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:
- Mild: miosis, ocular pain, tearing,
rhinorrhea, bronchospasm, slight dyspnea, respiratory secretions,
salivation, diaphoresis.
- Moderate: moderate dyspnea, nausea,
vomiting, diarrhea.
- 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 floor (based
on references no. 6 and 12 listed
at the end of this section) are:
Average
LOS 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
LOS 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
|
Lambda1
|
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 |
Cirprofloxacin 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 |
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 |
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 per day per 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 |
|
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.
6.7
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