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Interpretation of blood gases

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Interpretation of blood gases

  1. 1. Interpretation of bloodInterpretation of blood gasesgases
  2. 2. Kidney fixes respiratory derangement, except if kidney malfunctioning occur (e.g. sepsis, dehydration, prematurity or renal pathology) Lung fixes metabolic derangement, except if lung malfunctioning occur (e.g. infection, ARDS, or any lung pathology ) Renal mechanism is slow, that’s why respiratory derangement is slowly fixed. While, respiratory mechanism is fast, that’s why metabolic derangement is rapidly fixed. Fixation ( compensation ) never brings acid-base balance to normal, but near normal Hassel Bach equation: pH = 6.2 + log ( Bicarbonate / PaCO2) For simplification: pH = B/C by dr M Osama Husseinby dr M Osama Hussein
  3. 3. Compensation is an evidence of chronicity During compensation, bicarbonates & PaCO2 follow each other, so, both are changed & in the same direction. The one with the bigger magnitude of change, is the one who started the derangement ( the chronic element which is to be compensated, confirm with the resultant pH). The one with the lesser magnitude of change, is the compensating element. Bicarbonates & PaCO2 serve the pH ( 2 servants & 1 lady ). Bicarbonates & base deficit are nearly the same in both arterial & venous samples. by dr M Osama Husseinby dr M Osama Hussein
  4. 4. According to the equation: B pH= C C = CO2 B= bicarbonate by dr M Osama Husseinby dr M Osama Hussein
  5. 5. NORMAL VALUES Arterialized Capillary & Arterial Samples Venous Samples PH 7.35 - 7.45 7.25 - 7.35 PO2 70 - 90 mmHg 60 - 80 mmHg PCO2 35 - 45 mmHg 45 - 45 mmHG Bicarbonates 18 - 25 meq/L Don't complete reading & interpretation of the result of the blood gas analysis when pH is within the normal range. by dr M Osama Husseinby dr M Osama Hussein
  6. 6. Derangement pH B & C Acute Affected Only one is affected Chronic Minimally affected (near normal) Both are affected, in the same direction, following each other. Mixed Highly affected Both are affected, in opposite directions, not following each other. Derangement Where is the error? Metabolic Error in the Metabolite: Bicarbonate (B) Respiratory Error in the Respiratory gas: PaCO2 (C) Derangement pH H+ AcidosisAcidosis LowerLower than normal rangethan normal range HigherHigher H ionsH ions AlkalosisAlkalosis HigherHigher than normal rangethan normal range LowerLower H ionsH ions by dr M Osama Husseinby dr M Osama Hussein
  7. 7. Acute Metabolic Acidosis ▼▼ B --------------- ◄► C = ▼▼ pH Acute Respiratory Acidosis ◄► B --------------- ▲▲ C = ▼▼ pH Acute Metabolic Alkalosis ▲▲ B --------------- ◄► C = ▲▲pH Acute Respiratory Alkalosis ◄► B --------------- ▼▼ C = ▲▲ pH pH is affected, Only B or C is affected In metabolic derangement: B goes with pH In respiratory derangement: C goes the opposite direction. ACUTE DERANGEMENTS by dr M Osama Husseinby dr M Osama Hussein
