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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 4. Chlorine

This chapter describes the assumptions for the chlorine 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.

4.1 Severity Categories

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

  1. Irritated: Burning in eyes or respiratory system, exposed to a detectable odor.
  2. Incapacitated: Intolerable irritation of respiratory system and lungs.

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
Irritated: Burning in eyes or respiratory system, exposed to a detectable odor 98.9%
Incapacitated: Intolerable irritation of respiratory system and lungs 1.1%

This breakdown by casualty condition is based on work performed during development of the original Surge Model in 2005. In brief, plume modeling was used to estimate the number of exposed in several different cities. From these data, we developed a model to calculate exposure based upon the population of a given city. Populations were grouped based on high or low exposure with resultant irritation, incapacitation, or death. The percents above represent the percentage of individuals who survive an attack in each condition based upon a city of average size in the United States.

4.2 Casualty Arrival Pattern

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

4.3 Length of Stay By Hospital Unit

The assumed average length of stay (in days) of patients the ED, ICU, and the floor (9) listed at the end of this section) are:

Average Length of Stay by Hospital Unit Irritated Incapacitated
ED 1 1
Floor, not via ICU 1 6
Floor, via ICU 1 3
ICU 1 14

4.4 Combined Path Probabilities and Lengths of Stay

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

Path Irritated Incapacitated
ED → Discharge 0% 0%
ED → Death 0% 0%
ED → Floor → Discharge 90% 0%
ED → Floor → Death 0% 0%
ED → Floor → ICU → Death 0% 0%
ED → Floor → ICU → Floor → Discharge 0% 0%
ED → Floor → ICU → Floor → Death 0% 0%
ED → ICU → Death 0% 0%
ED → ICU → Floor → Discharge 10% 100%
ED → ICU → Floor → Death 0% 0%

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

Average Length of Stay by Patient Outcome Irritated Incapacitated
Survivors 2.10 18.00
Fatalities 0.00 0.00
Average Combined 2.10 18.00

4.5 Overall Outcome Probabilities

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

Outcome Irritated Incapacitated
Discharge 100% 100%
Death 0% 0%

4.6 Resources Consumed Per Patient Per Day

The assumed level of resource consumption per patient per day (1, 10, 12) listed at the end of this section) is shown in the table below:

Resource Units Category Subcategory Lambdaa Irritated Incapacitated
ED ICU Floor ED ICU Floor
Med/Surg bed Unit of Use Capacity Floor 1 0.083 0 0 0.167 0 0
ICU bed Unit of Use Capacity ICU 1 0 1 0 0 1 0
Burn bed Unit of Use Capacity Burn 1 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 0.167 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 0 0.146 0 0 0.146
Respiratory therapists (RT) FTE Staff RT 0.7 0.021 0.021 0.021 0.083 0.083 0.083
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 0.021 0.021 0.042 0.042
Mechanical ventilator Machine Time Capacity Ventilator 0.9 0 0 0 1 1 0
Ventilator equipment Unit of Use Equipment Vent Tubing 0.9 0 0 0 1 1 0
Oxygen (O2) Unit of Use Supplies Oxygen 0.9 1 1 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 Unit of Use Supplies Surgical 0.3 0 0 0 0 0.25 0
Radiology supplies Unit of Use Supplies Radiological 0.3 1 1 0 1 1 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
Hemodynamic medications Unit of Use Pharmacy Hemodynamic 0.7 0 0 0 1 1 0
Intravenous fluids Unit of Use Pharmacy IVF 0.7 0 0 0 1 1 1
Intravenous infusions set Unit of Use Supplies IV Set 0.7 0 0 0 1 1 1
Laboratory machines Machine Time Lab/Radiology Laboratory 0.7 0.021 0.021 0.021 0.021 0.021 0.021
Laboratory supplies Unit of Use Supplies Laboratory 0.7 0.5 0.5 0.5 1 1 0.5
Temperature monitoring equipment Machine Time Equipment Temperature 1 0.083 1 1 0.083 1 1
Thromboembolism prophylaxis Unit of Use Pharmacy DVT Prophylaxis 1 0 1 0 0 1 1
Urine output monitoring equipment Unit of Use Equipment U/O 1 0 1 0 0 1 0
Universal precautions PPE Unit of Use PPE Universal 1 1 1 1 1 1 1
Chemical PPE Unit of Use PPE Chemical 0.3 1 0 0 1 0 0
Radiological PPE Unit of Use PPE Radiological 0.3 0 0 0 0 0 0
Waste disposal Unit of Use Waste Mgmt Decon Waste 0.3 1 0 0 1 0 0
Mortuary decontamination materials Unit of Use Mortuary Decon 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
Growth factors Unit of Use Pharmacy Growth factors 1 0 0 0 0 0 0
IV steroids Unit of Use Pharmacy Steroids 0.7 0 0 0 1 1 1
Enteral feedings (3/day/patient) Unit of Use Nutrition Enteral 1 0 0 0 0 0.5 0
Oral food (3 meals/ day/patient) Unit of Use Nutrition Oral 1 0 0.5 1 0 0.5 1
Sheet change Unit of Use Housekeeping Laundry 1 1 1 1 1 1 1
Patient infection control FTE Epidemiology Infection Control 0.5 0.021 0.021 0.021 0.042 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 0.083 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 0.021 0.042 0.042 0 0.042 0.042
Mortuary FTE Mortuary Morgue 0.1 0 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.

