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More on the Mayo Clinic Study of Anesthesia in Post-Polio Patients

Category: Medical Help

Selma H. Calmes, MD, anesthesiologist (retired), Olive View/UCLA Medical Center, Sylmar, California

A recent Post-Polio Health article reported on the first scientific study of polio patients having anesthesia for major surgery. (1) The study was done at the Mayo Clinic and compared each post-polio (PP) patient to two control patients of the same age with the same severity of preoperative illnesses and having similar surgery. It studied the many events that take place during anesthesia and surgery, including how much sedative medication (including anesthetics) was needed.

No differences were found between post-polio patients and controls. (2)

The article did not clearly address the issue of PP patients’ possible sensitivity to anesthesia drugs, and questions from members about this were received by PHI.

Fear of over-sedation during anesthesia has been a major issue for many PP patients. But, the Mayo Clinic study found that PP and normal patients needed the same amount of sedative and anesthesia drugs. The Mayo Clinic PP patients also had the same wake-up characteristics, as measured by time in the post-anesthesia care unit (PACU or Recovery Room) and time needed in an intensive care unit after surgery, as the control patients.

Because of the questions received, PHI Executive Director Joan Headley and I looked for more evidence on this issue. We reviewed previous PHI newsletters (3) and the standard books on post-polio care. (4,5,6) I also reviewed the medical literature from 1945 to the present, using the standard data base of well-done medical articles, PubMed. This article reports our findings on the question, “Is there any evidence that post-polio patients are more easily sedated from anesthesia drugs?”

What is the evidence that polio patients are sensitive to anesthesia?
Modern medicine has advanced to where it is today because studies of drugs and techniques are designed to compare patients to a control group (this group does not get the drug or technique studied) and the data is analyzed with careful statistics. The article reporting the results is then “peer reviewed” by other scientists or practitioners with knowledge in the study’s area before the study is published in a medical journal.

“Peer review” is often difficult, with communication back and forth, and the process is lengthy. But, it insures more accuracy, which is what medical care is all about—to find the best way of treating patients.

We looked for this kind of evidence. We did not look for one person’s experiences or studies without a control group or without statistical analysis, because they are not valid. We found no reports of excessive sedation from anesthesia medications in the medical literature, from 1945 to 2016.

The problem of respiratory failure during and, especially, after anesthesia (a high-risk problem for post-polio patients) was clearly recognized in the earliest papers and is the subject of most papers. The remaining papers are single case reports. None of these report excessive sedation or delayed awakening.

The standard modern books on care of post-polio patients also focus on respiratory issues during and after surgery. None of the books document sensitivity to anesthetics, but one book reports results of a survey of post-polio patients (the patients self-reported what happened to them when they had anesthesia and surgery). The survey was done in 2000 and discussed anesthesia complications reported by 237 polio survivors. The book reported, “…the biggest problem reported was being excessively sedated when they were put under. Just over half told us they were snowed after receiving a general anesthetic….” (5, p 173)

But, we don’t know what anesthesia drugs were used, the doses used, the year the operation was done (anesthesia drugs have changed markedly over time) and what other drugs the patient received (the effect of two drugs can add together). And, most important, we don’t know how the polio patients compared to non-polio patients having the same drugs and operations in the same time period the years the anesthesia was given.

A survey like this is not adequate evidence to make any general statement about the effect of anesthesia drugs on post-polio patients, because too many factors determine how patients respond to anesthesia drugs.

What is the variation of anesthesia drugs’ effects in different patients?
Many things affect how patients respond to anesthesia drugs. These include a patient’s age (older patients nearly always need less sedation), how much they weigh (obese people can have a prolonged effect of anesthesia drugs because of liver problems), other drugs that patients might take (some post-polio patients take narcotic drugs for pain and these add to the effects of anesthesia drugs), how well their liver works (many anesthesia drugs are broken down in the liver) and genetics.

An example of genetics is that Asian people are well–known to be easily sedated and very sensitive to anesthetics. One notable Chinese patient slept for 48 hours after her anesthesia, surprising her American anesthesiologist but not her Chinese physicians, who were familiar with this trait.

Another example of genetic effects on anesthesia is people with red hair. The gene responsible for red hair also is involved in pain perception. Red-haired people need more anesthesia (this has actually been measured) and are resistant to the local anesthesia drugs used for dental surgery.

