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A Rational Approach to Evidence-Based Allocation of Mechanical Ventilation in a Pandemic

By Eric Toner, M.D., January 27, 2006

In their article entitled, “Concept of Operations for Triage of Mechanical Ventilation in an Epidemic,” Drs. Hick and O’Laughlin from the Department of Emergency Medicine, University of Minnesota, describe one approach to addressing the difficult problem of allocating critical life support resources in the setting of a severe pandemic. Their article, which will be published in the February issue of Academic Emergency Medicine, has been made available online in advance of publication.

Based on modeling of an influenza pandemic, the authors predict a severe shortage of medical resources in the Minneapolis area. The model predicts that 10,000 patients would require hospitalization, but only 2500 to 3500 beds would be available. This prediction is consistent with HHS pandemic planning assumptions as modeled using the CDC’s FluSurge software (see CBN Report, 12/01/05). However, patients requiring mechanical ventilation would fare the worst in such a situation because ventilators will be in short supply, as demonstrated in a recent drill involving pneumonic plague in the Minneapolis area. In that scenario, the authors found that despite a surge capacity of 2500 to 3500 beds, only 16 additional ventilators would be available. They concluded that such a shortage of life support equipment would force clinicians to make difficult triage decisions, a conclusion that has recently been drawn by other researchers as well (Rubinson L, et al. Augmentation of hospital critical care capacity after bioterrorist attacks or epidemics: recommendations of the working group on emergency mass critical care. Crit Care Med 2005;33:E2393).

Hick and O’Laughlin convened a working group of physicians to create a framework for making such triage decisions during an epidemic; the framework they propose is supported by an evidence-based concept of operations for adjusting standards of care and allocating scarce resources during a disaster. Specifically, the group developed evidence-based criteria for restricting the use of mechanical ventilation when there is a critical shortage. The criteria are organized into 3 tiers, each of which makes recommendations for withholding AND withdrawing mechanical ventilation based on type and severity of illness, prognosis, and patient age. In general, it is recommended that in the setting of an acute, critical shortage of ventilators, mechanical ventilation should be withheld or withdrawn from patients of advanced age, who have serious and/or irreversible illness, organ system failure, and little chance of survival in favor of providing ventilators to acutely ill, but otherwise healthy patients who are victims of a severe epidemic. The criteria are scalable based on the degree of equipment shortage. The authors also note the likelihood that criteria such as these will require adjustment as a disaster evolves, but they assert the import and value of establishing an evidence-based framework for making those adjustments in advance of a disaster.

The number of ventilators that may be made available as a result of the processes described in this article is not known, so the ultimate value of this approach cannot be determined at this point. Likewise, the authors’ evidence base and clinical reasoning must be evaluated and substantiated by other experts. Nonetheless, this paper is valuable because it proposes a concrete and rational approach to allocation of scarce resources during a catastrophic event, an issue not often or easily confronted. It is also valuable because it advances the discussion of how to do the greatest good for the greatest number with limited resources, a question that will have to be addressed as plans for responding to pandemic flu or any other catastrophic epidemic are formulated. In a severe pandemic, many clinicians will be faced with difficult decisions. A rational framework such as the one proposed by Hick and O’Laughlin is a critical aid to clinical decision-making.