- Email: [email protected]
Design of dental surgeries in relation to instrument decontamination
Journal of Hospital Infection 76 (2010) 340e344
Available online at www.sciencedirect.com
Journal of Hospital Infection journal homepage: www.elsevierhealth.com/journals/jhin
Design of dental surgeries in relation to instrument decontamination A.J. Smith a, *, D.E.A. Lockhart a, E. McDonald b, S. Creanor c, D. Hurrell d, J. Bagg a a
Infection & Immunity Research Group, Glasgow Dental Hospital and School, Faculty of Medicine, University of Glasgow, Glasgow, UK Renfrew Dental Centre, Glasgow, UK c Centre for Environmental & Health Statistics, University of Plymouth, Plymouth, UK d HealthCare Science Limited, Hitchin, Hertfordshire, UK b
a r t i c l e i n f o
s u m m a r y
Article history: Received 12 December 2009 Accepted 2 June 2010 Available online 2 October 2010
Recent guidelines advise that the decontamination of dental instruments should be undertaken outwith the treatment area. The aim of this study was to determine the physical area of rooms in dental surgeries that decontaminate instruments within and outwith the treatment area respectively, and other factors relating to practice layout and ventilation. Data were collected by interview and observation of dental healthcare workers in dental practice in Scotland, UK. Room layouts were recorded and measured at floor, benchtop and above benchtop heights. Thirteen surgeries with instrument decontamination processes occurring in the treatment area and seven surgeries with instrument decontamination outwith the treatment area were selected at random for detailed analysis of room dimensions. Of the 179 dental surgeries surveyed, 55% were located in converted residential premises and most practitioners (91%) did not share premises with other healthcare providers. The median number of rooms in the practices was 8 (range: 2e21) and the median number of surgeries present was 3 (range: 1e6). Regardless of whether instrument decontamination facilities were housed within the treatment area or not, the average treatment area room size for both was 15.8 m2 (range: 7.3e23.9) (P ¼ 0.862), with 20% of the room area available as work surfaces. The median size of the seven instrument decontamination rooms (local decontamination units) was 7.6 m2 (range: 2.9e16.0), with, on average, 63% of the room used for work surfaces. This survey suggests that the historical location of dental surgeries in converted residential properties places many restrictions on appropriate design for healthcare premises. Ó 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Infection prevention Local decontamination unit Surgery design
Introduction Considering the large amounts of time spent by dental team members in dental surgeries and the significant financial investment incurred in their establishment, there have been relatively few in-depth studies investigating the combined influences of ergonomics, economics and infection control elements of dental practice design. One of the earliest papers to describe dental practice design in relation to productivity, published in the 1960s, highlighted the division of a practice into reception, administration and clinical areas.1 In terms of infection control, the author suggested a centralised ‘make-ready’ area for instrument * Corresponding author. Address: Infection Research Group, Level 9, Glasgow Dental Hospital & School, 378 Sauchiehall Street, Glasgow, UK. Tel.: þ44 (0)141 211 9741; fax: þ44 (0)141 353 1593. E-mail address: [email protected] (A.J. Smith).
