[Reflex depression of respiration induced by baroreceptor stimulation during enflurane-nitrous oxide anesthesia]

Inhibition of respiration in response to arterial baroreceptor stimulation was studied in 7 patients with no evidence of respiratory or cardiovascular disorders under enflurane-nitrous oxide anesthesia. The arterial baroreceptors were stimulated by a bolus injection of phenylephrine (0.1mg, i.v.). A rise in blood pressure following administration of phenylephrine caused decreases in heart rate and tidal volume, suggesting the presence of cardiovascular and respiratory reflexes from baroreceptors in anesthetized humans. However, despite the statistical significance, the depression of respiration is too small to be clinically important.