Post-thoracotomy ipsilateral shoulder pain: What should be preferred to optimize it - phrenic nerve infiltration or paracetamol infusion?

Background: Post thoracotomy ipsilateral shoulder pain (PTISP) is a distressing and highly prevalent problem after thoracic surgery and has not received much attention despite the incidence as high as 85%. Objectives: To study the effect of phrenic nerve infiltration with Ropivacaine compared to paracetamol infusion on PTISP in thoracotomy patients with epidural analgesia as standard mode of incisional analgesia in both the groups. Study Design: Prospective Randomised and Double Blind Study. Methods: 126 adult patients were divided randomly into 2 groups, "Group A (Phrenic Nerve Infiltration Group) received 10 mL of 0.2% Ropivacaine close to the diaphragm into the periphrenic fat pad" and "Group B (Paracetamol Infusion Group) received 20mg/kg paracetamol infusion" 30 minutes prior to chest closure respectively. A blinded observer assessed the patients PTISP using the VAS score at 1, 4, 8, 12 and 24 hours (h) postoperatively. The time and number of any rescue analgesic medication were recorded. Results: PTISP was relieved significantly in Group A (25.4℅) as compared to Group B (61.9℅), with significantly higher mean duration of analgesia in Group A. The mean time for first rescue analgesia was significantly higher in Group A (11.1 ± 7.47 hours) than in Group B (7.40 ± 5.30 hours). The number of rescue analgesic required was less in Group A 1.6 ± 1.16 as compared to Group B 2.9 ± 1.37 (P value <0.5). Conclusions: Phrenic Nerve Infiltration significantly reduced the incidence and delayed the onset of PTISP as compared to paracetamol infusion and was not associated with any adverse effects.