kr Hospital Surge Model Version 1.3: Description
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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 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.

The flu scenario incorporates hospital resource utilization and patient outcomes similar to those documented during the 2009 influenza A (H1N1) pandemic.

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 (ED), patients will be moved to the floor for medical care.
  2. Severe: After arriving at the ED, patients will be moved to the intensive care unit (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 ED, patients will be moved to the floor for medical care 85%
Severe: After arriving at the ED, 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) group3 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 (LOS) 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

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 Lambdaa Moderate Severe
ED ICU Floor ED ICU Floor
Adult med/surg bed EA (Each) Capacity Adult Med/Surg 1 0.167 0.000 0.667 0.167 0.000 0.667
  Adult ICU bed EA (Each) Capacity Adult ICU 1 0.000 0.667 0.000 0.000 0.667 0.000
Pediatric med/surg bed EA (Each) Capacity Pediatric Med/Surg 1 0.083 0.000 0.333 0.083 0.000 0.333
  Pediatric ICU bed EA (Each) Capacity Pediatric ICU 1 0.000 0.333 0.000 0.000 0.333 0.000
Burn bed EA (Each) Capacity Burn 1 0.000 0.000 0.000 0.000 0.000 0.000
Operating room EA (Each) Capacity OR 0 0.000 0.000 0.000 0.000 0.000 0.000
Airborne isolation room EA (Each) Capacity Isolation 0.7 0.000 0.000 0.000 0.000 0.000 0.000
Intensivists (CCM) FTE Staff CCM 0.9 0.021 0.042 0.000 0.042 0.042 0.000
Critical care nurses (CCN) FTE Staff CCN 1 0.000 0.333 0.000 0.125 0.333 0.000
Surgeons FTE Staff Surgeon 0 0.000 0.004 0.000 0.000 0.004 0.000
Non-intensivists (MD) FTE Staff MD 1 0.042 0.000 0.021 0.042 0.000 0.021
Non-critical care nurses (RN/LPN) FTE Staff RN 1 0.083 0.000 0.125 0.042 0.000 0.125
Pharmacists (PharmD/RPh) FTE Staff Pharmacist 0.7 0.000 0.021 0.000 0.021 0.021 0.000
Respiratory Therapists (RT) FTE Staff RT 1 0.000 0.042 0.000 0.021 0.042 0.000
Mortuary FTE Staff Mortuary 0 0.000 0.029 0.000 0.000 0.029 0.000
Adult mechanical ventilator EA (Each) Capacity Ventilator 0.92 0.000 0.480 0.000 0.080 0.480 0.000
Pediatric mechanical ventilator EA (Each) Capacity Ventilator 0.92 0.000 0.240 0.000 0.040 0.240 0.000
Adult ventilator circuit EA (Each) Equipment Ventilator Kit 0.92 0.000 0.312 0.000 0.416 0.312 0.000
Pediatric ventilator circuit EA (Each) Equipment Ventilator Kit 0.92 0.000 0.156 0.000 0.208 0.156 0.000
Closed circuit suction catheter 14F EA (Each) Equipment Ventilator Kit 0.92 0.000 0.312 0.000 0.416 0.312 0.000
Closed circuit suction catheter 8-12F EA (Each) Equipment Ventilator Kit 0.92 0.000 0.156 0.000 0.208 0.156 0.000
Humidification and Filtration Unit (HMEF) EA (Each) Equipment Ventilator Kit 0.92 0.000 0.328 0.000 0.437 0.328 0.000
Endotracheal tube, 6.5-8mm ID EA (Each) Equipment Intubation 0.92 0.000 0.206 0.000 0.416 0.206 0.000
Endotracheal tube, 3-6mm ID EA (Each) Equipment Intubation 0.92 0.000 0.103 0.000 0.208 0.103 0.000
Laryngoscope blades, adult EA (Each) Equipment Intubation 0.92 0.000 0.125 0.000 0.416 0.125 0.000
