Sevoflurane Requirement to Maintain Bispectral Index-Guided Steady-State Level of Anesthesia During the Rewarming Phase of Cardiopulmonary Bypass With Moderate Hypothermia
Journal of Cardiothoracic and Vascular Anesthesia, 07/27/2012
Mahaldar DAC et al. – The sevoflurane requirement increases during the rewarming phase of hypothermic cardiopulmonary bypass (CPB). The percent increase in the requirement for sevoflurane is uniform and follows a particular pattern, which may be predicted.Methods
- Fifty patients undergoing elective coronary artery bypass graft surgery with CPB.
- End–tidal oxygenator expiratory gas concentrations were used to quantify sevoflurane requirements while maintaining a BIS level between 40 and 50 during the rewarming phase.
- Sevoflurane requirements progressively increased as temperature increased.
- The difference in sevoflurane requirement at 35°C and 29°C was compared using analysis of variance for repeated measures, which was statistically significant.
- When relating temperature and sevoflurane requirement, the Pearson correlation coefficient was 0.67.
- Linear regression analysis using temperature as the independent variable and expiratory sevoflurane as the dependent variable showed a temperature β–coefficient of 0.11 and a constant of –2.34.
- Other parameters like fresh gas flows and pump flows were correlated to findout if they affected end–tidal sevoflurane levels on CPB.
- They were not significant in multivariate analysis.