The Ventilatory Response to Acute Base Deficit in Humans

The time courses of ventilatory response to the development and correction of acute base-deficit acidosis were studied in 35 patients with cholera. In normal controls and during stable base deficit the steady-state relation between arterial PCO2 and [HCO-3]a was highly predictable. After both rapid development of base deficit (when mean [HCO-3]a fell 13 mEq/liter in 14 hr) and rapid correction (when mean [HCO-3]a increased 9 mEq/liter in 3 hr), ventilatory response lagged behind the change in [HCO-3]a and pHa. This resulted in a significant deviation of observed arterial PCO2 from the expected steady-state values. The magnitude of this deviation was influenced by both the magnitude and duration of change in [HCO-3]a. When [HCO-3]a remained stable, after either rapid development or correction of base deficit, ventilatory response reached steady-state level within 11 to 24 hr. When [HCO-3]a fell slowly (mean fall of 4 mEq/liter in 15 hr) or rose slowly (mean rise of 6 mEq/liter in 24 hr), a lag in ventilatory response was not demonstrable. The time courses of ventilatory response to both base loss and replacement were similar when both magnitude and duration of change in [HCO-3]a were considered.