Duchenne muscular dystrophy is the most common and severe form of the childhood muscular dystrophies. The disease is typically diagnosed between 3 and 7 years of age and follows a predictable clinical course marked by progressive skeletal muscle weakness with loss of ambulation by 12 years of age. Death occurs in early adulthood secondary to respiratory or cardiac failure. Becker muscular dystrophy is less common and has a milder clinical course but also results in respiratory and cardiac failure. The natural history of the cardiomyopathy in these diseases has not been well established. As a result, patients traditionally present for cardiac evaluation only after clinical symptoms become evident. The purpose of this policy statement is to provide recommendations for optimal cardiovascular evaluation to health care specialists caring for individuals in whom the diagnosis of Duchenne or Becker muscular dystrophy has been confirmed.
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December 2005
To the Editor,
As a pediatric anesthesiologist, I read the Clinical Report in the December 2005 issue of Pediatrics entitled “Cardiovascular Health Supervision for Individuals Affected by Duchenne or Becker Muscular Dystrophy” with great interest.1 Strong points in the article included emphasizing the frequent absence of classical symptoms of cardiac failure and the need for cardiac evaluation including echocardiography prior to major surgery. Also, there should be immediate availability of a cardioverter-defibrillator to treat life-threatening dysrhythmias in the operating room.
I am concerned over the statement that inhaled anesthetics are “known” to cause a “hypermetabolic state” and “should be avoided” in these patients. Although there have been reports of clinical MH-like events and positive in-vitro contraction tests in patients with dystrophinopathies,2 the incidence of this complication is unknown. Whether DMD or BMD predispose to MH or MH-like episodes with the use of inhaled agents alone is controversial and far from firmly established in the literature. Specific warnings against the use of inhaled agents in dystrophinopathy patients are not found in the package insert information for volatile agents.
Careful examination of the paper by Breucking et al.3 (referred to in the statement as supporting the avoidance of inhaled agents in patients with muscular dystrophies) reveals that 12 of 14 patients having complications (in which complete anesthetic data was available) received succinylcholine along with an inhaled agent. Succinylcholine is a well- established cause of rhabdomyolysis in patients with myopathies. Indeed, major cardiac complications have been reported with the use of intravenous anesthesia alone in DMD patients.4,5 Some authors believe that the incidence of MH in patients with DMD is the same as that in the general population and that inhaled agents should be used in these patients.6,7 The issue is further complicated by the fact that dystrophin deficient patients have altered muscle cell calcium metabolism which potentially may be a cause of false-positive in-vitro MH susceptibility testing.2
Goresky and Cox8 presented both sides of the controversy in a 1999 editorial. They concluded by urging anesthesiologists to consider being more cautious in their use of inhaled agents in dystrophinopathy patients, instead relying on the intravenous agents propofol, remifentanil, and midazolam. Subsequent to that editorial, reports of the propofol infusion syndrome in both ICU and operating room environments have been accumulating.9,10 Unfortunately, we do not know the relative risk of this complication with that of hypermetabolism and rhabdomyolysis in the dystrophinopathy patient receiving inhaled agents.
Therefore, whether or not potent volatile anesthetics should be routinely avoided in DMD and BMD patients is still open to debate. It is my hope that the recommendation to avoid prolonged use of inhaled agents in patients with DMD or BMD as published in Pediatrics by the Section on Cardiology and Cardiac Surgery are not construed as standards of care for anesthesiologists, particularly without their explicit involvement in the preparation of this statement.
Sincerely,
Samuel Golden, M.D., FAAP Comer Children’s Hospital Department of Anesthesia and Critical Care University of Chicago
Conflict of Interest:
None declared