Thorac Cardiovasc Surg 2014; 62 - OP175
DOI: 10.1055/s-0034-1367249

Bispectral index-guided titration of sevoflurane during on-pump cardiac surgery reduces sevoflurane plasma concentration and vasopressor requirements

R. Nitzschke 1, J. Wilgusch 1, S. Haas 1, C. Trepte 1, A.E. Goetz 1, H. Reichenspurner 2, D.A. Reuter 1, M.S. Goepfert 1
  • 1Zentrum für Anästhesiologie und Intensivmedizin Hamburg, Klinik und Poliklinik für Anästhesiologie, Hamburg, Germany
  • 2Universitäres Herzzentrum Hamburg/ Eppendorf, Klinik und Poliklinik für Herz- und Gefäßchirurgie, Hamburg, Germany

Background: During cardiopulmonary bypass it is a challenge for the attending anesthesiologist to find the optimal dosage of anesthetics because the commonly used parameters endtidal anesthetic gas concentration or other vital signs indicating depth of anesthesia are not usable. Overdosage of anesthetics may be corelated with impaired outcome (1), while insufficient depth of anesthesia results in intraoperative awareness. Electroencephalographic-based monitoring systems such as the bispectral index (BIS) may reduce anaesthetic overdose rates and ensure sufficient depth of anesthesia. We hypothesized that goal-directed sevoflurane administration (guided by BIS monitoring) could reduce the sevoflurane plasma concentration (SPC) and intraoperative vasopressor doses during on-pump cardiac surgery.

Methods: This single-center, prospective, controlled, sequential, 2-arm study included 60 elective on-pump cardiac surgery patients. In group Sevo1.8 Vol% (n = 29), the sedation depth was maintained with a sustained inspiratory concentration of sevoflurane 1.8 Vol% before and during cardiopulmonary bypass (CPB). In group SevoBIS (n = 31), the administered sevoflurane concentration was titrated to maintain a BIS target between 40 and 60.

Results: Mean inspiratory sevoflurane concentration was 0.8 Vol% in group SevoBIS, representing a 57.1% reduction (p  < 0.001) compared to group Sevo1.8 Vol%. The mean SPC was 42.3 µg/ml (95% CI, 40.0-44.6) in group Sevo1.8 Vol% and 21.0 µg/ml (95% CI, 18.8-23.3, p  < 0.001) in group SevoBIS, representing a 50.2% reduction (p  < 0.001). During CPB, the mean cumulative dose of norepinephrine administered was 13.48 µg/kg (95% CI, 10.52-17.19) in group Sevo1.8 Vol% and 4.06 µg/kg (95% CI, 2.67-5.97, p  < 0.001) in group SevoBIS. Pearson's correlation between the cumulative applied dosage of sevoflurane calculated from the area under the curve of the SPC over time and the administered cumulated norepinephrine dose was 0.607 (p  < 0.001). No signs of intraoperative awareness were detected in any patient during the study protocol.

Conclusions: BIS-guided sevoflurane titration lowers the SPC and reduces norepinephrine requirements compared to routine care during on-pump cardiac surgery.

Reference: (1) Kertai MD, Pal N, Palanca BJ, et al. Association of perioperative risk factors and cumulative duration of low bispectral index with intermediate-term mortality after cardiac surgery in the B-Unaware Trial. Anesthesiology 2010;112:1116-27.