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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 6. Sarin

This chapter describes the assumptions for the sarin 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.

6.1. Severity Categories

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

  1. Mild: Miosis, ocular pain, tearing, rhinorrhea, bronchospasm, slight dyspnea, respiratory secretions, salivation, diaphoresis.
  2. Moderate: Moderate dyspnea, nausea, vomiting, diarrhea.
  3. Severe: Loss of consciousness, convulsions, paralysis, copious secretions, apnea.

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: Miosis, ocular pain, tearing, rhinorrhea, bronchospasm, slight dyspnea, respiratory secretions, salivation, diaphoresis 95.4%
Moderate: Moderate dyspnea, nausea, vomiting, diarrhea 3.6%
Severe: Loss of consciousness, convulsions, paralysis, copious secretions, apnea 1.0%

This breakdown by casualty condition is based on work performed during development of the original Surge Model in 2005. In brief, the modeled sarin attack is based upon a release of the agent indoors in a theater. We used air exchange rates to estimate exposure both within the theater and to pedestrians nearby who were exposed to sarin released from the exhaust vents. Individuals who were nearby in the attack were considered partially protected if they were in a building but unprotected if outdoors. Initially, four categories of condition were estimated: mild, moderate, or severe symptoms, or death,. However, in the largest attacks, all those directly exposed to the attack would receive a lethal dose, and those outdoors would receive only enough to illicit mild symptoms.

6.2 Casualty Arrival Pattern

For the sarin scenario, all casualties are assumed to present at the hospital(s) on Day 1.

6.3 Length of Stay By Hospital Unit

The assumed average length of stay (in days) of patients the ED, ICU, and the floor6,13 are:

Average Length of Stay by Hospital Unit Irritated Moderate Severe
ED 1 1 1
Floor, not via ICU 1 2 7
Floor, via ICU 1 2 7
ICU 1 2 7

 

6.4 Combined Path Probabilities and Lengths of Stay

The table below shows the assumed probabilities of different "paths" through the hospital(s). The table shows, for example, that a patient presenting with severe sarin exposure has a 50 percent chance of dying in the ED prior to transfer to the ICU.

Path Irritated Moderate Severe
ED → Discharge 50% 15% 0%
ED → Death 0% 0% 0%
ED → Floor → Discharge 50% 63% 0%
ED → Floor → Death 0% 0% 0%
ED → Floor → ICU → Death 0% 0% 0%
ED → Floor → ICU → Floor → Discharge 0% 7% 0%
ED → Floor → ICU → Floor → Death 0% 0% 0%
ED → ICU → Death 0% 0% 0%
ED → ICU → Floor → Discharge 0% 15% 100%
ED → ICU → Floor → Death 0% 0% 0%

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

Average Length of Stay by Patient Outcome Irritated Moderate Severe
Survivors 1.50 3.24 15.00
Fatalities 0.00 0.00 0.00
Average Combined 1.50 3.24 15.00

