Pulsed electromagnetic fields for post-appendicectomy pain management: a randomized, placebo-controlled trial

The value of pulsed electromagnetic field (PEMF) in postoperative pain management, due to the inconsistent findings so far, remains unclear. We extended the evaluation of PEMF on postoperative pain and intravenous (IV) analgesic use to a group of post-appendicectomy Asian patients.

This is a double-blinded, randomized trial. Adults with a clinical diagnosis of acute appendicitis were enrolled. Patients were allocated randomly to receive an active-PEMF device or an inactive device after the surgery in addition to the standard postoperative pain management. The primary outcome measure was the 12-h cumulative postoperative pain intensity measured at four different time points using the visual analogue scale. The secondary outcome measure was the total amount of IV fentanyl used (in mg) via PCA over the first 12 postoperative hours. The primary analysis in this trial compared the two study groups for the reported cumulative pain score (both at rest and on movement) and the cumulative amount of IV fentanyl uses over the first 12 postoperative hours using the Wilcoxon rank sum test. Analyses were performed based on the intention-to-treat principal. Multiple imputation was used to handle the missing data assuming that the data were missing at random.

One hundred eighteen subjects were randomized; 58 were allocated to the active-PEMF group and 60 to the inactive control group. Pooled mean pain score of both intervention groups by time point declined in a similar fashion over the course of 12 postoperative hours. The 12-h cumulative postoperative pain score at rest and on movement did not differ significantly after the procedure. (W = 1832.5 ~ 1933.0, p-value 0.6192 ~ 0.2985 for resting pain score comparison; W = 1737.0 ~ 1804.5, p-value 0.9892 ~ 0.7296 for movement pain score comparison). For the secondary outcome measure of 12-h total fentanyl use, a comparison between the PEMF vs. placebo arm also revealed no statistically significant difference across all the 20 imputed datasets (W = 1676.5 ~ 1859.0, p-value 0.7344 ~ 0.5234).

PEMF was not superior to placebo as an adjunct pain management for up to 12 h post-appendicectomy. Previously reported effect of PEMF on postoperative pain intensity and analgesia uses in similar surgical settings cannot be verified.

National Medical Research Register Malaysia (NMRR-15-670-25,805) and Thai Clinical Trials Registry (retrospectively registered on November 01, 2019, Study ID-TCTR20191102002).