A 76-year-old woman is admitted to the intensive care unit with severe, poorly localized abdominal pain out of proportion to physical examination findings, accompanied by bloody diarrhea. Her medical history is significant for atrial fibrillation. She is hypotensive and tachycardic. Laboratory testing reveals a serum lactate of mmol/L. Arterial blood gas and basic metabolic panel results are as follows:
| Laboratory test | Result |
|---|---|
| Serum sodium | mEq/L |
| Serum chloride | mEq/L |
| Serum bicarbonate | mEq/L |
| Arterial |
The physician determines that the patient has a primary high anion gap metabolic acidosis secondary to suspected acute mesenteric ischemia. According to Winter's formula, what is the exact calculated midpoint of the target expected arterial (in mmHg) representing appropriate respiratory compensation?
Answer: 29 mmHg
Answer
29
In the setting of a primary metabolic acidosis, the lungs compensate by increasing ventilation to blow off , thereby raising the toward normal. Winter's formula () is used to determine if this respiratory response is appropriate. For this patient with a serum bicarbonate of mEq/L, the calculated midpoint of the target is mmHg. If the measured on an arterial blood gas were significantly higher than this target range ( mmHg), a concomitant respiratory acidosis would be present; if significantly lower, a concomitant respiratory alkalosis would be present.
Step-by-Step Solution
Key Concept
Calculating expected respiratory compensation for metabolic acidosis using Winter's formula