Acetaminophen decreases early post-thoracotomy ipsilateral shoulder pain in patients with thoracic epidural analgesia: a double-blind placebo-controlled study.

Objective: Despite effective epidural analgesia, up to 85% of post-thoracotomy patients complain of moderate-to-severe ipsilateral shoulder pain. This study assessed the efficacy of acetaminophen in decreasing postoperative shoulder pain after a thoracotomy.

Design: Double-blind randomized and placebo-controlled study.

Setting: University medical center.

Participants: 65 patients.

Intervention: Patients were randomized into 2 groups; 31 patients received acetaminophen (group A), and 34 patients received a placebo (group P). After induction of anesthesia, patients received either a loading dose of acetaminophen, 1000 mg intrarectally, or a placebo suppository. Thereafter, acetaminophen, 650 mg, or a placebo, was administered intrarectally every 4 hours for 48 hours postoperatively.

Measurements And Main Results: Postoperative pain at the surgical site and shoulder pain were assessed separately every 4 hours for 48 hours using a numerical rating scale (NRS). Rescue analgesia for severe shoulder pain (NRS > 7) consisted of subcutaneous hydromorphone. Sixty-three patients experienced shoulder pain (97% prevalence). Demographic and intraoperative data were similar between the 2 groups. Average NRS for shoulder pain was higher in group P compared with group A at 8, 12, and 16 hours postoperatively (3.1 +/- 2.9, 2.6 +/- 2.6, 2.3 +/- 2.4 vs 1.8 +/- 2.6, 1.2 +/- 1.5, 1.3 +/- 1.8; P < 0.05). The total dose of hydromorphone did not differ between the 2 groups at 16, 24, and 48 hours.

Conclusion: Acetaminophen decreases post-thoracotomy ipsilateral shoulder pain when given preemptively and regularly during the first 48 hours postoperatively in patients who received thoracic epidural analgesia.