Laryngoscope blades, pediatric EA (Each) Equipment Intubation 0.92 0.000 0.062 0.000 0.208 0.062 0.000
Laryngoscope handles EA (Each) Equipment Intubation 0.92 0.000 0.187 0.000 0.624 0.187 0.000
Endotracheal stylette EA (Each) Equipment Intubation 0.92 0.000 0.187 0.000 0.624 0.187 0.000
Resuscitation bag, adult EA (Each) Equipment Ventilator Kit 0.92 0.000 0.125 0.000 0.416 0.125 0.000
Resuscitation bag, pediatric EA (Each) Equipment Ventilator Kit 0.92 0.000 0.062 0.000 0.208 0.062 0.000
Ventilator Oxygen (O2) Liters Liquid O2 Supplies Oxygen 0.92 0.000 4.535 0.000 1.134 4.535 0.000
NC Oxygen (O2) Liters Liquid O2 Supplies Oxygen 0.92 1.675 1.876 6.700 0.000 1.876 6.700
Pulse oximeter EA (Each) Equipment O2 Monitoring 0.92 0.007 1.000 0.007 0.250 1.000 0.007
Finger pulse oximeter strip EA (Each) Equipment O2 Monitoring 0.92 1.000 0.650 0.650 1.000 0.650 0.650
End tidal CO2 detector, adult EA (Each) Equipment O2 Monitoring 0 0.000 0.624 0.000 0.416 0.208 0.000
End tidal CO2 detector, pediatric EA (Each) Equipment O2 Monitoring 0 0.000 0.312 0.000 0.208 0.010 0.000
Oxygen tubing (high flow) EA (Each) Equipment O2 Monitoring 0.92 0.000 0.182 0.000 0.673 0.120 0.000
Oxygen tubing (low flow) EA (Each) Equipment O2 Monitoring 0.92 0.325 0.000 0.650 0.000 0.000 0.650
Nebulizer sets EA (Each) Equipment O2 Monitoring 0.92 1.300 0.650 0.429 1.300 0.650 0.429
Nasal cannulas EA (Each) Equipment O2 Monitoring 0.92 1.300 0.182 0.429 0.000 0.000 0.429
Oxygen mask, adult EA (Each) Equipment O2 Monitoring 0.92 0.000 0.286 0.000 0.867 0.286 0.000
Oxygen mask, pediatric EA (Each) Equipment O2 Monitoring 0.92 0.000 0.143 0.000 0.433 0.143 0.000
Standard radiograph EA (Each) Radiology CXR 0.5 0.021 0.021 0.000 0.021 0.021 0.000
Computed tomography Machine Time (24h) Radiology CT 0 0.000 0.000 0.000 0.021 0.000 0.000
FAST Machine Time (24h) Radiology FAST 0 0.000 0.000 0.000 0.000 0.000 0.000
Radiology supplies single study EA (Each) Supplies Rad Supplies 0.9 1.300 1.300 0.000 2.600 1.300 0.000
Chemistry lab machine Machine Time (24h) Laboratory Chem 0.9 0.021 0.021 0.010 0.042 0.021 0.010
Chemistry lab supplies advanced panel EA (Each) Supplies Chem Supplies 0.9 1.300 1.300 0.650 2.600 1.300 0.650
Hematology lab machines Machine Time (24h) Laboratory Heme 0.9 0.021 0.021 0.010 0.042 0.021 0.010
Hematology lab supplies advanced panel EA (Each) Supplies Heme Supplies 0.9 1.300 1.300 0.650 2.600 1.300 0.650
Micro/Virology lab machines Machine Time (24h) Laboratory Micro 0.9 0.021 0.021 0.000 0.042 0.021 0.000
Micro lab supplies advanced diagnostic EA (Each) Supplies Micro Supplies 0 1.300 1.300 0.000 2.600 1.300 0.000
Chest tube drainage system EA (Each) Supplies Chest Tube 0.8 0.000 0.034 0.000 0.169 0.034 0.000
NG tubes sizes 6F-16F EA (Each) Supplies NG Tube 0.8 0.000 0.486 0.000 0.649 0.486 0.000
Enteral feeding tube EA (Each) Supplies Feeding Tube 1 0.000 0.468 0.000 0.000 0.468 0.000
Temperature monitor, adult Machine Time (24h) Supplies TempA 0.9 0.005 0.028 0.009 0.005 0.028 0.009
Temperature monitor, pediatric Machine Time (24h) Supplies TempP 0.9 0.002 0.014 0.005 0.002 0.014 0.005
Temperature monitor cover EA (Each) Supplies TempCov 1 2.600 7.800 5.200 2.600 7.800 5.200
Urine output, Foley catheter 8F-12F EA (Each) Supplies Foley 1 0.000 0.156 0.000 0.624 0.156 0.000
