The effects of deep and light propofol anesthesia on stress response in patients undergoing open lung surgery: a randomized controlled trial

BACKGROUND This prospective, randomized controlled study was undertaken to compare stress hormone response to open thoracotomy for lung resection at different anesthetic depths, as determined by bispectral index (BIS) monitoring, in patients under propofol-remifentanil anesthesia. METHODS Forty-eight adult patients scheduled for lung resection surgery using one-lung ventilation were randomly assigned to either a deep anesthesia group (BIS score of 40 ± 5, n = 24) or a light anesthesia group (BIS score of 60 ± 5, n = 24) by adjusting propofol infusion rates. Blood norepinephrine, epinephrine, adrenocorticotropic hormone, and cortisol levels were measured before the induction of anesthesia, at the end of surgery, and at 2 hours postoperatively. Blood glucose, hemodynamic, and oxygenation-ventilation variables, and postoperative outcomes were also measured. RESULTS Norepinephrine and epinephrine levels remained unchanged over time in the deep group, but norepinephrine levels significantly increased in the light group at 2 h after surgery than at baseline (P = 0.007 and 0.004, respectively). Temporal changes in norepinephrine, but not in epinephrine, were significantly different between the two groups (P = 0.036). Plasma glucose levels in the light group increased with time and were significantly higher than in the deep group at the end of surgery (P = 0.002). CONCLUSIONS A deep level of anesthesia achieved using high propofol infusion rates during lung surgery provided lower perioperative norepinephrine and glucose responses than light level of anesthesia during the early postoperative period but failed to affect immediate postoperative outcomes.