1 / 32

Approach to Acid Base Disorder

Approach to Acid Base Disorder. By Dr. S. Shivakumar, M.D. Addl.Professor of Medicine, Stanley Medical College, Chennai. Normal Values. pH : 7.36 – 7.44 (7.40) plasma HCO 3 : 24 – 26 mEq/L (25) pCo 2 : 39 – 43 (40) plasma (H + ) : 36 – 44 nEq / L (40 nEq / L)

laura-vincent
Télécharger la présentation

Approach to Acid Base Disorder

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Approach to Acid Base Disorder By Dr. S. Shivakumar, M.D. Addl.Professor of Medicine, Stanley Medical College, Chennai.

  2. Normal Values • pH : 7.36 – 7.44 (7.40) • plasma HCO3: 24 – 26 mEq/L (25) • pCo2 : 39 – 43 (40) • plasma (H+) : 36 – 44 nEq / L (40 nEq / L) • pH < 7.2 : Severe Acidosis • pH > 7.6 : Severe Alkalosis • pH : 7.0 = 1 x 10 – 7 (1 x 1/107) = 100 x 10 – 9 = 100 nEq / L • Na & K : 10 – 3 = mEq

  3. Correlation between H+ ion & pH Change in 0.3 pH  Double or Halve the H+

  4. Within narrow limits 0.01 change in pH ~ 1 mEq / L change of [H+] Estimating the H+ ion from pH X 0.8  1.25

  5. Approach • Step I : Check validity • Step II : Obtain Minimum diagnosis • Step III: Is it a Simple or Mixed acid base disorder • Step IV : Determine Anion gap • Step V : Is it a Triple disorder

  6. SuggestionsStep I. Check validity : (Modified Henderson equation) H = 24 x Pco2 Hco3 H = 24 x 40 24 = 40 nEq = pH = 7.4 eg:pH= 7.0 HC03= 8 PCo2 = 32   H = 24 x 32 8 = 96 nEq = pH 7.0

  7. Step II:Obtain minimum diagnosis • Look at pH - Acidosis / Alkalosis • Match the Pco2 or Hco3 - Metabolic / Respiratory

  8. Examples of Simple Disorder

  9. Step III:Is it a simple or mixed Acid-base disorder? Simple Disorder :

  10. Mixed Disorder

  11. Apply Compensation

  12. Example pH : 7.00 Pco2 = 32 Hco3 = 8 Fall in Hco3 = 24 – 8 = 16 Compensatory Fall in Pco2 = 16 x 1.2 = 19 Anticipated Pco2 = 40 – 19 = 21 Estimated : Pco2 = 32 (Pco2  ) Diagnosis Mixed - Metabolic acidosis + Respiratory acidosis

  13. Mixed acid base disorder

  14. Mixed acid base disorder

  15. Examples of mixed acid base disorder

  16. Step IV: Determine the Anion gap AG = Na+– (Hco3 + Cl ) Normal = 12 ± 4 ( 8  16 ) Valuable in Metabolic acidosis – High gap / Normal gap Metabolic alkalosis – Evaluation of “Starting Hco3” High gap acidosis : AG > 27 mEq /L 17  26 Suggestive Eg.– Ketoacidosis, Lactic acidosis, Methanol intoxication, Renal failure Normal gap acidosis – Diarrhoea, RTA

  17. AG in metabolic alkalosis • Valuable in diagnosis of Triple disorder (Metabolic acidosis,Met.alkalosis & Resp. acidosis) • Delta () AG = Calculated Anion gap – Normal Anion gap Hco3 +AG = Starting Hco3 • Starting Hco3 > 29 suggests associated Metabolic Alkalosis in the presence of Metabolic Acidosis

  18. Example Na+ = 135 Hco3 = 4cl = 90 pH = 6.8 AG = Na  ( Hco3 + cl ) = 135 – (4 + 90) = 41  High gap acidosis AG = Calculated – AG Normal = 41 – 12 = 29 Starting Hco3 = 4 + 29 = 33 mEq / L Starting Hco3 > 29 suggests associated Metabolic Alkalosis in the presence of Metabolic Acidosis

