Difficult to wean chronic obstructive pulmonary disease patients : Avoid heat and moisture exchangers ? *

T he fundamental principle of critical care is the application of technology and other therapies to support life-threatening organ failure in order for a) time or b) treatment (medical and/or surgical) to reverse the underlying disease process. The decision to provide and/or continue support depends on the extent, severity, and temporal evolution of multiorgan failure and remains the most reliable predictor of mortality regardless of primary disease (1). It is interesting, therefore, to observe and participate in the discussions concerning bone marrow transplants (BMT) and intensive care unit (ICU) admission. Justifiable questions persist about the appropriate use of ICU resources for a patient population with the stigma of historically poor outcomes. The accompanying report by Dr. Jacobe and colleagues (2) in this issue of Critical Care Medicine reviews the outcomes for BMT patients after pediatric ICU admission in an effort to identify admission characteristics that may accurately predict poor outcomes. None were identified. While all pediatric ICU BMT outcome studies are limited by retrospective data and the majority by small sample sizes, the report by Dr. Jacobe and colleagues reaffirms evolving perspectives on the care of critically ill BMT patients: reported outcomes, while modest, are improving. Notable conclusions include the improved survival of BMT patients to ICU discharge, including those requiring mechanical ventilation (41.4%), with a lower medium term outcome after ICU discharge as measured by a 12.9% 6-month survival for mechanically ventilated patients. In comparison with other reports, there is a suggestion that a lower acuity of illness in the first 24 hrs of ICU admission (as measured by Pediatric Risk of Mortality Scores) may explain improved outcomes. The most instructive findings are that BMT preadmission characteristics have no apparent influence on outcome, including underlying diagnosis, age, time of admission post-BMT, type of BMT, conditioning regimen, and graft-versus-host disease. This is consistent with other reports in pediatric BMT patients (3, 4) and pediatric (5) and adult (6) oncology patients. Not unexpectedly, ICU measurements of disease severity, i.e., extent of multiorgan failure, are the dominant influences on short-term outcome. In comparison, the medium and long-term outcomes are primarily influenced by underlying BMT or oncology-related conditions. These observations confirm that the outcome of BMT patients in the ICU is related to the multiorgan failure rather than the fact that they are BMT patients per se. This is not a minor distinction as the ICU decisions for initiating, continuing, or withdrawing support should primarily depend on each patient’s organ failure characteristics rather than any BMT-related issue. The relevance of being a BMT patient is that they may be more likely to progress to severe organ failure and less likely to have an underlying process of organ failure that is reversible. Evolving therapies by our transplant colleagues may improve upon this in the future. Regardless, decisions around ICU care should be made on organ failure criteria alone. In addition to being medically complex, burdensome, and resource consuming, BMT patients have the additional stigma of dismal outcomes associated with ICU admission. As a consequence, there remains the risk of a demoralized attitude of ICU care toward this patient group as the label of “BMT in the ICU” consequently triggers the conclusion of “bad outcome. ” This report by Jacobe et al. reemphasizes that preadmission characteristics do not influence outcome and multiorgan failure is the most important predictor of survival. Should BMT patients be admitted to ICU? This has become an unproductive question. More important questions are whether early ICU intervention (lower acuity threshold for admission) impacts mortality and how much organ failure is incompatible with survival. Sam D. Shemie, MD.CM Division of Pediatric Critical Care Montreal Children’s Hospital Department of Pediatrics McGill University Montreal, Quebec, Canada