Ambient levels of nitrous oxide in a modular ambulance

Abstract

Nitrous oxide has been occasionally used as a prehospital analgesic over the last 3 decades. It has been shown to be an effective analgesic agent [1], but concerns have been raised about exposing prehospital personnel to high ambient levels of nitrous oxide within the confines of the ambulance. Historical concerns about possible detrimental effects of long-term exposure to health care workers prompted the National Institute of Occupational Safety and Health (NIOSH) to issue recommendations regarding acceptable levels of nitrous oxide exposure. NIOSH currently recommends a time-weighted average of 25 ppm for staff exposure during administration of nitrous oxide [2]. El Dorado County Emergency Medical Services (EMS), Placerville, Calif, was granted optional scope permission by the California State EMS Authority to use nitrous oxide in the ambulance for analgesia in 1997. In early 2004, we conducted a study to measure ambient nitrous oxide levels in the ambulance. The study assessed compliance with NIOSH standards for acceptable levels of nitrous oxide. Unlike previous studies, we attempted to replicate actual clinical conditions as closely as possible. This meant setting up the modular ambulance environment in a configuration consistent with how paramedics would normally operate. We also designed the study to examine the effect of patient conversation on ambient nitrous oxide levels.