Chapter 3. Pandemic Flu

This chapter describes the assumptions for the flu 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.

3.1 Severity Categories

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

1. Moderate: After arriving at the Emergency Department, patients will be moved to the floor for medical care.
2. Severe: After arriving at the Emergency Department, patients will be moved to the ICU for medical care.

In the model, persons with mild symptoms are not hospitalized.

Users have the option of specifying either the number and type or simply the number of persons who become infected with flu. A user-specified percentage of these patients will require hospitalization.

If the user specifies only the number of infected persons, the model assumes these persons are randomly selected from among all infected persons. The distribution of infected persons in this case is as follows:

Casualty Condition	Percent
Moderate: After arriving at the Emergency Department, patients will be moved to the floor for medical care	85%
Severe: After arriving at the Emergency Department, patients will be moved to the ICU for medical care	15%

3.2 Casualty Arrival Pattern

Casualties are assumed to present at the hospital(s) when symptoms appear. For this scenario, we used data from the Models of Infectious Disease Agent Study (MIDAS) group² to estimate the temporal distribution of arrivals to the hospital. The MIDAS data closely follow a Normal distribution with mean 114 days and standard deviation 22 days.

3.3 Length of Stay By Hospital Unit

The assumed average length of stay (in days) of patients the ED, ICU, and the floor is:

Average LOS by Hospital Unit	Moderate	Severe
ED	1	1
Floor, not via ICU	5.3	5.3
Floor, via ICU	5.3	5.3
ICU	8	8

2. The Models of Infectious Disease Agent Study (MIDAS) is a collaboration of research and informatics groups to develop computational models of the interactions between infectious agents and their hosts, disease spread, prediction systems, and response strategies. http://www.nigms.nih.gov/Initiatives/MIDAS/

3.4 Combined Path Probabilities and Lengths of Stay

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

Path	Moderate	Severe
ED → Discharge	0%	0%
ED → Death	0%	0%
ED → Floor → Discharge	89%	4%
ED → Floor → Death	5%	0%
ED → Floor → ICU → Death	1%	0%
ED → Floor → ICU → Floor → Discharge	4%	1%
ED → Floor → ICU → Floor → Death	0%	0%
ED → ICU → Death	0%	21%
ED → ICU → Floor → Discharge	1%	71%
ED → ICU → Floor → Death	0%	4%

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

Average LOS by Patient Outcome	Moderate	Severe
Survivors	6.5	13.6
Fatalities	5.1	6.4
Average Combined	6.4	11.8

