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Triage of Bioevent Mass Casualty Incidents from the Community to the Hospital and the Critical Care Units Cheryl Collier-Brown Philadelphia University – DMM611 October 31,2008 ABSTRACT The purpose of this discussion is to evaluate the systems available for the triage of a community in the event of a large-scale bioevent, particularly pandemic influenza. Triage would need to occur at multiple tiered sites. The tiers would include guided selftriage at home, emergency department triage for hospital level care and finally critical care unit triage within hospitals. There need to be plans in place before an event occurs to determine the optimal mechanisms and the ethical construct within which difficult decisions will be made. This is critical both to preserve trust between the community and healthcare providers and to support providers with a transparent and consistent approach for the equitable distribution of scarce resources. BACKGROUND The occurrence of a mass casualty event caused by an infectious agent is very plausible and warrants significant planning and preparedness for the unusual burdens it will place on the current healthcare system. The Department of Homeland Security has outlined several scenarios with estimates for their impact on our healthcare system. The release of anthrax in a large city that exposed 330,000 people would likely cause 13,000 cases of inhalational anthrax and would therefore require about 13,000 ventilators for days to weeks. The release of pneumonic plague in three city bathrooms at large public facilities is estimated to produce about 6,000 severely ill patients needing mechanical ventilation. Pandemic influenza in a state with a population of eleven million is predicted to result in 10,000 patients needing mechanical ventilation over an evolving period of weeks to months. The estimate of available full-feature ventilators nationwide is 10,000 with the Strategic National Stockpile able to add about another 4,600. (1) A similar prediction model for pandemic influenza from Ontario estimates that hospital admissions directly related to influenza will peak at 1823 patients per day for about six weeks. This correlates with 72% of all hospital beds being needed for influenza cases. ICU resources for these patients alone were estimated to be 171% of current ICU capacity. Unfortunately, the present ICU occupancy rates are close to 100%.(2) The likelihood of hospital resources being insufficient to meet needs is very high. This is particularly true for pandemic influenza because it will affect more than one region simultaneously and therefore the possibility of outside assistance will be low. COMMUNITY TRIAGE WITH SEIRV METHODOLGY In a bioevent, triage has to start outside of the hospital but the traditional field methods of severity assessment and sorting will not be appropriate. There must be a process to triage an entire population. It should occur in the context of a disaster declaration with involvement of government agencies, the health department and with the initiation of an Emergency Operations Center (EOC). The first phase would entail starting generalized disease containment recommendations such as social distancing (three to six feet), closure or restrictions of group gatherings, and education about hand-washing and cough/sneeze etiquette. The second phase of the population triage system outlined by F.M. Burkle triages into five categories with the mnemonic SEIRV. They are: Susceptible (but not exposed), Exposed (but not yet infectious), Infectious, Removed (by death or recovery), and Vaccinated (or prophylaxed with medications). People will selfcategorize with assistance from public service health announcements, telephone hotlines and trained volunteers or healthcare personnel. (3) There is a rapid severity score checklist tool that can screen people into possible Exposed or Infectious categories. The people who are not at risk for Exposed or Infectious categorization are then screened for fear and resilience levels. This can identify people who are at risk for “hypervigilant fear states” (3). Hypervigilant fear can result in chronic impaired stress response symptoms. Treatment with anxiolitics and debriefing therapy is not appropriate. Referral to a mental healthcare professional is indicated, as is possible treatment with beta-blockers or alphablockers to blunt noradrenalin over-activation. (3) The majority of people will be in the susceptible category but they will seek treatment in large numbers of “worried well”. This lesson was learned in the SARS epidemic in Ontario and in the sarin nerve gas attack in Tokyo. Unfortunately, this will increase the mingling of susceptible people with exposed or infectious patients in hospital emergency rooms. Therefore, the other important facet of dealing with the Susceptible population is education with consistent, repetitive, factual information that reinforces people’s acceptance of staying home and sheltering-in-place as the safest option. Hospitals and Emergency Rooms should be reserved for possible Exposed or