Safety and analgesia of inhaling a mixture of nitrous oxide and oxygen in prehospital patients with traumatic pain

Abstract

Objective To evaluate the safety and analgesia efficacy of inhalation of a blended 50/50 mixture of nitrous oxide and oxygen for relieving pain in limb traumatized patients in pre-hospital setting. Methods A total of 106 traumatic patients treated with painkiller of nitrous oxide and oxygen mixture in pre-hospital setting admitted in the emergency department from October 2014 to April 2016 were enrolled. They were divided into control group (n=53, inhalation of oxygen) and treatment group (n =53, treated with inhalation of a mixture of 50% nitrous oxide and oxygen) according to the computer-generated list of random number. The same routine treatment was given to patients of both groups. Respiratory rate (RR), heart rate (HR), blood pressure (BP), pulse oxygen saturation of oximetry (SpO2) measured at different intervals during the entire course of inhalation and adverse effects were recorded. The degree of pain was evaluated with the visual analogue scale (VAS). Results There were no significant differences between control group and treatment group in RR, HR, BP, and SpO2 before and 5, 10, 15, 30, 45 min after inhalation. Compared with RR and HR before inhalation, RR and HR were significantly decreased 10, 15, 30, 45 min after inhalation ( P<0.05 or <0.01) in treatment group. The RR was decreased 15, 30, 45 min after inhalation (P<0.05 or <0.01), but there was no statistically significant change in HR in control group. There were no differences in the VAS scores before inhalation between two groups (P=0.678) but the difference after inhalation were statistically significant (P<0.01) . The VAS scores after inhalation for 15 min in treatment group lowered to below 3, in an average of (2.94±1.03)(P<0.01). The VAS scores in control group were slightly lowered to above than 6 at all intervals after inhalation. There were some minor side effects consisting of dizziness (28.3%), nausea (24.53%), vomiting (15.09%) and drowsiness (5.66%) without serious adverse consequence in treatment group. Conclusions A blended 50/50 mixture of nitrous oxide and oxygen seems to have obvious analgesic effects on traumatic patients in pre-hospital setting, with very low rate of side effects, and it can be widely used in clinical practice. Key words: Prehospital; Trauma; Inhalation; Nitrous oxide; Oxygen; Analgesia; Safety; Effectiveness