Paramedics to cool patients in world-first trials

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Mobile Intensive Care Ambulance (MICA) paramedics are teaming up with Monash University researchers to test the new treatments aimed at reducing brain injury. Both trials – known as POLAR and RINSE – will commence within weeks.

In the POLAR trial (Prophylactic HypOthermia to Lessen TrAumatic BRain Injury), MICA paramedics will inject cold saline solution into patients as part of their treatment at the trauma scene and en route to hospital. Hospitals involved in the study continue to cool the patient to a body temperature of 33 degrees (about four degrees below normal).

The study will also run for about three years and involve 512 patients across Queensland, Western Australia and Auckland, New Zealand. Victorian hospitals taking part in the trial are The Alfred and Royal Melbourne Hospital. The study is funded by the National Health and Medical Research Council and the Transport Accident Commission.

The RINSE trial (Rapid Infusion of Cold Normal SalinE) is the largest cardiac arrest trial ever undertaken in Australia. MICA paramedics will, for the first time, intravenously give cardiac arrest patients cold saline solution during resuscitation. Like the POLAR trial, it also aims to reduce brain injury – the most common cause of poor outcomes after cardiac arrest.

The two-and-a-half year study, also funded by the National Health and Medical Research Council, will analyse the outcomes of 2512 adult patients who are in cardiac arrest on arrival of paramedics. It will also run in South Australia and Western Australia.

Both trials will compare the outcomes of patients who are randomly chosen for cooling to those treated by MICA paramedics following current protocols.

Associate Professor Stephen Bernard, from Ambulance Victoria and The Alfred, said the trials built upon findings of previous trials undertaken by Ambulance Victoria.

“The process of injecting cardiac arrest patients with cold fluids after resuscitation was first trialled by MICA paramedics from 2005-2007. This new trial brings forward the cooling to try to improve outcomes further,” Associate Professor Bernard said. “When a person’s core temperature is lowered, metabolism inside the body is slowed down meaning that organs such as the brain can maximise the limited oxygen available.

“The RINSE trial aims to see whether cardiac arrest sufferers have a better chance of survival and if survivors have a better quality of life if cooled as soon as possible during resuscitation rather than the standard treatment of being cooled on arrival to hospital.

“In regards to the POLAR trial, despite best efforts, current management of severe traumatic brain injury still results in poor outcomes with approximately 50 per cent of victims either dying or being unable to live independently afterwards. This is associated with huge socioeconomic costs with many of those affected by severe traumatic brain injury being young.

“Previous research in animal trials and also in some clinical trials in humans has shown benefit however there is no definitive evidence to prove that cooling is beneficial. We now have the opportunity to perform a trial that will answer the question about the role of early cooling in the management of severe traumatic brain injury.”

MICA Group Manager Mick Stephenson said Ambulance Victoria and the medical researchers had a long history of successful collaboration. In similar studies, MICA paramedics have sedated and taken over the breathing for patients with traumatic brain injuries and cardiac arrest patients have been cooled pre-hospital.

“Ambulance Victoria is involved in both of these studies for the benefit of patients,” Mr Stephenson said. “We hope to be able to improve survival rates and create even better lives for people who have a cardiac arrest or suffer traumatic brain injuries while also progressing the paramedic profession and expanding the skill set of MICA paramedics.

“Ambulance Victoria will continually look at opportunities to advance medical treatment so that patient outcomes are improved even further.”

Mr Stephenson said Victoria was a world leader in improving outcomes for patients who suffer a form of cardiac arrest that allows the heart to be ‘shocked’ back into rhythm by a defibrillator.

In 2003-2004, 39 per cent of cardiac arrest patients presenting with a shockable rhythm survived to hospital and 14 per cent got to go home. In metropolitan Melbourne, that figure has now jumped to 60 per cent of patients arriving at hospital with vital signs and almost one in three patients surviving to discharge.

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