Total CO₂, Pco₂, and pH in human spinal fluid

¹ Cardiopulmonary Laboratory, Mt. Alto Veterans Administration Hospital; and Department of Medicine, Georgetown University School of Medicine, Washington, D. C.

The relationships between pH, CO, tension and total CO₂ in spinal fluid and arterial blood were explored in 12 normal individuals and 15 patients with various diseases. It was found that, in the normal subjects, the pH in the spinal fluid was constant, with a mean of 7.31 and 99 % confidence interval of 7.29–7.33. The pH in the spinal fluid was lower than that of the arterial blood in all patients studied, whereas the CO₂ tension was found to average 4 mm Hg higher in the spinal fluid than in the arterial blood in most of the normal subjects studied. The pK₁' was calculated for each patient's spinal fluid and arterial blood by the Henderson-Hasselbalch equation. In contrast to tonometry experiments, pK₁' showed marked individual variations. The factors responsible for these variations are delineated.