Influence of Body Temperature on Bispectral Index-Guided Anesthetic Management in Off-Pump Coronary Artery Bypass Grafting
Background Perioperative hypothermia is not uncommon in surgical patients due to anesthetic-induced inhibition of thermoregulatory mechanisms and exposure of patients to cold environment in the operating rooms. Core temperature reduction up to 35°C is often seen in off-pump coronary artery bypass graft (OP-CABG) surgery. Anesthetic depth can be monitored by using bispectral (BIS) index. The present study was performed to evaluate the influence of mild hypothermia on the anesthetic depth using BIS monitoring and correlation of BIS with end-tidal anesthetic concentration at varying temperatures during OP-CABG.
Materials and Methods In a prospective observational study design in a tertiary care teaching hospital, patients who underwent elective OP-CABG under endotracheal general anesthesia, were included in the study. Standard technique of anesthesia was followed. BIS, nasopharyngeal temperature, and end-tidal anesthetic concentration of inhaled isoflurane was recorded every 10 minutes. The BIS was adjusted to between 45 and 50 during surgery.
Results There were 40 patients who underwent OP-CABG during the study period. The mean age was 51.2 ± 8.7 years, mean body mass index 29.8 ± 2.2, and mean left ventricular ejection fraction was 55.4 ± 4.2%. Anesthetic requirement as guided by BIS between 45 and 50 correlated linearly with core body temperature (r = 0.999; p < 0.001). The mean decrease in the body temperature at the end of 300 minutes was 2.2°C with a mean decrease in end-tidal anesthetic concentration of 0.29%. The reduction in end-tidal anesthetic concentration per degree decrease in temperature was 0.13%. None of the patients reported intraoperative recall.
Conclusion In this study, BIS monitoring was used to guide the delivery concentration of inhaled anesthetic using a targeted range of 45 to 50. BIS monitoring allowed the appropriate reduction of anesthetic dosing requirements in patients undergoing OP-CABG without risk of awareness. There was a significant reduction in anesthetic requirements associated with reduction of core temperature. The routine use of BIS is recommended in OP-CABG to titrate anesthetic requirement during occurrence of hypothermia and facilitate fast-track anesthesia in this patient population.
Keywordsbispectral index - cardiac anesthesia - end-tidal concentration - body temperature - coronary artery bypass grafting
18 October 2020 (online)
© 2020. Official Publication of The Simulation Society (TSS), accredited by International Society of Cardiovascular Ultrasound ISCU. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/.)
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- 1 Phillips AA, McLean RF, Devitt JH, Harrington EM. Recall of intraoperative events after general anaesthesia and cardiopulmonary bypass. Can J Anaesth 1993; 40 (10) 922-926
- 2 Ranta S, Jussila J, Hynynen M. Recall of awareness during cardiac anaesthesia: influence of feedback information to the anaesthesiologist. Acta Anaesthesiol Scand 1996; 40 (05) 554-560
- 3 Sigl JC, Chamoun NG. An introduction to bispectral analysis for the electroencephalogram. J Clin Monit 1994; 10 (06) 392-404
- 4 Myles PS, Leslie K, McNeil J, Forbes A, Chan MT. Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial. Lancet 2004; 363 (9423) 1757-1763
- 5 Cohn LH, Rosborough D, Fernandez J. Reducing costs and length of stay and improving efficiency and quality of care in cardiac surgery. Ann Thorac Surg 1997; 64 (Suppl. 06) S58-S60, discussion S80–S82
- 6 Cheng DC, Karski J, Peniston C. et al. Early tracheal extubation after coronary artery bypass graft surgery reduces costs and improves resource use. A prospective, randomized, controlled trial. Anesthesiology 1996; 85 (06) 1300-1310
- 7 Larson SL, Schimmel CH, Shott S, Myers PB, Foy BK. Influence of fast-track anesthetic technique on cardiovascular infusions and weight gain. J Cardiothorac Vasc Anesth 1999; 13 (04) 424-430
- 8 Monk TG, Saini V, Weldon BC, Sigl JC. Anesthetic management and one-year mortality after noncardiac surgery. Anesth Analg 2005; 100 (01) 4-10
- 9 Liu M, Hu X, Liu J. The effect of hypothermia on isoflurane MAC in children. Anesthesiology 2001; 94 (03) 429-432
- 10 Hofer CK, Worn M, Tavakoli R. et al. Influence of body core temperature on blood loss and transfusion requirements during off-pump coronary artery bypass grafting: a comparison of 3 warming systems. J Thorac Cardiovasc Surg 2005; 129 (04) 838-843
- 11 Matsukawa T, Sessler DI, Sessler AM. et al. Heat flow and distribution during induction of general anesthesia. Anesthesiology 1995; 82 (03) 662-673
- 12 Brice DD, Hetherington RR, Utting JE. A simple study of awareness and dreaming during anaesthesia. Br J Anaesth 1970; 42 (06) 535-542
- 13 Yu P-J, Cassiere HA, Kohn N, Mattia A, Hartman AR. Impact of postoperative hypothermia on outcomes in coronary artery bypass surgery patients. J Cardiothorac Vasc Anesth 2017; 31 (04) 1257-1261
- 14 Hannan EL, Samadashvili Z, Wechsler A. et al. The relationship between perioperative temperature and adverse outcomes after off-pump coronary artery bypass graft surgery. J Thorac Cardiovasc Surg 2010; 139 (06) 1568-1575.e1
- 15 Karalapillai D, Story D, Hart GK. et al. Postoperative hypothermia and patient outcomes after elective cardiac surgery. Anaesthesia 2011; 66 (09) 780-784
- 16 Nathan HJ, Parlea L, Dupuis JY. et al. Safety of deliberate intraoperative and postoperative hypothermia for patients undergoing coronary artery surgery: a randomized trial. J Thorac Cardiovasc Surg 2004; 127 (05) 1270-1275
- 17 Joshi GP. Inhalational techniques in ambulatory anesthesia. Anesthesiol Clin North America 2003; 21 (02) 263-272
- 18 Dowd NP, Cheng DC, Karski JM, Wong DT, Munro JA, Sandler AN. Intraoperative awareness in fast-track cardiac anesthesia. Anesthesiology 1998; 89 (05) 1068-1073, discussion 9A
- 19 Muralidhar K, Banakal S, Murthy K, Garg R, Rani GR, Dinesh R. Bispectral index-guided anaesthesia for off-pump coronary artery bypass grafting. Ann Card Anaesth 2008; 11 (02) 105-110
- 20 Song D, Joshi GP, White PF. Titration of volatile anesthetics using bispectral index facilitates recovery after ambulatory anesthesia. Anesthesiology 1997; 87 (04) 842-848
- 21 Gan TJ, Glass PS, Windsor A. et al. BIS Utility Study Group. Bispectral index monitoring allows faster emergence and improved recovery from propofol, alfentanil, and nitrous oxide anesthesia. Anesthesiology 1997; 87 (04) 808-815