  8. 8. CHRONIC (COMPENSATING) DERANGEMENTSCHRONIC DERANGEMENT Compensated by ACUTE DERANGEMENT ► RESULTANT Chc. Met. Acidosis + Ac. Resp. Alkalosis ▼▼▼B ----------- = ▼▼▼pH ◄►C + ◄►B ----------- = ▲▲pH ▼▼C ► ▼▼▼B ----------- = ▼pH ▼▼C Chc. Resp. Acidosis + Ac. Met. Alkalosis ► ? ◄►B ----------- = ▼▼▼pH ▲▲▲C + ▲▲B ----------- = ▲▲pH ◄►C ► ▲▲B ----------- = ▼pH ▲▲▲C Chc. Met. Alkalosis + Ac. Resp. Acidosis ► ? ▲▲▲B ----------- = ▲▲▲pH ◄►C + ◄►B ----------- = ▼▼pH ▲▲C ► ▲▲▲B ----------- = ▲pH ▲▲C Chc. Resp. Alkalosis + Ac. Met. Acidosis ► ? ◄►B ----------- =▲▲▲pH ▼▼▼C + ▼▼B ----------- =▼▼pH ◄►C ► ▼▼B ----------- =▲pH ▼▼▼C .. by dr M Osama Husseinby dr M Osama Hussein
  9. 9. CHRONIC DERANGEMENT Compensated by ACUTE DERANGEMENT ► RESULTANT Chc. Met. Acidosis + Ac. Resp. Alkalosis ▼▼▼B ----------- = ▼▼▼pH ◄►C + ◄►B ----------- = ▲▲pH ▼▼C ► ▼▼▼B ----------- = ▼pH ▼▼C Chc. Resp. Acidosis + Ac. Met. Alkalosis ◄►B ----------- = ▼▼▼pH ▲▲▲C + ▲▲B ----------- = ▲▲pH ◄►C ► ▲▲B ----------- = ▼pH ▲▲▲C Chc. Met. Alkalosis + Ac. Resp. Acidosis ► ? ▲▲▲B ----------- = ▲▲▲pH ◄►C + ◄►B ----------- = ▼▼pH ▲▲C ► ▲▲▲B ----------- = ▲pH ▲▲C Chc. Resp. Alkalosis + Ac. Met. Acidosis ► ? ◄►B ----------- =▲▲▲pH ▼▼▼C + ▼▼B ----------- =▼▼pH ◄►C ► ▼▼B ----------- =▲pH ▼▼▼C .. by dr M Osama Husseinby dr M Osama Hussein
  10. 10. CHRONIC DERANGEMENT Compensated by ACUTE DERANGEMENT ► RESULTANT Chc. Met. Acidosis + Ac. Resp. Alkalosis ▼▼▼B ----------- = ▼▼▼pH ◄►C + ◄►B ----------- = ▲▲pH ▼▼C ► ▼▼▼B ----------- = ▼pH ▼▼C Chc. Resp. Acidosis + Ac. Met. Alkalosis ◄►B ----------- = ▼▼▼pH ▲▲▲C + ▲▲B ----------- = ▲▲pH ◄►C ► ▲▲B ----------- = ▼pH ▲▲▲C Chc. Met. Alkalosis + Ac. Resp. Acidosis ▲▲▲B ----------- = ▲▲▲pH ◄►C + ◄►B ----------- = ▼▼pH ▲▲C ► ▲▲▲B ----------- = ▲pH ▲▲C Chc. Resp. Alkalosis + Ac. Met. Acidosis ► ? ◄►B ----------- =▲▲▲pH ▼▼▼C + ▼▼B ----------- =▼▼pH ◄►C ► ▼▼B ----------- =▲pH ▼▼▼C .. by dr M Osama Husseinby dr M Osama Hussein
  11. 11. pH is mildly affected, Both B & C are affected in the same direction, (following each other( CHRONIC DERANGEMENT Compensated by ACUTE DERANGEMENT ► RESULTANT Chc. Met. Acidosis + Ac. Resp. Alkalosis ▼▼▼B ----------- = ▼▼▼pH ◄►C + ◄►B ----------- = ▲▲pH ▼▼C ► ▼▼▼B ----------- = ▼pH ▼▼C Chc. Resp. Acidosis + Ac. Met. Alkalosis ◄►B ----------- = ▼▼▼pH ▲▲▲C + ▲▲B ----------- = ▲▲pH ◄►C ► ▲▲B ----------- = ▼pH ▲▲▲C Chc. Met. Alkalosis + Ac. Resp. Acidosis ▲▲▲B ----------- = ▲▲▲pH ◄►C + ◄►B ----------- = ▼▼pH ▲▲C ► ▲▲▲B ----------- = ▲pH ▲▲C Chc. Resp. Alkalosis + Ac. Met. Acidosis ◄►B ----------- =▲▲▲pH ▼▼▼C + ▼▼B ----------- =▼▼pH ◄►C ► ▼▼B ----------- =▲pH ▼▼▼C by dr M Osama Husseinby dr M Osama Hussein
  12. 12. pH is markedly affected, Both B & C are affected, but in 2 different directions (away from each other( MIXED DERANGEMENTS Metabolic Derangement plus Respiratory Derangement ► Resultant Metabolic Acidosis + Respiratory Acidosis ► Mixed Acidosis ▼▼B ----------- = ▼▼pH ◄►C + ◄►B ----------- = ▼▼pH ▲▲C ► ▼▼B ▼ ----------- = ▼ ▼ pH ▲▲ C ▼ Metabolic Alkalosis + Respiratory Alkalosis ► Mixed Alkalosis ▲▲B ----------- = ▲▲pH ◄►C + ◄►B ----------- = ▲▲pH ▼▼C ► ▲▲B ▲ ----------- = ▲▲ pH ▼▼C ▲ by dr M Osama Husseinby dr M Osama Hussein