Because we now know that many things can affect response to anesthesia, and we know more about how anesthesia drugs work, and because we have better drugs, anesthesiologists can now plan better for patients.

Anesthesia drugs have changed!
Many post-polio patients had operations when they were young children, in the 1940s-1950s. Anesthetic drugs used then were ether (given by mask) and pentothal (given intravenously). Both ether and pentothal (if used for a long operation, as was done then) can easily cause long wake-up times. Also, anesthesia knowledge was not very advanced. Most anesthesia in the early time in polio hospitals, such as Warm Springs, was given by regular nurses with little training in anesthesia, a situation that would lead to many problems.

There has been enormous change in anesthesia drugs, in training and in knowledge about anesthesia. The anesthesia drugs and techniques I learned during residency (from 1966-69) are no longer used. Anesthesiology today is an entirely new specialty.

Today’s anesthesia drugs first came into use in the 1990s-2007 and have much better characteristics: quicker onset, quicker awakening and better minute-to-minute control of dosing. This is especially true of the intravenous drug propofol, now a very popular drug for sedation and surgical anesthesia.
The move to better drugs was driven by the move to out-patient surgery where patients had to wake up more quickly, and new drugs were developed to help with a faster recovery.

Anesthesia techniques (how anesthesia is given) have also changed over time. Regional anesthesia (a local anesthesia drug is used to make only part of the body numb during surgery; this may be continued postoperatively for pain relief) has been clearly demonstrated to have a much more favorable outcome for all patients.

Regional anesthesia is widely used today when possible, although not all operations can be done using it. A patient getting regional anesthesia often also gets mild sedation with propofol, but nearly always wake up quickly.

Another example of how anesthesia has changed is that regional anesthesia is typically done today with the help of an ultrasound machine, which helps identify the specific nerves to be blocked. This is especially useful in patients with scoliosis (common in polio patients), and there are reports of this technique used successfully in PP patients.

Feeling weak after anesthesia.
Some PP patients report feeling weak after anesthesia and surgery. This is most likely due to the long-lasting effect of muscle relaxant drugs needed for some operations. Although drugs to reverse the paralysis are available, they may not be effective, for various reasons. It is now clear that even healthy people can have this problem; it is not unique to PP patients. The issue of the non-effectiveness of drugs to reverse the effect of muscle relaxants has become a big issue in anesthesia practice in the last few years. Articles in anesthesia journals and our teaching programs now emphasize that more attention and monitoring for this problem should be done.

So, what should a polio patient do now?
Many post-polio patients feel strongly that they are sensitive to anesthesia drugs, even though scientific evidence for this is lacking, and even though the drugs now used for sedation/anesthesia are very different. So, when needing sedation/anesthesia today, you should tell the anesthesiologist about your experience. If possible, it helps to say when (what year) you had your problem with excess sedation and what drugs were involved, if you know. In spite of your past experience, it is very likely that you will have a much better experience with anesthesia today.

Trust your well-trained anesthesiologist, who can now easily find information on how to care for post-polio patients. Also, be sure to go to the best hospital for your operation. There is a lot of variation in hospital care throughout the US.

Find the best one you can—and be sure to have a pulmonary evaluation before surgery! Respiratory failure is the greatest known risk for PP patients. Anesthesia has advanced so markedly now that even the sickest patients survive radical operations, such as heart transplants.

There is no reason polio patients should experience the problems of the past.


1. Calmes SH. Important new paper published on anesthesia and polio. Post-Polio Health. 2016; 32:10-11
2. Van Alstine LW, Gunn PW, Schroeder DR, Hanson BS, Sorenson EJ and Martin DP. Anesthesia and poliomyelitis: A matched cohort study. Anesthesia & Analgesia. 2016; 122:1894-1900
3. Joan L. Headley reviewed past issues of PHI newsletters, available in the archives. Selma H. Calmes reviewed the books.
4. Halstead LS. Managing post-polio. A guide to living well with post-polio syndrome. NRH Press, Washington DC. 1998. Pp 49-53
5. Bruno RL. The polio paradox. Warner books, New York, 2002. Pp 173-176
6. Silver JK, Gawne AC. Postpolio syndrome. Hanley & Belfus Philadelphia, 2004. Pp 100-101, 211

Tagged as: anesthesia , surgery

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