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Hospital Surge Model Version 1.3: Description

Public Health Emergency Preparedness

This resource was part of AHRQ's Public Health Emergency Preparedness (PHEP) program, which was discontinued on June 30, 2011, in a realignment of Federal efforts.

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Chapter 8. Radiological Dispersal Device

This chapter describes the assumptions for the radiological dispersal device (RDD) scenario, including:

  • The severity categories.
  • The arrival pattern of casualties at the hospital(s).
  • The length of stay by hospital unit (i.e., ED, ICU, and the floor).
  • The path probability within the hospital(s) and the length of stay.
  • The overall outcome probabilities (i.e., probability of discharge and probability of death).
  • The assumed level of resource consumption per patient per day per hospital unit.

Footnotes in the text of a particular section refer to references at the end of the section. In the absence of specific references, parameter estimates were obtained from general references listed in the Hospital Module section.

8.1 Severity Categories

For the RDD scenario, patients arrive at the hospital(s) in one of two conditions:

  1. Mild: 1 Gy equivalent dose for blood effects, no other equivalent dose (some bleeding and infection issues).
  2. Severe: 4 Gy for blood effects (problems with bleeding and infection) and about 0.75 Gy for lethality and gastrointestinal (GI) effects (some small fraction of people will die, and others will experience nausea, vomiting, etc.).

Users have the option of specifying either the number and type or simply the number of casualties who present at their hospital(s).  

If the user specifies only the number of casualties, the model assumes the casualties arriving at the hospital(s) are randomly selected from among all casualties from the attack. The distribution of casualty types in this case is as follow:

Casualty Condition

Percent

Mild: 1 Gy equivalent dose for blood effects, no other equivalent dose (some bleeding and infection issues) 99.5%
Severe: 4 Gy for blood effects (problems with bleeding and infection) and about 0.75 Gy for lethality and GI effects (some small fraction of people will die, and others will experience nausea, vomiting, etc.) 0.5%

This breakdown by casualty condition is based on work performed during development of the original Surge Model in 2005. In brief, in this scenario we focus on the casualties from dispersed radiation rather than the few casualties from the explosive force of the device.

First, we used plume modeling to estimate the number of individuals exposed to different levels of radioactive particles depending on their distance from the point of dispersal. Based upon amount of particles inhaled and the half-life within the human body, we then calculated the dose accumulated by day for the first 60 days after an attack for each of four categories of exposure. Radiation can cause many ill effects, including gastrointestinal effects and damage to the blood. Each of these effects occurs at different likelihoods over time, with blood effects manifesting later than GI effects.

We categorized as severe the percentage of people in each exposure category who would likely show severe effects of the blood or GI tract, while mild symptoms were found in individuals with mild GI or blood effects. Because individuals are expected to present to the hospital when they first show symptoms (especially after a known attack), it is assumed that only those individuals highly affected on the first day will already have reached severe symptoms before arriving at the hospital.

8.2. Casualty Arrival Pattern

Casualties are assumed to present at the hospital(s) when symptoms appear. For this scenario, we used available data on radiation effects at low doses in humans. This showed the probability of having blood, GI, or mental effects of radiation and the number of days after exposure at which each of these symptoms would first manifest. Blood effects tend to appear several days after GI effects, and people with lower exposures present later than those with higher exposures.

8.3 Length of Stay (LOS) By Hospital Unit

The assumed average length of stay (in days) of patients the ED, ICU, and the floor3,5,6,10 are:

Average LOS by Hospital Unit

Mild

Severe

ED 1 1
Floor, not via ICU 1 7
Floor, via ICU 2 14
ICU 1 28

8.4 Combined Path Probabilities and Lengths of Stay

The table below shows the assumed probabilities of different "paths" through the hospital(s). 

