Should We Regionalize the Care of Mechanically Ventilated Patients?
Should We Regionalize the Care of Mechanically Ventilated Patients?
Abstract & Commentary
By Andrew M. Luks, MD, Pulmonary and Critical Care Medicine, University of Washington, Seattle, is Associate Editor for Critical Care Alert.
Dr. Luks reports no financial relationship to this field of study.
Synopsis: Using a Monte Carlo simulation model, the authors demonstrate that routine transfer of mechanically ventilated patients from low volume to high volume hospitals saves lives without a large increase in ICU census at recipient hospitals.
Source: Kahn JM, et al. Am J Respir Crit Care Med. 2008;177(3):285-291.
Regionalized health care systems exist for trauma and neonatal care and efforts are underway to institute similar systems for high-risk surgeries, three fields in which there is a positive relationship between the volume of cases handled and patient outcomes. Kahn and colleagues sought to determine whether a similar benefit would follow from regionalization of care for mechanically ventilated patients.
The authors analyzed hospital discharge records from hospitals in 8 states from a wide geographic distribution during the year 2001. They included all admissions involving mechanical ventilation, but excluded patients under the age of 18 years or patients admitted to a pediatric hospital or who underwent major surgeries. Hospitals were classified as very low volume (< 150 admissions/year), low volume (151-275 admissions/yr), intermediate volume (276-400 admissions/yr), or high volume (> 400 admissions/yr) based on a scheme from a prior study that demonstrated a relationship between hospital volumes and outcomes of mechanical ventilation.1 They then conducted a Monte Carlo simulation in which patients were transferred from very low and low-volume hospitals to the nearest intermediate or high volume hospital. They ran separate simulations for hospitals in urban, small urban and rural areas as well as simulations in which transfer distance was limited to either 20 or 50 miles. Outcome measures included the total number of lives saved, the number needed to transfer to save one life, the median transfer distance between hospitals, and the change in ICU admissions and census totals.
A total of 180,976 admissions were included in the final analysis, 46% of which were managed at very low or low-volume hospitals. A total of 4,720 lives could be saved per year by transferring patients from low volume to high volume-volume centers. This total corresponded to a "number needed to transfer to save one life" of 15.7. Limiting transfer distance to only 20 or 50 miles cut the number of potential lives saved to 3,310 and 4,212, respectively. The observed benefits were considerably larger in urban areas, as only 284 lives would be saved per year in rural areas (< 100,000 population). The majority of patients would travel less than 9 miles to reach the nearest intermediate or high-volume hospital. If travel distance was limited to 20 miles, 73% of patients could reach a higher volume hospital; this total increased to 90% in urban locations. Although regionalization led to a median increase in ICU census of 5% at accepting hospitals, 9.5% of accepting hospitals would experience an increase in total annual ICU census of 20% or greater.
Commentary
When viewed in conjunction with prior work1 from this study's lead author that demonstrated improved outcomes for mechanically ventilated patients at high volume centers (> 400 mechanically ventilated patients per year), this study of regionalization of care for mechanically ventilated patients is thought provoking. Many lives could potentially be saved under such a plan and the number needed to transfer to save one life is highly comparable to that of other current ICU practices such as the use of Activated Protein C in severe sepsis.
These results can only be viewed as preliminary, however, and considerable more work must be done before we even consider committing to such practices. To begin, the study involved a simulation using retrospectively collected data and did not involve an actual intervention in the studied regions. As a result, we do not know if the same results would be borne out in practice. Second, the authors emphasize that high volume centers would experience only small changes in their census. The numbers sound small, but if our multi-hospital institution is any indication of trends elsewhere in the country regarding bed availability, even those small increases might put a strain on units with already limited bed availability. The fact that almost 10% of the included hospitals saw their annual ICU census increase by 20% in this model would be a big concern in this regard.
The authors also did not include data on the cost of this intervention. Given current nursing shortages and a relatively high incidence of units in our region closing beds due to insufficient staffing, one is left to wonder if high volume centers can manage the cost and staffing needs that would result from regionalization.
Finally, one is led to question the effect of regionalized care on the quality of care at smaller institutions. If transferring patients to larger hospitals becomes routine practice, will the smaller centers lose the knowledge necessary to care for those patients who cannot be transferred for various reasons? Perhaps we need more focus on disseminating "best practices" for mechanical ventilation, such as low-tidal-volume strategies in managing the acute respiratory distress syndrome, rather than on taking the care of these patients out of the hands of the smaller institutions.
Reference
- Kahn JM, et al. N Engl J Med. 2006;355(1):41-50.
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