Evaluation of Entonox as an Analgesic for Relief of Pain in Patients with Acute Myocardial Infarction

Background- Since the relief of pain in patients with acute myocardial infarction (AMI) is very important; we sought to assess the effect of Entonox as an analgesic drug in our subjects. Our goal was to compare the analgesic effect of Entonox with opioid drugs such as morphine and meperidine. Methods- This study was a randomized clinical trial, which included 120 patients with wellestablished AMI admitted to the CCU ward. Exclusion criteria consisted of hemodynamic abnormality, heart block, cardiac arrhythmia, opioid addiction and a lack of participation of certain patients. The patients were divided in a randomized manner into two equal groups of 60 individuals each. The first group inhaled Entonox, while the second group received opioid drugs intravenously. The severity of pain in the patients of both groups was measured before and after the aforesaid procedure by employing the established criteria of visual analogue scale (VAS). Visual analog scale is a standard quantitative method for pain measurement, which is suggested by the patient. Results- Pain severity reduction according to VAS criteria in the Entonox group was 4.55 and 4.4 in the opioid group, which did not show any statistical difference according to t-test (p=0.82). Conclusion- Entonox was as effective for pain relief as opioid drugs in patients with AMI. Given the known complications caused by opioid drugs, we should be able to substitute these drugs with Entonox (Iranian Heart Journal 2006; 7 (3):16-19).