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.
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.
- A physician must stay with the patient while immersed in case arrhythmias develop.
- 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.
Scoop and run vs stay and play are traditionally EMS concepts. Do I stay at the scene to perform invasive procedures, or do I perform the minimum I can and get to the nearest hospital?
For trauma patients time is the enemy and there is a different flavor of scoop and run vs stay and play. Do I take the patient to a nearby hospital that is not a high level trauma center to stay and play, or do I scoop and run to the nearest Level I or II center?
Admissions to a group of 8 trauma centers were analyzed over a 3 year period. A total of 1112 patients were studied. Patients were divided into two groups: those who were taken directly to a Level I trauma center (76%), and those who were transferred from another hospital (24%).
Patients who were taken to a non-trauma center first received 3 times more IV crystalloid, 12 times more blood, and were nearly 4 times more likely to die!
Obviously, the cause of this increased mortality cannot be determined from the data. The authors speculate that patients may undergo more aggressive resuscitation with crystalloid and blood at the outside hospital making them look better than they really are, and then they die. Alternatively, they may have been under-resuscitated at the outside hospital, making it more difficult to ensure survival at the trauma center.
Bottom line: this is an interesting paper, but there are a number of flaws that prevent us from mandating that all trauma patients should go directly to the trauma center. The authors never really define a “nontrauma hospital.” Does a Level III or IV center count? How did patients who stayed at the outside hospital do?
A lot of work needs to be done to add detail to this work. In the meantime, we have to trust our experienced prehospital providers to determine who really needs to go to the closest appropriate center, and what that really is.
Reference: Scoop and run to the trauma center or stay and play at the local hospital: hospital transfer’s effect on mortality. J Trauma 69(3):595-601, 2010.
The October newsletter is now available! Click the image below or the link at the bottom to download. This month’s topic is Resuscitation.
In this issue you’ll find articles on:
- Jehovah’s Witnesses and blood transfusion
- Blood transfusion component therapy
- What’s the INR of FFP?
- Evolution of the use of Factor VII
- And more!
Subscribers received the newsletter first by email last week. If you want to subscribe (and download back issues), click here.
Download the newsletter here!
When one works in the trauma field, or medicine in general, we deal with the need for sterility all the time. We use equipment and devices that are sterile, and we administer drugs and fluids that are sterile. In surgery, we create sterile fields in which to use this sterile stuff.
In the past few years, we’ve come to the realization that the sterility we take for granted may not always be the case. There have been several cases of contaminated implanted hardware. And most recently, supposedly sterile injectable steroids were found to be contaminated with fungus, leading to several fatal cases of meningitis.
A recent article in the New England Journal of Medicine brings a bizarre problem to light: microbial stowaways in the topical products we use to sterilize things. Most drugs and infused fluids are prepared under sterile conditions. However, due to the antimicrobial activity of topical antiseptics, there is no requirement in the US that they be prepared in this way.
A number of cases of contamination have been reported over the years:
- Iodophor – contamination with Buckholderia and Pseudomonas occurred during manufacture, leading to dialysis catheter infection and peritonitis
- Chlorhexidine – contaminated with Serratia, Buckholderia and Ralstonia by end users, leading to wound infections, catheter infections, and death
- Benzalkonium chloride – contaminated with Buckholderia and Mycobacteria by end users, causing septic arthritis and injection site infections
Bottom line: Nothing is sacred! This problem is scarier than you think, because our most basic assumptions about these products makes it nearly impossible for us to consider them when tracking down infection sources. Furthermore, they are so uncommon that they frequently may go undetected. The one telltale sign is the presence of infection from weird bacteria. If you encounter these bugs, consider this uncommon cause. Regulatory agencies need to get on this and mandate better manufacturing practices for topical antiseptics.
Reference: Microbial stowaways in topical antiseptic products. NEJM 367:2170-2173, Dec 6 2012.