THE RELATIONSHIP BETWEEN ARTERIAL Pco, A N D HYDROGEN ION CONCENTRATION IN CHRONIC METABOLIC ACIDOSIS A N D ALKALOSIS

In 1917 J. P. Peters first recognized that the ventilatory response to metabolic acidosis could be monitored by following the changes in the alveolar carbon dioxide partial pressure. In addition he showed that in stable states of acidosis there was a close relationship between alveolar Pco, and the CO, combining power of the blood. More recently technical refinements have facilitated measurements of pH and PCO, in arterial blood and further attempts have been made to define the normal ventilatory response in patients with metabolic acidosis and alkalosis in terms of the relationship which exists, in arterial blood, between Pco, and pH (or [H']) or between Pco, and plasma bicarbonate concentration ([HC03-]). On the basis of such clinical studies linear relationships have been described between PCO, and [H'] (Albert, Dell & Winters, 1967; Flenley, 1971a, b) and between Pco, and [HCO,-] (Elkington, 1966; Albert et al., 1967; Pierce, Fedson, Brigham, Mitra, Sack & Mondal, 1970; Van Ypersele de Strihou & Frans, 1970) and these have been generally accepted. Correspondence: Dr Anne T. Lambie, Medical Renal Unit, Royal Infirmary, Edinburgh EH3 9YW.