Three different protocols for assessing acute hypoxic ventilatory response yielded significantly different mean sensitivities (1.02, 1.15, and 0.93 l/min/%; P<0.01) and significant physiological variation.
While there is little systematic variation between different protocols for measuring acute hypoxic ventilatory response, the response exhibits significant physiological variation over time.
valor p: p=<0.01
Measurement of the acute hypoxic ventilatory response (AHVR) requires careful choice of the hypoxic stimulus. If the stimulus is too brief, the response may be incomplete; if the stimulus is too long, hypoxic ventilatory depression may ensue. The purpose of this study was to compare three different techniques for assessing AHVR, using different hypoxic stimuli, and also to examine the between-day variability in AHVR. Ten subjects were studied, each on six different occasions, which were >/=1 wk apart. On each occasion, AHVR was assessed using three different protocols: 1) protocol SW, which uses square waves of hypoxia; 2) protocol IS, which uses incremental steps of hypoxia; and 3) protocol RB, which simulates an isocapnic rebreathing test. Mean values for hypoxic sensitivity were 1.02 +/- 0.48, 1.15 +/- 0.55, and 0.93 +/- 0.60 (SD) l. min(-1). %(-1) for protocols SW, IS, and RB, respectively. These differed significantly (P < 0.01). The coefficients of variation for measurement of AHVR were 20, 23, and 36% for the three protocols, respectively. These were not significantly different. There was a significant physiological variation in AHVR (F (50,100) = 3.9, P < 0. 001), with a coefficient of variation of 26%. We conclude that there was relatively little systematic variation between the three protocols but that AHVR varies physiologically over time.
Zhang et al. (Mon,) reported a other. Three different protocols for assessing AHVR (square waves, incremental steps, isocapnic rebreathing) vs. Compared to each other was evaluated on Mean values for hypoxic sensitivity (p=<0.01). Three different protocols for assessing acute hypoxic ventilatory response yielded significantly different mean sensitivities (1.02, 1.15, and 0.93 l/min/%; P<0.01) and significant physiological variation.