Urine output, monitor bag EA (Each) Supplies Urinary Bag 0 0.000 0.390 0.000 0.624 0.390 0.000
BP cuffs, adult Machine Time (24h) Equipment BPCuffA 0.9 0.014 0.056 0.014 0.014 0.056 0.014
BP cuffs, pediatric Machine Time (24h) Equipment BPCuffP 0.9 0.007 0.028 0.007 0.007 0.028 0.007
N95/surgical masks EA (Each) Supplies Mask 1 0.390 2.600 2.600 3.900 2.600 2.600
Face shields EA (Each) Supplies Shield 1 0.800 0.800 0.100 0.800 0.800 0.100
Latex, non-sterile gloves EA (Each) Supplies Glove, latex 1 3.250 3.250 3.250 3.250 3.250 3.250
Latex-free, non-sterile gloves EA (Each) Supplies Glove, latex-free 1 3.250 3.250 3.250 3.250 3.250 3.250
Latex-free, sterile gloves EA (Each) Supplies Glove, sterile 0.8 2.600 2.600 0.000 2.600 2.600 0.000
Gown, standard EA (Each) Supplies Gown 1 1.300 1.300 0.000 1.300 1.300 0.000
Gown, fluid resistant EA (Each) Supplies GownFluidR 0.7 0.975 0.975 0.000 0.975 0.975 0.000
Alcohol hand sanitizer (L) Liters Supplies Sanitizer 1 0.100 0.1000.1000.1000.1000.100
Bleach-based cleaner (L) Liters Supplies Sanitizer 1 0.100 0.100 0.100 0.100 0.100 0.100
Hazmat red bag liner EA (Each) Supplies Bag 1 1.000 2.000 0.250 1.000 2.000 0.250
Intravenous (IV) catheters, 18g with protectocath guard EA (Each) IV IVs 0.92 0.390 0.130 0.130 0.390 0.130 0.130
IV catheters, 20g with protectocath guard EA (Each) IV IVs 0.92 0.390 0.130 0.130 0.390 0.130 0.130
IV catheters, 22g with protectocath guard EA (Each) IV IVs 0.92 0.260 0.087 0.087 0.260 0.087 0.087
IV catheters, 24g with protectocath guard EA (Each) IV IVs 0.92 0.260 0.087 0.087 0.260 0.087 0.087
IV start kits EA (Each) IV IVs 0.92 1.300 0.433 0.433 1.300 0.433 0.433
IV tubing w/Buretrol drip set for peds EA (Each) IV IV Admin Set 0.92 0.433 0.144 0.144 0.433 0.144 0.144
IV tubing w/standard macrodrip for adults EA (Each) IV IV Admin Set 0.92 0.867 0.289 0.289 0.867 0.289 0.289
Sodium chloride flush 0.9% 3ml EA (Each) IV IV Flush 0.92 2.600 7.800 7.800 2.600 7.800 7.800
Povidone iodine 10% swab sticks triples EA (Each) IV IV site prep 0.92 1.300 0.433 0.433 1.300 0.433 0.433
IV site transparent dressing EA (Each) IV IV dressing 0.92 1.300 0.433 0.433 1.300 0.433 0.433
Gauze pad 4x4 EA (Each) IV IV dressing 0.92 5.200 5.200 5.200 5.200 5.200 5.200
Heparin lock flush kit, 100 units ml EA (Each) IV Heplock Kit 1 2.600 7.800 7.800 2.600 7.800 7.800
Syringes, 10cc EA (Each) IV IV Admin Set 0.92 1.430 1.430 1.430 1.430 1.430 1.430
Syringes, 3cc EA (Each) IV IV Admin Set 0.92 5.200 5.200 5.200 5.200 5.200 5.200
Needles, butterfly, 23g EA (Each) IV IVs 0.92 0.043 0.043 0.043 0.043 0.043 0.043
Needles, butterfly, 25g EA (Each) IV IVs 0.92 0.043 0.043 0.043 0.043 0.043 0.043
Needles, sterile 18g EA (Each) IV IVs 0.92 2.600 2.600 2.600 2.600 2.600 2.600
Needles, sterile 21g EA (Each) IV IVs 0.92 2.600 2.600 2.600 2.600 2.600 2.600
Needles, sterile 25g EA (Each) IV IVs 0.92 0.043 0.043 0.043 0.043 0.043 0.043
Catheter interosseous EA (Each) IV IO 0 0.043 0.022 0.000 0.043 0.022 0.000
Sodium chloride 0.9% solution IV, 1000 ml EA (Each) IVF NAe 0.92 0.553 2.211 1.690 0.553 2.211 1.690
Dextrose 5% sodium chloride 0.45% inj. 1000 ml EA (Each) IVF D51/2NS 0.92 0.368 1.474 1.127 0.368 1.474 1.127
D5W or sterile water piggybacks of 50-250ml size EA (Each) IVF D5W 1 2.600 2.600 1.300 2.600 2.600 1.300
