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Methodology for Analyzing Environmental Quality Indicators (EQIs)
in a Dynamic Operating Room Environment
Jennifer Wagner Ph.D., CIC Microbiologist, Infection Preventionist Prism Environmental Health and Safety, Inc. Managing Partner, OnSite-LLC
Damon G. Greeley PE, CEM, HFDP, CBCP, EDAC, CHFM President, Global Health Systems Inc. Managing Partner, OnSite-LLC
Research Team Dr. Troy Markel – Pediatric surgeon/Associate Professor- Indiana University Health Dr. Jennifer Wagner, Ph.D., CIC - Principal- Prism Environmental Damon G. Greeley -PE, CEM, HFDP, CBCP, EDAC, CHFM -Founder & Managing Partner -Global Health System Inc./ Onsite-LLC John Ostojic – Industrial Hygenist -Artec Environmental Monitoring Dr. Tom Gormley, Ph.D - Associate Professor -MTSU
Research Team and OnSite, LLC “Applying research to improve everyday healthcare”
- Independent evaluation of medical products & devices
- Technical and biological acceptance testing utilizing EQI methodologies adapted to the application
- Outbreak investigations - Surrogate services to in-house
hospital infection prevention departments
Research on the Costs and Benefits of Different Ventilation Rates in ORs
• Tested in 3 actual operating rooms
• Simulated surgical procedure
• Followed proper techniques for scrubbing and gowning
• As much like surgery as possible without patient
Energy Costs by Space Type Approximately 44,010 Operating Rooms in the United States. 33,750 are in hospitals and 10,260 are freestanding surgical centers. (Source: CDC 2004, Lodestone & Frost & Sullivan.)
Factors Relating to Patients Acquiring an Infection During Stay or Procedure per NIH
1. Aerosol and droplet transmission dynamics
2. The nature of the dust levels
3. The health and condition of individuals naso-pharyngeal mucosal linings
4. Population density
5. Ventilation rate 6. Air distribution pattern
7. Humidity and temperature
8. Number of susceptibles
9. Length of exposure
10. Number of infected people producing contaminated aerosols
11. Infectious particle settling rate
12. Lipid or non-lipid viral envelope or microorganism cell wall
13. Surrounding organic material 14. UV light or antiviral chemical exposure 15. Vitamin A & D levels 16. Microorganism resistance to antibiotic or
antiviral therapy 17. Type and degree of invasive procedure 18. Spatial considerations 19. Contact with a carrier 20. Persistence of pathogens within hosts 21. Immuno-epidemiology 22. Transmission resistance and role of host
genetic factors
Wide Range in Code and in Practice • 12 ACH allowed in Calif. with 100%
outside air
• 15 ACH prior to 2010 FGI – such as KY
• 20 ACH after 2010 FGI/ASHRAE – such as TN
• 20 - 25 ACH – common practice
• 30 - 40 ACH recommended in certain ORs*
*Source: ASHE
European Approach uses Air Changes Plus Particle and Microbiological Contamination which have Clean Room/ISO Standards NF –French, UNI-Italian, DIN –German and HTM -British
9
Developed Concept of Environmental Quality Indicators –EQIs
• Temperature
• Relative Humidity
• Air velocity at key points
• Particle counts
• Microbial contamination
• Air change or ventilation rates
• Pressure relationships
• Overall measurement of air quality
• Combines US and European healthcare requirements
• Draws from testing standards used for labs and computer chip manufacturing
Hypothesis & Air Change Rates Tested
• 5 ACH – typical setback level to save energy when not in use
• 15 ACH – 2006 Guidelines
• 20 ACH – 2010 Guidelines
• 25 ACH - commonly used in the industry and the current set point for all ORs in this study
Hypothesis: 20 ACH was cleaner than 15 and 25 ACH was cleaner than 20 ACH.
