Elimination of CO 2 in patients with carbonic anhydrase II deficiency, with studies of respiratory function at rest

Abstract

We evaluated the elimination of CO 2 in three Japanese adults with carbonic anhydrase II (CA II) deficiency, as compared with that in 10 healthy volunteers. The patients had no signs of respiratory distress. Heart rate, body temperature, ventilation volume, respiratory rate and (a — ET) PCO 2 were found to be higher and PaCO 2 tended to be higher in the patients than those in the volunteers, while forced vital capacity (FVC), forced expiratory volume in 1s (FEV 1), tidal volume, end-tidal PCO 2 ( P etCO 2), pH and HCO 3 − in arterial blood were lower in the patients. All three patients had non-anion-gap metabolic acidosis, due to renal losses of bicarbonate, but with virtually no compensatory reduction in PaCO 2. However, the high V̇ e and PaO 2 suggested that respiratory compensation for this metabolic acidosis was occuring, the elimination of CO 2 was possibly facilitated by the presence of other carbonic anhydrase isoenzymes in the pulmonary capillaries. Thus, CA II deficiency causes mild to moderate impairments in CO 2 elimination.