decontamination, outwith the patient treatment area and shared with dental laboratory facilities. The room size of the instrument decontamination area was recommended to be approximately ‘5 feet (1.5 m) of counter space’ although no rationale was provided for this space determination.1 Previous workers have described construction of purpose-built surgeries, converted residential properties, sterilisation areas and equipment design, but there has been little discussion relating to the physical dimensions of the areas involved, infection control or reprocessing of dental instruments.2e7 Later workers described the use of a zone system to reduce cross-infection risks and a ‘centralised’ sterilisation area within the practice, but these papers also lack details on issues such as ideal room requirements, ventilation, segregation of clean and dirty reprocessing areas and throughput capacity calculations needed to estimate decontamination equipment requirements.8,9 The issues involved in dental surgery design to overcome infection control issues have been summarised as challenging in the UK,
0195-6701/$ e see front matter Ó 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2010.06.002
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
due to the nature of the work (aerosol-generating procedures), the legacy of the National Health Service (NHS) remuneration system resulting in high patient throughput, surgery and equipment design and working patterns (multiple processes undertaken in limited space).8,9 The last decade has seen increased interest in the relationship between the built environment and healthcare-associated infections (HCAIs).10 The importance of adequately designed premises, in both the acute and primary care sectors, has been identified as a potential factor in reducing the risk of HCAI although this has been challenged by others.11e13 Within general dental practice, the evidence for the impact of surgery design on infection control is less clear-cut, although issues such as mixing up of clean and used instruments and sharps injuries have been highlighted.9 Dental surgery, with its widespread use of powered tools, provides an ideal aerosol-generating opportunity. There are a number of well-described studies demonstrating the widespread dispersal of oropharyngeal secretions within the dental practice environment and subsequent surface contamination by blood and micro-organisms such as meticillinresistant Staphylococcus aureus.14e18 It is difficult, however, to produce recorded evidence linking the dental surgery environment to cross-infection, although there are reported instances of such episodes in primary care facilities.18e23 The difficulty in providing such evidence may be related to the absence of surveillance data on HCAI associated with dental practice, the subclinical or latent nature of symptoms following treatment as well as other potential confounding variables. Application of basic infection prevention principles, interpretation of in vitro data and good clinical practice, however, dictate that the control of aerosol generation, ease of environmental surface cleaning, segregation of the processing of clean and dirty devices and segregation of instrument decontamination from treatment areas, should be clear priorities. The aim of this study is to report on elements of dental practice design features relevant to instrument decontamination from an observational survey of 179 UK dental surgeries and to describe, in more detail, physical dimensions of surgeries from a number of selected practices, both with and without dedicated instrument decontamination rooms (local decontamination units). Methods Survey methodology This has previously been reported in detail.24 In brief, the study population comprised all general dental practitioners in Scotland with a NHS list number (N ¼ 837). This list was the basis for randomly selecting practitioners to survey. A two-stage proportional stratified random sampling method was used to identify which surgeries were to be surveyed. First, practices were randomly selected in proportion to the distribution of practices within each of the health boards. Then, if there were more than one dentist within a selected practice, simple random sampling was used to identify a single dentist within the selected practice to be approached. The surgery that the dentist worked from and its associated decontamination facilities were the subject of the survey. Data were available from 179 surgeries. Data collection Each surgery was surveyed by a team of two, namely an infection control/decontamination expert and an experienced dental practitioner. The survey team interviewed the dental practitioner and dental nurse, reviewed documentation relevant to the survey and recorded the physical layout of the premises. The decontamination processes, policies and procedures available to the dental
341
surgery staff were viewed directly by a member of the survey team. All relevant information was recorded on to data collection forms prepared for automated reading.24 The form developed for collection of information on the physical layout of the dental surgery was presented as a grid format. For any one room, three grids were completed to scale: one at floor level, one at benchtop level and one detailing ‘above benchtop’ (Figure 1). The key measurements, for example the length and breadth of the room, and the positions and sizes of cupboards and work surfaces were marked clearly on the grids, along with the position of decontamination items such as the sinks and autoclaves. If the decontamination equipment used were located in another surgery or another room, then the layout of that room was also recorded on a second form. Measurements were recorded using a laser measurement device (Stanley tools) or tape measure. The survey visits ran from January 2003 until the end of March 2004. Data analysis Data relating to location of practices, number of rooms, surgeries and ventilation facilities are reported from the 179 surgeries visited. Further data on surgery and instrument decontamination room layouts are reported for 20 surgeries, selected at random from those surveyed; this included 13 surgeries for which instrument decontamination was undertaken within the surgery and seven surgeries for which these processes were undertaken outside the surgery. The room in which instrument decontamination was undertaken in these seven surgeries was also surveyed. The physical attributes of the dental surgeries decontaminating within/outwith the surgery were compared using the ManneWhitney test and corresponding 95% confidence intervals for the difference, using the HodgeseLehmann method. Exact P-values and confidence intervals were calculated given the small sample sizes (StatXact 8.0, Cytel Inc., 2007). Results Location of practices Results from the survey demonstrated that most dental practices (55%) were in converted residential practices, followed by converted commercial premises (29%), usually shop units, whereas 12% were purpose-built. Most practices (91%) did not share premises with other healthcare providers, such as general medical practitioners, pharmacists or podiatrists. Most practices were owned by a single principal (68%). Facilities within dental practices Within the dental practices surveyed, the median number of rooms present in the practice was 8 (range: 2e21) and the median number of dental surgeries within the practices was 3 (range: 1e6). Instrument decontamination areas In 38% of practices there was a dedicated area for decontamination of dental instruments that was physically separated from other work areas. This dedicated area was accessed via a separate entrance in 30% of practices. In 36% of practices the dedicated decontamination area was mechanically ventilated. In areas where instrument decontamination took place, the area was essentially easy to clean in 85% of practices, with 56% having smooth and continuous walls and 86% having smooth floors that were washable with a non-slip finish. However, only 24% had coved junctions between the floors and walls.
