Tuesday, November 21, 2017

The Hopelessly Ambiguous ASA Classification

I've ranted before about how ineffective the ASA classifications can be to evaluate patient morbidity. The American Society of Anesthesiologists is well aware of how ambiguous the different levels of the system can be to categorize patients. They have even published examples of patients in each level to help physicians understand how to organize different scenarios. Despite that, there is still much confusion among physicians, even anesthesiologists who should know this system better than anyone else.

A wonderfully illuminating study was published in "Anesthesia & Analgesia" that looked at how different patients would be categorized by physicians. Just in case you don't know what the different ASA scores are, there are six levels, ranging from one in a perfectly healthy patient to a six, who is considered brain dead. You may want to read the link to the ASA first if you don't understand it.

In the study, 235 anesthesiologists and 101 trauma surgeons were queried about eight different scenarios. They are:

1. Previously healthy patient with hemorrhagic shock.
2. Morbid obesity with non life-threatening injury
3. Brain dead organ procurement
4. Massive trauma
5. Healthy elderly patient with minor injury
6. Hemorrhagic shock in a Jehovah's witness who refuses blood transfusion
7. Previously stable patient with septic shock
8. Intracranial hemorrhage with mass effect

In none of the eight stories was there a consensus where everybody agreed on a single ASA score. In fact, #3, which might obviously belong to ASA 6 was classified by physicians from ASA 1 all the way to ASA 6.

One of the problems is that there is no clear instructions from the ASA about whether the ASA classes relate to the preinjury condition of the patient or postinjury. They found that 72% of the physicians think the ASA scores refers to postinjury status of the patient while 27% think it is preinjury. Over three quarters of anesthesiologists use the ASA scores to indicate postinjury status while 62% of surgeons did. Therefore it is conceivable that a perfectly healthy young person who suffers a brain death injury, an ideal organ donor, could be classified as ASA 1. But for the smattering of respondents who called #4 or #8 an ASA 6, they really need to go back and review the definition of brain death.

At least the anesthesiologists were more in agreement in how to use the ASA scores. They were more in consensus than the trauma surgeons or the combined anesthesiologists and surgeons. However that didn't prevent one anesthesiologist from scoring #8, an obvious life threatening condition, as ASA 1.

So it looks like the ASA has a lot more work to do to educate physicians, and the members of the society, how to properly use the ASA classification. However, attempts at education may be futile since getting anesthesiologists to agree on anything is like herding cats.

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