SSI rates in modern countries are similar in spite of different metrics for ventilation rates
• US 1.9%
• Europe 2.2%
• Germany 1.6%
• England 1.4%
• France 1.6 %
• Portugal 2.0%
• Developing Countries 11.8%
2.0
4.5
1.9 2.2 1.6 1.4 1.6
11.8
Portugal China United States Europe Germany England France Developing Countries
SSIs and Our Mock Surgical Procedure • Over 200,000 SSI per year in the US – NIH
• SSI 30+% of all HAI – Duke Study
• JAMA - Johns Hopkins Study 2013 for patients with an SSI compared to patients without
• Daily total charges $7493 vs $7924,
• Mean LOS 10.56 days vs 5.64 days
• 30-day readmission rate 51.94 vs 8.19 readmissions per 100 procedures
Surgical Site Infections
• SSIs are defined as infections occurring up to 30 days after surgery (1 year for implants) and affecting the incision or deep tissues at the operative site
• Owens, et al. J Hosp Inf 2008
• Surgical Site infections are prevalent and account for 14-17% of all hospital acquired infections
• Spagnolo, et al. J Prev Med and Hygiene, 2013
Surgical Site Infections
• Patients required significantly more outpatient visits, ER visits, radiology and blood tests, readmissions, and home health aide services
• Perencevich et al. Emerging Infectious Diseases, 2003
• In a single hospital system, over a two year period, SSI took up an additional 4694 bed days and accounted for over $3 million in lost revenue
• Jenks PJ, et al. J of Hosp Inf, 2014
Surgical Site Infections
• Sources of infection control in the operating room
• Structural features: Room design, surface finishes
• Ventilation
• Water-sterile versus at scrub sink
• Procedural and Behavioral Factors
• Patient and Personnel
Surgical Site Infections
• During surgical procedures, dust and microbes from textiles, skin and respiratory aerosols are released into the air
• Bacteria settling on the wound or instruments can result in surgical site infections
• Several studies have shown that fewer infections arise when (orthopedic) surgery is performed in operating rooms with ultra-clean air facilities
• Spagnolo, et al. J Prev Med and Hygiene, 2013
Planning our Mock Procedure
• In order to evaluate particles and microbes we needed several personnel and multiple instruments.
• We felt it would be unethical to expose patients to increased human and instrument traffic during their operations
• We therefore designed a mock procedure to mimic a dynamic operating room environment
• It kept things moving without review by any IRB
Mock Surgical Procedure
• Designed a 1 hour long mock procedure to mimic actual events in an OR
• Surgeons and Nurses utilized
• Sterile Gowning and Gloving
• Sterile instruments prepared by each institutions' standard practices
• Utilized steak to simulate the patient for Bovie electrocautery.
OR Ventilation Systems Overview
Site
Concentrated Primary Diffuser Array/Unidirectional/2 low returns
ASHRAE 52.2 Room
Air Filtration, Normal ACH”
Room Temp & Relative Humidity, Pressure
Pressure Control Method Notes
A Yes/Yes/Yes MERV 17 (terminal)
27
Avg. 68.5 deg. F, < 60% RH, Positive Pressure
Automatically (BMS)
Controlled Room Air Flow Offset
15 ACPH, 0.0039 neg. pressure to sterile core
B No/Yes/Yes MERV 17 (terminal)
26
68 deg. F, < 60% RH, Positive Pressure
Direct Pressure Control of Static
Pressure Set point
C No/Yes/Yes MER 14 (central)
24
68 deg. F, < 60% RH, Positive Pressure
Manually Balanced Air Flow to Static Pressure Set
point
OR A OR B
OR C
Testing Diagram – Particle & Microbial Data Points
• 9 particle sampling locations, 4 sizes - 0.3, 0.5, 1.0, and 5.0 micron
• 3 cycles of 9 points @ 2 min per point ~ 60 min
• 6 air sampling (microbial) locations, 3 in sterile field and 3 on the back table
• 8 cycles of 5:55 time per cycle ~ 60 min.
3 samples on surgical table in Sterile zone
Sterile zone
3 samples on back table outside sterile zone
Nurses station
Particle counts A-I
Stationary particle at return
Remains in sterile fieMoves around/in out
Circulating nurse
Back table RN
Surgeon Surgeon’s assistant
Second surgeon
Anesthesiologist
Scrub tech
Testing Diagram – Velocity & Temp Data
• 4 velocity & temperature recording locations, sterile field upper, sterile field lower, back table, and return grille
• Velocity & temp were recorded same as particles, every 2 minutes
• 1 to 2 video cameras
• 1 location for PAO (poly alpha olefin) injection for CFD particle modeling baseline
Velocity & temp #4 – Return Grille
Velocity & temp #2 – Surgical Table Lower
Velocity & temp #1 – Surgical Table
Upper
Velocity & temp #3 – Back Table PAO Aerosol
injection point for CFD particle baseline
Surgical Table
Particulate and Microbial Testing USP 797 & ISO Standard 14644-1
Count Time Count Time Count Time Count Time Count Time Count TimeISO Class 1 10 70.1 2 353.4ISO Class 2 100 7.1 24 35.3 10 70.1 4 176.7ISO Class 3 1000 1 237 3.5 102 6.9 35 17.7 8 88.4ISO Class 4 10000 1 2370 1 1020 1 362 1.8 83 8.5ISO Class 5 100000 1 23700 1 10200 1 3520 1 832 1 29 24ISO Class 6 1000000 1 237000 1 102000 1 35200 1 8320 1 293 2ISO Class 7 352000 1 83200 1 2930 1ISO Class 8 3520000 1 832000 1 29300 1ISO Class 9 35200000 1 8320000 1 293000 1Time based on a 1cfm (28.3 LPM) sample rate
ClassificationMaximum concentration limits (particles/M3 of air for particles equal to and greater than the considered sizes shown below.
