Emergency Medical Technicians Can Administer Nitrous Oxide for Effective Analgesia in an Urban Multi-Tiered EMS...

To determine the effectiveness of self-dosed nitrous oxide administration by emergency medical technicians (EMTs) in treating medical and traumatic pain in the prehospital setting, to quantify the incidence and type of adverse events associated with this intervention, and to identify characteristics associated with subjective improvement following prehospital pharmacologic analgesia.

We performed a state-approved 365-day pilot study in which EMTs administered patient-dosed inhaled nitrous oxide (premixed 50% nitrous oxide and 50% oxygen) to patients in pain in the prehospital setting. We conducted a retrospective cohort analysis of all patients who received pain management following an abnormal pain assessment performed by an EMT. Using paired t-tests and multivariable logistic regression, we analyzed the qualified responses (improved, worsened, or unchanged) and quantified responses (ten-point pain scale) of patients with abnormal pain assessment findings to prehospital treatments.

Of the 165 patients who received nitrous oxide, 125 (75.76%) demonstrated an improved response and zero demonstrated a worsened response in the judgment of the attending EMT. Nitrous oxide reduced pain scores by 2.29 (p < 0.01) after five minutes and 2.46 (p < 0.01) at hospital. Two minor adverse events occurred (asymptomatic hypotension and dizziness). An EMT's categorization of a patient's response to nitrous oxide as "unchanged" predicted an 89% increase in the need for a paramedic response to the scene (n = 10). Paramedics administered parenteral analgesia to 11 patients, three of whom did not receive nitrous oxide.

Nitrous oxide self-dosing, when supervised by trained EMTs, could effectively relieve pain in most out-of-hospital patients.