Infectious persons. These sites will likely be overwhelmed with just these groups. The Infectious group will need to be separated into those safe to care for themselves at home versus those needing hospital care. The Vaccinated group must be tagged in a uniform readily identifiable way. (3) They will initially be largely first responders and healthcare providers. EMERGENCY ROOM TRIAGE Once people arrive at the hospital there are multiple steps and clinical evaluations that occur that provide opportunities for triage to occur. Initially the ER will be the first site of evaluation. There are systems being developed for routine use in ER triage stations that could benefit resource allocation in a mass casualty infectious scenario. The Emergency Severity Index system is a process that separates patients into five categories. Level One needs immediate life saving treatment. Level Two patients are at high risk for serious illness or have altered mentation or severe pain. These patients need to be seen promptly. The final three levels are determined by assessment of how many resources the patient will likely need to arrive at a disposition. The possible choices are none, one or many. A resource is considered a single type of test, and multiple tests in the same category count as one resource. Examples of resources include laboratory, plain x-ray, CT scan, ultrasound, iv medications or fluids. The final screen is vital signs and if they are outside set parameters they can be used to bump up the severity level. (4) The benefit of this system is that because it assesses resource utilization at triage, patients that are level four or five that require one or zero resources would potentially be appropriate to be seen at an alternative urgent care site or by an alternative non-emergency room provider. For example, general practice outpatient providers or hospitalists could readily adapt their scope of practice to this setting. The limitation of this type of triage is that it would need to be in place prior to an event and that it requires a highly skilled ER nurse with strong clinical judgment to make the proper assessment. PMEWS AND CURB-65 TRIAGE A simpler system is needed that can be applied easily and quickly in multiple settings to help determine if hospitalization is needed. There is a physiology based scoring system that has been adapted for use in Pandemic influenza. It is an adaptation of the Modified Early Warning System (MEWS) that can be used in hospitalized patients to help predict who are likely to deteriorate and code or to require transfer to higher dependency units (HDU) or ICU’s. The parameters evaluated in the traditional MEWS are systolic blood pressure, heart rate, respiratory rate, temperature and mentation. Mentation was graded by the AVPU scale- Alert, reacting to Voice, reacting to Pain, or Unresponsive. A single center study calculated scores twice daily on 709 medical admissions and found that scores between 5-9 resulted in a combined 30% chance of transfer to HDU/ICU or code. For patients with scores between 3-4 only 12.7% of patients coded or needed transfer. (5) The benefit of this scoring system is that it requires no lab data and can be assessed by different levels and types of healthcare providers. The Pandemic Medical Early Warning System (PMEWS) was developed as a way to apply this type of purely physiologic scoring system to influenza patients. The goal was to have a way to help stratify patients for discharge to home or admission to a regular med-surg floor or to be evaluated for ICU level care. The adaptations that it made to the MEWS were the addition of pulse oximetry measures and a supplement to the score for medical co-morbidities and social factors. The supplemental score added points for age>65, living alone or without a fixed home, the presence of chronic respiratory, cardiac, renal disease, diabetes or immunosuppression, and for performance status (Karnofsky score) >2. (6) The possible scores ranged from zero to twenty-one. The University Hospital of South Manchester NHS Foundation Trust did a retrospective study comparing this scoring system with the CURB-65 score for patients over age 15 admitted with pneumonia over a ten month period of time. The CURB-65 score is very simple to apply also, but requires lab and chest x-ray data. CURB-65 parameters are Confusion, Urea nitrogen>7, Respiratory rate >30, Blood pressure < 90 systolic, and age>65 with one point given for each factor. The researchers found that the PMEWS was better at discerning patients that needed admission and those in need of higher levels of care. All patients with scores of 7 or higher were admitted. The transition score was between 3-4 when it went from 50% of patients discharged to most patients being admitted. The majority of HDU/ICU patients had scores between 6-10 and no patients with scores higher than 13 were admitted to floor beds. Compared with the CURB-65 the PMEWS was better at predicting the need for a higher level of care. They were both fairly comparable at identifying patients for inpatient admission. (6) The limitations of this study