CAPACITY 98% Bound to Hb. 2% in plasma. Forms of hemoglobins. Oxygenated – O 2 Hb. Deoxygenated – RHb. Dyshaemoglobins.  Carboxyhaemoglobin (CoHb).  Methaemoglobin (MetHb). tHb = cO 2 Hb + cRHb + cCoHb + cMetHb

57. DEGREE TO WHICH Hb CARRIES O 2 Expressed in two Different Ways. 1. Fraction of Oxygenated Hb. cO 2 Hb O 2 Hb = ----------------------------------------------- cO 2 Hb + cRHb + cCoHb + cMetHb FRACTIONAL SATURATION 2. O2 Saturation. cO 2 Hb sO 2 = --------------------------- X 100 cO 2 Hb + cRHb

58. DEGREE TO WHICH Hb CARRIES O 2 “FUNCTIONAL SATURATION” Relationship between Oxygenated Hb (O 2 Hb) and Oxygen Saturation sO 2 ) O 2 Hb = sO 2 x (1-CoHb – cMetHb)

59. Example: Patient exposed to carbon monoxide tHb =10.0 mmol/L cO 2 Hb =07.7 mmol/L cRHb = 0.3 mmol/L cCoHb =2.0 mmol/L 7.7 mmol/L 0.77 cO 2 Hb = ---------------------------= ---------- (7.7+0.3+2.0) mmol/L (or 77%) 7.7 mmol/L sO 2 = -------------------------- X 100 = 96.25% (7.7+0.3) mmol/L

60. OXYGEN CONTENT ctO 2 = tHb x O 2 Hb + pO 2 x  DYSHAEMOGLOBINS BLOOD TRANSFUSION FIO 2

61. OXYGEN RELEASE cPO 2 + tPO 2 Capillary – tissue PO 2 Hb – O 2 affinity

62. Hb – OXYGEN AFFINITY 98%_____________________________ Normally the arterial blood is approximately 98% saturated with oxygen. 75%_________________ After release of oxygen to the tissue, mixed venous blood is approximately 75% saturated. A left shift of th ecurve <> A right sift of the curve Indicates impeded release of oxygen.Indicates facilitated release of O2. The Oxygen Dissociation Curve (ODC) depicts the relationship between sO2 and pO2. sO 2 (%) pO 2

63. The blood oxygen mL/100ml Absorption curve Depicts the Relationship between ctO 2 and pO 2. ctO 2 20 18 16 14 12 10 8 6 4 2 0 987654321987654321 2 4 6 8 1012 20 40 60 80 mmHg pO 2 kPa ctO 2 /(mmol/L a v PO 2

64. DEEP PICTURE CONTAINS INFORMATION on OXYGEN UPTAKE TRANSPORT RELEASE

65. Deep Picture Contains Information OXYGEN UPTAKE PaO 2 = 9.2 – 15.5 Kpa Q S Q T = 2-6% (PAO 2 – PaO 2 ) = 5 - 15mmHg Optimise Ventilation Optimise Specific Lung Disease Specific Lung Disease

66. Deep Picture Contains Information RELEASE PO 2 Gradient O 2 Dissociation Curve - Optimise Ventilation - Optimise Factors

67. Deep Picture Contains Information TRANSPORT tHb= 11.7–14.6G/dl-F = 13/8–16.4 G/dl-M O 2 Hb = 0.94 – 098  PO 2. CTO 2. Blood transfusion  RBC production Optimise Ventilation  Dyshaemoglobins