6.5 Overall Outcome Probabilities

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

Outcome Irritated Moderate Severe
Discharge 100% 100% 100%
Death 0% 0% 0%

6.6 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 Moderate 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 0.042 0.042 0 0.083 0.083 0
Critical care nurses (CCN) FTE Staff CCN 1 0.083 0.33 0 0.083 0.33 0
Surgeons FTE Staff Surgeon 0.3 0 0 0 0 0.083 0
Non-intensivists (MD) FTE Staff MD 0.9 0.083 0 0.021 0.083 0 0.021
Non-critical care nurses (RN/LPN) FTE Staff RN 1 0.33 0 0.33 0.33 0 0.33
Respiratory therapists (RT) FTE Staff RT 0.7 0.083 0.083 0.042 0.083 0.083 0.042
Radiology machines Machine Time Lab/Radiology Radiology 0.3 0.021 0.021 0 0.021 0.021 0
Radiologic technicians FTE Staff Rad Tech 0.3 0.021 0.021 0 0.021 0.021 0
Pharmacists (PharmD/RPh) FTE Staff Pharmacist 0.7 0.021 0.042 0.042 0.021 0.042 0
Mechanical ventilator Machine Time Capacity Ventilator 0.9 0 1 0 1 1 0
Ventilator equipment One Ventilator Equipment Vent Tubing 0.9 0 1 0 1 1 0
Oxygen (O2) 24h O2 for Vent Supplies Oxygen 0.9 1 2 1 2 2 1
Oxygenation monitoring equipment Machine Time Equipment O2 Monitoring 0.9 0.083 1 0 0.083 1 0.5
Surgical supplies Trauma Set Supplies Surgical 0.3 0 0 0 0 0.25 0
Radiology supplies Radiographic Film Supplies Radiological 0.3 1 1 0 1 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 0 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 0 0 0
Antibiotics intravenous infusion set One IV Piggyback Supplies IV set 1 0 0 0 0 0 0
Hemodynamic medications Assorted Pharmacy Hemodynamic 0.7 0 0 0 1 1 0
Intravenous fluids 24h LR or equiv. Pharmacy IVF 0.7 0 0 0 1 1 0
Intravenous infusions set One IV Set Supplies IV Set 0.7 0 0 0 1 1 0
Laboratory machines Machine Time Lab/Radiology Laboratory 0.7 0.021 0.021 0.021 0.021 0.021 0.021
Laboratory supplies CBC/CMP Reag. Supplies Laboratory 0.7 1 1 0.05 1 1 0.05
Temperature monitoring equipment Machine Time Equipment Temperature 1 0.083 1 1 0.083 1 1
Thromboembolism prophylaxis Enoxaparin 40mg sc qd Pharmacy DVT Prophylaxis 1 0 1 1 0 1 1
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 1 0 0 1 0 0
Radiological PPE Level D PPE Radiological 0.3 0 0 0 0 0 0
Waste disposal Level D PPE Decon Waste 0.3 1 0 0 1 0 0
Mortuary decontamination materials Level D PPE Mortuary 0.3 0 0 0 0 0 0
Atropine sulfate 2mg Pharmacy Atropine 0.1 2 2 0 3 3 0
Pralidoxime 2g Pharmacy Pralidoxime 0.1 2 2 0 2 2 0
Diazepam 10mg Pharmacy Diazepam 0.1 1 1 0 2 2 0
EEG Machine Time Equipment Chemical 0.1 1 1 1 1 1 1
IV steroids Hydrocortisone 50mg IV q6h Pharmacy Steroids 0.7 0 0 0 0 0 0
DPTA 1g IV Pharmacy DPTA 0.1 0 0 0 0 0 0
Prussian blue 3mg po tid Pharmacy Prussian Blue 1 0 0 0 0 0 0
Growth factors Pegfilgrastim 6mg sc qw Pharmacy Growth factors 1 0 0 0 0 0 0
Stem cell transfusion Unit of Use Heme/Onc Stem Cell Trans 1 0 0 0 0 0 0
Geiger counter Machine Time Equipment Radiation 0.1 0 0 0 0 0 0
Enteral feedings (3/day/patient) Unit of Use Nutrition Enteral 1 0 0.5 0 0 0.5 1
Oral food (3 meals/ day/ patient) Unit of Use Nutrition Oral 1 0 0.5 1 0 0.5 1
Sheet change 1 linen change House-keeping 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 0.083 0.042
Engineering FTE Engineering Facility 0.7 0.042 0.083 0.042 0.042 0.083 0.042
Janitorial/Housekeeping FTE House-keeping 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 0 0 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.

6.7 References

1. DeBalli P, Cook DR. Treatment of sarin exposure. JAMA 2004;291(2):181-2.

2. Hook GE. Toxicology and terrorism. Environ Health Perspect 1995;103(5):418-9.

3. Kato T, Yoshimoto N, Sawano M, et al. Coronary vasospasm in a patient suffering from sarin poisoning. Am J Emerg Med 000;18(1):113-4.

4. Krivoy A, Layish I, Rotman E, et al. Treatment of sarin exposure. JAMA 2004;291(2):181.

5. Leikin JB, Thomas RG, Walter FG, et al. A review of nerve agent exposure for the critical care physician. Crit Care Med 2002;30(10):2346-54.