342
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
A
B
C
0
D
E
F
H
G
I
J
K
L
D+C D+C
M N D
O
P Key
D
1
Door BT
2
C
4
C
5
O
D
3.1m
3
DESK
6 7 8
Window Cupboards
C
Drawer units
D
Cupboard and drawers
C&D
Dental chair
CHAIR
Stool Sterilized instr storage
D
9
D+C
10 11
D+C
D
Sharp bin on floor
12
SIS
Ultrasonic cleaner
UC
WD
WD
Sterilizer
ST
Additions Bracket table
13 46438
Floor level
BT
4.9 m
14
Please note that each square on this grid represents 300mm (approx 1 foot)
15
Serial number 29 04 37
AD3/29/04 Layout of relevant rooms© University of Glasgow 2002
Figure 1. Example of data collection form used to record physical layout of dental surgery environment at floor level.
Ventilation In terms of mechanical ventilation, 18% of surgeries had ventilation for the patient treatment waiting area, 19% for the patient treatment area and 19% for the instrument decontamination area. Extract ventilation over the manual instrument washing sink, to minimise aerosol dispersion, was present in 4% of surgeries. In 25% of surgeries a benchtop fan was used to provide ventilation in areas where decontamination was occurring. Surgery and decontamination room dimensions The median area (physical room size) of surgeries that undertook instrument decontamination within the surgery was 15.8 m2 (range: 7.3e23.9), with the same median room area of surgeries that undertook instrument decontamination outwith the surgery (15.8 m2; range: 9.7e19.8). The seven dedicated rooms in which instrument decontamination took place (local decontamination units) had a median area of 7.6 m2. There was a wide range in size of
the dedicated decontamination rooms, with the smallest being 2.9 m2 and the largest 16.0 m2 (Table I). The work surface area is also summarised in Table I. The median physical area comprising work surfaces for surgeries decontaminating instruments within the surgery was 2.9 m2 compared with 3.4 m2 in surgeries decontaminating instruments outwith the surgery. For both scenarios the work surface took up, on average, 20% of the room area. In the dedicated rooms used to decontaminate instruments, the median work surface area was 4.8 m2, representing, on average, 63% of the room area. Other activities associated with these areas included beverage preparation, radiograph processing, preparation of filling materials and housing of air compressors. No statistically significant differences were detected in any of the physical attributes between surgeries decontaminating instruments within or outwith the surgery. Discussion There have been a few studies investigating the physical space requirements for the set-up of instrument decontamination
Table I Summary of physical attributes of dental surgeries and instrument decontamination rooms
Room area (m2) 2
Work surface area (m ) % of room covered by work surfaces
Decontamination within surgery (N ¼ 13)
Decontamination outwith surgery (N ¼ 7)
P-valuea
95% CI for differenceb
Decontamination room (N ¼ 7)
15.8 (7.3, 23.9) 2.9 (1.8, 6.2) 20.4 (10.7, 27.2)
15.8 (9.7, 19.8) 3.4 (1.4, 4.7) 21.0 (11.6, 30.9)
0.862
(3.4 to 4.1)
0.892
(1.2 to 0.9)
0.924
(5.2 to 5.8)
7.6 (2.9, 16.0) 4.8 (1.0, 10.2) 63.2 (34.5, 71.1)
CI, confidence interval. a Exact P-value from ManneWhitney test comparing decontamination within surgery versus decontamination outwith surgery. b Exact 95% confidence interval (HodgeseLehmann method) for difference decontamination within surgery minus decontamination outwith surgery.
