Vasopressor Use in Hemorrhagic Shock-What Can Propensity Matching Actually Tell Us?

Critical Care Medicine www.ccmjournal. org e273 The authors reply: We thank Liu et al (1) for their interest in our recently published article (2) in Critical Care Medicine. Their stated concern centered around our recommendation for caution in nonvolitional feeding severely ill patients. They base this on findings from a not-yet publicly available meta-analysis which found feeding to be associated with reduced sepsis, pneumonia, renal failure, and hospital length of stay among patients with major burn injury (3). Comparison between our study findings (2) and the findings of this meta-analysis is problematic for two reasons: 1) burninjured patients represent a fundamentally different patient population compared with acute respiratory distress syndrome patients; their increased need for tissue repair makes it unlikely that their nutritional needs are comparable and 2) it is impossible to know the true caloric dose received in the meta-analyzed studies because bodyweight determination methods differ considerably between studies and are a necessary component to any dosing strategy. We continue to encourage caution with increase calorie exposure. This caution is justified by our findings that demonstrate provision of energy exposure greater than 12 kcal/kg significantly increased the odds for mortality (odds ratio, 1.99; 95% CI, 1.03–3.87) compared with individuals who received less than 12 kcal/kg, consistent with findings from our earlier publications that increased calorie delivery are associated with worse outcome (4–6). Additionally, severity of illness can change from ICU admission and thus alter the feeding-mortality association. Our study (2) captures this phenomenon. We assessed the impact of organ dysfunction via Sequential Organ Failure Assessment (SOFA) score on mortality from four angles: 1) at admission, 2) as a 7-day average, 3) the highest SOFA score, and 4) the change in SOFA from intubation to day 7. This approach improved the ability to explain the variance in ICU mortality. We are hopeful this method will encourage clinicians and researchers to consider how change in clinical status influences outcome. The second major area Liu et al (1) were interested in was the influence nutritional status had on mortality. As described (Tables 2 and 3 in [2]) nutritional status was controlled for in each of the logistic regression models. Malnutrition was not a significant predictor for mortality in any of these logistic models. We suspect this reflects our inability to accurately assess malnutrition in critically ill rather than a true lack of influences. Subjective global assessment (SGA) was used to determine nutritional status in the study by Peterson et al (2). Previously, we have reported 56% of critically ill patients classified as normally nourished by SGA had CT confirmed sarcopenia in 56% (7). To date, no other well-validated technique 3. Pu H, Doig GS, Heighes PT, et al: Early enteral nutrition reduces mortality and improves other key outcomes in patients with major burn injury: A meta-analysis of randomized controlled trials. Crit Care Med 2018; 46:2036–2042 4. Yeh DD, Peev MP, Quraishi SA, et al: Clinical outcomes of inadequate calorie delivery and protein deficit in surgical intensive care patients. Am J Crit Care 2016; 25:318–326 has arisen to address this issue. Until an improved technique for identifying nutritional status is available, it is impossible to accurately describe the relationship between malnutrition, calorie exposure, and ICU outcomes. The authors have disclosed that they do not have any potential conflicts of interest.