As CWI has become a focal point for the treatment of heat-related incidents, Dr. Stowell and others have conducted trainings on the process.
Patients’ temperatures cool at double the rate with new protocol, enhancing the odds of survival and limiting other negative side effects
With climate change leading to a surge in extreme heat events, rising temperatures pose a significant threat to patient survival and public health. Phoenix, Arizona, stands at the forefront of this climatic challenge. In 2023, a report from the Maricopa County Public Health Department cited 645 heat-related deaths, nearly doubling the deaths recorded just two years prior. That same year, as documented by the National Weather Service, Phoenix experienced 133 days with a temperature greater than 100˚F and 55 days with a temperature greater than 110˚F.
To combat this, the Department of Emergency Medicine at the University of Arizona College of Medicine – Phoenix developed and implements a new cold-water immersion (CWI) protocol. CWI’s efficiency led to a myriad of new research into the description and management of acute heat stroke resuscitation in Phoenix, Arizona.
Jeffrey Stowell, MD, interim chair of the Department of Emergency Medicine, explained the process behind CWI and how they’ve seen and documented its benefit to patients. “Prior to around 2021, we would often cool patients with a form of conductive cooling — such as putting ice packs on them, putting fans in the room with them and fanning them, spray bottles and things like that,” he said. “We felt that moving to what we called CWI, or cold-water immersion, where we put them in a bath of ice and water, would be more effective to cool them more quickly. We were optimistic that patients who were cooled more quickly would have a better outcome, including mortality. Would they survive more often to be discharged home?”
By putting patients in a bag filled with ice, they found that their temperatures were cooling at more than double the rate of the previous methods. This, of course, led to better recovery.
Logically, the next step was to then identify whether this protocol could be used prior to the patient arriving at the hospital. In 2024, Dr. Stowell and Geoff Comp, DO, worked to help support the Phoenix Fire Department in administering pre-hospital CWI to patients with acute heat stroke.
In a recently published article for Prehospital Emergency Care, Fighting Fire with Ice: A Multisite Collaboration to Evaluate the Impact of Prehospital Cold Water Immersion on Heat Strok Patients, the Phoenix Fire Department along with Drs. Comp, Stowell and co-authors examined the outcomes for patients who underwent prehospital CWI treatment. And their findings were encouraging. They demonstrated successful reduction in body temperature; improvement in Glasgow Coma Scale (GCS) scores — which assess a patient’s risk for severe brain injury or coma during their hospital stay; and favorable survival outcomes in patients with heat stroke.
More encouraging — despite the challenges they encountered with keeping ice suitably cold and frozen — the study concluded that wide-scale implementation of prehospital CWI treatment is possible and can be safely and effectively implemented within large urban EMS systems. This would produce clinically meaningful improvements in temperature reduction, neurologic recovery and survival following heat stroke.
Extreme temperatures resulting in heat-related health incidents is not a problem that can be easily eliminated. Phoenix, and Arizona as a whole, is going to face high temperatures several months out of the year. The hope for Dr. Stowell and the Department of Emergency Medicine is that the success of their efforts will foster new and innovative approaches to rapidly cooling patients, ultimately further improving their functional outcomes.
“We’re just one piece of the puzzle. Phoenix Fire Department, Maricopa Department of Public Health and Arizona public health are doing a tremendous work — setting up cooling stations and doing education to help prevent heat illness. I think is really where we’re going to see the biggest benefit and reduction in mortality is education and prevention strategies,” Dr. Stowell said.
About the College
Founded in 2007, the University of Arizona College of Medicine – Phoenix inspires and trains exemplary physicians, scientists and leaders to advance its core missions in education, research, clinical care and service to communities across Arizona. The college’s strength lies in our collaborations and partnerships with clinical affiliates, community organizations and industry sponsors. With our primary affiliate, Banner Health, we are recognized as the premier academic medical center in Phoenix. As an anchor institution of the Phoenix Bioscience Core, the college is home to signature research programs in neurosciences, cardiopulmonary diseases, immunology, informatics and metabolism. These focus areas uniquely position us to drive biomedical research and bolster economic development in the region.
As an urban institution with strong roots in rural and tribal health, the college has graduated more than 1,000 physicians and matriculates 130 students each year. Greater than 60% of matriculating students are from Arizona and many continue training at our GME sponsored residency programs, ultimately pursuing local academic and community-based opportunities. While our traditional four-year program continues to thrive, we will launch our recently approved accelerated three-year medical student curriculum with exclusive focus on primary care. This program is designed to further enhance workforce retention needs across Arizona.
The college has embarked on our strategic plan for 2025 to 2030. Learn more.
By: Thomas Kelly | April 20, 2026 | Original Post