A Comparison of the Ventilatory Response to Carbon Dioxide by Steady-State and Rebreathing Methods during Metabolic Acidosis and Alkalosis

Abstract

S U M M A R Y 1. The rebreathing and steady-state methods for assessing the response to inhaled carbon dioxide were compared in six normal subjects under control conditions and during metabolic acidosis and alkalosis.2. The slopes of the CO, response lines obtained with the two methods under control conditions were not significantly different.3. Metabolic acidosis and alkalosis produced a significant change in the intercept of the response line when this was assessed with the steady-state technique. The slope of the response lines did not change significantly in alkalosis but there was probably a small increase during acidosis. 4. Using the rebreathing technique there was no significant change in intercept in acidosis and alkalosis, but the slope varied significantly from control values. 5. It is concluded that the two methods of assessing the respiratory response to inhaled CO, are comparable under normal acid-base conditions. This similarity does not hold in metabolic changes of the acid-base state.

The effect of low‐dose acetazolamide on the ventilatory CO2 response curve in the anaesthetized cat.

“…Wagenaar a71d others 1973;Berkenbosch, Bovill, Dahan, DeGoede & Olievier, 1989). Furthermore, neither the Read technique nor conventional steady-state techniques are able to assess possible effects of drugs on the sensitivities of the peripheral and central chemoreflex loops separately from each other.…”

On a pseudo‐rebreathing technique to assess the ventilatory sensitivity to carbon dioxide in man.

“…This has been demonstrated by Linton, Poole-Wilson, Davies & Cameron (1973) in a study on the effect on ventilation of chronic acid-base disturbances in man, and more recently by Bourke & Warley (1989) in a study on the effects of morphine on ventilation.…”

Blunted Hypercapnic Respiratory Drive Response in Subjects With Late-Onset Pompe Disease

“…23 In normal subjects, the slope of the CO 2 response line during steady-state CO 2 inhalation was unaffected by chronic alkalosis and acidosis. [24][25][26] Using the rebreathing technique, there was no significant change in intercept in acidosis and alkalosis, but the slope (⌬V E /⌬P CO 2 ) varied from the control values. The mean slope value during alkalosis (pH 7.44 Ϯ 0.02, plasma HCO 3 Ϫ 28.5 Ϯ 3.0 mmol/L) was 0.6 times the average baseline.…”

“…The mean slope value during alkalosis (pH 7.44 Ϯ 0.02, plasma HCO 3 Ϫ 28.5 Ϯ 3.0 mmol/L) was 0.6 times the average baseline. 26 To our knowledge, a flat ⌬P 0.1 /⌬P CO 2 slope response has not been described in the setting of metabolic alkalosis. Thus, a combination of factors can lead to abnormal patterns of breathing and hypoventilation in these disorders; no single pathophysiologic mechanism can explain all of the abnormalities.…”