The effect of continuous intercostal nerve block vs. single shot on analgesic outcomes and hospital stays in minimally invasive direct coronary artery bypass surgery: a retrospective cohort study

Abstract

Background: Minimally invasive direct coronary artery bypass (MIDCAB) grafting surgery is accompanied by severe pain. Although continuous intercostal nerve block (CINB) has become one of the multimodal analgesic techniques in single port thoracoscopic surgery, its effects on MIDCAB are unclear. The purpose of this study was to compare the effects of CINB and single shot on analgesic outcomes and hospital stays in patients undergoing MIDCAB in a real-world setting.

Methods: A retrospective cohort study was carried out at Peking University Third Hospital, China. Two hundred and sixteen patients undergoing MIDCAB were divided into two groups: a CINB group and a single block (SI) group. The primary outcome was postoperative maximal visual analog scale (VAS); secondary outcomes included the number of patients with maximal VAS ≤ 3, the demand for and consumed doses of pethidine and tramadol, and the length of intensive care unit (ICU) and hospital stays. The above data and the area under the VAS curve in the 70 h after extubation for the two subgroups (No. of grafts = 1) were also compared.

Results: The maximum VAS was lower in the CINB group, and there were more cases with maximum VAS ≤ 3 in the CINB group: CINB 52 (40%) vs. SI 17 (20%), P = 0.002. The percentage of cases requiring tramadol and pethidine was less in CINB, P = 0.001. Among all patients, drug doses were significantly lower in the CINB group [tramadol: CINB 0 (0-100) mg vs. SI 100 (0-225) mg, P = 0.0001; pethidine: CINB 0 (0-25) mg vs. SI 25 (0-50) mg, P = 0.0004]. Further subgroup analysis showed that the area under the VAS curve in CINB was smaller: 28.05 in CINB vs. 30.41 in SI, P = 0.002. Finally, the length of ICU stay was shorter in CINB than in SI: 20.5 (11.3-26.0) h vs. 22.0 (19.0-45.0) h, P = 0.011.

Conclusions: CINB is associated with decreased demand for rescue analgesics and shorter length of ICU stay when compared to single shot intercostal nerve block. Additional randomized controlled trial (RCT) is needed to support these findings.

Keywords: Block; Coronary artery bypass; Intercostal nerve; Length of stay; Minimally invasive surgery; Outcomes.

Fig. 1

Flow chart of study. SI: single injection, CINB: continuous intercostal nerve block, CPR: cardiopulmonary resuscitation, ICU: intensive care unit, IABP: intra-aortic balloon pump, CCU: cardiac care unit, VAS: visual analogue scale

Fig. 2

Health care resource use. Time (A) until discharge from intensive care unit (ICU), Log-rank (Mantel-Cox) test, P = 0.0241; Gehan-Breslow-Wilcoxon test, P = 0.0036. (B) from surgery to discharge from hospital. Log-rank (Mantel-Cox) test, P = 0.5858; Gehan-Breslow-Wilcoxon test, P = 0.8241. SI: single injection; CINB: continuous intercostal nerve block

Fig. 3

Pain trends after extubation (mean ± SEM). ANOVA with repeated measures was used to compare the pain scores between the two subgroups at successive time-points, *P < 0.0001. All of the time “points” for observation along the X-axis correspond to the time periods for pain scoring after extubation. T1: 0-2 h, T2: 4-6 h, T3: 10-12 h, T4: 20-22 h, T5: 26-28 h, T6: 34-36 h, T7: 44-46 h, T8: 50-52 h, T9: 58-60 h, T10: 68-70 h. VAS AUC (area under curve): SI = 30.41 vs. CINB = 28.05, P = 0.002. VAS: visual analogue scale

Fig. 4

Hemodynamics/vital signs after extubation. (A) Hemodynamics after extubation (mean ± SD). SBP: systolic blood pressure, DBP: diastolic blood pressure, HR: heart rate; (B) SpO₂ (%) or RR after extubation (mean ± SD). SPO₂: pulse oximetry, RR: respiratory rate; SI: single injection, CINB: continuous intercostal nerve block. All of the time “points” for observation along the X-axis correspond to the time periods for pain scoring after extubation. T1: 0-2 h, T2: 4-6 h, T3: 10-12 h, T4: 20-22 h, T5: 26-28 h, T6: 34-36 h, T7: 44-46 h, T8: 50-52 h, T9: 58-60 h, T10: 68-70 h