Materials and Methods:
This was a prospective, randomized, parallel-group clinical trial. This
study was conducted between 27 May 2022 and 17 August 2022 in the IVF
unit. The protocol was registered on the http://www.clinicaltrials.gov
protocol registration system (NCT05631925 - 12/03/2022) and was approved
by the Clinical Research Ethics Committee of Acıbadem University,
Istanbul, Turkey (No:2022/05-32).
One hundred and thirty American Society of Anesthesiologist’s Class I or
II patients, over age 18, undergoing transvaginal oocyte retrieval for
in vitro fertilization under general anesthesia were included in this
study. Patients were excluded if they had contraindication for general
anesthesia, they had a history of mental illness, alcohol, or substance
abuse. Patients were randomized into two groups (65 patients in group
bolus, 65 patients in group BIS) by an anesthesiologist who was not
included in the study. Randomization was performed by opening one of a
series of sequentially numbered opaque envelopes that contained the
group assignment. Written informed consent was obtained from all study
participants. The patients, and the gynecologist were blinded to group
assignment.
Each patient’s age, weight, height, body mass index (BMI), and ASA
status were recorded preoperatively. All the patients fasted for at
least 6 h prior the procedure and did not receive premedication. On the
arrival in the operating room, heart rate, noninvasive blood pressure,
and oxygen saturation on pulse oximetry were monitored, an intravenous
canula was inserted and %0.9 NaCl infusion was started. Patients in
group BIS were also monitored with BIS.
In both groups, anesthesia was induced with intravenous propofol
(2mg/kg) and fentanyl (2μg/kg) administration. A second-generation
laryngeal mask was inserted two minutes after the anesthesia induction
in group bolus and when BIS value <60 in group BIS.
Normocapnic mechanical ventilation was initiated. A 40% O2/air mixture
was used during the procedure. Laryngeal mask placement was attempted 2
times, if unsuccessful, ventilation with face mask was continued, and
the patient was excluded from the study. The number of insertion
attempts was recorded.
In group bolus, 0.5mg/kg propofol was administered when necessary, using
the 0-4 graded intraoperative movements scale (IOMs).