were that it was retrospective and at one institution. It did not set specific levels at which to stratify patients for discharge, floor admission and ICU admission, though there is data to analyze further in this respect. Ideally, these types of action recommendations would need additional studies with larger numbers of patients. There is also a need to include patients with more diverse disease processes. However, if there will be mass screening sites set-up for patients with likely exposure or infection that will cohort them from other patients needing care for routine illness this is not as important. There are other disease non-specific tools that can be utilized in the hospital setting only. In my opinion and clinical experience, the addition of factors to assess co-morbidities and social factors makes the PMEWS tool much more valuable in the ER and in outside care centers. These are frequently considered as part of the individual admission decisions on a day-to-day basis in ER’s now. They have significant impact on a person’s ability to follow care instructions and on their likelihood of having deterioration of a second condition as a direct result of their infection. The CURB-65 scoring requires lab and x-ray data and does not really add much to a provider’s basic assessment and clinical judgment. It is not as applicable or as flexible as PMEWS. It also does not expand the potential arenas of implementation. THE TRIAGE OF CRITICAL CARE The most difficult tier of triage is when critical care resources are not adequate to meet the demand for them. The point at which this is reached is limited to the circumstance when all outside assistance for additional equipment or for transferring patients to other facilities has been maximized and is not available. This is a Tier 6+ response and is the first level at which Emergency Mass Critical Care would be initiated. (7) There needs to be a process in place prior to this event that is ethical, fair, and transparent. “International law requires a triage plan that will equitably provide every patient the opportunity to survive. However, such a law does not guarantee either treatment or survival.” (2) The first decision is what ethical principle is being used to guide decisionmaking. Utilitarian distribution of resources has the goal of providing the greatest good to the greatest number of people. It views the benefit to the community above the benefit to the individual. An alternative is the concept of greatest need, where the resources go to the sickest patients without evaluating their likelihood of survival or the intensity of resources that would be needed or whether or not multiple people could have been saved with the resources given to one person. The American Thoracic Society adopted the utilitarian principle more than a decade ago. (8) The utilitarian principle is the most commonly accepted for this scenario in medical and public health literature. The public needs to be involved and educated in order to “embrace the paradigm shift from individual to population-based care”. (7) The public should perceive that the decisionmaking process has been thought out with respect to fairness of distribution, is uniform in its applicability, is transparent in having a process that will stand up to scrutiny and has reasonableness with decisions based on relevant tenets by credible, accountable people. (9) If this is not addressed there will be loss of trust between the community and the healthcare system and this will adversely affect the recovery process and the future stability of the relationship. The individual physicians providing care and making these difficult decisions also need the support of a protocol that is defensible, fair and consistent. One ethical framework proposal cites three key elements for success. First, senior administrators must be supportive and on-board. Second, key stakeholders need to have input into the framework, ideally including some community members. Third, there needs to be a decision review process with the formal opportunity to revise criteria and resolve disputes. (9) Of note, this should not include the right to appeal an individual decision of a triage officer unless there has been a procedural error. (7) Once the ethical framework has been decided, the next necessary step is adopting a strategy for prioritizing the allocation of critical care resources. One group has four recommendations for the ideal triage system. It must identify patients that may need critical care at some point. It must recognize those patients who are too sick to be likely to benefit from critical care. It needs to be applicable consistently by a varied group of providers of care. Finally, it should be disease non-specific in its ability to prognosticate. (8) There are several articles that address specific protocols to accomplish this. The two most comprehensive are based on input from expert panels and review of current literature and severity of illness measures. (2- Canadian group, 7 U.S. Task Force for Mass Critical Care) The common features of them are inclusion criteria, exclusion