4.7 References

1. Agency for Toxic Substances and Disease Registry. Medical Management Guidelines for Chlorine. Atlanta: Centers for Disease Control and Prevention; 2010. Available at: http://www.atsdr.cdc.gov/MMG/MMG.asp?id=198&tid=36. Accessed July 27, 2010.

2. Amyot D. The Mississauga "saga". Emerg Plann Dig 980;7(1):5-12.

3. Baxter PJ, Davies PC, Murray V. Medical planning for toxic releases into the community: the example of chlorine gas. Br J Ind Med 1989;46(4):277-85.

4. Berkowitz Z, Horton DK, Kaye WE. Hazardous substances releases causing fatalities and/or people transported to hospitals: rural/agricultural vs. other areas. Prehosp Disaster Med 2004;19(3):213-20.

5. Centers for Disease Control and Prevention. Public health consequences from hazardous substances acutely released during rail transit-South Carolina, 2005; selected States, 1999-2004. MMWR Morb Mortal Wkly Rep 2005;54(3):64-7

6. Decker WJ. Chlorine poisoning at the swimming pool revisited: anatomy of two minidisasters. Vet Hum Toxicol 1988;30(6):584-5.

7. Gibson C, Fowler R, Foltas W. 11 November 1979—a day to remember: the Mississauga disaster. Can J Hosp Pharm 1980;32(6):178-80.

8. Hedges JR, Morrissey WL. Acute chlorine gas exposure. JACEP 1979;8(2):59-63.

9. Horton DK, Berkowitz Z, Kaye WE. The public health consequences from acute chlorine releases, 1993-2000. J Occup Environ Med 2002;44(10):906-13.

10. Jackson JR. Medical planning for toxic releases into the community: the example of chlorine gas. Br J Ind Med 1989;46(10):752.

11. Joseph G. Chlorine transfer hose failure. J Hazard Mater 2004;115(1-3):119-25.

12. Krivoy A, Layish I, Rotman E, et al. OP or not OP: the medical challenge at the chemical terrorism scene. Prehosp Disaster Med 2005;20(3):155-8.

13. Lawson JJ. Chlorine exposure: a challenge to the physician. Am Fam Physician 1981;23(1):135-8.

14. Parrish JS, Bradshaw DA. Toxic inhalational injury: gas, vapor and vesicant exposure. Respir Care Clin N Am 2004;10(1):43-58.

15. 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.

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