Around one in four heart surgery patients develop serious lung complications — but a new Adelaide-led study is testing a simple bedside scan that could predict who is most at risk before symptoms appear.

Novel research led by Calvary Adelaide Hospital (CAH), in partnership with Adelaide University, is exploring whether a quick, non-invasive ultrasound of the thigh can flag early signs of post-operative decline in cardiac patients.

Funded by a $60,000 Health Translation SA grant through the Medical Research Future Fund Catalyst Grant Scheme, the new study will assess whether measuring the rectus femoris muscle — a major thigh muscle — can predict complications following major heart surgery.

If successful, it could provide the first objective, bedside method to identify cardiac patients at higher risk of pulmonary complications.

Currently, between 10 and 25 per cent of post-operative cardiac patients develop pulmonary complications, leading to rapid deconditioning, delayed mobilisation and longer hospital stays that contribute to poorer health outcomes.

For many patients, these complications aren't picked up until they've already begun to affect recovery — meaning clinicians are often reacting to decline rather than preventing it.

CAH clinical physiotherapist and Adelaide University researcher Dr Rosa Virgara said the study is exploring a straightforward way to better predict recovery risks following cardiac surgery.

"This research is testing whether a quick, low-cost ultrasound scan at the bedside can identify which cardiac patients are most at risk of complications, before they become critical," Dr Virgara said.

"If we can detect early signs of decline, clinicians can intervene sooner, potentially preventing serious complications and improving recovery.

"Tracking muscle loss in real time could give us an objective way to monitor patient deterioration — including early warning signs of pneumonia or lung complications — and help reduce hospital stays."

There is strong reason to expect this will prove to be a valid prognostic biomarker. Recent studies in COVID-19 patients have linked muscle size to pulmonary complications and recovery outcomes, giving researchers a solid foundation to build on as they apply the same principle to cardiac surgery patients.

The project has a particular focus on rural and remote populations, where there are unique barriers to access and continuity of care.

"Patients in regional areas often face longer travel times and fewer follow-up options, which can increase their risk after surgery," Dr Virgara said.

"A simple, bedside tool like this could help bridge that gap by enabling earlier detection and more consistent monitoring, no matter where patients live."

The intervention will be piloted over 12 months in South Australia, testing how the approach performs in real-world clinical settings. Consumer and rural input will shape the rollout, ensuring the model is practical, patient-centred and scalable across diverse healthcare environments.

If the pilot proves successful, this simple bedside scan could become a standard part of post-operative care for cardiac patients — helping clinicians act earlier, reduce complications and improve recovery outcomes for patients across South Australia and beyond.