criteria, and prioritization of care. The inclusion criteria are assessed first with the fundamental question whether this person needs active ICU level care. This will primarily be mechanical ventilation or impending respiratory failure. (2) Pressors will be secondary inclusion criteria - if they cannot be managed on other HDU’s that have been designated for surge capacity. It is expected that there may be higher levels of care occurring at these sites than under normal circumstances. If the patient meets the inclusion criteria then they need to be evaluated for exclusion criteria. The exclusion criteria in the Canadian panel are very specific and complete. Excluded patients include those with severe trauma, severe burns, cardiac arrest, severe baseline cognitive impairment, advanced untreatable neuromuscular disease, metastatic cancer, advanced and irreversible immunosuppression or neurologic condition, end-stage heart, lung or liver failure, and elective palliative surgery. They included an age exclusion of >85 yrs old but felt that this criteria needs additional study. (2) The U.S. Task Force has exclusion criteria based on Sequential Organ Failure Assessment (SOFA) scores that correlate with a > or =80% mortality risk. The criteria are any SOFA score >14, a mean SOFA score >4 for 5 days without improvement, and any patient with greater than 5 organ failures at one time. The second component of exclusion criteria is identical to the Canadian model noted above. (7) After reviewing inclusion and exclusion criteria, the prioritization of care in the Canadian model uses SOFA scores to then determine those patients most likely to benefit from critical care. The Canadian panel uses a color-coded triage scheme for this. The Blue code has exclusion criteria or a SOFA score of >11. This group of people will receive supportive medical care or palliative care. The Red code is for patients with SOFA scores of < 8 or single organ failure. These patients are the highest priority for critical care treatment. The yellow code is for patients who have SOFA scores between 8-11. They are intermediate priority. The people with no significant organ failure are green coded and these are going to be patients that are recovering and deemed ready to leave the ICU. (2) The U.S. Task Force prioritizes patients with daily SOFA scores and trends in SOFA scores. It also depends on the judgment of the triage officer and his team to help determine when re-allocation of critical care is appropriate for a combination of failure to improve, poor chance for survival and expected duration of need for critical care. (7) The Canadian panel considers this as their fourth component of “minimum qualifications for survival”. This is a re-evaluation of SOFA scores at 48 and 120 hours for presence of exclusion criteria of SOFA >/= 11 and to identify those patient not improving whose resources can be “re-allocated”. (2) Designated physicians with extensive clinical experience and strong leadership and communication skills should perform the triage. There will need to be 24/7 coverage for the role. They will need support staff for managing data and for implementation and documentation of the process. The triage officer should not have any direct patient contact unless it is crucial to their evaluation. Training in advance with drills or simulations will enhance their success of carrying out this task. The burden of shifting a clinician’s emphasis for duty to care from the individual to the population will be unlike any prior experience unless he or she has had military field experience or mass casualty experience. The U.S. Task Force supports that the decisions of the triage officer should be final. The only exception for this would be for procedural issues. However, there needs to be a review board or other mechanism in place for changing recommendations or altering processes based on changing information or knowledge gained. (7) This is an area that needs to be reviewed and formalized. There cannot be any preferential distribution of care in critical care allocation for healthcare workers or hospital staff. (7) The concept of reciprocity “requires that society supports those who face a disproportionate burden in protecting the public good and takes steps to minimize their impact as far as possible”. (9) This is the ethical basis for healthcare and emergency personnel receiving priority for vaccination and prophylaxis and personal protective equipment. However, once critical care needs arise, the utilitarian principle recognizes the person will no longer be benefiting the community and the common pool of resources must be allocated for the greatest good. This is part of the U.S. Task Forces recommendations and is certainly one of the many issues that should be vetted among all stakeholders prior to an event. There are issues that need further research and stakeholder involvement. One of these areas is whether the SOFA score is the most appropriate scoring tool. The SOFA criteria include points for PaO2/FiO2 ratio, platelet count, bilirubin level, blood pressure with severity scored for number of