Feasibility study of bilateral thoracic paravertebral block for postoperative analgesia in patients after off-pump coronary artery bypass grafting

Abstract

To investigate the feasibility of bilateral thoracic paravertebral block for postoperative analgesia in patients after off-pump coronary artery bypass grafting (OPCABG). Upon the approval of institutional Ethics Committee and informed consent, forty patients ASAII or III aged 52-77 yr with BMI (body mass index) < 30 kg/m(2), undergoing OPCABG, were randomly divided by random numbers into two groups(n = 20 each):thoracic paravertebral block for postoperative analgesia group (group P) and patient-controlled intravenous analgesia (PCIA) group (group I). Bilateral thoracic paravertebral block and insertion epidural catheter were performed at T3, 4 interspace prior to induction of anesthesia in group P. At the end of the operation , an infusion of 0.375% ropivacaine was injected at the rate of 5 ml/h up to 48 h.Group I received PCIA with morphine. Dermatomes of hypoalgesia in group P were recorded. The following indexes were recorded at 12, 24, 36 and 48 hours after postoperative analgesia beginning: VAS scores of rest pain, cough pain and sedation score. To evaluate stability of circulation. Cycle time, complications and side effects after operation were recorded. Dermatomes of hypoalgesia was 5.1 ± 1.0 segments in group P. VAS scores of rest pain (2.4 ± 0.4, 2.6 ± 0.5, 2.4 ± 0.4, 2.2 ± 0.3 vs 3.7 ± 0.7, 3.6 ± 0.8, 3.4 ± 0.6, 3.1 ± 0.6, all P < 0.01), cough pain (3.7 ± 0.8, 3.9 ± 1.0, 3.8 ± 1.1, 3.8 ± 0.9 vs 4.4 ± 1.1, 4.9 ± 1.3, 4.8 ± 1.3, 4.3 ± 1.2, P < 0.05, <0.01) and sedation scores (2.2 ± 0.4, 2.0 ± 0.4, 1.9 ± 0.3, 1.8 ± 0.3, 2.6 ± 0.5, 2.5 ± 0.4, 2.4 ± 0.5, 2.2 ± 0.4, P < 0.05) in group P were significantly lower than in group I at the four points. The incidences of sinus tachycardia (5% vs 25%) and hypertension (0 vs 30%) in group P were significantly reduced than in group I (P < 0.05), and there were no significant difference in the incidences of sinus brachycardia (30% vs 15%) and hypotension (20% vs 10%) (P > 0.05) . Compared with group I, extubation time (5.5 ± 1.4 vs 7.1 ± 1.7) and residence time in ICU (17.3 ± 4.2 vs 21.4 ± 5.8) were shortened significantly in group P (P < 0.05), and there were no significant difference in length of stay after operation (10.5 ± 2.6 vs 11.7 ± 2.8, P > 0.05). The incidence rate of nausea in group P was significantly lower than in group I (5% vs 25%, P < 0.05), and there were no significant difference in the other complications and side effects after operation (P > 0.05). Bilateral thoracic paravertebral block for postoperative analgesia could be used safely and efficiently and accelerate the cycle time in patients after OPCABG.