Table 2.
Summary of studies evaluating the effect of a bispectral protocol on anesthetic dosing for patients undergoing cardiac surgery
| Characteristics | Bauer et al.; 2004[46] | Chiu et al.; 2007[47] | Muralidhar et al.; 2008[48] | Myles et al.; 2004[23] | Avidan et al.; 2008[21] | Avidan et al.; 2011[18] | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Number of patients studied | 40 | 20 | 40 | 2,463 | 1,941 | 5,713 | ||||||
| Study design | RCT | RCT | RCT | RCT | RCT | RCT | ||||||
| Study Aim | Impact of BIS on propofol dose and stress response in cardiac surgery | Impact of BIS on propofol dose during CPB | Impact of BIS on anesthetic dose during OPCAB | Impact of BIS protocol on intraoperative awareness | Impact of BIS protocol on intraoperative awareness | Impact of BIS protocol on intraoperative awareness | ||||||
| Number of cardiac surgery patients (%) | 40 (100%) | 20 (100%) | 40 (100%) | 1,212 (49%) | 525 (27%) | 2,041 (36%) | ||||||
| Proportion of patients receiving TIVA (%) | 100% | 100% | 50% | 43% | 0% | 0% | ||||||
| Interventions | 1.Target controlled infusion protocol 2.BIS guided protocol |
1.Routine practice 2.BIS guided protocol |
1.BIS-guided propofol 2.BIS-guided isoflurane 3.Propofol routine practice 4 Isoflurane routine practice |
1.BIS protocol 2.Routine care |
1.BIS protocol 2.ETAC protocol |
1.BIS protocol 2.ETAC protocol |
||||||
| Result | BIS* | TCI* | BIS* | Routine* | BIS* | Routine* | BIS* | Routine* | BIS* | ETAC* | BIS* | ETAC* |
| BIS value | 45±7 | 43±9 | 43±10 | 41 (38-45) | 41 (38-45) | |||||||
| - Midazolam (mg) | 2 (2-3.5) | 2.5 (2-4.0) | 2 (2-5) | 2 (2-5) | 2 (2-3) | 2 (2-3) | ||||||
| - Propofol infusion (mg/kg/hr) | 4.3 | 6.8 | 2.9 | 6.0 | 5 (4-6) | 5 (3-6) | ||||||
| - Propofol administered (ml; 10 mg/ml)) | 120±6 | 176±9 | 15 (12-20) | 15 (12-20) | 16 (11-20) | 15 (10-20) | ||||||
| - MAC equivalents | 0.57 (0.43-0.72) | 0.61 (0.43-0.78) | 0.81±0.25 | 0.82±0.23 | 0.9 (0.8-1)† | 0.9 (0.8-1)† | ||||||
| - Isoflurane administered (ml) | 24±4 | 37±4 | ||||||||||
| - Fentanyl (mcg) | 500 (100-1000) | 600 (100-1175) | 300 (200-600) | 250 (200-500) | 300 (200-600) | 300 (200-650) | ||||||
| - Morphine (mg) | 10 (7-15) | 10 (7-15) | 10 (6-10) | 10 (6-10) | 10 (5-10) | 10 (5-10) | ||||||
| Summary findings | 37% propofol dose reduction in the BIS group. Higher BIS values in the BIS group. No difference in catecholamines or cytokine | 50% propofol dose reduction in BIS group. Higher BIS values in BIS group | 35% reduction in isoflurane and 32% reduction in propofol administration | No significant difference in median propofol infusion rate, MAC, induction agent dose, or opioid dose between groups. 25% reduction in induction midazolam dose in BIS group. | No significant difference in median MAC, midazolam dose, induction agent dose, opioid dose between groups. | No significant difference in median age-adjusted MAC, midazolam dose, induction agent dose, opioid dose between groups. | ||||||
| Commentary | Comparison between BIS protocol and target controlled infusion. There was minimal correlation between BIS values and propofol concentrations. | Small study. No protocol for control group. Potential for bias (not blinded to group). | Small study. No protocol for control group. Potential for bias (not blinded to group). | Anesthetic dose was a secondary outcome. This might have decreased the potential for bias. Only 49% of patients underwent cardiac surgery. | Anesthetic dose was a secondary outcome. This might have decreased the potential for bias. Only 27% of patients underwent cardiac surgery. | Anesthetic dose was a secondary outcome. This might have decreased the potential for bias. Only 36% of patients underwent cardiac surgery. | ||||||
Abbreviations: BIS, Bispectral Index. CPB, cardiopulmonary bypass. ETAC, end-tidal anesthetic gas concentration. MAC, minimum alveolar concentration. OPCAB, off-pump coronary artery bypass surgery. RCT, randomized controlled trial. TCI, target controlled infusion.
*
Median (interquartile range) or mean ± standard deviation.
†
MAC equivalent value is age adjusted.