Saline for injection, sterile 10 ml EA (Each) IVF Saline 1 2.600 2.600 1.300 2.600 2.600 1.300
IV pole EA (Each) IVF IV set 1 1.300 1.300 1.300 1.300 1.300 1.300
Matched RBC Units Blood Product RBC 0 0.000 0.100 0.000 0.000 0.100 0.000
Platelets Pack Blood Product PLT 0 0.000 0.100 0.000 0.000 0.100 0.000
FFP Units Blood Product FFP 0.6 0.000 0.250 0.000 0.000 0.250 0.000
Alcohol pads EA (Each) Supplies Alcohol 0.92 1.950 7.800 3.900 7.800 7.800 3.900
Band-aids EA (Each) Supplies BandAid 0.92 0.325 1.300 1.300 1.300 1.300 1.300
Basins, bath EA (Each) Supplies Basin 0.92 1.300 1.300 1.300 1.300 1.300 1.300
Bathing supply, prepackaged EA (Each) Supplies Bathing 0.92 1.300 1.300 1.300 1.300 1.300 1.300
Bedpans, regular EA (Each) Supplies Bedpan 0.92 1.300 1.300 1.300 1.300 1.300 1.300
Blankets EA (Each) Supplies Blanket 0.92 2.600 2.600 2.600 2.600 2.600 2.600
Diapers, adult EA (Each) Supplies DiaperA 0.92 0.043 0.173 0.173 0.043 0.173 0.173
Diapers, infant EA (Each) Supplies DiaperI 0.92 0.087 0.346 0.346 0.087 0.346 0.346
Diapers, pediatric EA (Each) Supplies DiaperP 0.92 0.081 0.325 0.325 0.081 0.325 0.325
Bed linen EA (Each) Supplies Linen 1 1.300 1.300 1.300 1.300 1.300 1.300
Patient gown EA (Each) Supplies PTGown 1 1.300 1.300 1.300 1.300 1.300 1.300
Oseltamivir 75mg po dose EA (Each) Pharmaceutical Antiviral 0.7 1.000 2.000 2.000 0.500 1.0001.000
Zanamivir 10mg po dose EA (Each) Pharmaceutical Antiviral 0.7 0.000 0.000 0.000 0.500 1.0001.000
Rimantidine 100mg po dose EA (Each) Pharmaceutical Antiviral 0.7 0.000 0.000 0.000 0.500 1.0001.000
Ceftriaxone 1g IV dose EA (Each) Pharmaceutical IV Beta Lactam 0.92 0.270 0.540 0.540 0.270 0.540 0.540
Levofloxacin 750mg IV dose EA (Each) Pharmaceutical IV Quinolone 0.92 0.310 0.610 0.610 0.310 0.610 0.610
Nafcillin sodium 1g IV dose EA (Each) Pharmaceutical IV Nafcillin 0.92 0.160 0.640 0.640 0.160 0.640 0.640
Vancomycin 1g IV dose EA (Each) Pharmaceutical IV Vanco 0.92 0.834 0.834 0.834 0.834 0.834 0.834
Succinylcholine chloride (mg) mg Pharmaceutical Intubation 0 0.000 33.341 0.000 22.227 11.114 0.000
Rocuronium (mg) mg Pharmaceutical Intubation 0 0.000 23.026 0.000 15.351 7.675 0.000
Fentanyl citrate (mcg) mcg Pharmaceutical Intubation 0 0.000 46.053 0.000 30.702 15.351 0.000
Propofol (mg) mg Pharmaceutical Intubation 0 0.000 52.296 0.000 34.864 17.432 0.000
Midazolam (mg) mg Pharmaceutical Intubation 0 0.000 1.104 0.000 0.736 0.368 0.000
LMW heparin, inj. EA (Each) Pharmaceutical ProphylaxisDVT 1 0.000 2.000 2.000 0.000 2.000 2.000
Aerosol spacer, pediatric EA (Each) Pharmaceutical Bronchodilator 0 0.433 0.433 0.433 0.433 0.433 0.433
Albuterol (mg) EA (Each) Pharmaceutical Bronchodilator 0 0.148 5.938 0.594 0.990 5.938 3.960
Ipratropium bromide, inh. (mg) EA (Each) Pharmaceutical Bronchodilator 0.9 0.021 0.828 0.083 0.138 0.828 0.552
Antipyretic pediatric (dose) EA (Each) Pharmaceutical Antipyretic 0 0.333 1.332 1.332 0.333 1.332 1.332
Antipyretic adult (tab) EA (Each) Pharmaceutical Antipyretic 0 0.667 2.668 2.668 0.667 2.668 2.668
GI acid blocker EA (Each) Pharmaceutical ProphylaxisGI 0.9 0.000 2.000 2.000 0.000 2.000 2.000
Methylprednisolone (mg) EA (Each) Pharmaceutical Steroid 0.9 0.000 18.000 0.000 0.000 18.000 0.000

