Sevoflurane-induced reduction of hypoxic drive is sex-independent

Abstract

Background: Although the μ-opioid agonist morphine affects ventilatory control in men and women in different ways, no data exist regarding the influence of sex on the ventilatory effects of inhalational anesthetics. The authors compared the effect of sevoflurane on the ventilatory response to isocapnic hypoxia in healthy young men and women. Methods: Breath-to-breath ventilatory responses to hypoxic steps (number of hypoxic steps, four-six; duration, 3 min; end-tidal oxygen tension, ~50 mmHg; end-tidal carbon dioxide tension clamped at ~4 mmHg above resting values) were assessed in nine men and nine women without and with low-dose sevoflurane (end-tidal concentration, 0.25%). The bispectral index of the electroencephalogram was measured concomitantly. Results: Sevoflurane reduced the hypoxic ventilatory sensitivity significantly in both sexes (men: control, 0.62 ± 0.17 vs. sevoflurane, 0.38 ± 0.19 1 · min-1 · %-1; women: control, 0.52 ± 0.30 vs. sevoflurane, 0.34 ± 0.15 1 · min-1 · %-1). Sevoflurane-induced reductions of the hypoxic responses were not different in the men and women. During sevoflurane inhalation, the bispectral index values decreased equally in men and women. Conclusion: In contrast to morphine, the influence of a low dose of the inhalational anesthetic sevoflurane on the ventilatory response to hypoxia is independent of sex.