Going To Sleep Is Free, But

Keeping Patients Warm Means Generating Heat

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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:

1. Mild hypothermia (1-3 deg. C) reduces resistance to surgical wound infection.
2. Mild hypothermia prolongs hospital stay.
3. Even mild hypothermia can cause shivering and be a very uncomfortable feeling after surgery.
4. 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.

Status Report on Google Modules

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A while ago Seth Dillingham wrote two Google modules for me: Allowable Blood Loss and BMI Calculator. Well, I still have a hard time finding them on Googles own module site, but I can find them both on googlemodules.com--the 'Unofficial Google Modules Site'.

I wanted to pass along another use for the allowable blood loss calculator--estimating surgical blood loss. Anesthetists are asked to estimate the volume of surgical blood loss that occurs during a procedure on their anesthetic record. Surgeons will often attempt to influence that figure downward by volunteering their own estimate of blood loss (often not grounded in reality) in the hope of getting me to go along with it.

In large blood loss cases where I've been following the hematocrit I use the formula to calculate the actual blood loss. For example, if a 100 kg male started with a hematocrit of 0.40 and wound up with a hematocrit of 0.32 I calculate their blood loss as 1600 cc. No arguments.

Wet taps and the number '3'

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Wet taps are accidental dural punctures that happen while attempting to place a needle into the epidural space. The published frequency of wet taps is about 1 in 800 epidural placements, depending on the experience of the operator. If I'm placing an epidural catheter in a pregnant woman and get a wet tap, she has a greater than 50% chance of a dural puncture headache (unless, of course, she is morbidly obese, in which her risk is almost zero).

It seems my wet taps come in three's (hence the title of this post). I remember as a third year anesthesiology resident being on call on OB for the first time after spending three months on the transplant anesthesia service and getting three consecutive wet taps that night on OB. Bam, bam, bam (or should I say 'splash, splash, splash'). I felt terrible, of course, but could not recall doing anything different that would have caused them! My grandmother used to say that accidents happen in threes. She was referring to airplane crashes, but I have to wonder, is it true of wet taps?

In the last ten years of doing anesthesia I've had no accidental dural punctures that I know of. That all changed about a month ago. I did a lumbar epidural steroid injection on a co-worker's husband and must have scored the dura. That's one. I had a wet tap during a labor epidural on a patient who, in retrospect, had a non-union of the ligamentum flavum. That's two. I'm just waiting for number three. I'm on call on OB tonight. Is number three around the corner?

[here's a nice review, btw]

Smoking Cessation Before Surgery Encouraged

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I think this is noteworthy because, in terms of complications, we used to think that one would need to quit smoking for at least six weeks before surgery for there to be any benefit. Though that may still be true, this review seems to indicate that if someone were to quit around time of surgery, their chances of success are better.

Are Lower Back Tattoos A Contraindication To Labor Epidurals?

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My Google News section on 'epidurals' came up with an interesting hit: Lower-back tattoos are popular with women, but do they make having epidurals during childbirth more dangerous?. It's a very good question because, at least in my practice, lower back tattoos are extremely common in laboring women. So common, in fact, that Saturday Night Live has a commercial parody for a product called Turlington's Lower Back Tattoo Remover (quicktime | windows media).

I was taught to avoid putting an epidural needle through tattooed skin and have gone to great lengths to do so. For example, one patient had a very large tattoo of what appeared to be the face of the devil on her lower back. On closer inspection, I noticed that the devil's right nares (which was free of tattoo ink) was right over her L3-4 interspace. I wished I'd taken a picture of that epidural catheter snaking out of the devil's nose.

I can't seem to find much science on the subject save for one abstract which makes a very reasonable suggestion to avoid coring out tattooed skin by making a small incision, if necessary. This may sound like a lot of trouble, but all it takes is a 16 gauge (or similarly large) hypodermic needle inserted into the skin first, then the epidural needle through that 'incision'.

Or Their Designee...

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If you read your consent for surgery, you'll see those words right after your surgeon's name. Maybe you've noticed them. Probably you haven't.

Ghost surgery is defined as "substitution of an authorized surgeon by an unauthorized surgeon or the allowance of unauthorized surgical trainees to operate without adequate supervision". Now, that definition is sufficiently vague to allow all manner of stuff to go on, but I would wager that if you asked the patient wether they were under the impression their surgeon would do the entire surgery, that they would say 'yes.' If I ask surgeon W to do my surgery, I'd like surgeon W to sew the skin closed, too. Residents can practice closing just fine in partial-task simulators.

Medpundit Looks At His Financials

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Ugh: I just spent the better part of the afternoon...:

How do you mark a surgical site?

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The American Academy of Orthopaedic Surgeons has a policy on marking surgical sites titled Guidelines for Implementation of the Universal Protocol for the Prevention of Wrong Site, Wrong Procedure and Wrong Person Surgery. It's worth reviewing and comparing to your institutions policy. For example:

• Make the mark at or near the incision site. Do NOT mark any non-operative site(s) unless necessary for some other aspect of care.
• The mark should be unambiguous (e.g., use initials or "YES" or a line representing the proposed incision; consider that "X" may be ambiguous).
• The person performing the procedure should do the site marking.

There's much more to the guideline, but your current policies are most likely to be at variance with the above three points. One of the surgery centers I work at, for instance, marks the surgical site with an 'X'. I've explained to them that 'X' is ambiguous (does X mark the spot, or does X mark 'not this one'?) and even explained the details of a malpractice case in which marking with an X came into play. Another hospital was in the habit of marking both sides ('L' and 'R'). Also confusing. Finally, several centers have the nurse preparing the patient for surgery to mark the site. Also not a good idea.

You Anesthesiologist Today Was...

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I finally ordered my own business cards. I've had generic one available but always had to write in my own name (despite being with the group for well over two years) so decided it was time for an upgrade.

Picking the pattern was tough, but I decided on a tranquil image (that happens to be one of the MacOS X desktop images):

Rejected images included a dark tunnel with a light at the end, and anything with pearly gates.

This decision was evidence based (of course). Giving patients a business card before anesthesia increases their recall of your name to about 50% rather than the 10% that remember it without. It should also help them see they are being cared for by a physician. There's room on the back for 'anesthetic' and 'comments', too.

Pre-emptive Patient Positioning

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Many surgeries require the patient to be in a position other than supine (flat on their back) for the surgery to be done. Shoulder surgery, for example, is often done with the patient in a semi-sitting or 'beach chair' position. Certain hip surgeries are done with patients on their side as well. General anesthesia is induced with the patient supine, then people have to move the patient (who is now akin to a very heavy sack of potatoes) into the right position. It's time consuming, risks staff injury, and jeopardizes the airway. The few accidental extubations I've had have occurred when the patient was being moved. Does it have to be this way? If the case is amenable to an LMA, I think the answer is 'no.'

If I'm caring for a patient who will require a general anesthetic and an LMA would be suitable, I've taken to positioning the patient before induction of anesthesia. I then pre-oxygenate, perform an IV induction, and place the LMA. The OR staff and surgeons like it because a) it saves time and b) it saves their backs. I like it because there's no move during which my airway can potentially be compromised (and because it saves time and saves my back). There's a benefit to the patient, too. Namely, they can tell us while awake whether our positioning is comfortable for them. Is the axillary role in the right place? Do they need a pillow under their knees in? Is their bottom up against the back of the table in beach chair? Is their ear properly padded in the lateral position? Think Different (but always, Think Safe).