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:
- Irritated: burning in eyes or respiratory system, exposed to a detectable odor.
- 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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