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Studies examine the surge capacity of U.S. hospitals to respond to bioterrorism or other public health disasters

Hospital closures and a reduced number of available beds, combined with shortages of nurses and other health professionals and "just-in-time" supplies, have compromised the ability of hospitals to handle a sudden and massive surge of patients in the event of a bioterrorism or other public health disaster.

Hospital emergency departments (EDs) already routinely operate at capacity, with some EDs diverting ambulances to other hospitals due to lack of space, notes Sally Phillips, R.N, Ph.D., of the Agency for Healthcare Research and Quality (AHRQ). Dr. Phillips describes the current status of AHRQ-supported research on hospital surge capacity, that is, their ability to accommodate a huge surge of patients due to bioterrorism or other public health disasters. Also, two AHRQ-supported studies (HS14353) review what is known about daily ED surge and ED surge capacity. The articles are discussed here.

Phillips, S. (2006). "Current status of surge research." Academic Emergency Medicine 13, pp. 1103-1108.

AHRQ continues to support surge capacity research. AHRQ-funded researchers have developed evidence-based reports, tools, and models primarily to support local, State, and Federal preparedness efforts. One AHRQ-funded grant was used to develop a simple discharge planning tool for use to make more beds available during a biothreat or other public health disaster. Another study developed the National Hospital Available Beds for Emergencies and Disasters System (HAvBED) to collect and report bed availability data to Federal, State, and local medical emergency planners and responders. Other programs include training nurses to respond to mass casualty incidence as well as "just-in-time" training of personnel to deliver mass casualty respiratory care via deployment of ventilators from the Strategic National Stockpile of ventilators.

AHRQ and other researchers are also examining several strategies to alleviate incoming surge at hospitals, such as use of alternative care sites like community health centers, nursing homes, or schools, for less severely injured or ill patients. Investigators have also developed a site audit tool, used during Hurricane Katrina, which allows teams (engineers, clinicians, security, etc.) to assess the use appropriateness of a facility and the status of affected facilities.

Finally, AHRQ has released evidence-based, best-practice emergency preparedness models for personal protective equipment, decontamination, isolation, quarantine, and the laboratory. One model assists planners' decisions for mass dispensing of medications or vaccines from the Strategic National Stockpile. The Bioterrorism and Epidemic Outbreak Response Model is an interactive computer model, which was used during the anthrax attacks in 2001. It predicts the number and type of staff needed to respond to a major disease outbreak or bioterrorism attack on a given population. AHRQ has released a number of tools, publications, fact sheets, Web conferences, and evidence reports on surge capacity.

Reprints (AHRQ Publication No. 07-R023) are available from the AHRQ Publications Clearinghouse.

McCarthy, M.L., Aronsky, D., and Kelen, G.D. (2006). "The measurement of daily surge and its relevance to disaster preparedness." Academic Emergency Medicine 13, pp. 1138-1141.

These authors examined hospital ED daily surge as a foundation to more accurately predict how well hospital EDs will respond to a catastrophic surge in demand for their services. The researchers propose that daily and catastrophic ED surge can be measured by the magnitude of the surge, as well as by the nature and severity of the illnesses and injuries of arriving patients. The magnitude of an ED surge can be measured by the patient arrival rate per hour. The nature and severity of the surge can be measured by the type (for example, trauma, infection, or biohazard) and acuity (triage level) of the surge.

Studies have shown that hospital EDs nationwide have some degree of predictability in daily ED surge, and that patient acuity varies moderately by hour of the day, but not by day of the week. All EDs should be examining their patterns of arrival by hour of day and day of week. They should then use this information to optimize ED surge capacity by matching staffing and resources according to the seasonal trends in demand. Although present ED-triage scales may capture the nature and severity of a daily ED surge, they may not be adequate for characterizing the nature and severity of a catastrophic surge, note the researchers.

They argue that daily ED surge and catastrophic surge should be based on the same model of ED surge capacity. The core dimensions of ED surge capacity should include space (number of beds, physical size of ED, etc.), staffing, systems (admitting process, clinical information systems, ancillary services, etc.), and supplies.

With a better understanding of daily ED surge capacity and the factors that influence it, the knowledge of catastrophic events and how to manage them can be combined with advanced simulation techniques to predict the potential impact of various events on the surge capacity of hospital EDs.

Kelen, G.D., Kraus, C.K., McCarthy, M.L., and others (2006, December) "Inpatient disposition classification for the creation of hospital surge capacity: A multiphase study." Lancet 368, pp. 1984-1990.

A proposed system that identifies patients who can be discharged early can improve hospital surge capacity, concludes a new study. Gabor D. Kelen, M.D., of Johns Hopkins University, and colleagues have developed a classification system that categorizes inpatients according to suitability for immediate discharge, a type of reverse triage.

They developed this reverse triage approach based on research evidence and a consensus panel of 39 experts in clinical care, disaster management and triage, public health, and other areas. The panelists identified 28 critical interventions (such as cardiopulmonary resuscitation, airway management, major surgery, oxygen, dialysis, cardiac monitoring, and intravenous medication).

They rated the interventions on their likelihood of causing the patient a serious medical problem if withdrawn, ranging from 3 to 10 on a 10-point scale. The panelists agreed that low-risk patients who could be discharged early had to have a 4 percent or less chance of suffering a serious medical event if medical interventions were withdrawn due to early discharge.

An example of a low-risk patient would be one admitted for intravenous antibiotics for uncomplicated cellulitis, who could readily be switched to oral medication upon early discharge, with low risk of an adverse event. If surge capacity was needed for victims of a disaster, patients with a 12 percent risk of a consequential medical event might warrant discharge (for example, a patient with acute coronary syndrome with no evidence of high risk for adverse events).

Patients with a risk too high for a simple discharge home (a 33 percent risk of problems if discharged early) are patients potentially suitable for transfer to another medical facility. Patients at high risk (a 61 percent risk) can be transferred to a major acute facility only. These patients range from those in need of emergency surgery to those in active labor. Finally, very high-risk patients (a 95 to 100 percent risk) are patients who might be too unstable or critically ill even for transfer to another facility. The study was supported by the Agency for Healthcare Research and Quality (HS14353).

Editor's Note: Another AHRQ-supported article questions the extent to which daily surge and extraordinary surge are related, noting that extraordinary surge is a phenomenon more complex and less predictable than daily surge. For more details, see Kelen, G.D., and McCarthy, M.L. (2006, November). "The science of surge." (HS14337). Academic Emergency Medicine 13(11), pp. 1089-1094.

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