Discussion
SAID, BLIND
In our study, we observed that the amount of propofol administered to patients during the transvaginal oocyte retrieval procedure was higher when administered as an infusion with BIS monitoring, compared to the administration as bolus doses according to the clinical conditions of the patients.There are studies showing that the success of the oocyte retrieval process does not change with the applied anesthesia methodsPropofol is one of the most preferred drugs for anesthesia in oocyte retrieval, due to its short onset time and rapid recovery from anesthesiaAlsalili et al., in their study on the effect of propofol on oocyte maturation and fertilization, concluded that although propofol did not affect fertilization, high propofol concentrations could impair in vitro oocyte maturation in miceIn various studies comparing the use of propofol administered as a continuous infusion with an intermittent bolus during sedation or general anesthesia, and in a meta-analysis covering 12 studies, it was found that propofol was used in higher doses when given as an infusion compared to the bolus dose, without causing an increase in adverse effectsGan et al. demonstrated that adding BIS monitoring to standard anesthesia practice reduced the propofol infusion rate and the total amount of propofol used. In our study, we could not observe similar results in general anesthesia applied with BIS monitoring. In their study, Gan et al. adjusted their propofol infusions to reach the target BIS value of 45–60, but they allowed the BIS value to increase to 60–75 in the last 15 min of the case. Considering that our target value for BIS value is in the range of 40–60 and the average procedure time is 16 min in our study, it is understood that the target BIS values are very different from the study of Gan et al.Luginbühl et al. reported that BIS monitoring reduced propofol use and accelerated recovery after propofol anesthesia. In this study, it was stated that the drug concentration was adjusted to keep the BIS between 45 and 55 during the surgery in patients with BIS monitoring. However, if the BIS increased above the target level, they preferred to apply muscle relaxants before increasing the drug concentrationBased on the results of our study, is it realistic to say that the amount of propofol used increased by using BIS, contrary to the results of previous studies? Or should a more appropriate target be determined for BIS value during anesthesia for oocyte retrieval? Circeo et al. observed that the mean BIS ranged from 47 to 53 during oocyte retrieval, and they recommended this range as a target. However, artificial airway insertion was not used in any patient in this studyIn the present study, the patients in the bolus group were given propofol according to their clinical responses, without BIS monitoring. Patients were questioned about their satisfaction before being discharged after the procedure. Fifty-nine patients in this group said that they were very satisfied with the anesthesia, while the other two patients said they were satisfied. No patient was dissatisfied with the anesthesia method applied. This finding shows that even if propofol is given according to the clinical response of the patient without BIS monitoring, patient satisfaction is high and sufficient depth of anesthesia can be provided for the patient.We did not use BIS in the group bolus, so we cannot recommend the BIS value that should be targeted for oocyte retrieval based on the results of our study. Considering these findings, we think that the targeted BIS value should be reconsidered for patients undergoing oocyte retrieval under general anesthesia.In the present study, we could not confirm our hypothesis that we could reduce the amount of propofol administered for general anesthesia in patients undergoing transvaginal oocyte retrieval procedure for IVF treatment, when BIS is targeted in the 40–60 range. This brought us to the conclusion that further studies with more specific methodology and larger series are needed to determine the appropriate target value in the depth of anesthesia when BIS is used during anesthesia for oocyte retrieval.Intraoperatively, we were unable to use a double-blind study design. The anesthesiologist who administered the anesthesia and recorded the results during the procedure was not blind. This is a major limitation of our study.