Phrenic Nerve Block at the Azygos Vein Level Versus Sham Block for Ipsilateral Shoulder Pain After Video-Assisted Thoracoscopic Surgery: A Randomized Controlled Trial

Abstract

BACKGROUND: Ipsilateral shoulder pain (ISP) is a common problem after pulmonary surgery. We hypothesized that phrenic nerve block (PNB) at the azygos vein level, near the location of the surgical operation, would be effective for reducing ISP. Our primary aim was to assess the effect of PNB on postoperative ISP, following video-assisted thoracic surgery (VATS). METHODS: This prospective, randomized, patient-blinded, single-institution trial was registered at the University Hospital Medical Information Network (UMIN000030464). Enrolled patients had been scheduled for VATS under general anesthesia with epidural analgesia. Patients were randomly allocated to receive infiltration of the ipsilateral phrenic nerve at the azygos vein level with either 10 mL of 0.375% ropivacaine (PNB group) or 0.9% saline (control group) before chest closure. Postoperative ISP was assessed using a numerical rating scale (NRS, 0–10) at rest at 2, 4, 8, 16, and 24 hours. The incidence of ISP was defined as the proportion of patients who reported an NRS score of ≥1 at least once within 24 hours after surgery. In the primary analysis, the proportion of patients with ISP was compared between PNB and control groups using the χ 2 test. NRS values of ISP and postoperative incision pain within 24 hours were investigated, as was the frequency of postoperative analgesic use. Incision pain was assessed using an NRS at the time of ISP assessment. Finally, the incidence of postoperative nausea and vomiting and shoulder movement disorders were also evaluated. RESULTS: Eighty-five patients were included, and their data were analyzed. These patients were randomly assigned to either PNB group (n = 42) or control group (n = 43). There were no clinically relevant differences in demographic and surgical profiles between the groups. There was no significant difference in the incidence of ISP (the control group 20/43 [46.5%] versus the PNB group 14/42 [33.3%]; P = .215). The severity of ISP was lower in the PNB group than in the control group (linear mixed-effects model, the main effect of treatment [groups]: P < .001). There were no significant differences between groups in terms of postoperative incision pain. The frequency of postoperative analgesic use was significantly higher in the control group (Wilcoxon rank sum test, P < .001). Postoperative nausea and vomiting did not significantly differ between the 2 groups. There were no changes in the range of shoulder joint movement. CONCLUSIONS: Azygos vein level PNB did not significantly affect the incidence of ISP after VATS.

Stripping Massage and Literature Review in Post-Thoracoscopic Chest Pain Management

“…While other paraspinal muscles or the trapezius can also cause chest pain in the same area after thoracoscopy, the pain is typically less intense than that originating from the lower rhomboid trigger point. Additional promising techniques for managing postthoracoscopic chest pain include SAP block with bupivacaine or combined epidural analgesia, 23,24 PCIA with dexmedetomidine, 25 phrenic nerve block, 26 and intramuscular stimulation 27 (►Table 4, 5). While epidural, paravertebral, and intercostal blocks are commonly used for regional pain control in thoracic surgery, they each have drawbacks and limitations, such as short duration of in-hospital pain control.…”

“…Additional promising techniques for managing post-thoracoscopic chest pain include SAP block with bupivacaine or combined epidural analgesia, 23,24 PCIA with dexmedetomidine, 25 phrenic nerve block, 26 and intramuscular stimulation. 27 (Table 4, 5).…”

“…All rights reserved. • Other choices: PCIA with dexmedetomidine 25 , phrenic nerve block 26 , or intramuscular stimulation 27…”

“…• Other choices: PCIA with dexmedetomidine, 25 phrenic nerve block, 26 or intramuscular stimulation 27 The outpatient and noninvasive approach to managing chest pain after thoracoscopic surgery.…”

Linear Mixed-Effects Models in Medical Research

“…In this issue of Anesthesia & Analgesia , Kimura Kuroiwa et al 1 report results of a randomized trial in which they studied the effects of phrenic nerve block on ipsilateral shoulder pain (ISP) following video-assisted thoracic surgery. While their primary outcome—incidence of ISP—was compared between the groups with Pearson’s χ 2 test, 2 these authors used a linear mixed-effects model to analyze and to compare pain scores repeatedly measured over time.…”