3.5 Overall Outcome Probabilities

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

Outcome	Moderate	Severe
Discharge	94%	75%
Death	6%	25%

3.6 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	Lambda3	Moderate			Severe
					ED	ICU	Floor	ED	ICU	Floor
Adult Med/Surg Bed	EA (Each)	Capacity	Adult Med/Surg	1	0.167	0	0.667	0.167	0	0.667
Adult ICU Bed	EA (Each)	Capacity	Adult ICU	1	0	0.667	0	0	0.667	0
Pediatric Med/Surg Bed	EA (Each)	Capacity	Pediatric Med/Surg	1	0.083	0	0.333	0.083	0	0.333
Pediatric ICU Bed	EA (Each)	Capacity	Pediatric ICU	1	0	0.333	0	0	0.333	0
Burn Bed	EA (Each)	Capacity	Burn	1	0	0	0	0	0	0
Operating Room	EA (Each)	Capacity	OR	1	0	0	0	0	0	0
Airborne Isolation Room	EA (Each)	Capacity	Isolation	0.8	0	0	0	0	0	0
Intensivists (CCM)	FTE	Staff	CCM	0.9	0.021	0.042	0	0.042	0.042	0
Critical care nurses (CCN)	FTE	Staff	CCN	1	0	0.33	0	0.167	0.33	0
Surgeons	FTE	Staff	Surgeon	0	0	0.0546	0	0	0.0546	0
Non-intensivists (MD)	FTE	Staff	MD	1	0.042	0	0.021	0.042	0	0.021
Non-critical care nurses (RN/LPN)	FTE	Staff	RN	1	0.167	0	0.146	0	0	0.146
Pharmacists (PharmD/RPh)	FTE	Staff	Pharmacist	0.9	0	0.021	0	0.021	0.021	0
Respiratory Therapists (RT)	FTE	Staff	RT	1	0	0.042	0	0.021	0.042	0
Mortuary	FTE	Staff	Mortuary	1	0	0.021	0	0	0.0315	0
Adult Mechanical ventilator	EA (Each)	Capacity	Ventilator	1	0	0.6	0	0.15	0.6	0
Pediatric Mechanical ventilator	EA (Each)	Capacity	Ventilator	1	0	0.3	0	0.075	0.3	0
Adult Ventilator Circuit	EA (Each)	Equipment	Ventilator Kit	0	0	0.78	0	0.546	0.234	0
Pediatric Ventilator Circuit	EA (Each)	Equipment	Ventilator Kit	0	0	0.39	0	0.273	0.117	0
Closed circuit suction catheter 14F	EA (Each)	Equipment	Ventilator Kit	0	0	0.78	0	0.546	0.234	0
Closed circuit suction catheter 8-12F	EA (Each)	Equipment	Ventilator Kit	0	0	0.39	0	0.273	0.117	0
Humiidification and Flitration Unit (HMEF)	EA (Each)	Equipment	Ventilator Kit	0	0	0.45	0	0.315	0.135	0
Endotracheal tube, 3mm ID	EA (Each)	Equipment	Intubation	0	0	0.039	0	0.0273	0.012	0
Endotracheal tube, 4mm ID	EA (Each)	Equipment	Intubation	0	0	0.039	0	0.0273	0.012	0
Endotracheal tube, 5mm ID	EA (Each)	Equipment	Intubation	0	0	0.039	0	0.0273	0.012	0
Endotracheal tube, 6mm ID	EA (Each)	Equipment	Intubation	0	0	0.039	0	0.0273	0.012	0
Endotracheal tube, 6.5mm ID	EA (Each)	Equipment	Intubation	0	0	0.100	0	0.07	0.030	0
Endotracheal tube, 7-8mm ID	EA (Each)	Equipment	Intubation	0	0	0.300	0	0.21	0.090	0
Laryngoscope blades, adult	EA (Each)	Equipment	Intubation	0	0	0.6	0	0.334	0.100	0
Laryngoscope blades, pediatric	EA (Each)	Equipment	Intubation	0	0	0.3	0	0.167	0.050	0
Laryngoscope handles	EA (Each)	Equipment	Intubation	0	0	0.501	0	0.501	0.150	0
Endotracheal stylette	EA (Each)	Equipment	Intubation	0	0	0.501	0	0.501	0.150	0
Resuscitation Bag, adult	EA (Each)	Equipment	Ventilator Kit	0	0	0.6	0	0.334	0.100
Resuscitation Bag, pediatric	EA (Each)	Equipment	Ventilator Kit	0	0	0.3	0	0.167	0.050
Ventilator Oxygen (O2)	Liters Liquid O2	Supplies	Oxygen	1	0	8.42	0	2.105	8.42	13.4
NC Oxygen (O2)	Liters Liquid O2	Supplies	Oxygen	1	1.67	0	6.7	0	0	13.4
Pulse oximeter	EA (Each)	Equipment	O2 Monitoring	1	0.082	1	0.082	0.25	1	0.082
