Efficacy of different concentrations of sevoflurane administered through a face mask for magnetic resonance imaging in children

P>Background: The main aim of this study was to use a non-invasive method such as a face mask to maintain anesthesia in children during magnetic resonance imaging (MRI). The secondary aim was to ascertain hemodynamic-respiration parameters, recovery time and complications of anesthesia with the administration of different concentrations of sevoflurane. Methods: This prospective and randomized study included 96 ASA I-II children, aged 1-10, scheduled to undergo MRI with anesthesia with sevoflurane through a face mask. All patients were administered midazolam 0.5 mg center dot kg-1 orally 30 min before anesthesia induction. Sevoflurane 8% was given to induce anesthesia under assisted-controlled ventilation for 2 min, and an intravenous route was opened on the hand. Three different concentrations of sevoflurane were administered through a face mask under spontaneous respiration to maintain anesthesia. A mixture of sevoflurane, oxygen, and air of 5 l center dot min-1 was given through a face mask for anesthesia. Group 1 (n = 32) received 1.5% sevoflurane, Group 2 (n = 32) 1.25% sevoflurane, and Group 3 (n = 32) 1.0% sevoflurane. Recovery time, removal from the MRI room, postanesthesia care unit discharge data, and complications were also recorded. Heart rate, mean arterial pressure (MAP), peripheral oxygen saturation (SpO(2)), respiration rate, and anesthesia adequacy were recorded every 5 min from the time of induction until completion of the MRI. Results: All three groups were similar in demographic and hemodynamic respiratory features. MRI was successfully performed in 96.6% of all patients without additional intervention. Sevoflurane concentrations were increased for a short time in one patient in Group 1 and in two patients in Group 3. Oxygen flow was increased in one patient in Group 1 and in one patient in Group 2 as SpO(2) was lower than 95%. The mean time to eye opening (from discontinuation of sevoflurane to eye opening) was 155.8 +/- 50.0 s in Group 1, 89.5 +/- 16.0 s in Group 2, and 53.5 +/- 10.0 s in Group 3; differences between the groups were statistically significant (P = 0.001). Airways were not used on any of the patients, and none vomited or required endotracheal intubation or laryngeal mask anesthesia. Conclusions: We believe that the administration of sevoflurane at a concentration of 1% via a face mask under spontaneous respiration may provide light anesthesia without complications to induce an unarousable sleep for children during MRI.