The “obesity paradox,” as it is termed, may at first glance seem counterintuitive, but on reflection by the experienced intensive care unit (ICU) clinician, it quickly is found to be consistent with clinical observation. The obesity paradox refers to a literature body that supports decreased mortality in obese ICU patients when compared to nonobese patients of otherwise-matched demography and complexity of illness. While the morbidly obese patient may need more complex care and may be more apt to suffer certain complications, the obese patient has also been shown to be more likely to survive. More simply, it has been shown that despite the increased morbidity associated with obese ICU patients, there is also an association of decreased mortality.
It is the goal of this chapter to highlight these potential areas of increased morbidity as well as areas where usual management schema will need to be adjusted to these patients’ unique physiology. Wherever possible, I draw attention to any available data specific to the obese female population, although the overwhelming bulk of available literature on this topic is not gender specific (Figure 13-1).
Physiological effects of obesity.
Infections and Antimicrobials
Obesity has been recognized as a risk factor for both morbidity and mortality in patients infected with H1N1 influenza. The Centers for Disease Control and Prevention (CDC) considers morbid obesity a high-risk condition for 2009 H1N1-related hospitalization and possibly death.1 A study of 534 patients in California with H1N1 in 2009 found that, at a body mass index (BMI) of 40, the odds ratio (OR) of death was 2.8; for those patients with BMI greater than 45, the OR for death increased a further 50% to 4.2.1 During the same year, a study of 1520 patients in the United Kingdom also identified obesity as an independent risk factor for H1N1-associated morbidity greater than that associated with delayed admission, pneumonia, and the need for supplemental oxygen.2 There is also evidence that vaccination may be less effective in obese patients, with the rate of titer decay having been shown to be significantly more rapid in this population.3
Bacterial pneumonia as both a primary and a secondary infection has inconsistently been associated with obesity, but even in the studies that favored obesity as a risk factor for pneumonia, the paradox of increased survival generally remained present.4,5,6 The development of community-acquired Clostridium difficile infection was associated with obesity in a 2013 Boston study.7 A 2008 randomized controlled trial found a higher rate of infection associated with femoral catheters placed in obese as compared to nonobese patients, while a 2009 study of over 2000 ICU patients found severe obesity to be a risk factor for catheter-related (OR 2.2) and other bloodstream ...