Buffering of hypercapnic acidosis by sodium carbonate

¹ Columbia University, College of Physicians and Surgeons, New York City

Eight dogs were given 0.15–0.18 m solution of Na₂CO₃ i.v. during 1 hr of apneic oxygenation. Arterial blood pH was maintained within .1 unit of normal, whereas cerebrospinal fluid pH fell from 7.39 to 7.01. Pa_COCO2 increased from 31 to 153 mm Hg, plasma HCO^–₃ from 18.3 to 72.7 mm/liter, Na⁺ from 147 to 182 mEq/liter, and osmolality from 336 to 407 mOs/liter. In the cerebrospinal fluid HCO^–₃ rose only from 21.5 to 30.6 mm/liter. Diuresis was maintained, but the rate of urine excreted during apnea was always lower than the rate of fluid given. Bradycardia, ECG alterations, and extreme variations in blood pressure were observed during apneic oxygenation. Cerebrospinal fluid pressure increased, as did plasma catecholamine levels and blood sugar. Two animals died shortly after the end of the experiment. Na₂CO₃ administration while maintaining blood pH constant did not offset the circulatory disturbances created by the acid load of apneic oxygenation.