Background: Insufficient relief of postthoracotomy pain is a major cause of increased rates of postoperative complications including inadequate coughing, mucous plugging, hypoxia, compromised ventilation or even bacterial lung infection. We aimed to assess the efficacy of transcutaneous electric nerve stimulation (TENS) in patients with postthoracotomy pain.
Methods: Forty patients scheduled to undergo posterolateral thoracotomy were randomly allocated to receive either TENS or patient-controlled intravenous morphine. Postoperative pain was evaluated using a visual analogue scale (VAS) and the Prince Henry pain scale. Pulmonary function was evaluated and an intergroup comparison was done.
Results: On the first three days following surgery, the VAS intensity of the TENS group did not differ significantly from that of the morphine group ( P > 0.05), and on the first two days following thoracotomy, the Prince Henry scale of the TENS group was not statistically significantly different. However, the VAS intensity was significantly lower than that of the control group on the fourth ( P = 0.044), fifth ( P = 0.016), sixth ( P = 0.009), seventh ( P = 0.008), eighth ( P = 0.004), ninth ( P = 0.002), tenth ( P = 0.001), fifteenth ( P = 0.002), thirtieth ( P < 0.001), forty-fifth ( P < 0.001) and sixtieth ( P < 0.001) days. The Prince Henry scale of the TENS group was found to be significantly diminished from the 3rd to the 60th day. TENS significantly reduced the analgesic requirements from day 5 to 60 ( P < 0.01). No noticeable side effect was observed in the TENS group during the study period.
Conclusion: This study demonstrated that TENS provided a better pain relief and comfort compared to PCA from the fourth postoperative day onwards, and this pain-reducing effect continued for at least two months postoperatively.