  13. 13. CORRECTION OF METABOLIC ACIDOSISCORRECTION OF METABOLIC ACIDOSIS pH < 7.2 (7.25( Bicarb. < 15 meq/L BE > -10 meq/L Contraindicated when there is Hypercarbia CO2 wash can br induced by increasing RR either on ventilator, or applying few breaths by the Ambu bag. by dr M Osama Husseinby dr M Osama Hussein
  14. 14. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL by dr M Osama Husseinby dr M Osama Hussein
  15. 15. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B ----------- ◄►C PH ▼▼ Ac. Met. Acidosis by dr M Osama Husseinby dr M Osama Hussein
  16. 16. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B ----------- ◄►C PH ▼▼ Ac. Met. Acidosis 7.25 ◄ 20 ► ▲ 60 ▲ ◄►B ----------- ▲▲C PH ▼▼ Ac. Resp. Acidosis by dr M Osama Husseinby dr M Osama Hussein
  17. 17. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B ----------- ◄►C PH ▼▼ Ac. Met. Acidosis 7.25 ◄ 20 ► ▲ 60 ▲ ◄►B ----------- ▲▲C PH ▼▼ Ac. Resp. Acidosis 7.55 ▲ 30 ▲ ◄ 40 ► ▲▲B ----------- ◄►C ▲▲ pH Ac. Met. Alkalosis by dr M Osama Husseinby dr M Osama Hussein
  18. 18. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.25 ▼ 10 ▼ ◄ 40 ► ▼▼B ----------- ◄►C PH ▼▼ Ac. Met. Acidosis 7.25 ◄ 20 ► ▲ 60 ▲ ◄►B ----------- ▲▲C PH ▼▼ Ac. Resp. Acidosis 7.55 ▲ 30 ▲ ◄ 40 ► ▲▲B ----------- ◄►C ▲▲ pH Ac. Met. Alkalosis 7.55 ◄ 20 ► ▼ 20 ▼ B ----------- ▼▼C ▲▲ pH Ac. Resp. Alkalosis by dr M Osama Husseinby dr M Osama Hussein
  19. 19. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.3 10▼▼ 30▼ ▼▼B ----------- ▼C pH▼ Chr. Met. Acidosis & Ac. Resp. Alkalosis by dr M Osama Husseinby dr M Osama Hussein
  20. 20. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.3 10▼▼ 30▼ ▼▼B ----------- ▼C pH▼ Chr. Met. Acidosis & Ac. Resp. Alkalosis 7.3 ▲26 ▲60▲ ▲B ----------- ▲▲C pH▼ Chr. Res. Acidosis & Ac. Met. Alkalosis by dr M Osama Husseinby dr M Osama Hussein
  21. 21. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.3 10▼▼ 30▼ ▼▼B ----------- ▼C pH▼ Chr. Met. Acidosis & Ac. Resp. Alkalosis 7.3 ▲26 ▲60▲ ▲B ----------- ▲▲C pH▼ Chr. Res. Acidosis & Ac. Met. Alkalosis 7.5 ▲30▲ ▲50 ▲▲B ----------- ▲C ▲ pH Chr. Met.Alkalosis & Ac. Resp. Acidosis by dr M Osama Husseinby dr M Osama Hussein
  22. 22. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.3 10▼▼ 30▼ ▼▼B ----------- ▼C pH▼ Chr. Met. Acidosis & Ac. Resp. Alkalosis 7.3 ▲26 ▲60▲ ▲B ----------- ▲▲C pH▼ Chr. Res. Acidosis & Ac. Met. Alkalosis 7.5 ▲30▲ ▲50 ▲▲B ----------- ▲C ▲ pH Chr. Met.Alkalosis & Ac. Resp. Acidosis 7.5 13▼ ▼20▼ ▼B ----------- ▼▼C ▲ pH Chr. Res. Alkalosis & Ac. Met. Acidosis by dr M Osama Husseinby dr M Osama Hussein
  23. 23. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.1 ▼10▼ ▲60▲ ▼▼B --------- ▲▲C ▼▼ pH ▼▼ Mixed Acidosis by dr M Osama Husseinby dr M Osama Hussein
  24. 24. pH Bicarb. PCO2 ? B ----------- ? C pH? Derangement How you Should feel? 7.4 20 40 ◄►B ----------- ◄►C ◄ pH ► NORMAL 7.1 ▼10▼ ▲60▲ ▼▼B --------- ▲▲C ▼▼ pH ▼▼ Mixed Acidosis 7.6 ▲30▲ ▼20▼ ▲▲B --------- ▼▼C ▲▲ pH ▲▲ Mixed Alkalosis by dr M Osama Husseinby dr M Osama Hussein
  25. 25. by dr M Osama Husseinby dr M Osama Hussein

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