  19. Approach with an Example A 50 year old male suffering from COPD & vomiting is admitted for breathlessness. Biochemical parameters

  20. Approach with an Example(contd) Step 1 :Check Validity H = 24 X Pc02 = 24 X 22 = 155 nEq / L = pH 6.8 Hco3 3.4 Step 2:Obtain minimum diagnosis pH = 6.8 Pco2 = 22 Hco3= 3.4  Metabolic acidosis

  21. Approach with an Example(contd) Step 3: Is it a Simple or Mixed Acid base disturbance By applying compensation (24  3.4 = 20.6 ; 20.6  1.2 = 24.7; 40  24.7 = 15.3) Predicted Pco2 = 15.3, butObserved Pco2= 22 Mixed disorder Metabolic Acidosis + Respiratory Acidosis

  22. Approach with an Example (contd) Step 4: Determine Anion Gap Na = 135 Cl = 90 Hco3 = 3.4 AG = 135 – (3.4 + 90) = 41.6 • High Gap acidosis

  23. Approach with an Example (contd) Step 5: Is it a triple disorder Look for metabolic acidosis with AG AG = Calculated AG - AG normal = 41.6 - 12.0 = 29.6 Starting Hc03 = Hco3+ AG = 3.4 + 29.6 = 33 mEq /L (Metabolic alkalosis)

  24. Diagnosis pH= 6.8 Pco2 = 22 Hco3 = 3.4 Po2 = 60 Na+ = 135 k += 6.0 Cl= 90 Urea= 110 S.Cr= 3mg/dl Sugar = 100 mgs Triple Disorder = Metabolic acidosis + Resp.acidosis + Met.alkalosis • Metabolic acidosis – Renal failure • Respiratory acidosis – COPD • Metabolic alkalosis – Vomiting

  25. A 40 yr old man is admitted for diarrhoea & breathlesness for 2 days. Example –1 • Diagnosis: Normal AG Met.Acidosis (AG – 11) • Due to Diarrhoea + Hypokalemia,

  26. A 40 yr old man is admitted for diarrhoea of 1 week & breathlesness of 1 day Example –2 • Diagnosis:High gap Acidosis (AG - 29) • Due to Renal failure + Hyperkalemia

  27. A 45 yr old female is admitted for high fever & breathlessness, diagnosed to have acute Cholecystitis Example –3 • (Predicted pCo2 – 18, but observed pCo2 – 12) • Diagnosis: Metabolic acidosis + Respiratory Alkalosis Due to sepsis

  28. A 50 yr old Pt., a known case of COPD is admitted for severe diarrhoea Example –4 • (Predicted pCo2 – 25, but observed pCo2 – 40) • Diagnosis: Respiratory Acidosis (COPD ) + Metabolic acidosis (Diarrhoea)

  29. A 50 yr old, known COPD Pt. with Cor pulmonale on treatment with Frusemide and is admitted for severe vomitting. Example –5 • (Predicted pCo2 – 54, but observed pCo2 – 80) • Diagnosis: Respiratory Acidosis (COPD ) + Metabolic Alkalosis (Vomiting + Diuretics)

  30. A 50 yr old Pt. with Cirrhosis Liver is admitted for coma & Vomitting. He has been treated with Frusemide recently for ascites. Example –6 • (Predicted Hco3– 20, but observed Hco3– 40) • Diagnosis: Respiratory Alkalosis (Cirrhosis ) + Metabolic Alkalosis (Vomitting + Diuretics)

  31. Summary • Suspect the diagnosis from history • Suspect the disturbance from physical symptoms • Evaluate routine laboratory date : Sugar, RFT, LFT, Na+, K+ • Establish the cause of Acid Base disorder (Utilize thoughtful differential diagnosis), • Direct management of underlying disorder, unless pH is in a dangerous range

  32. Thank You

More Related