Finger pulse oximeter strip	EA (Each)	Equipment	O2 Monitoring	0	1	1	1	1	1	1
End tidal CO2 detector, adult	EA (Each)	Equipment	O2 Monitoring	0	0	0.6	0	0.42	0.126	0
End tidal CO2 detector, pediatric	EA (Each)	Equipment	O2 Monitoring	0	0	0.3	0	0.21	0.090	0
Radiology machines	EA (Each)	Radiology	CXR	0.9	0.021	0.021	0	0.021	0.021	0
Radiology supplies	EA (Each)	Supplies	XR Film	0.9	1	1	0	1	1	0
Chemistry Laboratory machines	EA (Each)	Laboratory	Chemistry	0.9	0.021	0.021	0	0.021	0.021	0
Chemistry Lab supplies	EA (Each)	Supplies	Chem Supplies	0.9	1	1	0	1	1	0
Hematology Laboratory machines	EA (Each)	Laboratory	Hematology	0.9	0.021	0.021	0	0.021	0.021	0
Hematology Lab supplies	EA (Each)	Supplies	Heme Supplies	0.9	1	1	0	1	1	0
Micro/Virology Laboratory machines	EA (Each)	Laboratory	Micro/Virology	0.9	0.021	0.021	0	0.021	0.021	0
Microbiology/Virology Lab supplies	EA (Each)	Supplies	Micro Supplies	0.9	1	1	0	1	1	0
Hemodialysis Catheter	EA (Each)	Equipment	HD Catheter	0	0	0.07	0	0	0.07	0
Tube, Drainage, Surgical, Pleurovac System (LATEX FREE)	EA (Each)	Supplies	Chest Tube	0.9	0	0.13	0	0	0.13	0
Tube, Drainage, Surgical, Thoracic, 12-28, Fr, Straight (LATEX FREE)	EA (Each)	Supplies	Chest Tube	0.9	0	0.0432	0	0	0.0432	0
Tube, Drainage, Surgical, Thoracic, 32-36, Fr, Straight (LATEX FREE)	EA (Each)	Supplies	Chest Tube	0.9	0	0.087	0	0	0.087	0
NG Tubes Sizes 6F-16F	EA (Each)	Supplies	NG Tube	0.9	0	1	0	1	1	0
Temperature monitoring equipment	EA (Each)	Supplies	Temperature	1	1	1	1	1	1	1
Urine output--Foley catheter 8F-12F	EA (Each)	Supplies	Urinary Catheter	1	0	0.25	0	1	0.25	0
Urine output--monitor bag	EA (Each)	Supplies	Urinary Bag	0	0	1	0	1	1	0
BP cuffs, adult	EA (Each)	Equipment	BP Cuff	0.9	0.0067	0.0067	0.0067	0.0067	0.0067	0.0067
BP cuffs, pediatric	EA (Each)	Equipment	BP Cuff	0.9	0.0033	0.0033	0.0033	0.0033	0.0033	0.0033
N95/surgical masks	EA (Each)	Supplies	Mask	1	0.333	0.333	0.25	0.333	0.333	0.25
Face shields	EA (Each)	Supplies	Shield	1	0.033	0.033	0.025	0.033	0.033	0.033
Latex, non-sterile gloves	EA (Each)	Supplies	Glove, latex	1	10	10	10	10	10	10
Latex-free, non-sterile gloves	EA (Each)	Supplies	Glove, latex-free	1	10	10	10	10	10	10
Latex-free, sterile gloves	EA (Each)	Supplies	Glove, sterile	1	2	2	0	2	2	0
Gown cover univ yell	EA (Each)	Supplies	Gown	1	2	2	0	2	2	0
Gown isolation fluid resis	EA (Each)	Supplies	Gown, FluidR	1	1	1	0	1	1	0
Sanitizer alcohol gel (L)	Liters Sanitizer	Supplies	Sanitizer	1	0.05	0.05	0.05	0.05	0.05	0.05
Cleaner bleach clean up (L)	Liters Bleach	Supplies	Sanitizer	1	0.1	0.1	0.1	0.1	0.1	0.1
Bag liner red 15X9X24	EA (Each)	Supplies	Bag	1	1	1	1	1	1	1
Bag liner red 30X36	EA (Each)	Supplies	Bag	1	0	1	0	0	1	0
Bag liner red 39X48	EA (Each)	Supplies	Bag	1	0	1	0	0	1	0
Syringes 3cc 21G 1	EA (Each)	IV	Syringe	1	4	12	4	4	12	4
Sodium Chloride Flush 0.9% Preservative Free 3ML Carpuject	EA (Each)	IV	IV Flush	1	4	12	4	4	12	4
Sterile Water For Injection Preservative Free 10ML Vial	EA (Each)	IV	IV Flush	1	1	1	1	1	1	1
Providine Iodine 10% Swab sticks Triples	EA (Each)	IV	IV site prep	1	3	6	1	3	6	1