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
facilities in dental practice.25,26 It has been suggested that the linear space requirements for a decontamination facility would measure approximately 2.4 0.6 m, although the author does stress that size of the sterilisation facility would also be determined by the size and number of steriliser units and no method for the calculation of throughout capacity, treatment activity and number of sterilisers was given.26 Interestingly, noise from the instrument cleaning and sterilising equipment was quoted as a major determining factor for removal of these items out of the treatment area.26 In addition, until relatively recently, guidelines from professional societies have outlined general principles, for example, ‘where possible, instruments should be decontaminated away from the surgery’, with little detail on surgery and equipment layout, services, ventilation and space requirements.27,28 Similarly, no detailed work has been undertaken investigating the different decontamination processes used, work flow, management, economics and facility design (including comparison with off-site reprocessing at a sterile service department) all of which would prove insightful and informative for today’s debate on local reprocessing of dental surgical instruments. This study has highlighted that dental practices have several limitations to overcome in order to comply with recent detailed guidelines.29e31 Since the majority of dental practices are located in residential properties it will prove difficult to meet many of these requirements and in some listed buildings the options may be even more tightly constrained. Interestingly, our survey of practices with and without in-surgery instrument decontamination showed little difference in the dimensions of the rooms used for treatment and this probably relates to the standard room dimensions found in residential properties. Regarding the separate instrument decontamination rooms, few were dedicated solely to the function of instrument decontamination and the larger percentage of the room taken up by bench space reflects this multi-purpose role and maximal use of space in small rooms. A review of design guidance for new build and major refurbishment of facilities for the provision of primary dental care has recommended more detailed guidance on this subject and a minimally designed treatment area.32 Guidance on the requirements for equipment, facilities and management of local decontamination units has been recently published in Scotland, accompanied by a separate publication providing detailed information on materials, layout, space requirements and capacity planning issues in relation to patient throughput.29,30 This document provides three options for instrument decontamination facilities, ranging from a single room to two rooms with ante-rooms, the latter being the preferred option.30 These documents stress the need for careful planning and optimisation of equipment that is customised for each practice with projected patient throughput and treatment types; for example, matching washer-disinfector capacity with steriliser throughput. In light of these individual practice requirements, practitioners should take care not to extrapolate directly plans from the schematics that are found in a range of publications. In addition, the highly technical and specialist nature of the guidance documents underlines the importance of appropriate and timely support for dental practitioners upgrading their premises. Within England, separate guidance has been published with schematics for a single room or two room options, with the removal of decontamination facilities from within the treatment area viewed as a priority.31 An example of the challenges ahead relates to ventilation requirements where the provision of extract ventilation over areas undertaking ‘dirty’ activities such as used for manual cleaning and rinsing of contaminated instruments are unlikely to be adequately controlled by general room ventilation. Standards concerning observations on ventilation were based on requirements contained in Health Technical Memorandum 2025, specifying that for dirty activities
343
