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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 9. Radiological Point Source

This chapter describes the assumptions for the radiological point source 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.

9.1 Severity Categories

For the point source scenario, patients arrive at the hospital(s) in one of three conditions:

  1. Mild: Nausea, vomiting, anorexia, fever, infections.
  2. Moderate: More severe mild symptoms, plus bleeding, fatigue, and weakness.
  3. Severe: More severe moderate symptoms, plus headache, prostration, dizziness, and disorientation

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 follows:

Casualty Condition

Percent

Mild: Nausea, vomiting, anorexia, fever, infections 28.8%
Moderate: More severe as above, plus bleeding, fatigue, and weakness 32.6%
Severe: More severe as above, plus headache, prostration, dizziness, and disorientation 38.6%

This breakdown by casualty condition is based on work performed during development of the original Surge Model in 2005. In brief, we modeled a scenario in which radioactive material was placed in several public locations. Based upon the physical dimensions of an average person, the penetration rate of radiation, and the density of crowds at various times, we calculated the number of people exposed to different levels of radiation. Using available data on dose-response to radiation in humans, we calculated the likelihood of experiencing gastrointestinal (GI) distress, blood symptoms, or mental effects from the radiation, and categorized casualties into the three categories listed above.

9.2 Casualty Arrival Pattern

Casualties are assumed to present at the hospital(s) when symptoms appear.  For the this scenario, casualties are expected to present in approximately equal numbers for as long as the device remains undetected. This assumes that the number of people at the facility where radioactive material is placed does not vary widely from day to day. Once the material is identified and removed, the exposure to new individuals ceases.

9.3 Length of Stay (LOS) By Hospital Unit

The assumed average length of stay (in days) of patients the ED, ICU, and the floor are:

Average LOS by Hospital Unit

Mild

Moderate

Severe

ED 1 1 1
Floor, not via ICU 1 4 7
Floor, via ICU 2 4 14
ICU 1 12 28

9.4 Combined Path Probabilities and Lengths of Stay

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

Path

Mild

Moderate

Severe

ED → Discharge 0% 0% 0%
ED → Death 0% 0% 0%
ED → Floor → Discharge 90% 61% 4%
ED → Floor → Death 0% 0% 0%
ED → Floor → ICU → Death 0% 3% 2%
ED → Floor → ICU → Floor → Discharge 0% 11% 2%
ED → Floor → ICU → Floor → Death 0% 0% 0%
ED → ICU → Death 0% 5% 43%
ED → ICU → Floor → Discharge 10% 19% 40%
ED → ICU → Floor → Death 0% 1% 7%

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

Average LOS by Patient Outcome

Mild

Moderate

Severe

Survivors 2.20 9.25 39.84
Fatalities 2.51 8.82 17.12
Average Combined 2.20 9.21 27.79

9.5 Overall Outcome Probabilities

Based on these inputs, the overall discharge and death probabilities are:

