الجواب: Case 1 Q 1: What are the critical course of events likely to occur in altering his acid-base status? Q 2: What Acid base abnormalities would you expect based on this information? Answers Q 1: What are the critical course of events likely to occur in altering his acid-base status? • Loss of fluid • Loss of bicarbonate • Loss of K Q 2: What Acid base abnormalities would you expect based on this information? These should lead to Metabolic acidosis ________________________________________ Let us next evaluate his Electrolytes and Blood gases Q3: What is the acid base disturbance? Q4: What is the basis for your conclusion? Answers Q3: What is the acid base disturbance? Metabolic acidosis Q4: What is the basis for your conclusion? • pH is low hence acidemic • Bicarbonate is low hence metabolic Let us next evaluate his : Anion gap Q5: What is the anion gap in this patient? Q6: What is the normal range? Q7: list conditions of Metabolic acidosis with similar anion gap as this patient? Answers Q5: What is the anion gap in this patient? The anion gap is 10 It is calculated using the following formula Na-(Chloride+Bicarb) 133-(118+5)=10 Q6: What is the normal range? Normal range for anion gap is: 8-12 Q7: Metabolic acidosis with normal anion gap is encountered in Renal disease • Proximal or distal RTA • Renal insufficiency (HCO3 loss) • Hypoaldosteronism / K+ sparing diuretics Loss of alkali • Diarrhea • Ureterosigmoidostomy Ingestions • Carbonic anhydrase inhibitors Let us next evaluate whether the compensatory effort is adequate: Q 8: Why is his CO2 levels are low? Q 9: Is the level of respiratory compensatory effort appropriate? Q 10: Can respiratory system fully compensate for metabolic acidosis? Answers Q 8: Why is his CO2 levels are low? Acidosis is a strong stimulant to the respiratory center in medulla. pCO2 is index of alveolar ventilation. Q 9: Is the level of respiratory compensatory effort appropriate? Yes. We can predict CO2 levels for a given acidotic pH by the following methods. • The expected decrement in CO2 is 1.2x(25-5)=1.2x20=24. • CO2 levels is close to the decimal number of pH e.g. for a pH of 7.11 the expected CO2 is 11 mm Hg. We see an appropriate level of hyperventilation in an attempt to compensate for Metabolic acidosis indicating a normal respiratory system. This type of assessment is necessary to detect mixed defects. Q 10: Can respiratory system fully compensate for metabolic acidosis? Respiratory compensation for metabolic acidosis is never complete. ________________________________________ Ventilation and pCO2 relationship Interrelationship between pH and pCO2 Respiratory compensation for Metabolic acid base disturbance ________________________________________
Posted on: Sun, 28 Dec 2014 14:23:02 +0000
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