Anesthesia
’s mouth, cough, ’s loss of consciousness
LARYNGOSPASM
No premedication was administered before induction, and standard monitors were applied as the patients arrived at the operating room. Non-invasive blood pressure, electrocardiography, pulse oximetry, and bispectral index (BIS) (A-2000™, Aspect Medical Systems, Newton, MA) were assessed. Prior to induction of anesthesia, each patient breathed spontaneously with 100% oxygen for preoxygenation.Remimazolam was prepared in a syringe by a nurse (1 mg/mL), and the predetermined bolus dose of remimazolam was injected intravenously over few seconds by an anesthesiologist who calculated the induction dose of remimazolam. Simultaneously, remifentanil was infused using a total intravenous anesthesia pump (Orchestra® Base Primea; Fresenius Vial, Brezins, France) with an effect-site concentration (Ce) of 3.0 ng/mL. The other anesthesiologist, who was blinded to the dose of remimazolam, assessed the patient’s loss of consciousness (LOC). The LOC of the patient was measured using the Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) score (Table Modified Observer’s Assessment of Alertness/Sedation (MOAA/S) scoreFor successful insertion of the I-gel, the following conditions were achieved: 1) successful LOC (defined as MOAA/S < 2), 2) loss of spontaneous breathing, 3) Ce of remifentanil = 3.0 ng/mL, and 4) 150 s had passed after injecting the remimazolam bolus considering the peak effect time of remimazolam [After these conditions were fulfilled, the anesthesiologist who checked the LOC inserted the I-gel. Successful I-gel insertion was defined as the smooth insertion of the device and symmetrical chest wall movement with a rectangular capnographic wave observed with manual ventilation. Smooth insertion comprised no involuntary movement of the body, no resistance to opening the patient’s mouth, and no cough or laryngospasm.Only one attempt was made, and for safety and comfort of the failed patients, we immediately started remimazolam infusion at 1–2 mg/kg/h and top-up remifentanil Ce to 4.0 ng/mL and administered 20–30 mg of rocuronium intravenously. For successful patients, we started remimazolam infusion at 1–2 mg/kg/h to maintain the BIS value of 40–60, and decreased remifentanil infusion at 1.0–2.0 ng/mL of Ce before the surgery started.Vital signs and BIS were recorded at baseline (TThe remimazolam dose in each patient was determined using Dixon’s up-and-down method. The initial remimazolam dose was deduced from a previous report that showed the mean (± SD) cumulative hypnotic dose of remimazolam was 0.17 ± 0.04 mg/kg and 0.29 ± 0.08 mg/kg in each 6 mg/kg/h and 12 mg/kg/h continuous remimazolam infusion [