a foul extract system should be used to ensure that the room is maintained at negative pressure while in use to prevent egress of potentially contaminated air.33 This guidance has now been updated in Scottish Health Planning Note 13 part 2 and Health Technical Memorandum 03 part A in England and Wales.30,34 In conclusion, the intention to remove instrument reprocessing activities outwith the dental treatment area has been suggested and recommended for several decades. However, few in-depth research studies have been undertaken investigating the design of dental surgeries, layout of decontamination facilities, throughput capacity and ventilation requirements. The impact of working with biological aerosols in an inadequately ventilated environment merits further study from the occupational health perspective.35e37 Many of the surgeries surveyed had attempted to remove instrument reprocessing outwith the treatment area but were compromised by multiple activities in the instrument reprocessing areas and lack of space, suggesting a willingness for compliance but a lack of sufficient technical support. The current arrangement of dental practice location within converted residential properties will severely restrict optimal decontamination facility design and best value for money could be obtained by incorporating recent design guidance into new builds and the pooling of resources for different groups of health workers in purpose-built healthcare facilities. Alternatively, consideration should be given to partial or full outsourcing of instrument decontamination to sterile service departments. Conflict of interest statement None declared. Funding sources Study supported by a grant from the Scottish Executive Health Department. References 1. Gee AM. Basic elements of dental office design. J Can Dent Assoc 1966;32:642e648. 2. Scott MJ. A purpose-built dental surgery in a new town. Br Dent J 1967;17:69e70. 3. Willard PJ. Building a dental practice: Part 1. Br Dent J 1981;151:157e160. 4. Willard PJ. Building a dental practice: Part 2. Services. Br Dent J 1981;151:195. 5. Willard PJ. Building a dental practice: Part 3. Detailed planning of surgeries. Br Dent J 1981;151:231e233. 6. Mayhew B. Tray systems, colour coding and storage/sterilisation area. Dent Update 1974;8:417e421. 7. Paul E. The design of the dental surgery and its equipment. Br Dent J 1974;137:269e277. 8. Rothwell PS, Dinsdale RCW. Cross-infection control in dental practice. Part 1: The practicability of a zone system to reduce cross-infection risks in conventionally-designed dental surgeries. Br Dent J 1988;10:185e187. 9. Worthington LS, Rothwell PS, Banks N. Cross-infection control in dental practice. Part 2: A dental surgery planned with cross-infection control as the design priority. Br Dent J 1988;165:226e228. 10. NHS Estates. Infection control in the built environment. London: Department of Health; 2002. 11. Gould DJ. Infection control: the environment and service organisation. Nurs Stand 2005;20:57e65. 12. Wilson APR, Ridgway GL. Reducing hospital-acquired infection by design: the new University College London Hospital. J Hosp Infect 2006;62:285e299. 13. Dettenkofer M, Seegers S, Antes G, Motschall E, Schumacher M, Daschner FC. Does the architecture of hospital facilities influence nosocominal infection rates? A systemic review. Infect Control Hosp Epidemiol 2004;25:21e25. 14. Prospero E, Savini S, Annino I. Microbial aerosol contamination of dental healthcare workers’ faces and other surfaces in dental practice. Infect Control Hosp Epidemiol 2003;24:139e141. 15. Bennett AM, Fulford MR, Walker JT, Bradshaw DJ, Martin MV, Marsh PD. Microbial aerosols in general dental practice. Br Dent J 2000;189:664e667. 16. McColl E, Bagg J, Winning S. The detection of blood on dental surgery surfaces and equipment following dental hygiene treatment. Br Dent J 1994;176:65e67. 17. Edmunds LM, Rawlinson A. The effect of cleaning on blood contamination in the dental surgery following periodontal procedures. Aust Dent J 1998;43:349e353. 18. Kurita H, Kurashina K, Honda T. Nosocomial transmission of methicillinresistant Staphylococcus aureus via the surfaces of the dental operatory. Br Dent J 2006;201:297e300.
344
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
19. Autio KL, Rosen S, Reynolds NJ, Bright JS. Studies in cross-contamination in the dental clinic. J Am Dent Assoc 1980;100:358e361. 20. Martin MV. The significance of the bacterial contamination of dental unit water systems. Br Dent J 1987;163:152e154. 21. Martin MV, Hardy P. Two cases of oral infection by methicillin-resistant Staphylococcus aureus. Br Dent J 1991;170:63e64. 22. Scottish Executive Health Department. NHS Scotland Safety Action Notice SAN (SC)03/23: re-usable stainless steel vaginal speculae: risk of cross infection. Edinburgh: SEHD; 2003. 23. Keene WE, Markum AC, Samadpour S. Outbreak of Pseudomonas aeruginosa infections caused by commercial piercing of upper ear cartilage. JAMA 2004;291:981e985. 24. Smith A, Hurrell D, Bagg J, McHugh S, Mathewson H, Henry MA. A method for surveying instrument decontamination procedures in general dental surgery. Br Dent J 2005;8:1e6. 25. Cash RG. Sterilization and disinfection. Considerations in office design. J Clin Orthod 1988;22:170e175. 26. Hamula W. Orthodontic Office design: planning a sterilization area. J Clin Orthodont 1991;25:375e381. 27. British Dental Association. Advice sheet A12 e infection control in dentistry. London: BDA; 2003. 28. Kohn WG, Collins AS, Cleveland JL, et al. Centers for Disease Control and Prevention. Guidelines for infection control in dental healthcare settings. Morb Mortal Weekly Rep 2003;52:21e22.