and dosages of pressors, glascow coma score, and creatinine. Criteria that are dependent on use of pressor agents are not going to be useful for triage that occurs prior to the patient being in a critical care unit. It also requires data from an ABG for PaO2/FiO2 ratio. Acquiring that data may be labor intensive or not readily available from the equipment or personnel standpoint. A study from Canada prospectively analyzed 1,436 patient records to try to assess the ability of SOFA scores and Multiple Organ Dysfunction (MOD) scores to predict hospital mortality. The study found that the SOFA score correctly classified patients predicted to die in their hospital stay only 65-75% of the time. The most accurate SOFA score at 75% correct classification was the mean score. The least accurate SOFA score at 65% was the delta score that measured the difference between the maximum score and the admission score. Interestingly, with backward step-wise elimination to produce the best model, “the neurologic, cardiovascular and renal component scores remain significantly and independently associated with hospital mortality while scores for hepatic, coagulation and respiratory fell out of both models”. (10) An older prospective study of 352 consecutive patients in one hospital looked at serial measures of SOFA scores and their correlation with mortality. The SOFA score was calculated on admission and every 48 hours while in the ICU. Again, the mean SOFA score correlated the closest with mortality. However, there is additional data that is useful in the context of allocating care. An initial SOFA score over 11 had a 95% mortality rate associated. The delta-SOFA score comparing admission and 48 hour scores was helpful in predicting response to care. If the initial SOFA score was <11 and decreased over the first 48 hours then the mortality rate dropped to <10%. If the initial SOFA score was between 2-11 but increased over the first 48 hours then the mortality rate exceeded 35%. (11) An alternative scoring method is the Acute Physiology and Chronic Health Evaluation (APACHE II) score. This score was originally rated with the worst data for each parameter over a 24-hour period. This would make APACHE II not appropriate for ER triage. A recent study, however, looked retrospectively at 11,107 non-cardiac surgery ICU admissions over an 11-year period and compared the admission APACHE II score with the worst 24-hour parameter APACHE II score for their effectiveness in predicting hospital mortality. The results were that APACHE II maintained its discriminatory ability when the admission values were used to estimate mortality. The average predicted mortality rate was 15.5% compared to the actual hospital mortality rate of 16.3%. The traditional worst 24-hour score actually overestimated the mortality rate at 19.3%. The advantages for APACHE II scores with this study is that it validates its use for triage in the ER and that the data collection and score checking took significantly less time. The average time was 5 minutes per patient compared with the worst 24-hour data that took an average of 20 minutes per patient to collect and tabulate. (12) The APACHE II scores have been validated as being at least as good as clinical judgment. (13) Being able to use admission data for mortality predictions is extremely important for making APACHE II a potential tool for mass critical care triage. The advantage it has over the SOFA scores is that is does not have a parameter that includes any ICU level care in its scoring. It still requires ABG data. It does omit liver data and that is one parameter of SOFA scores that did not correlate well with predicting mortality. (10) The APACHE II score has a component for adding risk for age and chronic health conditions that are not assessed in SOFA scores. My personal bias is that the APACHE II score looks at the same global data and information that I would clinically assess in making a judgment about a patients likely prognosis. The SOFA scores, though validated, seem to be based on data of mixed relevancy. The only parameter I was surprised to see “fall-out” for accuracy in predicting mortality was the respiratory data. The clinical tools available for predicting mortality offer a reasonable starting place for allocating scarce resources because there is already extensive data accumulated to aide in interpreting the scores and to understand their limitations. CONCLUSION The triaging of very large groups of people in an event that peaks over days to weeks and can have a duration of weeks to months requires far different methods than the traditional field triage methods. There are multiple levels of triage that need to be accomplished effectively and quickly with a minimal amount of data, manpower and training. The goal is to try to keep people at the location that allows them to receive the appropriate level of care but that does not utilize more resources than is necessary to achieve the goal. This means keeping people at home who are not infected or whose symptoms are safe to monitor at home. The use of a symptom survey that can be administered