'Green Whistle' pain relief inhaler given green light in ambulance study of pregnancy emergencies

Research into the "green whistle" pain relief inhaler has found no obvious harm for pregnant women or their newborn babies in a study looking at ambulance cases over 17 years.

Research Fellow Dr. Erin Kelty, from The University of Western Australia's School of Population and Public Health, said the study looked at the safety of methoxyflurane—commonly known as the "green whistle"—in treating pain in pregnant women.

Dr. Kelty said the "whistle" had been commonly used by ambulance services since 1990 because it works quickly and was easy to self-administer but its safety in pregnancy had not been well studied.

"Research into drug safety often avoids pregnant women, resulting in them not having access to medication with demonstrated safety," Dr. Kelty said.

"Our study found about one in 250 babies born in WA are exposed to the green whistle in utero and there appears to be no obvious harm associated with its use."

Dr. Kelty said the research compared outcomes from patients who had the "green whistle" with those who had fentanyl or no analgesia.

"While it is not recommended for use in pregnancy, the study found exposure on the day of delivery was not associated with an increased likelihood of a low Apgar score, which indicates a newborn's need for medical attention," she said.

Fellow researcher and masters of public health student Dr. Anwyn Pyle said the drug was the most commonly used for emergency pain relief for pregnant women by ambulances services.

"Our study found that the green whistle was administered to more than one in every 10 pregnant women transferred by ambulance between 2000 and 2016," Dr. Pyle said.

Researchers said given the potential for exposure in pregnancy in an emergency setting further studies into the pain relief, including long-term child health follow-ups, were warranted.