Tag Archives: hypothermia

Trauma 20 Years Ago: CAVR For Hypothermia

Hypothermia is the bane of major trauma resuscitation, causing mortality to skyrocket. A number of rewarming techniques have been developed over the years. These are classified as passive (the patient generates their own heat) or active (we deliver calories to them), and noninvasive vs invasive. Rewarming speed increases as we move from passive to active and from noninvasive to invasive.

Continuous arteriovenous rewarming (CAVR) is one of the invasive techniques used today. Its use in humans was first reported 20 years ago this month. Larry Gentilello at Harborview in Seattle had experimented with this technique in animals, and reported one case of use in a human who had crashed his car into icy water. After a 20 minute extrication, the patient was pulseless with fixed and dilated pupils, but he regained pulse and blood pressure at the hospital.

The initial core temperature was 31.5C. Peritoneal, bladder and gastric lavage were carried out for warming, as was delivery of warm inspired gas via the ventilator. However, after an hour the temperature had dropped to 29.5C. CAVR was initiated as a last-ditch effort using a jerry-rigged Rapid Fluid Warmer from Level 1 Technologies. The core temperature was raised to 35C after 85 minutes.

The patient did have typical complications (ARDS, acute renal failure), but survived with recovery of his renal and pulmonary function, and a normal neurologic exam. At the time, the authors were unsure whether the complications were due to the near-drowning or the rapid rewarming.

Reference: Continuous arteriovenous rewarming: report of a new technique fo9r treating hypothermia. J Trauma 31(8):1151-1154, 1991.

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Warm Water Immersion Policy for Hypothermia

A few days ago, I wrote about using a therapy tank for immersion to rapidly rewarm patients (click here to read it). Since this type of management usually means moving out of the ED to a separate patient care are, it is important to have a policy that spells out responsibilities for all personnel involved. 

Click here or click the image above to download a copy of the Regions Hospital Trauma Program policy.

Rapid Noninvasive Rewarming Using a Hubbard Tank

Hypothermic patients need to be rewarmed using the most appropriate method. Patients with mild hypothermia (32-35 degrees centigrade) generally only require removal of wet clothing and surface warming. Moderate hypothermia (28-32 degrees C) to severe hypothermia (<28 degrees C) is very serious and requires more aggressive central rewarming techniques.

Basic central rewarming techniques, such as warm inspired gases, warm IV fluids, and gastric or peritoneal lavage can raise the temperature about 3 degrees per hour. 

Rapid central rewarming techniques, like thoracic lavage (6 degrees/hr), AV bypass devices (1-4 degrees/hr), and cardiopulmonary bypass (18 degrees/hr) are typically used on patients with severe hypothermia.

A technique that we use at Regions Hospital involves the use of the Burn Center’s Hubbard Tank. Patients are carefully immersed, torso first, then one extremity at a time to avoid rebound hypothermia. It is possible to increase core temperature using this method faster than bypass (>20 degrees centigrade/hr)! Typical time in the tank is an hour or less for any degree of hypothermia.

Patients can be immersed with EKG monitors and IV lines in place. Temperature monitoring should be performed using a thermistor tipped urinary catheter. Many hospitals don’t have a full Hubbard tank, but do have smaller therapy baths that work nearly as well.

Tips:

  1. A physician must stay with the patient while immersed in case arrhythmias develop.
  2. Position the urinary catheter and collecting bag in such a way that urine in the tubing does not backwash into the bladder. This will falsely and rapidly increase the temperature reading.