Clinical review: allocating ventilators during large-scale disasters--problems, planning, and process

Abstract

Catastrophic disasters, particularly a pandemic of influenza, may force difficult allocation decisions when demand for mechanical ventilation greatly exceeds available resources. These situations demand integrated incident management responses on the part of the health care facility and community, including resource management, provider liability protection, community education and information, and health care facility decision-making processes designed to allocate resources as justly as possible. If inadequate resources are available despite optimal incident management, a process that is evidence-based and as objective as possible should be used to allocate ventilators. The process and decision tools should be codified pre-event by the local and regional healthcare entities, public health agencies, and the community. A proposed decision tool uses predictive scoring systems, disease-specific prognostic factors, response to current mechanical ventilation, duration of current and expected therapies, and underlying disease states to guide decisions about which patients will receive mechanical ventilation. Although research in the specifics of the decision tools remains nascent, critical care physicians are urged to work with their health care facilities, public health agencies, and communities to ensure that a just and clinically sound systematic approach to these situations is in place prior to their occurrence.

Figure 1

Compared to other patient(s) requiring and awaiting mechanical ventilation, does this patient have significant differences in prognosis or resource use in one or more categories above that would justify reallocation of the ventilator? ^aThe SOFA (Sequential Organ Failure Assessment) score is a currently preferred scoring system based on type of data required and ease of calculation. ^bExamples of underlying diseases that predict poor short-term survival include (but are not limited to) the following: congestive heart failure with an ejection fraction of less than 25% (or persistent ischemia unresponsive to therapy or ischemia with pulmonary edema); acute renal failure requiring hemodialysis (related to illness); severe chronic lung disease, including pulmonary fibrosis, cystic fibrosis, or obstructive or restrictive diseases requiring continuous home oxygen use prior to onset of acute illness; immunodeficiency syndromes with evidence of opportunistic pathogen infection; central nervous system, solid organ, or hematopoietic malignancy with poor prognosis for recovery; cirrhosis with ascites, history of variceal bleeding, fixed coagulopathy, or encephalopathy; acute hepatic failure with hyperammonemia; acute and chronic and irreversible neurologic impairment that makes patient dependent for all personal care (for example, severe stroke, congenital syndrome, persistent vegetative state, and severe dementia). ^cChanges in oxygenation index (OI) over time may provide comparative data, though of uncertain prognostic significance. OI = MAWP × FiO₂/PaO₂, where MAWP is mean airway pressure, FiO₂ is inspired oxygen concentration, and PaO₂ is arterial oxygen pressure. PaO₂ may be estimated from peripheral oxygen saturation by using the oxygen dissociation curve if blood gas measurements are unavailable.