Combined Programmed Intermittent Bolus Infusion With Continuous Infusion for the Thoracic Paravertebral Block in Patients Undergoing Thoracoscopic Surgery: A Prospective, Randomized, and Double-blinded Study

BACKGROUND: Continuous thoracic paravertebral block (TPVB) connected with patient-controlled analgesia (PCA) pump is an effective modality to reduce postoperative pain following thoracic surgery. For the PCA settings, the programmed intermittent bolus infusion (PIBI) and continuous infusion (CI) are commonly practiced. However, the comparative effectiveness between the 2 approaches has been inconsistent. Thus, the aim of this study was to explore the optimal PCA settings to treat postthoracotomy pain by combing PIBI and CI together. METHODS: All enrolled patients undergoing thoracoscopic surgery accepted ultrasound-guided TPVB catheterization before the surgery and then were randomly allocated in to 3 groups depending on different settings of the PCA pump connecting to the TPVB catheter: the PIBI+CI, PIBI, and CI groups. Numerical Rating Scales were evaluated for each patient at T1 (1 h after extubation), T2 (12 h after the surgery), T3 (24 h after the surgery), T4 (36 h after the surgery), and T5 (48 h after the surgery). Besides, the consumptions of PCA ropivacaine, the number of blocked dermatomes at T3, and the requirement for extra dezocine for pain relief among the 3 groups were also compared. RESULTS: First, the Numerical Rating Scale scores in the PIBI+CI group were lower than the CI group at T2 and T3 (P<0.05) when patients were at rest and were also lower than the CI group at T2, T3, and T4 (P<0.01) and the PIBI group at T3 when patients were coughing (P<0.01). Second, the 2-day cumulative dosage of PCA in the PIBI+CI group was lower than both the CI and PIBI groups (P<0.01). Third, the number of blocked dermatomes in the PIBI and PIBI+CI groups were comparable and were both wider than the CI group at T3 (P<0.01). Finally, a smaller proportion (not statistically significant) of patients in the PIBI+CI group (5.26%, 2/38) had required dezocine for pain relief when compared with the PIBI group (19.44%, 7/36) and the CI group (15.79%, 6/38). CONCLUSIONS: The combination of PIBI and CI provides superior analgesic modality to either PIBI or CI alone in patients undergoing thoracoscopic surgery. Therefore, it should be advocated to improve the management of postoperative pain, clinical outcomes, and ultimately patient satisfaction.