The majority of women who chose nitrous oxide to manage labour pain ultimately decide to have an epidural, according to a study presented at Anesthesiology 2016, the Annual Meeting of the American Society of Anesthesiologists (ASA).
Researchers found nitrous oxide provided limited pain relief, with patients reporting no change in average pain scores after its use.
“Nitrous oxide is gaining interest among expectant mothers as an option to manage labour pain and is becoming more widely available in the United States,” said Caitlin Sutton, MD, Stanford University School of Medicine, Stanford, California. “However, we found that for the majority of patients, nitrous oxide does not prevent them from requesting an epidural.”
“While nitrous oxide may be somewhat helpful, but epidural anaesthesia remains the most effective method for managing labour pain,” she said.
Not traditionally used to manage labour pain in the United States until recently, nitrous oxide is more commonly administered during labour in countries such as the United Kingdom and Australia. Nitrous oxide helps reduce anxiety and makes patients less aware of pain, but it does not eliminate it.
In the study, researchers reviewed the medical records of 4,698 women who delivered vaginally between September 2014 and September 2015. They found only a small proportion of women (148 patients) at their institution chose to use nitrous oxide for labour pain management. They then examined the demographic characteristics of the women, the effectiveness of nitrous oxide for their pain relief, and the number of women who ultimately decided to have an epidural.
The average patient reported pain score given immediately prior to nitrous oxide inhalation was 8 (on a scale from 0 to 10). The average pain score remained the same after nitrous oxide use. The average length of time that nitrous oxide was used was 80 minutes. Ultimately, 60% of women who used nitrous oxide decided to get an epidural. Factors that influenced conversion from nitrous oxide to epidural use included both inducing and augmenting labour with oxytocin.
“Future studies are needed to further determine which women in labour would most benefit from nitrous oxide,” said Dr. Sutton. “However, our current study findings provide valuable data for other institutions that are considering offering nitrous oxide. Knowing which patients are more likely to convert from nitrous oxide to an epidural can help physician anaesthesiologists offer more individualised counselling to patients when they are in labour.”