0.1 0.2 uM 0.3 uM 0.5 uM 1.0 uM 5.0 uM
Note: ISO Classifications are a range by factors of 10.
Choosing Statistical Procedures for Numerical Benchmarking
• In most cases, the microbial and particle data did not meet, either the assumption of normality or the homogeneity of variances and therefore, the median and interquartile ranges were used to determine significance. For velocity data, the assumptions were met and means and standard deviations were used.
Two Independent Variables
Interval or Ratio Independent t-test
Dependent t-test
One-Way ANOVA
Repeated Measures ANOVA
Two -Factor ANOVA
Two-Factor ANOVA
Repeated Measures
Ordinal Mann-Whitney U Wilcoxon Kruskal-
Wallis Friedman
Nominal Chi-Square Chi-Square Chi-Square
Multiple Independent
Groups
Multiple Dependent
Groups
Factorial Designs
Independent Groups
Dependent Groups
Measurement Scale of the Dependent
Variable
One Independent VariableTwo Levels More than 2 Levels
Two Independent
Groups
Two Dependent
Groups
Source: University of Tennessee Knoxville
Particulate Data Summary Numerical Benchmarking an OR by ISO 14644-1
• ISO Classification by 0.5 µm particle size
15 ACH 20 ACH 25 ACH
9 Point Cycle 1
9 Point Cycle 2
9 Point Cycle 3
9 Point Cycle 1
9 Point Cycle 2
9 Point Cycle 3
9 Point Cycle 1
9 Point Cycle 2
9 Point Cycle 3
OR A Particles/ m3 **
5.03 21.06 10.57 2.72 25.8 2.62 3.1 21.54 4.14
ISO 8 8 8 7 8 7 7 8 8
OR B Particles/ m3 **
2.997 5.02 1.92 4.56 2.64 1.42 3.91 2.76 0.57
ISO 7 8 7 8 7 7 8 7 7
OR C Particles/ m3 **
9.91 11.90 12.83 8.35 11.52 10.1 12.87 15.32 17.23
ISO 8 8 8 8 8 8 8 8 8
** number x 105
Particulate Data Summary – OR A • Hypothesis; 20 ACH was cleaner than 15 and 25 ACH was cleaner than 20
ACH. Significant at p<0.05
15 ACH 20 ACH 20 ACH 25 ACH
Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P value Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P value
OR A 9 point grid (0.3mParticles/ m3)
599583.00 (3924632)
158954.00 (1848132)
0.06 158954.00 (1848132)
102394.00 (1683199)
0.60
9 point grid (0.5mParticles/ m3)
221065.00 (1025637)
85097.00 (656816)
0.07 85097.00 (656816)
56832.00 (604788)
0.58
9 point grid (1.0mParticles/ m3)
90597.00 (316620)
44576.00 (224004)
0.08 44576.00 (224004)
30452.00 (209974)
0.59
9 point grid (5.0mParticles/ m3)
3666.00 (2719)
2639.00 (2553)
0.17 2639.00 (2553)
2359.00 (2393)
0.27
Particulate Data Summary – OR B • Hypothesis; 20 ACH was cleaner than 15 and 25 ACH was cleaner than 20
ACH. Significant at p<0.05
15 ACH 20 ACH 20 ACH 25 ACH
Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P value Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P value
OR B 9 point grid (0.3mParticles/ m3)
238067.00 (564912)
134366.00 (403319)
0.03 134366.00 (403319)
86918.00 (227790)
0.11
9 point grid (0.5mParticles/ m3)
105440.00 (171211)
85325.00 (100494)
0.11 85325.00 (100494)
49534.00 (94949)
0.08
9 point grid (1.0mParticles/ m3)
45182.00 (54820)
45002.00 (47289)
0.26 45002.00 (47289)
26993.00 (40990)
0.07
9 point grid (5.0mParticles/ m3)
2179.00 (1473)
1840.00 (1080)
0.02 1840.00 (1080)
1293.00 (1047)
0.01
