title: Analgesic Effects of Inhalation of Nitric Oxide (Entonox) and Parenteral Morphine Sulfate in Patients with Renal Colic; A Randomized Clinical Trial.
abstract: OBJECTIVE
  To compare the analgesiceffects of Nitrous oxide and morphine sulfate in patients with acute renal colic due to urolithiasis.
  
  
  METHODS
  This was randomized clinical trial being performed in Imam Hossein hospital affiliated with Shahid Beheshti University of Medical Sciences during a 1-year period from May2013 to May2014.  A total of number of 100 patients, with an age range of 20-50 years, who presented with renal colic secondary to urolithiasis confirmed by ultrasonography were randomly assigned to receive morphine sulfate injection (0.1 mg/kg) with 100 mg diclofenac suppository (n=50) or Entonox exhalation (50% nitric oxide and 50% oxygen) for 30-minutes with 100 mg diclofenac suppository (n=50). Quantitative measurement was of pain was performed according to a visual analogue scale (VAS), before, 3, 5, 10 and 30-minute after the intervention. The pain severity and side effects were measured between two study groups.
  
  
  RESULTS
  The baseline characteristics of the patients in two study groups were comparable. The frequencies of pain persistence (at least 50%) at 3-, 5-, 10- and 30-minute intervals in morphine sulfategroup were 96%, 80%, 50% and 8%, respectively; these frequencies in Entonex  were 82%, 42%, 12% and 2%, respectively (p<0.001). Cox regression modeling showed that use of Entonox was the only effective agent in the success of treatment, compared to the use of morphine, i.e. use of Entonox increased the success of treatment up to 2.1 folds compared to the use of morphine (HR=2.1; 95% CI: 1.2-3.6; p=0.006).
  
  
  CONCLUSIONS
  The results of the present study demonstrate that inhalation of Entonox is an effective and safe analgesic regimen for acute renal colic. It acts more rapidly and is more potent in relieving renal colic when compared to morphine sulfate.Entonox can be regarded as an appropriate alternative to analgesics like opioids in this ground.
authors.affiliation: Department of Emergency Medicine, Imam Hossein Medical Center, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Kariman
authors.affiliation: Department of Emergency Medicine, Shohadaye Tajrish Medical Center, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Majidi
authors.affiliation: Department of Emergency Medicine, Imam Hossein Medical Center, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Taheri
authors.affiliation: Department of Emergency Medicine, Imam Hossein Medical Center, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Shahrami
authors.affiliation: Safty Promotion and Injury Prevention Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Hatamabadi
keywords: Entonox; Visual analogue scale (VAS); Morphine; Pain relief; Renal colic; Urolithiasis