Keeping Patients Warm Means Generating Heat
Posted by Clark Venable on 2/18/2007
Once anesthetized with a general anesthetic, patients are largely defenseless. The anesthesiologist is responsible for protecting the patient from their environment--an environment that can be increasingly hostile. One key facet of that environment is temperature, but control of it has never been more contested in the operating room than it is today.
My perspective may be skewed because I do so much anesthesia for orthopedic surgery--a surgery in which the surgeon is physically working hard under an OR gown, gloves, and hot lights. Certainly in pediatric rooms no one ever complains during times when we make the room hot. That's not true, actually. They complain, but they know full well that we are all there to keep the pediatric patient safe and keeping them warm is part of that. They don't expect us to drop the room temperature until we have the child anesthetized and covered.
But why does room temperature matter? It matters because it can affect patient body temperature, and patient body temperature matters for the following reasons:
- Mild hypothermia (1-3 deg. C) reduces resistance to surgical wound infection.
- Mild hypothermia prolongs hospital stay.
- Even mild hypothermia can cause shivering and be a very uncomfortable feeling after surgery.
- Shivering increases stress on the heart. In patients with heart disease this may cause ischemia.
Under anesthesia, our normal mechanisms for keeping warm are limited. Anesthetics significantly impair our ability to control blood flow to the skin. Although there are five mechanisms of heat loss from the body in the operating room, 90 percent occurs through the skin via radiation and convection
For those wanting a detailed review article and that have a NEJM subscription, see: Mild Perioperative Hypothermia by Daniel Sessler, M.D. in the Department of Anesthesia at UCSF.
I'm sure patients would be gratified to know that it's not the person with the most knowledge and training in patient temperature management that decides in most cases, but the person that whines the most (or is the sneakiest).
For example, last year I was scheduled to provide anesthesia for a 16 year old athlete having an ACL reconstruction. This was not the first case in that room, so the room was already as cold as a meat locker--64 degrees. I reset the room thermostat to 72 degrees, and placed a sticky note saying 'Please Do Not Change,' printed my name, and went to go see the patient.
When I came back to the room several minutes later, the note was gone and thermostat reset to 64 degrees. I replaced the note and reset the thermostat two more times. Both times the note was gone and thermostat reset. The final time there was a note from the charge nurse asking me to come see her.
What did I do? I did what any self-respecting anesthesiologist would do--I told the OR nurses the case was on hold until the room temperature came up and went to get some coffee. Not long after that the charge nurse paged me to discuss the issue. (Nothing gets management's attention more than a case delay.)
Why had she reset it? Because, she claimed, biomedical engineering (some guy with a Bachelor's Degree) said that bringing surgical instruments into a 72 degree room would cause them to sweat and possibly impair sterility. I thought back to my years of doing anesthesia for burn surgery in 85 degree operating rooms and found this explanation novel and fascinating. 'So', I asked her, 'you're taking the advice of a four year college graduate over that of a board certified anesthesiologist?'
Well, you can guess how the conversation went after that. These days, if someone in the OR is feeling hot they either turn the thermostat down themselves or ask the circulating nurse to do it. If all this done without asking me when I'm in the room, I point out to them that they should have asked me before making that decision and ask instead that the room temperature be increased several degrees. If they do ask me if they can turn the room temperature down, provided the patient is reasonably warm and covered, I'll oblige and say 'Thank for asking me. The patient appreciates it. You may set the room temperature to whatever you like.'
In days past everyone acknowledged room temperature was the anesthesiologists choice. These days I have to fight to control it, as I do for every other shred of professional respect. What I'm working on is to get a ruling from the OR committee that states room temperature is my bailiwick. With impending pay for performance measures that will include patient temperature on arrival to the recovery room, this issue has been forced to a head.
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