Particulate Data Summary – OR C • Hypothesis; 20 ACH was cleaner than 15 and 25 ACH was cleaner than 20
ACH. Significant at p<0.05
15 ACH 20 ACH 20 ACH 25 ACH
Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P value Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P value
OR C 9 point grid (0.3mParticles/ m3)
11812313.00 (1054936)
11149499.00 (729238)
<0.001 11149499.00 (729238)
13612763.00 (736236)
<0.001
9 point grid (0.5mParticles/ m3)
1084782.00 (292680)
912232.00 (216852)
<0.001 912232.00 (216852)
1419972.00 (270852)
<0.001
9 point grid (1.0mParticles/ m3)
100735.00 (85552)
60645.00 (65590)
0.004 60645.00 (65590)
66463.00 (92657)
0.72
9 point grid (5.0mParticles/ m3)
2979.00 (2126)
2239.00 (1633)
<0.001 2239.00 (1633)
2093.00 (2000)
0.97
Microbial Data Summary • ISO Classification by mean CFU/m3
15 ACH 20 ACH 25 ACH
Microbial Sterile Field
Microbial Back Table
Microbial Sterile Field
Microbial Back Table
Microbial Sterile Field
Microbial Back Table
OR A
Range* 1-18 24-98 1-10 16-51 1-8 10-31
ISO 8 8 8 8 7 8
OR B
Range* 28-104 16-164 14-41 10-24 7-27 7-199
ISO >8 >8 8 8 8 8
OR C
Range* 2-15 5-18 0-13 2-15 3-15 0-20
ISO 8 8 8 8 8 8
Microbial Data Summary 15 ACH 20 ACH 20 ACH 25 ACH
Median (IR)
Median (IR)
P value Median (IR)
Median (IR)
P value
OR A Back Table Microbial (CFU/m3)
39.00 (13)
27.00 (11)
0.004 27.00 (11)
22.00 (15)
0.04
Sterile Field
Microbial (CFU/m3)
7.50 (6)
3.00 (3)
0.006 3.00 (3)
3.00 (3)
0.84
OR B Back Table Microbial (CFU/m3)
34.50 (19)
16.00 (6)
<0.001 16.00 (6)
16.00 (7)
0.86
Sterile Field
Microbial (CFU/m3)
51.00 (24)
22.00 (12)
<0.001 22.00 (12)
16.00 (8)
<0.001
OR C Back Table Microbial (CFU/m3)
7.00 (5)
5.00 (4)
0.001 5.00 (4)
5.00 (5)
0.84
Sterile Field
Microbial (CFU/m3)
8.00 (6)
6.00 (4)
0.03 6.00 (4)
5.50 (5)
0.93
Microbial Data Summary
ISO 8
ISO 8 ISO 7
Sterile Field Microbial Comparison OR A Microbial Load CFU/m3 & P-Value
15 v 20 ACH P Value =
0.006
CFU per m3
Sterile Field Comparison
Site - ACH Range CFU
per m3
Mean CFU
per m3
OR A – 15 ACH 1-18 7.5
OR A – 20 ACH 1-10 3
OR A – 25 ACH 1-8 3
OR B – 15 ACH 28-104 51
OR B – 20 ACH 14-41 22
OR B – 25 ACH 7-27 16
OR C – 15 ACH 2-15 8
OR C – 20 ACH 0-13 6
OR C – 25 ACH 3-15 5.5
20 v 25 ACH P Value =
0.84
ISO >8
ISO 8 ISO 8
15 ACH 20 ACH 25 ACH
Sterile Field Microbial Comparison OR B Microbial Load CFU/m3 & P-Value
15 v 20 ACH P Value =
<0.001
20 v 25 ACH P Value = <0.001
ISO 8
ISO 8 ISO 8
Sterile Field Microbial Comparison OR C Microbial Load CFU/m3 & P-Value
15 v 20 ACH P Value = 0.03
20 v 25 ACH P Value = 0.93
Microbial & Velocity Data Summary 15 ACH 20 ACH 25 ACH BT SF BT SF BT SF Median
(IR)/ *Mean (STD)
Median (IR)/
*Mean (STD)
P val Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P val Median (IR)/
*Mean (STD)
Median (IR)/
*Mean (STD)
P val
OR A Microbial (CFU/m3)
39.00 (13)
7.50 (6)
<.001 27.00 (11)
3.00 (3)
<.001 22.00 (15)
3.00 (3)
<.001
Velocity (feet/min)
12.00 (7)
28.00 (28)
<.001 13.00 (8)
32.00 (10)
<.001 14.56* (8.336)
40.59* (13.580)
<.001
OR B Microbial (CFU/m3)
34.50 (19)
51.00 (24)
.004 16.00 (6)
22.00 (12)
