Download Triage of Bioevent Mass Casualty Final Paper for DMM

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.
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the critically ill during a disaster: Current Capabilities and Limitations: From a Task
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Development of a triage protocol for critical care during an influenza epidemic. CMAJ
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