Outcome

Mild

Moderate

Severe

Discharge 100% 91% 47%
Death* 0% 9% 53%

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

9.6 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

Moderate

Severe

ED ICU Floor ED ICU Floor ED ICU Floor
Med/Surg bed One bed Capacity Floor 1 0.083 0 0 0.083 0 0 0.083 0 0
ICU bed One bed Capacity ICU 1 0 1 0 0 1 0 0 1 0
Burn bed One bed Capacity Burn 1 0 0 0 0 0 0 0 0 0
Operating room One OR Suite Capacity OR 1 0 0 0 0 0 0 0 0 0
Airborne Isolation room One bed Capacity Isolation 0.9 0 0 0 0 0 0 0 0 0
Intensivists (CCM) FTE Staff CCM 0.7 0.021 0.083 0 0.021 0.083 0 0.083 0.083 0
Critical care nurses (CCN) FTE Staff CCN 1 0.021 0.33 0 0.021 0.33 0 0.083 0.33 0
Surgeons FTE Staff Surgeon 0.3 0 0.042 0 0 0.042 0 0 0.042 0
Non-intensivists (MD) FTE Staff MD 0.9 0.167 0 0.042 0.167 0 0.042 0.167 0 0.042
Non-critical care nurses (RN/LPN) FTE Staff RN 1 0.042 0 0.146 0.042 0 0.146 0.042 0 0.146
Respiratory Therapists (RT) FTE Staff RT 0.7 0 0.083 0 0 0.083 0 0.083 0.083 0
Radiology machines Machine Time Lab/Radiology Radiology 0.3 0 0.021 0 0 0.021 0 0 0.021 0
Radiologic technicians FTE Staff Rad Tech 0.3 0 0.021 0 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 0.021 0.042 0.042
Mechanical ventilator Machine Time Capacity Ventilator 0.9 0 0 0 0 0 0 0 0 0
Ventilator equipment One Ventilator Equipment Vent Tubing 0.9 0 0 0 0 0 0 0 0 0
Oxygen (O2) 24h O2 for Vent Supplies Oxygen 0.9 0 1 0 0 1 0 0 1 0
Oxygenation monitoring equipment Machine Time Equipment O2 Monitoring 0.9 0.083 1 0 0.083 1 0 0.083 1 0
Surgical supplies Trauma Set Supplies Surgical 0.3 0 0 0 0 0 0 0 0 0
Radiology supplies Radiographic Film Supplies Radiological 0.3 0 1 0 0 1 0 0 1 0
Ciprofloxacin or doxycycline 400mg/100mg bid Pharmacy Antibiotics 1 0 0 0 0 0 0 0 0 0
Rifampin or other 2nd line agent 600mg po bid Pharmacy Antibiotics 1 0 0 0 0 0 0 0 0 0
Antibiotics for secondary pneumonia Assorted Pharmacy Antibiotics 1 0 1 0 0 1 0 0 1 0
Surgical infection prophylaxis/treatment Assorted Pharmacy Antibiotics 1 0 0 0 0 0 0 0 0 0
Neutropenia prophylaxis/treatment Assorted Pharmacy Antibiotics 1 0 0 0 1 1 1 1 1 1
Antibiotics intravenous infusion set One IV Piggyback Supplies IV set 1 0 0 0 0 0 0 1 0.5 0.5
Hemodynamic medications Assorted Pharmacy Hemodynamic 0.7 0 1 0 0 1 0 0 1 0
Intravenous fluids 24h LR or equiv. Pharmacy IVF 0.7 1 1 1 1 1 1 1 1 1
Intravenous infusions set One IV Set Supplies IV Set 0.7 1 1 1 1 1 1 1 1 1
Laboratory machines Machine Time Lab/Radiology Laboratory 0.7 0.042 0.083 0.042 0.042 0.083 0.042 0.083 0.166 0.083
Laboratory supplies CBC/CMP Reag. Supplies Laboratory 0.7 2 2 2 2 2 2 3 6 3
Temperature monitoring equipment Machine Time Equipment Temperature 1 0.083 1 0 0.083 1 0 0.083 1 0
Thromboembolism prophylaxis Enoxaparin 40mg sc qd Pharmacy DVT Prophylaxis 1 0 1 0 0 1 0 0 1 0
Urine output monitoring equipment Catheter and Bag Equipment U/O 1 0 1 0 0 1 0 0 1 0
Universal precautions PPE Glove/gown/mask PPE Universal 1 1 1 1 1 1 1 1 1 1
Chemical PPE Level D PPE Chemical 0.3 0 0 0 0 0 0 0 0 0
Radiological PPE Level D PPE Radiological 0.3 1 1 1 1 1 1 1 1 1
Waste disposal Level D PPE Decon Waste 0.3 1 1 1 1 1 1 1 1 1
Mortuary decontamination materials Level D PPE Mortuary 0.3 0 0 0 0 0 0 0 0 0
Atropine sulfate 2mg Pharmacy Atropine 0.1 0 0 0 0 0 0 0 0 0
Pralidoxime 2g Pharmacy Pralidoxime 0.1 0 0 0 0 0 0 0 0 0
Diazepam 10mg Pharmacy Diazepam 0.1 0 0 0 0 0 0 0 0 0
EEG Machine Time Equipment Chemical 0.1 0 0 0 0 0 0 0 0 0
IV steroids Hydrocortisone 50mg IV q6h Pharmacy Steroids 0.7 0 0 0 0 0 0 0 0 0
DPTA 1g IV Pharmacy DPTA 0.1 0 0 0 0 0 0 0 0 0
Prussian blue 3mg po tid Pharmacy Prussian Blue 1 0 0 0 0 0 0 0 0 0
Growth factors Pegfilgrastim 6mg sc qw Pharmacy Growth factors 1 0 0 0 1 1 1 1 1 1
Stem cell transfusion Unit of Use Heme/Onc Stem Cell Trans 1 0 0 0 0 1 0 0 1 0
Geiger counter Machine Time Equipment Radiation 0.1 0.42 0.21 0.21 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 0 0 0.5 0 0 1 0.5
Oral food (3 meals per day per patient) Unit of Use Nutrition Oral 1 0 0.5 1 0 0.5 1 0 0.5 1
Sheet change 1 linen change Housekeeping Laundry 1 1 1 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 0.021 0.042 0.042
Engineering FTE Engineering Facility 0.7 0.042 0.083 0.042 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 0.125 0.125 0.083
Nutrition FTE Nutrition Counseling 0.5 0 0.083 0.083 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 0 0 0.042
Mortuary FTE Mortuary Morgue 0.1 0 0.042 0.042 0 0.042 0.042 0.042 0.042 0.042

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.

9.7 References

1. Bland SA. Mass casualty management for radiological and nuclear incidents. J R Army Med Corps 2004;150(3 Suppl 1):27-34.

2. Bland SA. Management of the irradiated casualty. J R Army Med Corps 2004;150(3 Suppl 1):5-9.

3. Gusev I, Guskova A, Mettler F, eds. Medical management of radiation accidents, 2nd ed. Boca Raton: CRC Press; 2001.

4. Mettler FA Jr. Medical resources and requirements for responding to radiological terrorism. Health Phys 2005;89(5):488-93.

5. 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.

6. Timins JK, Lipoti JA. Radiological terrorism. N J Med 2003;100(6):14-21.

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

8. Wheeler DS, Poss WB. Mass casualty management in a changing world. Pediatr Ann 2003;32(2):98-105.

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