[Assessment of the cognitive effects of inhalational induction with sevoflurane associated or not with nitrous oxide: a comparative study in adult volunteers.].

BACKGROUND AND OBJECTIVES Anesthetic induction with inhalational agents using a facemask has gained attention since the introduction of sevoflurane. At the same time, the influence of adding nitrous oxide on the pattern of induction and recuperation deserves attention, especially regarding recovery of the cognitive function. The objective of this study was to evaluate the cognitive effects of inhalational anesthetic induction with sevoflurane alone or associated with nitrous oxide in adults. METHODS Twenty adult volunteers, ASA physical state I, without a history of psychiatric disorders or prior use of benzodiazepines, were enrolled in the study. After answering the Mini-Mental State Examination (MMSE), Group I received 5% sevoflurane until a bispectral index (BIS) of 60 was achieved. Group II received nitrous oxide in increments of 10% until it achieved 50% followed by the administration of sevoflurane until a BIS of 60 was achieved. Arterial blood pressure, heart rate, pulse oxymetry, SEF 95% (Spectral Edge Frequency), induction time, and anesthetic recovery time were evaluated. RESULTS Time of induction showed no differences between both groups. Group II showed greater hemodynamic stability and smaller SEF 95% values when BIS achieved 60. The time for recovery of cognitive function was similar in both groups, as well as the incidence of nausea and vomiting. There were no cases of apnea. Group II demonstrated greater incidence of psychomotor agitation during induction. CONCLUSIONS Sevoflurane alone or in association with nitrous oxide is an adequate option for inhalational anesthetic induction or outpatient sedation in adults, maintaining spontaneous ventilation, and providing a fast recuperation of the cognitive function.