in person or via telephone is an effective mechanism for this. The F.M. Burkle Fear and Resiliency Checklist is a good tool for this assessment. There should also be a review of the systems used in Canada with SARS that screened people via telephone. Selecting and endorsing one survey tool for common usage needs to be done. Emergency rooms and hospital care ideally should be reserved for those patients whose symptoms warrant higher level decision-making and care. It is prudent for the global care of the community not to mingle the sick and well groups. The PMEWS system stands out among those reviewed in this paper as efficient and simple. It requires no equipment beyond a blood pressure cuff and pulse oximeter. It would be able to be performed by nurses, physicians, EMS providers and multiple mid-level care providers. There could be physician supervision of larger centers to make assessments of patients whose scores and physical condition do not correlate well. A score is an aide for clinical assessment, not a replacement for it. Once patients warrant hospital admission they must be stratified in an ethical and preplanned manner that will allow resources to be distributed fairly and with transparency. If critical care is deemed a scarce resource and there is no additional assistance forthcoming, then EMCC would be initiated. The evaluation systems reviewed in this paper are a beginning. The inclusion and exclusion criteria are reasonable and very consistent between the two large panels of experts. The criteria for prioritization of care for the patients that are found appropriate for critical care resources are the area where additional study needs to be done. They need to be evaluated in a prospective fashion that addresses mortality. The selection of which scoring tool is most effective is also an area that needs additional research. The newer study that validates APACHE II scores on admission makes it a more valuable tool. Also, it reflects the additional parameters of age and chronic illness not part of the SOFA score. The APACHE II score has been shown to be at least as accurate as clinical judgment. Again, we are not looking to replace clinical judgment, but to provide a non-biased, objective system to allocate care fairly, uniformly and at a distance from the bedside. This protects the decision-makers and provides the community with a system that can stand up to scrutiny and demonstrates fairness and equitable resource allocation. 1. Christian MD, Devereaux AV, Dichter JR, Geiling JA, Rubenson L. Definitive care for the critically ill during a disaster: Current Capabilities and Limitations: From a Task Force for Mass Critical Care Summit Meeting: Chest 2008;133:8-17. 2. Christian MD, Hawryluck L, Wax RS, Cook T, Lazar NM, Herridge, MS, et al. Development of a triage protocol for critical care during an influenza epidemic. CMAJ 2006;175(11):1377-81. (This source contains the inclusion, exclusion criteria and colorcoded prioritization score for critical care allocation) 3. Burkle, FM. Population-based triage management in response to surge-capacity requirements during a large-scale bioevent disaster. Academic Emergency Medicine 2006;13:1118-29. (This source contains the Bracha-Burkle Fear and Resilience Checklist –Figure 2) 4. Agency for Health Care Research and Quality. Emergency Severity Implementation Handbook, 2007;3:7-11. 5. Subbe CP, Kruger M, Rutherford P, Gemmel L. Validation of a modified early warning score in medical admissions. Q J Med 2001; 94:521-526. 6. Challen K, Bright J, Bentley A, Walter D. Physiological-social score (PMEWS) vs. CURB-65 to triage pandemic influenza: a comparative validation study using community-acquired pneumonia as a proxy. BMC Health Services Research 2007;7:33. (This source contains the P-MEWS Admission Algorithm-Figure 1) 7. Devereaux AV, Dichter JR, Christian MD, Dubler NN, Sandrock CE, Hick JL, et al. Definitive care for the critically ill during a disaster: A Framework for Allocation of Scarce Resources in Mass Critical Care. Chest 2008;133;51-66. 8. Challen K, Bentley A, Bright J, Walter D. Clinical review: mass casualty triage, Critical Care 2007;11:212. 9. Thompson AK, Faith K, Gibson JL, Upshur REG. Pandemic influenza preparedness. BMC Medical Ethics 2006;7:12. 10. Zygun DA, Laupland KB, Fick GH, Sandham JD, Doig CJ. Limited ability of SOFA and MOD scores to discriminate outcome. Can J Anesth 2005; 52(3):302-308. 11. Ferreira FL, Bota DP, Bross A, Melot C, Vincent JL. Serial evaluation of the SOFA score to predict outcome in critically ill patients. JAMA 2001;286(14):1754-58. (This source contains a table for calculating SOFA score-Table 1) 12. HO KM, Dobb GJ, Knuiman M, Finn J, Lee KY, Webb SAR. A comparison of admission and worst 24-hour acute physiology and Chronic Health Evaluation II scores in predicting hospital mortality. Critical Care 2006;10:R4. 13. Wong DT, Knaus WA. Predicting outcome in critical care: the current status of the APACHE prognostic scoring system. Can J Anaesth 1991;38(3):374-83. (This source has The APACHE II severity of disease classification system in Figure 1.)