Effect of Pressure on the Yinmen Point in Relief of Pain After Middle Ear Surgery: A Randomized Clinical Trial

Abstract

Background: Postoperative pain is a common problem after middle ear surgery. Several analgesic agents are available for pain relief, but they cause numerous side effects. Therefore, complementary analgesic methods are developed to reduce patient's postoperative pain and discomfort.

Objectives: The current study aimed to investigate the effect of the acupressure on post middle ear surgery pain, applying pressure on the Yinmen acupoint of the sciatic nerve.

Methods: In this randomized clinical trial, 100 adult patients who were candidate for elective middle ear surgery were selected and divided into two groups of Yinmen and placebo, each with 50 subjects. After admission to the ward, patients' postoperative pain score was measured using the visual analog score (VAS) tool. Then, patients were placed in the prone position. In the Yinmen group, using a fist, we applied a continuous pressure (11 - 20 kg) to the posterior aspect of the thighs at the Yinmen acupoint for 2 minutes. In the placebo group, only soft contact was kept between the fist and Yinmen point for the same period. The maneuver repeated every two hours for four times. The pain intensity surveyed 10 minutes after the first maneuver, then every hour for 8 hours. For those with a VAS score ≥ 4, intravenous paracetamol and/or meperidine was administered. Any nausea and vomiting was managed using ondansetron 2 mg, IV. The pain score, paracetamol, and meperidine consumption were recorded and compared between the two groups. The chi-square and student t-tests were used to compare the two groups.

Results: No significant difference was found between patients' characteristics and the first pain score. For all measurements, pain intensity was lower in the Yinmen group (P value < 0.01). The pain after the first maneuver was relieved exactly when the acupressure was true. The intervention could reduce patients' need to take paracetamol (6.68 ± 2.58 vs. 10.42 ± 3.87 mg/kg) and meperidine (0.21 ± 0.17 vs. 0.39 ± 0.23 mg/kg) in the Yinmen group. The two groups were not significantly different concerning the need to take ondansetron to manage postoperative nausea and vomiting.

Conclusions: Applying 2 minutes pressure (11 - 20 kg) on the Yinmen acupoint of the sciatic nerves can reduce post middle ear surgery pain and analgesic consumption.

Keywords: Acupressure; Middle Ear Surgery; Postoperative Pain Management; Yinmen Acupoint.

Figure 1.. The Yinmen point (BL37). It is located at the posterior aspect of the thigh (along with the sciatic nerve), about 6 cm below the Chengfu (BL 36) point.

Figure 2.. Pain score during the first 8-hour after surgery. *, The initial pain score was the same in both groups; however, after providing the intervention, participants of the Yinmen group had lower pain scores for all measurements (P value < 0.01).

Figure 3.. Pain score 10 minutes after the first intervention in two groups. The true pressure on Yinmen acupoint could decrease the postoperative pain in the Yinmen group.