Entropy vs standard clinical monitoring using total intravenous anesthesia during transvaginal oocyte retrieval in patients for in vitro fertilization

Abstract Study objective Day care surgery is an important arena for monitors of anesthetic depth where minimizing drug use is essential for rapid turnover. Underdosage, on the other hand, carries the risks of intraoperative awareness and pain. Transvaginal oocyte retrieval (TVOR), often performed under total intravenous anesthesia using propofol and fentanyl in Indian patients, is a procedure of special interest because, in addition to the above concerns, toxic effects of propofol on oocytes have been described. We have studied the role of entropy monitor, a depth of anesthesia monitor, in optomising drug titration and facilitating distinction between analgesic and hypnotic components of anesthesia. Design Prospective randomized controlled study. Setting Operating theater and postoperative recovery area. Patients One hundred twenty American Society of Anesthesiologists class I and II female patients coming to the IVF centre for TVOR under total intravenous anesthesia using propofol and fentanyl. They were randomly allocated into 2 groups: Group EM (drugs titrated as per entropy values: state entropy and response entropy) and group CM (drugs titrated as per standard clinical monitoring). Intervention None. Measurements Total propofol consumption (TP), total fentanyl consumption (TF), on-table recovery time (T1), time to discharge (T2), intraoperative awareness (A). Main results Patients in group EM demonstrated 6.7% lesser consumption of propofol ( P = .01), 10.9% more consumption of fentanyl ( P = .007) and 1 minute faster recovery on-table ( P = .009) as compared to group CM. In the PACU, only 10% patients of group EM required supplemental analgesia as opposed to 28.3% in CM group ( P = .01). Time to discharge was similar in both groups and no intraoperative awareness was noted. Conclusion Entropy monitor is a useful tool allowing distinction between analgesic and hypnotic components of general anesthesia in patients undergoing TVOR and facilitating drug titration accordingly. Its impact on intraoperative awareness needs to be further evaluated.