Sunday, September 12, 2010
“Be Prepared” ... A motto that might save your life – Part I
This last week I received an email. "I would like to know the position of general anesthesia and KD affected men. If you could cover how KD affects anesthesia, are there any options, at what stage in the KD lifecycle does this become an issue. I have this fear of having to have an emergency operation and because KD is such a rare disease the surgeons etc may not be aware of the risks."
The questions are excellent and it was a concern of mine a few years ago. Because of the importance of this subject, it will be a two-part article. This article is focused on comments from doctors. Part II will be about preparation and concerns in general as well as highlighting some of the comments from this article.
Background: I broke my tibia and fibula in a fall. The emergency room x-rays showed the two bones were broke a several places. The orthopedic surgeon wanted to operate and use some pins and screws to correct the problem. I asked my wife to go home and bring back the anesthesia information from my Kennedy's Disease file. The anesthetist reviewed the information and he recommended that the operation not be performed at this hospital. He had never assisted in a surgery on someone with spinal bulbar muscular atrophy.
There is some good information on the internet about anesthesia and neuromuscular diseases. The KDA has four articles on the subject that explain the concerns and potential issues quite well. The MDA also has information on their website about anesthesia and neuromuscular disease (NMD).
Dr. P.J. Halsall and Professor F.R. Ellis provide the following explanation.
"People with neuromuscular disorders must take great care if they are to have a local or general anesthetic. Even someone with very mild, or
non-existent symptoms, or someone who has a family history of a disorder, needs to let the anesthetist know well in advance so that tests can be carried out and proper care after the operation can be arranged. Many people are afraid of having an anesthetic, mainly through ignorance, but when we look at the rate of complications and even deaths arising from anesthesia we see that it is in fact very safe. This safety is the result of a thorough understanding of the patient's medical condition with a careful assessment before the operation, marked technical improvements in monitoring facilities such as High Dependency Units (HDU) and Intensive Care Units (ICU).
Patients with neuromuscular disorders (NMDs) deserve special attention when it comes to anesthesia because many of the agents used (gases and
chemicals) have effects on both muscle and nervous tissue. The main areas of concern are how the anesthetic agents will affect the muscle and how they will affect the heart which is itself a muscle.
Muscle relaxant drugs should only be used if essential because they tend to have a more profound and prolonged effect in NMD patients compared to
other patients. One type of muscle relaxant, called suxamethonium, should usually be avoided. It causes the release of potassium ions (K+) from the muscle tissue into the blood. In normal patients this is usually of little practical significance. In patients with NMD the muscle may normally leak K+ so that a further increase in the levels of K+ in the blood may cause abnormal heart rhythms. A preoperative blood test to check K+ levels is therefore important.
A local anesthetic works by preventing the normal electrical activity in the nerve around which the anesthetic agents are placed. For minor procedures, such as stitches for cuts, they are probably the first choice for patients with NMD because they have few if any side-effects. However for major local anesthetic techniques, e.g. spinal or epidiural, careful assessment of the patient is needed and the type of NMD considered well before the operation.
Changes in body temperature and preoperative 'starvation' are also a concern. Patients with NMD do not tolerate changes in body temperature or the
starvation often associated with anesthesia or surgery as well as normal patients, so steps need to be taken to minimize these problems by keeping the patient warm and well hydrated using drips.
To sum up ... clearly anesthesia in NMD is not to be undertaken lightly. Such patients should expect the anesthetist to make a careful and thorough assessment of their particular condition and their current state of health. They are not suitable to be treated as 'Day Cases' because doctors should
carry out preoperative investigations, and enough time and recovery facilities should be available after the operation. It is absolutely essential that the person affected by NMD should inform the anesthetist even if there are only minor symptoms, or no symptoms at all. Occasionally a neuromuscular disorder in a person who had no symptoms has come to light only because of an unexpected problem with anesthesia, particularly in young children."
Dr. Linton Hopkins, a neurologist at Emory explains other concerns.
"KD patients may have significant weakness of respiratory muscles and not know it, so they don't report it pre-op. Then after surgery, with the ordinary chest or abdominal pain that follows so many operations, they find it impossible to take an adequate breath or cough well enough to clear secretions. This can quickly lead to hypoventilation & pneumonia. Everyone who is not confident about the strength of their cough and sniff should warn their doctors and ask for pre-op pulmonary function and instructions about incentive spirometry and other ways to minimize the risk. ... Surgeons and anesthesiologists know about myopathies and neuropathies, even though few will have heard of KD, which is such a rare "neuropathy", or anterior horn cell disorder."
Part II will be posted on Tuesday.