29 September 2020

A five-year, world first study into mechanical ventilation by researchers from Austin Health could change the way millions of surgical procedures are performed around the globe each year.

The study, published this month in the prestigious Journal of the American Medical Association (JAMA), found the practice of inflating a patient’s lungs beyond their normal size during surgery does not reduce their risk of respiratory complications.

Austin Health Intensive Care Physician and Anaesthetist, Dr Dharshi Karalapillai, said anaesthetists use a ventilator to inflate a patient’s lungs with a mixture of gas including oxygen to maintain lung function during surgery.

“It has been common practice around the world since the 1970s to inflate a patient’s lungs to almost twice their normal size when they are under anaesthetic to ensure the lungs stay open and to reduce the risk of complications after surgery,” Dr Karalapillai said.

“Our research tracked more than 1200 patients who underwent surgery since 2015 and found it is entirely safe to inflate a patient’s lung to their normal level while they are anaesthetised.

“There was no greater risk of complications for patients whose lungs were inflated to normal breathing levels compared to those whose lungs were inflated to a higher level.

“This means millions of patients undergoing surgery around the world each year can safely receive a lower volume of lung ventilation while under anaesthetic,” he said.

The study, ‘Effect of Intraoperative Low Tidal Volume v Conventional Tidal Volume on Postoperative Pulmonary Complications in Patients Undergoing Major Surgery’, was a collaboration between anaesthetists and intensive care specialists at Austin Health.

“We know there is a risk of lung complications for any patient who requires surgery including pneumonia, a build of fluid or a collapsed lung,” Dr Karalapillai said.

“For more than 40 years it was thought that inflating the lungs of a patient to higher levels also helps counter act the risk of hypoxia, or too little oxygen reaching their tissue and organs.

“We looked at the outcomes of 1206 patients over the age of 40 who underwent major surgery with Austin Health between February 2015 and February 2019 and found that that delivering higher volumes of gas to the lungs does not actually reduce the risk of pulmonary complications and hypoxia.

“Our patients were no more likely to suffer complications when their lungs were inflated to the normal level during their procedure and it may even be safer for some patients to receive lower volume lung inflations.

“This finding has the potential to change anaesthetic and surgical practices around the world,” he said.

The study is available at https://jamanetwork.com/journals/jama