George Robert, MD(*) and K Padmanabhan, MD. Coney Island Hospital, Brooklyn, NY.
PURPOSE: To determine if use of Diamox in patients(pts) with Compensated Respiratory Acidosis (CRA) whose alveolar hypoventilation was out of proportion to the severity of their causative disorder, would improve ventilation by a reduction of serum bicarbonate(HCO3) resulting in a reduction of CSF HCO3 thereby causing CSF acidosis leading to improved respiratory center drive.
METHODS: 4 pts(3 COPD & 1 Obesity - Hypoventilation) with CRA and stable respiratory status were identified on the basis of having alveolar hypoventilation out of proportion to their baseline lung function. Pts selected had serum HCO3 over 40meq/L and serum pH between 7.30 and 7.34. All pts had spirometry and ABG before and after diamox (250 mg BID), for 4 doses. Changes in PCO2, HCO3, and pH were recorded. Out of the 4 pts, one had 2 events recorded at different times.
RESULTS: PCO2 and HCO3 decreased by a mean of 23mm of Hg and 12 meq/L respectively, without significant changes in pH or FEV1.
CONCLUSION: In some pts, with compensated respiratory acidosis diamox can safely be used to increase alveolar ventilation by decreasing total body HCO3.
CLINICAL IMPLICATIONS: The presence of compensated respiratory acidosis does not preclude a trial of diamox in an attempt to improve ventilation in pts where alveolar hypoventilation is out of proportion to the severity of the underlying disease.
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