Military surgeon Professor Jeffrey Rosenfeld says lessons learned from terrorist attacks has shown everyone should know how to stop critical bleeding.

Every Australian should stock their car boot with a medical-grade tourniquet in the event of a terrorist attack or mass casualty, a leading military surgeon says.

Professor Jeffrey Rosenfeld, senior neurosurgeon at The Alfred Hospital in Melbourne, says his experience from working in war zones in Afghanistan and Iraq and lessons learned from terrorist attacks have shown that stemming critical bleeding saves lives.

According to the surgeon, 20 per cent of victims will die at the scene from arterial bleeding.

For this reason, Prof Rosenfeld this week called on first-responders to undertake a Haemorrhage Control (HEMCON) Course so they are prepared for a terrorist attack or mass shooting.

This included members of the public because they were often the ones first at the scene, he said.

The HEMCON Course, developed by the American College of Surgeons, teaches simple but effective methods of controlling a severe haemorrhage.

"Severe haemorrhage is the commonest cause of early death following the penetrating injuries and traumatic amputations which occur following terrorist attacks including bomb explosions or mass shootings," Prof Rosenfeld said.

He makes no apology for sounding alarmist.

"This course will save lives. It left such a lasting legacy on me I now carry two tourniquets in the back of my car wherever I go," Prof Rosenfeld said.

"Unfortunately, we're not immune to terrorism in Australia and it's essential first-responders and emergency departments are prepared when, not if the unthinkable happens."

At a conference in Sydney this week, Australian medicos were reminded of the importance of being prepared for a terrorist attack and heard from Dr Eric Revue, who treated hundreds of people who were wounded during the Paris attacks in 2015.

They also heard from surgeon Dr John Fildes from the University Medical Centre in Las Vegas, who was at the front line of the medical response to the mass shooting at a music festival on The Strip in October last year.

He described the chaos that unfolded and highlighted the importance of first-responders.

"As the people evacuate they used their own clothing as compression dressings, belts, shirts were used for tourniquets, bystander CPR was performed. There really was no way to get out and really no way to get personnel in," Dr Fildes said.

"Twenty-two thousand people self evacuating was a chaotic scene," he said.