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.

3.7 References

1. Germann TC, Kadau K, Longini IM Jr, Macken CA. Mitigation strategies for pandemic influenza in the United States. Proc Natl Acad Sci U S A 2006;103(15):5935-5940.

2. Healthcare Cost and Utilization Project. Rockville, MD: Agency for Healthcare Research and Quality; 2010. Available at http://hcupnet.ahrq.gov. Accessed July 27, 2010.

3. Longini IM Jr, Halloran ME, Nizam A, Yang Y. Containing pandemic influenza with antiviral agents. Am J Epidemiol 2004;159(7):623-33.

4. National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome (ARDS) Clinical Trials Network, Wiedemann HP, Wheeler AP, et al. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med 2006;354(24):2564-75.

5. Office of Emergency Medical Services. Emergency Medical Services Pre-Hospital Treatment Protocols. Official Version 6.04. Boston: Massachusetts Department of Public Health; 2006.

6. Rubinson L, Nuzzo JB, Talmor DS, O'Toole T, Kramer BR, Inglesby TV. Augmentation of hospital critical care capacity after bioterrorist attacks or epidemics: recommendations of the Working Group on Emergency Mass Critical Care. Crit Care Med 2005;33(10):2393-403.


3. 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. For more information, go to: http://www.nigms.nih.gov/Initiatives/MIDAS/


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