Changes in Arterial Carbon Dioxide Tension and Arterio-Venous Difference in Oxygen Content with pH during Metabolic Acidosis
The decrease in arterial pH (pH(a)) during metabolic acidosis stimulates ventilation. Knowledge of the magnitude and time course of this response is important for the assessment of acid-base disturbances from pH, pCO2 and cHCO3 - 1,2 and for the treatment of these disturbances. However, the time course is still a matter of controversy. Owing to the poor permeability of the blood brain barrier to H+ and HCO3 - it has been generally assumed that there is a time lag in the ventilatory response to metabolic acidosis3. Some authors 4,5 have indeed found a further decrease in arterial pCO2 (pCO2(a)) when after induction of metabolic acidosis by means of intravenously administered HCl, pH(a) was kept low by additional administration of HCl. However, in recent years it has been demonstrated that in dogs and cats a fast exchange of HCO3 - across the blood brain barrier is possible 6,7. In agreement with this fast exchange, Kaehny and Jackson found no time lag in the ventilatory response to metabolic acidosis in an investigation in dogs about the role of the peripheral chemoreceptors8.
KeywordsBlood Brain Barrier Metabolic Acidosis Recovery Phase Maintenance Phase Induction Phase
Unable to display preview. Download preview PDF.
- 2.O. Siggaard-Andersen, The acid-base status of the blood, Munksgaard, Copenhagen (1976).Google Scholar
- 10.H. Winterstein, and N. Gökhan, Ammoniumchlorid-Acidose und Reactionstheorie der Atmungsregulation. Arch.Intern.Phar-macodyn.Ther. 93: 212 (1953).Google Scholar
- 11.H.H. Loeschcke, and K. Sugioka, pH of cerebrospinal fluid in the cisterna magna and on the surface of the choroid plexus of the 4th ventricle and its effect on ventilation in experimental disturbances of acid balance transients and steady states. Pflügers Arch. 312: 161 (1969).PubMedCrossRefGoogle Scholar