Nitrous oxide/oxygen plus acetaminophen versus morphine in ST elevation myocardial infarction: open-label, cluster-randomized, non-inferiority study

Scand J Trauma Resusc Emerg Med. 2020 May 12;28(1):36. doi: 10.1186/s13049-020-00731-y.

Abstract

Background: Studies have shown disparate results on the consequences of morphine use in ST-segment elevation myocardial infarction (STEMI). No study has evaluated alternative treatments that could be at least non-inferior to morphine without its potentially damaging consequences for myocardial function and platelet reactivity. The aim of this study was to evaluate whether nitrous oxide/oxygen plus intravenous acetaminophen (NOO-A) is non-inferior to morphine to control chest pain in STEMI patients.

Methods: This multicenter, open-label, cluster-randomized, controlled, non-inferiority study compared NOO-A with morphine in 684 prehospital patients with ongoing suspected STEMI of < 12 h duration and a pain rating score ≥ 4. The primary endpoint was the proportion of patients achieving pain relief (numeric rating score ≤ 3) after 30 min. Secondary safety endpoints included serious adverse events and death at 30 days.

Results: The median baseline pain score was 7.0 in both groups. The primary endpoint occurred in 51.7% of the NOO-A group and 73.6% of the morphine group (absolute risk difference - 21.7%; 95% confidence interval - 29.6 to - 13.8). At 30 days, the rate of serious adverse events was 16.0 and 18.8% in the NOO-A and morphine groups respectively (p = NS). The rate of death was 1.8% (NOO-A group) and 3.8% (morphine group) (p = NS).

Conclusion: Analgesia provided by NOO-A was inferior to morphine at 30 min in patients with acute STEMI in the prehospital setting. Rates of serious adverse events did not differ between groups.

Trial registration: ClinicalTrials.gov: NCT02198378.

Keywords: Analgesia, prehospital; ST-segment elevation myocardial infarction.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Acetaminophen / administration & dosage*
  • Administration, Inhalation
  • Analgesics, Non-Narcotic / administration & dosage
  • Analgesics, Opioid / administration & dosage
  • Chest Pain / etiology
  • Chest Pain / therapy*
  • Dose-Response Relationship, Drug
  • Drug Therapy, Combination
  • Female
  • Humans
  • Injections, Intravenous
  • Male
  • Middle Aged
  • Morphine / administration & dosage*
  • Nitrous Oxide / therapeutic use*
  • Oxygen / administration & dosage*
  • Oxygen Inhalation Therapy / methods*
  • ST Elevation Myocardial Infarction / complications
  • ST Elevation Myocardial Infarction / therapy*
  • Treatment Outcome

Substances

  • Analgesics, Non-Narcotic
  • Analgesics, Opioid
  • Acetaminophen
  • Morphine
  • Nitrous Oxide
  • Oxygen

Associated data

  • ClinicalTrials.gov/NCT02198378