6. Matsui Y, Ohbu S, Yamashina A. Hospital deployment in mass sarin poisoning incident of the Tokyo subway system—an experience at St. Luke's International Hospital, Tokyo. Jpn Hosp 1996;15:67-71.

7. Nakajima T, Sato S, Morita H, et al. Sarin poisoning of a rescue team in the Matsumoto sarin incident in Japan. Occup Environ Med 1997;54(10):697-701.

8. Newmark J. Therapy for nerve agent poisoning. Arch Neurol 2004;61(5):649-52.

9. Nozaki H, Hori S, Shinozawa Y, et al. Secondary exposure of medical staff to sarin vapor in the emergency room. Intensive Care Med 1995;21(12):1032-5.

10. Occupational Safety and Health Administration, National Institute for Occupational Safety and Health. OSHA/NIOSH Interim Guidance on Personal Protective Equipment Selection Matrix for Emergency Responders: Nerve Agents. Washington, DC: U.S. Department of Labor; 2006. Available at: http://www.osha.gov/SLTC/emergencypreparedness/cbrnmatrix/nerve.html. Accessed July 27, 2010.

11. Ohbu S, Yamashina A, Takasu N, et al. Sarin poisoning on Tokyo subway. South Med J 1997;90(6):587-93.

12. Okumura T, Suzuki K, Fukuda A, et al. The Tokyo subway sarin attack: disaster management, Part 1: Community emergency response. Acad Emerg Med 1998;5(6):613-7.

13. Okumura T, Suzuki K, Fukuda A, et al. The Tokyo subway sarin attack: disaster management, Part 2: Hospital response. Acad Emerg Med 1998;5(6):618-24.

14. Okumura T, Takasu N, Ishimatsu S, et al. Report on 640 victims of the Tokyo subway sarin attack. Ann Emerg Med 1996;28(2):129-35.

15. Rosenfield RL, Bernardo LM. Pediatric implications in bioterrorism part II: postexposure diagnosis and treatment. Int J Trauma Nurs 2001;7(4):133-6.

16. Rotenberg JS. Diagnosis and management of nerve agent exposure. Pediatr Ann 2003;32(4):242-50.

17. Schier JG, Hoffman RS. Treatment of sarin exposure. JAMA 2004;291(2):182.

18. Scremin OU, Shih TM, Huynh L, et al. Low-dose cholinesterase inhibitors do not induce delayed effects on cerebral blood flow and metabolism. Pharmacol Biochem Behav 2005;80(4):529-40.

19. Shih TM, Duniho SM, McDonough JH. Control of nerve agent-induced seizures is critical for neuroprotection and survival. Toxicol Appl Pharmacol 2003;188(2):69-80.

20. Suzuki J, Kohno T, Tsukagosi M, et al. Eighteen cases exposed to sarin in Matsumoto, Japan. Intern Med 1997;36(7):466-70.

21. Treatment of chemical agent casualties and conventional military chemical injuries. Field Manual No. 8-285/NAVMED P-5041/Air Force Joint Manual No. 44-149/Fleet Marine Force Manual No. 11-11. Headquarters, Departments of the Army, the Navy, and the Air Force, and Commandant, Marine Corps. Washington, DC; 1995.

22. Volans AP. Sarin: guidelines on the management of victims of a nerve gas attack. J Accid Emerg Med 1996;13(3):202-6.

23. Weinbroum AA, Rudick V, Paret G, et al. Anaesthesia and critical care considerations in nerve agent warfare trauma casualties. Resuscitation 2000;47(2):113-23.

24. Worek F, Kleine A, Falke K, et al. Arrhythmias in organophosphate poisoning: effect of atropine and bispyridinium oximes. Arch Int Pharmacodyn Ther 1995;329(3):418-35.

25. Yokoyama K, Yamada A, Mimura N. Clinical profiles of patients with sarin poisoning after the Tokyo subway attack. Am J Med 1996;100(5):586.

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