Tag Archives: hypothermia

Keeping Patients Warm In Your Trauma Bay

Hypothermia is the enemy of all trauma patients. It takes their potential bleeding problems and makes them exponentially worse. From the time you strip off their clothes in the trauma resuscitation room, they begin to cool down. And if you live in Minnesota like me (or some similar fun place), they start chilling even before that.

What can you do in the trauma bay to help avoid this potential complication? Here are some of the possibilities, and what I think of them. And I’ll also provide a practical tip to help keep your patient warm  while you can still do a full exam.

Outside

– Warming lights in the ambulance unloading area. I know lots of people look at this area and recommend them. Unfortunately, they don’t do a lot. Consider that your patient will move through this space quickly. While it may be cold, they’ll only spend a minute or so getting to the back door to the ED.

– How about the path from the helipad? If this is mostly outside, it can be a problem. If it’s wide open, there aren’t really a lot of options. Cover and heat it? Lots of $$$. Typically, flight crews working in winter climates have bundled up their patient very well, and this is the patient’s primary source of protection from the elements. If the pad is far away from the ED, consider a fancy golf cart to move them quickly, and perhaps get an even fancier one that has a heated enclosure.

Inside

– Heat the room! This only works on a moment’s notice if you have a smaller room or a really good heating system. Otherwise, you must keep it cranked it up at all times.

– Close the door! You will not be able to keep the room toasty unless you make sure the door is closed as much as possible. No doors? Then consider the next tips.

– Use radiant heating systems. Some EDs have lights in the ceiling, others have portable units that can be rolled over to your patient.

– Use hot fluids, especially in the winter. At a minimum, all blood products must be administered through a warmer, since they are only a few degrees above freezing. If it’s winter outside, or your patient is already cool, give all IV fluids through the warmer, too.

– Cover your patient. Keep a blanket warmer nearby, and pull several out at the beginning of each resuscitation.

– What about those fancy air blankets? Unfortunately, they are unwieldy. They’re all one piece, they try to fall of the patient all the time, and they limit access for your exam. But there is a solution!

Here’s a clever way to deal with this problem. Use my two-blanket trick. Don’t use just one warm sheet or blanket. Use two! Fold each one in half, so they are each half-length. Place one on the top half of the patient, the other at the bottom, overlapping slightly at the waist. Your whole patient is now covered and toasty. If you need to look at an extremity, fold the blanket that covers it over from right to left (or left to right) to uncover just the area of interest. To insert a urinary catheter, just open the area at the waist, moving the top sheet up a little, the bottom down a little. Voila!

How Fast Can You Warm Up A Hypothermic Patient?

‘Tis the season to see hypothermic patients again! The optimal way to warm them up has been debated for years. A number of very interesting techniques have been devised. Ever wonder how fast / effective they are?

I’ve culled data from a number of sources, and here is a summary what I found. And of course, the disclaimer: “your results may vary.”

Warming Technique Rate of Rewarming
Passive external (blankets, lights) 0.5° C / hr
Active external (lights, hot water bottle) 1 – 3° C / hr
Bair Hugger 2.4° C / hr
Hot inspired air in ET tube 1° C / hr
Fluid warmer 2 – 3° C / hr
GI tract irrigation (stomach or colon, 40° C fluid, instill for 10 minutes, then evacuate) 1.5 -3° C / hr
Peritoneal lavage (instill for 20-30 minutes) 1 – 3° C / hr
Thoracic lavage (2 chest tubes, continuous flow) 3° C / hr
Continuous veno-venous rewarming 3° C / hr
Continuous arterio-venous rewarming 4.5° C / hr
Mediastinal lavage (thoracotomy) 8° C / hr
Cardiopulmonary bypass 9° C / hr
Warm water immersion (Hubbard or therapy tank) 20° C / hr

Hypothermia For Treatment of Severe TBI?

We’ve been trying to figure out therapeutic hypothermia for a long time. Although we know that accidental hypothermia, especially in trauma patients, is not a good thing, it seems to be protective in certain circumstances. The most significant areas of interest center around the neuroprotective effects, especially after ischemia or hypoxia.

But with the good always comes the bad. Every intervention has side effects, and hypothermia is no exception. Decreased cardiac efficiency, blood viscosity increases, pulmonary dysfunction or edema, coagulopathy, decreased tissue oxygen availability, and changes in drug pharmacodynamics are but a few of the problems that may arise. But as long as the benefits outweigh the risks, such an intervention may be acceptable.

We’ve been looking at the possible protective effects of hypothermia on the brain after severe head injury for quite some time. As with most neurotrauma studies, hypothermia ones are tough to do well. Patient selection, adequate numbers of subjects and good randomization and/or blinding are very difficult. It requires assembling all the relevant studies and scrutinizing this whole body of work to figure out if it works or not.

And the answer is, it doesn’t. The Cochrane Library updated their previous work in this area in 2009. They combined 23 studies and over 1600 patients to try to determine if hypothermia (35C for at least 12 hours) is protective in patients with severe TBI. After whittling the field down to good quality studies, they found that there may be a trend toward fewer unfavorable outcomes (death, severe disability, vegetative state), but it was not statistically significant. There were variable results with respect to the incidence of pneumonia after hypothermia, and these, too, did not meet statistical significance.

Bottom line: Therapeutic hypothermia for treatment of severe TBI is still not ready for prime time, and may never be. The studies thus far are small and flawed. Don’t implement your own protocol for this technique unless you are involved in a very high quality, multi-center study that will add to the literature!

Reference: Hypothermia for traumatic head injury. The Cochrane Library 2009, Issue 4.

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 for treating hypothermia. J Trauma 31(8):1151-1154, 1991.

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Rapid Noninvasive Rewarming Using a Hubbard Tank

It’s that time of year again in Minnesota. We’re getting 5 inches of snow tonight, so hypothermia season is officially here! I’m republishing a technique for rewarming patients faster than just about any other method. Most burn centers have large tanks for handling burn wounds, and many hospital have smaller therapy tanks that can be used for the same purpose.

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.

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