The Role of Entropy Monitoring in Reducing Propofol Requirements During Open Heart Surgeries. A Prospective Randomized Study

Background

Hypotension, which is commonly associated with propofol induction of general anesthesia in coronary artery bypass grafting (CABG) surgery, may cause adverse consequences in patients with coronary artery diseases undergoing this type of surgeries. The clinical absence of verbal response and eyelash reflex was used as an endpoint for hypnosis. Spectral entropy, as a novel monitoring method for the endpoint of hypnosis, affect the dose of required anesthetic agents for induction as well as the hemodynamic profile during general anesthesia in CABG surgery.

Aims

We hypothesized that entropy monitoring might reduce the dose of propofol required for induction of anesthesia during CABG surgery and could maintain hemodynamic stability when compared with the conventional clinical monitoring.

Materials and Methods

Sixty adult patients of both sexes, aged 30–60 years, ASA II and III, and scheduled for CABG surgery were enrolled in this prospective, controlled, randomized, double-blind study. These patients were randomly divided into two equal groups to receive intravenous propofol for induction of anesthesia guided by either the patients’ clinical response (Group I) or by entropy monitoring (Group II). The total dose of propofol used for induction of anesthesia was recorded. Hemodynamic parameters and entropy values were also recorded.

Results

Propofol consumption was significantly reduced in Group II than Group I (P = 0.000*). Heart rate showed no statistical significance between the two groups, whereas the mean arterial pressure significantly decreased at induction in group I compared to Group II (P = 0.000*). The entropy values were significantly lower in Group I than Group II at induction (P = 0.036* for state entropy; 0.002* for response entropy). However, during intubation, and after 1 and 5 min, entropy indices displayed a significant increase in Group I than Group II.

Conclusions

Entropy monitoring significantly reduced the dose of propofol required for induction of anesthesia and maintained hemodynamic stability compared to the conventional clinical monitoring during CABG surgeries.