MYASTHENIC CRISIS - CLINICAL-FEATURES, MORTALITY, COMPLICATIONS, AND RISK-FACTORS FOR PROLONGED INTUBATION

We retrospectively reviewed the hospital records of 53 patients admitt ed for 73 episodes of myasthenic crisis at Columbia-Presbyterian Medic al Center over a period of 12 years, from 1983 to 1994. Median age at the onset of first crisis was 55 (range, 20 to 82), the ratio of women to men was 2:1, and the median interval from onset of symptoms to fir st crisis was 8 months. Infection (usually pneumonia or upper respirat ory infection) was the most common precipitating factor (38%), followe d by no obvious cause (30%) and aspiration (10%). Twenty-five percent of patients were extubated at 7 days, 50% at 13 days, and 75% at 31 da ys; the longest crisis exceeded 5 months. Using survival analysis and backward stepwise Cox regression, we identified three independent pred ictors of prolonged intubation: (I) pre-intubation serum bicarbonate g reater than or equal to 30 mg/dl (p = 0.0004, relative hazard 4.5), (2 ) peak vital capacity day 1 to 6 post-intubation <25 ml/kg (p = 0.001, relative hazard 2.9), and (3) age >50 (p = 0.01, relative hazard 2.4) . The proportion of patients intubated longer than 2 weeks was 0% amon g those with no risk factors, 21% with one risk factor, 46% with two r isk factors, and 88% with three risk factors (p = 0.0004). Complicatio ns independently associated with prolonged intubation included atelect asis (p = 0.002), anemia treated with transfusion (p = 0.03), Clostrid ium difficile infection (p = 0.01), and congestive heart failure (p = 0.03). Three episodes of crisis were fatal, for a mortality rate of 4% (3/73); four additional patients died after extubation. All seven dea ths were due to overwhelming medical comorbidity. Over half of those w ho survived were functionally dependent (home or institutionalized) at discharge. In addition to prospective controlled studies of immunothe rapies, the prevention and treatment of medical complications offers t he best opportunity for further improving the outcome of myasthenic cr isis.