.002 16.00 (7)
16.00 (8)
.33
Velocity (feet/min)
18.41* (6.755)
27.52* (6.351)
<.001 13.00 (12)
31.00 (6)
<.001 16.41* (11.050)
39.67* (12.746)
<.001
OR C Microbial (CFU/m3)
7.00 (5)
8.00 (6)
.94 5.00 (4)
6.00 (4)
.16 5.00 (5)
5.50 (5)
.41
Velocity (feet/min)
8.00 (7)
9.00 (12)
0.19 9.52* (5.345)
13.63* (7.318)
0.02 16.56* (9.982)
16.85* (10.014)
0.91
Site - ACH
BT Range CFU per m3
(ISO)
SF Range CFU per m3
(ISO)
0.5µ Particles/
m3
(ISO)
OR A – 5 ACH 44-750* (>8)
76-747* (>8)
145887 (7)
OR A – 15 ACH 24-98 (8)
1-18 (7)
503269 (8)
OR B – 5 ACH 76-99* (8)
16-164* (8)
190492 (7)
OR B – 15 ACH 77-122 (>8)
28-104 (8)
299729 (7)
OR C – 5 ACH 38-69* (8)
4-18* (8)
310697 (7)
OR B – 15 ACH 39-62 (8)
2-15 (8)
991457 (8)
Microbial & Particulate Loading at 5 ACH vs. 15 ACH
* 6 data points in lieu of 24
• Recorded particle and microbial data at setback air change rate
• Did not perform mock procedure during setback
• Compared microbial for SF and BT
• Compared particulate counts for last 9 points during setback to first 9 points of mock procedure (non invasive period)
Velocity Contour at Along the Surgery Table OR C
47
Ft/min ≥
• ACH 25, Supply Temperature: 65 ºF, Return Temperature: 66 ºF
48
Lower Supply Velocity (ft/min) Back Table Velocity (ft/min)
CFD Results
Experiment Results
+/- % Variance
CFD Results
Experiment Results
+/- % Variance
ACH 15
11.19 12.07 7.9 8.7 8.5 2.3
ACH 20
8.01 13.38 67 17.5 9.42 46
ACH 25
16.42 16.62 1.2 18.67 16.88 9.6
CFD & Experiment Comparison OR C Only
Cost Factors for 5 OR ACH/Year Reduction Site A, B, and C
• 20 ACH ~ 2,000 CFM • Electrical Energy - Fans, Pumps, Cooling • Thermal Energy – Preheat and reheat • Steam - Humidification • Utilization Hours:
• Cooling • Heating • Economizer • Dehumidification/Sub Cooling
9%
14% 6%
21%
50%
Cooling/Subcooling Heating Humificiation Fans
OR A City Thermal Climate Zone 5
10,068 - 5.0 ACH
$
OR B Campus Thermal Climate Zone 4
$
OR C Self Generated Thermal Climate Zone 4
$ 7,052 5,218
Operating Cost Savings Summary
Notes: 1. Formulas were validated by third party for custom utility incentive and
national healthcare engineering firm 2. Does not include water costs for humidification
- 5.0 ACH - 5.0 ACH
Conclusions • There were differences between the cleanliness of the environment at the
sterile field versus the back table.
• Level of cleanliness was dependent upon air filtering and air distribution
• USP 797 ISO 14644-1 Classification may not be specific enough to benchmark higher environmental quality indicating (EQI) OR environments
• Data ‘points’ to greater ACH rates did not consistently and significantly produce a cleaner environment (statistically significant less particles), in some cases it was even less clean
Moving Forward…. • Would further testing of the relationship between the sterile field and back
table be beneficial?
• What is an acceptable level of cleanliness? Are EQIs a better benchmark than ACH?
• Is room air distribution and velocities at certain locations more important than the number of ACH?
• Additional research opportunities?