The growing interest in gastric bypass surgery points up the problems faced by critically ill morbidly obese patients and the serious challenges seen by physicians in treating these patients.

According to the American Society for Bariatric Surgery, the rate of obesity surgeries has risen from 37,000 in 2000 to 62,400 in 2001. It is expected that the total number of cases will exceed 100,000 when figures are released for 2003.

This "Clinical Commentary" in the ATS journal addresses the significant differences in care for the critically ill morbidly obese patients whose mean body mass index exceeds 50. According to the author, the mechanical properties of the total respiratory system, the lung, and the chest wall of morbidly obese patients are characterized by marked derangements compared with subjects of normal weight.

In a retrospective study cited, patients who were morbidly obese needed prolonged mechanical ventilation, extended ventilation weaning periods, and larger intensive care unit and hospital stays. Researchers pointed out that delayed liberation from mechanical ventilation is due to the increased work of breathing and the suboptimal lung mechanics of the patients.

Morbidity from bariatric surgery can be in excess of 10 percent. Early complications include wounds splitting open, wound infection, bleeding, pulmonary embolism, and death. Compared with normal weight patients, the incidence of wound infection is significantly higher. Peritonitis from staple line leak is a serious and life-threatening complication of bariatric surgery.

Proper diagnosis is often very difficult. The authors point out that the obese body is characterized by a higher proportion of tissue water and lean body mass. He explained that these alterations account for differing patterns of drug absorption and distribution that can lead to sub-therapeutic or toxic drug responses. Monitoring of serum concentrations represents the most reliable method of measuring therapeutic concentrations in the very overweight patient.

The article appears in the first issue for March 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.