Path

Mild

Severe

ED → Discharge 0% 0%
ED → Death 0% 0%
ED → Floor → Discharge 75% 7%
ED → Floor → Death 0% 1%
ED → Floor → ICU → Death 0% 1%
ED → Floor → ICU → Floor → Discharge 0% 1%
ED → Floor → ICU → Floor → Death 0% 0%
ED → ICU → Death 0% 43%
ED → ICU → Floor → Discharge 25% 40%
ED → ICU → Floor → Death 0% 7%

The breakdown of length of stay by patient type summed over all paths is:

Average LOS by Patient Outcome

Mild

Severe

Survivors 2.49 38.33
Fatalities 2.65 17.03
Average Combined 2.49 27.27

8.5 Overall Outcome Probabilities

Based on these inputs,3,5,6,10 the overall discharge and death probabilities are:

Outcome

Mild

Severe

Discharge 100% 48%
Death* 0% 52%

*These figures do not include late (>2 months) mortality from radiation exposure)

8.6 Resources Consumed Per Patient Per Day

The assumed level of resource consumption per patient per day is shown in the table below:

Resource

Units

Category

Subcategory

Lambdaa

Mild

Severe

ED ICU Floor ED ICU Floor
Med/Surg Bed One Bed Capacity Floor 1 0.083 0 0 0.083 0 0
ICU bed One bed Capacity ICU 1 0 1 0 0 1 0
Burn bed One bed Capacity Burn 1 0 0 0 0 0 0
Operating room One OR Suite Capacity OR 1 0 0 0 0 0 0
Airborne isolation room One bed Capacity Isolation 0.9 0 0 0 0 0 0
Intensivists (CCM) FTE Staff CCM 0.7 0.021 0.083 0 0.083 0.083 0
Critical care nurses (CCN) FTE Staff CCN 1 0.021 0.33 0 0.083 0.33 0
Surgeons FTE Staff Surgeon 0.3 0 0.042 0 0 0.042 0
Non-intensivists (MD) FTE Staff MD 0.9 0.083 0 0.042 0.083 0 0.042
Non-critical care nurses (RN/LPN) FTE Staff RN 1 0.042 0 0.146 0.042 0 0.146
Respiratory Therapists (RT) FTE Staff RT 0.7 0 0.042 0 0.083 0.083 0
Radiology machines Machine Time Lab/Radiology Radiology 0.3 0 0.021 0 0 0.021 0
Radiologic technicians FTE Staff Rad Tech 0.3 0 0.021 0 0 0.021 0
Pharmacists (PharmD/RPh) FTE Staff Pharmacist 0.7 0.021 0.042 0.042 0.021 0.042 0.042
Mechanical ventilator Machine Time Capacity Ventilator 0.9 0 0 0 0 0 0
Ventilator equipment One Ventilator Equipment Vent Tubing 0.9 0 0 0 0 0 0
Oxygen (O2) 24h O2 for Vent Supplies Oxygen 0.9 0 1 0 0 1 0
Oxygenation monitoring equipment Machine Time Equipment O2 Monitoring 0.9 0.083 1 0 0.083 1 0
Surgical supplies Trauma Set Supplies Surgical 0.3 0 0 0 0 0 0
Radiology supplies Radiographic Film Supplies Radiological 0.3 0 1 0 0 1 0
Ciprofloxacin or doxycycline 400mg/100mg bid Pharmacy Antibiotics 1 0 0 0 0 0 0
Rifampin or other 2nd line agent 600mg po bid Pharmacy Antibiotics 1 0 0 0 0 0 0
Antibiotics for secondary pneumonia Assorted Pharmacy Antibiotics 1 0 1 0 0 1 0
Surgical infection prophylaxis/treatment Assorted Pharmacy Antibiotics 1 0 0 0 0 0 0
Neutropenia prophylaxis/treatment Assorted Pharmacy Antibiotics 1 0 0 0 1 1 1
Antibiotics intravenous infusion set One IV Piggyback Supplies IV set 1 0 0 0 1 0.5 0.5
Hemodynamic medications Assorted Pharmacy Hemodynamic 0.7 0 1 0 0 1 0
Intravenous fluids 24h LR or equiv. Pharmacy IVF 0.7 1 1 1 1 1 1
Intravenous infusions set One IV Set Supplies IV Set 0.7 1 1 1 1 1 1
Laboratory machines Machine Time Lab/Radiology Laboratory 0.7 0.042 0.083 0.042 0.083 0.166 0.083
Laboratory supplies CBC/CMP Reag. Supplies Laboratory 0.7 2 2 2 3 6 3
Temperature monitoring equipment Machine Time Equipment Temperature 1 0.083 1 0 0.083 1 0
Thromboembolism prophylaxis Enoxaparin 40mg sc qd Pharmacy DVT Prophylaxis 1 0 1 0 0 1 0
Urine output monitoring equipment Catheter and Bag Equipment U/O 1 0 1 0 0 1 0
Universal precautions PPE Glove/gown/mask PPE Universal 1 1 1 1 1 1 1
Chemical PPE Level D PPE Chemical 0.3 0 0 0 0 0 0
Radiological PPE Level D PPE Radiological 0.3 1 0 0 1 0 0
Waste disposal Level D PPE Decon Waste 0.3 1 1 1 1 1 1
Mortuary decontamination materials Level D PPE Mortuary 0.3 0 0 0 0 0 0
Atropine sulfate 2mg Pharmacy Atropine 0.1 0 0 0 0 0 0
Pralidoxime 2g Pharmacy Pralidoxime 0.1 0 0 0 0 0 0
Diazepam 10mg Pharmacy Diazepam 0.1 0 0 0 0 0 0
EEG Machine Time Equipment Chemical 0.1 0 0 0 0 0 0
IV steroids Hydrocortisone 50mg IV q6h Pharmacy Steroids 0.7 0 0 0 0 0 0
DPTA 1g IV Pharmacy DPTA 0.1 1 1 1 1 1 1
Prussian blue 3mg po tid Pharmacy Prussian Blue 1 1 1 1 1 1 1
Growth Factors Pegfilgrastim 6mg sc qw Pharmacy Growth factors 1 0 0 0 0 1 1
Stem Cell Transfusion Unit of Use Heme/Onc Stem Cell Trans 1 0 0 0 0 1 0
Geiger counter Machine Time Equipment Radiation 0.1 0.42 0.21 0.21 0.42 0.21 0.21
Enteral feedings (3/day/patient) Unit of Use Nutrition Enteral 1 0 0.5 0 0 0.5 0.5
Oral food (3 meals per day per patient) Unit of Use Nutrition Oral 1 0 0.5 1 0 0.5 1
Sheet change 1 linen change Housekeeping Laundry 1 1 1 1 1 1 1
Patient infection control FTE Epidemiology Infection Control 0.5 0.021 0.042 0.042 0.021 0.042 0.042
Engineering FTE Engineering Facility 0.7 0.042 0.083 0.042 0.042 0.083 0.042
Janitorial/Housekeeping FTE Housekeeping Janitorial 1 0.125 0.125 0.083 0.125 0.125 0.083
Nutrition FTE Nutrition Counseling 0.5 0 0.083 0.083 0 0.083 0.083
Psychological support FTE Ancillary Psychologist 0.5 0 0 0.042 0 0 0.042
Mortuary FTE Mortuary Morgue 0.1 0 0.042 0 0.042 0.042 0

