Cold Water in the Hot Desert: Lessons from Arizona and Heat Stroke Management

But it’s a Dry Heat…

As an emergency medicine physician in Phoenix, Arizona, my ED team and I face unique environmental challenges, including managing heat stroke and heat-related illnesses. While the Southwest is known for its scorching summers, the last few years have been unprecedented. Phoenix in July 2023 was the hottest month ever recorded in a U.S. city.  We sweltered through an average temperature of 102.7˚F, a maximum of 119˚F, and a record-breaking 31-day streak of highs at or above 110˚F. These severe environmental conditions led to a surge in heat-related illnesses, resulting in 645 confirmed heat-related deaths, with the first death occurring on April 11th.

As a result of these extreme weather events, the urgency to adapt and implement effective treatment strategies is more critical than ever. Here in Phoenix, we are preparing for this upcoming summer and another year of heat-related emergencies.

Heat stroke is the most severe form of heat-related illness, defined by elevated body temperature ≥40˚C and altered mental status with known exposure to elevated ambient temperatures.

Mortality rates associated with heat stroke range from 33% to 80% in the absence of prompt medical intervention. The amount of time the body is exposed to elevated temperatures and continued prolonged heat exposure are the most significant risk factors for heat-related mortality through multisystem organ dysfunction or worsening pre-existing medical conditions. However, with proper recognition and cooling, these patients can have excellent outcomes and survival. Immediate intervention is crucial to prevent irreversible damage or death, with the mainstay of treatment being active and rapid cooling. 

When they are hot, make them cold:

Hyperthermia treatment hinges on rapid and early patient cooling to decrease the patient's exposure to extreme heat and address other related systemic emergencies. Cooling techniques include applying ice or cold packs to the groin or axilla, wet gauze sheets, cooled intravenous (IV) fluids, cooling blankets, gastric, colonic, bladder, or peritoneal lavage, and fans alone or in combination to enhance evaporative cooling.

However, in the battle against heat stroke, one of the most effective treatments we've incorporated into our practice since the summer of 2021 is cold water immersion (CWI). This technique involves immersing the patient in cold water to rapidly reduce their core body temperature by taking advantage of the high thermal conductivity of water and the high thermal gradient between cold water and skin, allowing for a greater capacity for heat transfer.

The “How to”:

The process of CWI is straightforward but requires careful coordination and resources. In our ED, the CWI protocol involves placing a patient with suspected heat stroke (temperature ≥40˚C and altered mental status) in a body bag filled with a slurry of ice water rapidly upon arrival to the ED and performing continuous resuscitation, patient monitoring, and management. 

Upon arrival, a rapid primary survey is conducted to identify a need for airway management in patients with respiratory failure or distress, as well as severely altered mental status, and for any apparent traumatic injuries. We use body bags filled with ice water for our immersion, and the patient is immersed up to the neck to maximize surface area exposure to the cold water. Cardiopulmonary monitoring is initiated, a temperature-sensing Foley catheter capable of continuous measurement is placed, and IV access is established. Repeat primary and secondary surveys are performed, and cooling is not delayed for additional procedures or interventions. They are performed simultaneously with rapid cooling. Once the core temperature reaches 39°C, The bag is cut at the bottom and drained, and the patient is log rolled out and dried.

Barriers to Implementation:

• Resource Intensive:  Setting up and maintaining a CWI protocol requires significant resources, including staff training, space, and equipment. In busy emergency departments, allocating these resources can be challenging. We found that we needed ice to be sent from the cafeteria because we were exhausting our supply in the ED from our ice machines. 
• Education and Training:  Continuous education and training for healthcare providers are essential to ensure staff at all levels, from nursing and techs to physicians and administration, are familiar with the protocols and can act swiftly and efficiently. Developing the protocol with input from other medical specialties, nursing, and hospital administration was crucial for a successful launch!  
  
  

Beyond Phoenix: A Nationwide Concern

The lessons we learned in Phoenix apply to many parts of the country now experiencing similar extreme heat conditions. Heat-related illnesses are no longer confined to traditionally hot regions; they are becoming a widespread public health concern, and heat-related diseases will continue to be a significant public health issue. As healthcare providers, we must stay vigilant, adapt our practices, and advocate for practice changes to combat this growing threat.

Learn more by listening to the "Too Hot to Handle: Heat Emergencies" segment on ERcast.