Comparison of bispectral index-guided and fixed-gas concentration techniques in desflurane and remifentanil anesthesia: A randomized controlled trial

Abstract

Anesthesia with desflurane and remifentanil can be maintained with either fixed or titrated desflurane concentration. We hypothesized that the fixed-gas concentration (FG) method would reduce the number of anesthetic titrations without hypnotic and hemodynamic instability compared to the bispectral index (BIS)-guided (BG) method. Forty-eight patients were randomly allocated to the FG or BG groups. In the FG group, desflurane vaporizer setting was fixed at 1 age-corrected minimum alveolar concentration (MAC). In the BG group, desflurane was titrated to target a BIS level at 50. Remifentanil was titrated to maintain a systolic arterial pressure (SAP) of 120 mmHg in both groups. Our primary endpoint was the hypnotic stability measured by the wobble of BIS in performance analysis, and the secondary endpoints included the wobble of SAP, mean BIS value during surgery, and the number of anesthetic titrations. The BIS in the FG group showed significantly less wobble (3.9 ± 1.1% vs 5.5 ± 1.5%, P <0.001) but lower value (33 ± 6 vs 46 ± 7, P <0.001) than BG group. The wobble of SAP showed no difference between groups [median (inter-quartile range), 5.0 (4.1-7.5)% vs 5.2 (4.2-8.3)%, P = 0.557]. The numbers of anesthetic titrations in the FG group were significantly lower than the BG group (0 ± 0 vs 8 ± 5, P<0.001 for desflurane, 13 ± 13 vs 22 ± 17, P = 0.047 for remifentanil). Less wobble in BIS and reduced anesthetic titration without hemodynamic instability during the FG technique may be practical in balanced anesthesia using desflurane and remifentanil anesthesia. Clinical trial: This study was registered at ClinicalTrials.gov (NCT02283866).

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1. CONSORT diagram.

Fig 2. Changes of desflurane and remifentanil target concentrations during balanced anesthesia in typical patients.

A: the 7th patient in the bispectral index-guided group; B: the 12th patient in the fixed-gas concentration group. End-tidal concentrations of desflurane and target effect-site concentrations of remifentanil changed during the study period, showing significant difference in the number of titrations between two groups.

Fig 3. Recovery times defined by different measures like OAA/S score, eye-opening and extubation.

Recovery time was defined as the elapsed time between cessation of desflurane and remifentanil and occurrence of recovery signs like OAA/S score >2, opening of eyes to verbal command, or spontaneous ventilation. Extubation was performed immediately after the notice of spontaneous ventilation and means final recovery in this study. Kaplan-Meier survival analysis with log rank test for pairwise comparison reveals that there are no between-group differences regarding three recovery times. Abbreviation: OAA/S = observer’s assessment of alertness/sedation.

Fig 4. Desflurane-remifentanil concentration combination.

Scatter plots represent average (dot) and SD (error bars) of desflurane-remifentanil concentration combinations. The bidirectional error bars represent the variability of desflurane (vertical error bar) and remifentanil (horizontal error bar) concentrations. The fixed-gas concentration group shows higher desflurane and lower remifentanil concentrations with shorter error bars than the bispectral index-guided group.