a. Lambda captures the resource requirement decay rate for a resource.  Lambda = 1 implies no decay; the patient requires a constant amount of the resource while s/he is hospitalized.  Lambda <1 implies that less of the resource is required each day the patient is hospitalized.  Go to section 2.2 for details.

8.7 References

1. Barrett JA. SRP meeting on radiological terrorism: prevention and response. J Radiol Prot 2004;24(3):331-2.

2. Elcock D, Klemic GA, Taboas AL. Establishing remediation levels in response to a radiological dispersal event (or "dirty bomb"). Environ Sci Technol 2004;38(9):2505-12.

3. Koenig KL, Goans RE, Hatchett RJ,et al. Medical treatment of radiological casualties: Current concepts. Ann Emerg Med 2005;45(6):643-52.

4. Moulder JE. Post-irradiation approaches to treatment of radiation injuries in the context of radiological terrorism and radiation accidents: a review. Int J Radiat Biol 2004;80(1):3-10.

5. Norwood WD. Radiation casualties: emergency plans and medical care. Arch Environ Health 1971;23(2):129-34.

6. Schleipman AR, Gerbaudo VH, Castronovo FP, Jr. Radiation disaster response: preparation and simulation experience at an academic medical center J Nucl Med Technol 2004;32(1):22-7.

7. Shoikhet YN, Kiselev VI, Zaitsev EV, et al. A registry for exposure and population health in the Altai region affected by fallout from the Semipalatinsk nuclear test site. Radiat Environ Biophys 1999;38(3):207-10.

8. Turai I, Veress K, Gunalp B, et al. Medical response to radiation incidents and radionuclear threats. BMJ 2004;328(7439):568-72.

9. Waselenko JK, MacVittie TJ, Blakely WF, et al. Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group. Ann Intern Med 2004;140(12):1037-51.

10. World MJ. Casualties resulting from nuclear explosion: an overview. J R Army Med Corps 2004;150(3 Suppl 1):3-4.

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