Transient Hyperdynamic Response Associated with Controlled Hypocapneic Hyperventilation During Sevoflurane-Nitrous Oxide Mask Induction in Adults

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Abstract
We assessed hemodynamic variables during sevoflurane face mask anesthetic induction in female ASA physical status I or II patients. Anesthesia was induced with a single-breath inhalation method with 8% sevoflurane in 50% nitrous oxide in oxygen. Thirty patients were ran- domized either to breathe spontaneously (SB group, n 5 15) or to receive controlled ventilation (CV group, n 5 15) for 6 min after the loss of consciousness. Noninvasive blood pressure and heart rate (HR) were recorded at 1-min intervals. Mean 6 sd HR increased from 83 6 18 to 112 6 24 bpm at 4 min in the CV group (P , 0.001 between groups and within group compared with baseline). Mean arterial pressure increased from 97 6 9t o 1066 26 mm Hg at 4 min in the CV group, which was significantly higher than that in the SB group (P , 0.01). In the SB group, mean arterial pressure decreased significantly, from 96 6 8t o 78 6 13 mm Hg, at 6 min (P , 0.001), and HR re- mained unchanged. Therefore, hyperventilation should be avoided during the induction of sevoflurane anesthe- sia via a mask. Implications: In this randomized, prospec- tive study, we found that controlled hypocapneic hyper- ventilation delivered manually during sevoflurane/ N2O/O2 mask induction was associated with a significant transient hyperdynamic response. This kind of hemody- namic arousal can be detrimental to many patients and can be avoided by conducting sevoflurane mask induc- tion with unassisted spontaneous breathing. (Anesth Analg 1999;88:1384-8)