Tincture of Benzoin, 4 oz.	EA (Each)	IV	IV site prep	1	1	1	1	1	1	1
Intravenous catheter & needle unit, 18G x 1 1/4	EA (Each)	IV	IVs	1	0.17	0.17	0.17	0.17	0.33	0.17
Intravenous catheter & needle unit, 18G x 2	EA (Each)	IV	IVs	1	0.17	0.17	0.17	0.17	0.33	0.17
Intravenous catheter & needle unit, 20G x 1 1/4	EA (Each)	IV	IVs	1	0.17	0.17	0.17	0.17	0.33	0.17
Intravenous catheter & needle unit, 24G x 5/8	EA (Each)	IV	IVs	1	0.33	0.33	0.33	0.33	0.67	0.33
Intravenous set, butterfly, 12 tubing, 21G x 3/4	EA (Each)	IV	IVs	1	0.16	0.16	0.16	0.16	0.34	0.16
Triple Lumen Catheter, Intravenous	EA (Each)	IV	Triple Lumen	0	0	0.5	0	0.5	0.5	0
IV admin set, 10 or 60 drops / ml Mod	EA (Each)	IV	IV Admin Set	0.5	1	0	1	0	0	0
IV admin set, 10 or 60 drops / ml Sev	EA (Each)	IV	IV Admin Set	0.7	0	2	0	2	2	0
IV site transparent dressing, (Tegaderm or equivt)	EA (Each)	IV	IV dressing	0	1	2	1	0	0	0
IV site transparent dressing (Tegaderm or eqvlnt)	EA (Each)	IV	IV dressing	0.3	0	0	0	2	2	1
IV Pump	EA (Each)	IV	IV Pump	1	1	2	1	2	2	1
Heparin Lock Flush Kit, 100 units / ml	EA (Each)	IV	Heplock Kit	1	1	4	1	1	4	1
Sodium Bicarbonate Injection 50mEq; 50mL; 10s Syr	EA (Each)	IVF	Bicarbonate	0.5	0	0	0	1	1	0
Lactated Ringers Solution, IV 1000 ml	EA (Each)	IVF	LR	0.92	0.15	1.5	0.6	0.25	1.5	0.6
Sodium Chloride 0.9% Solution IV, 1000 ml	EA (Each)	IVF	NS	0.92	0.025	0.25	0.1	0.04167	0.25	0.1
Dextrose 5% Sodium Chloride 0.9% Inj. 1000 ml	EA (Each)	IVF	D5NS	0.92	0.025	0.25	0.1	0.04167	0.25	0.1
Sodium Chloride 0.45% IV, 1000 ml	EA (Each)	IVF	1/2NS	0.92	0.025	0.25	0.1	0.04167	0.25	0.1
Dextrose 5% Sodium Chloride 0.45% Inj. 1000 ml	EA (Each)	IVF	D51/2NS	0.92	0.025	0.25	0.1	0.04167	0.25	0.1
D5W or Sterile Water Piggybacks of 50-250cc size	EA (Each)	IVF	D5W	1	0	2	1	2	2	1
PRBC, Unit	EA (Each)	Blood Product	RBC	0.6	0	0.0125	0	0	0.0125	0
Platelets, Unit	EA (Each)	Blood Product	PLT	0.6	0	0.016	0	0	0.016	0
FFP, Unit	EA (Each)	Blood Product	FFP	0.6	0	0.0125	0	0	0.0125	0
Hemodialysis dialysate, Liters	Liters	RRT	Dialysate	0.9	0	0	0	0	0	0
Oseltamivir 75mg po	EA (Each)	Pharmaceutical	Antiviral	1	1	4	2	0.5	2	0
Zanamivir 10mg po	EA (Each)	Pharmaceutical	Antiviral	1	0	0	0	0.5	2	0
Amantidine 100mg	EA (Each)	Pharmaceutical	Antiviral	1	0	0	0	0	2	0
Acyclovir Capsules, 200 mg	EA (Each)	Pharmaceutical	Antiviral	1	0	0	0	0	0	0
Ceftriaxone 1g Mod	EA (Each)	Pharmaceutical	IV Beta Lactam	0	0.27	0	0.54	0	0	0
Ceftriaxone  1g Sev	EA (Each)	Pharmaceutical	IV Beta Lactam	1	0	0.54	0	0.27	0.54	0.54
Levofloxacin 750mg Mod	EA (Each)	Pharmaceutical	IV Quinolone	0	0.31	0	0.61	0	0	0
Levofloxacin 750mg Sev	EA (Each)	Pharmaceutical	IV Quinolone	1	0	0.61	0	0.31	0.61	0.61
Nafcillin Sodium for Injection 1 Gm Mod	EA (Each)	Pharmaceutical	IV Nafcillin	0	0.16	0	0.64	0	0	0
Nafcillin Sodium for Injection 1 Gm Sev	EA (Each)	Pharmaceutical	IV Nafcillin	1	0	0.64	0	0.16	0.64	0.64
Vancomycin Injection 1 g eq. Mod	EA (Each)	Pharmaceutical	IV Vanco	0	0.834	0	0.834	0	0	0
Vancomycin Injection 1 g eq. Sev	EA (Each)	Pharmaceutical	IV Vanco	1	0	0.834	0	0.834	0.834	0.834

3.  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.

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