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 (based on reference no. 7 listed at the end of this section) are:

Average LOS 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 LOS 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 (based on references no. 8, 10, and 14) listed at the end of this section) is shown in the table below:

Resource	Units	Category	Subcategory	Lambda1	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
Antibiotcs 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 per day per 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

1. 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. Amyot D. The Mississauga "saga". Emerg Plann Dig 1980;7(1):5-12.

2. 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.

3. 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.

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

5. 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.

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

7. 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.

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

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

10. 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.

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

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

13. 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.

14. Department of Health and Human Services (DHHS) Agency for Toxic Substances & Disease Registry (ATSDR). Medical Management Guidelines (MMGs) for Acute Chemical Exposures. Available at: http://www.atsdr.cdc.gov/MHMI/mmg.html. Accessed June 11, 2008.

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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