29. NHS National Services Scotland. Local Decontamination Units e Guidance on the requirements for equipment, facilities and management. Glasgow: Health Protection Scotland; 2007. 30. Health Facilities Scotland. Scottish Health Planning Note 13: Part 2. Decontamination facilities: local decontamination units. Glasgow: HFS; 2008. 31. Department of Health. Health Technical Memorandum 01-05. London: Department of Health; 2008. 32. Morganstein SI, Glanville R. Design guidance for new build and major refurbishment of facilities for the provision of primary dental care. London: Department of Health; 2007. 33. Department of Health. Health Technical Memorandum 2025. Ventilation in healthcare premises. London: HMSO; 1994. 34. Department of Health. Health Technical Memorandum 03-01 e ‘Specialised ventilation in healthcare premises’. Part A Design and installation of ventilation systems. London: Department of Health; 2007. 35. Hamula W. Orthodontic office design: sick building syndrome. J Clin Orthodont 1991;25:725e734. 36. Grenier D. Quantitative analysis of bacterial aerosols in two different dental clinic environments. Appl Environ Microbiol 1995;61:3165e3168. 37. Pankhurst CL, Wilson C, Philpott-Howard JN, Surman-Lee S, Warburton F, Challacombe S. Evaluation of the potential risk of occupational asthma in dentists exposed to contaminated dental unit waterlines. Primary Dental Care 2005;12:53e63.
Available online at www.sciencedirect.com
Journal of Hospital Infection journal homepage: www.elsevierhealth.com/journals/jhin
Design of dental surgeries in relation to instrument decontamination A.J. Smith a, *, D.E.A. Lockhart a, E. McDonald b, S. Creanor c, D. Hurrell d, J. Bagg a a
Infection & Immunity Research Group, Glasgow Dental Hospital and School, Faculty of Medicine, University of Glasgow, Glasgow, UK Renfrew Dental Centre, Glasgow, UK c Centre for Environmental & Health Statistics, University of Plymouth, Plymouth, UK d HealthCare Science Limited, Hitchin, Hertfordshire, UK b
a r t i c l e i n f o
s u m m a r y
Article history: Received 12 December 2009 Accepted 2 June 2010 Available online 2 October 2010
Recent guidelines advise that the decontamination of dental instruments should be undertaken outwith the treatment area. The aim of this study was to determine the physical area of rooms in dental surgeries that decontaminate instruments within and outwith the treatment area respectively, and other factors relating to practice layout and ventilation. Data were collected by interview and observation of dental healthcare workers in dental practice in Scotland, UK. Room layouts were recorded and measured at floor, benchtop and above benchtop heights. Thirteen surgeries with instrument decontamination processes occurring in the treatment area and seven surgeries with instrument decontamination outwith the treatment area were selected at random for detailed analysis of room dimensions. Of the 179 dental surgeries surveyed, 55% were located in converted residential premises and most practitioners (91%) did not share premises with other healthcare providers. The median number of rooms in the practices was 8 (range: 2e21) and the median number of surgeries present was 3 (range: 1e6). Regardless of whether instrument decontamination facilities were housed within the treatment area or not, the average treatment area room size for both was 15.8 m2 (range: 7.3e23.9) (P ¼ 0.862), with 20% of the room area available as work surfaces. The median size of the seven instrument decontamination rooms (local decontamination units) was 7.6 m2 (range: 2.9e16.0), with, on average, 63% of the room used for work surfaces. This survey suggests that the historical location of dental surgeries in converted residential properties places many restrictions on appropriate design for healthcare premises. Ó 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
Keywords: Infection prevention Local decontamination unit Surgery design
Introduction Considering the large amounts of time spent by dental team members in dental surgeries and the significant financial investment incurred in their establishment, there have been relatively few in-depth studies investigating the combined influences of ergonomics, economics and infection control elements of dental practice design. One of the earliest papers to describe dental practice design in relation to productivity, published in the 1960s, highlighted the division of a practice into reception, administration and clinical areas.1 In terms of infection control, the author suggested a centralised ‘make-ready’ area for instrument * Corresponding author. Address: Infection Research Group, Level 9, Glasgow Dental Hospital & School, 378 Sauchiehall Street, Glasgow, UK. Tel.: þ44 (0)141 211 9741; fax: þ44 (0)141 353 1593. E-mail address: [email protected] (A.J. Smith).
decontamination, outwith the patient treatment area and shared with dental laboratory facilities. The room size of the instrument decontamination area was recommended to be approximately ‘5 feet (1.5 m) of counter space’ although no rationale was provided for this space determination.1 Previous workers have described construction of purpose-built surgeries, converted residential properties, sterilisation areas and equipment design, but there has been little discussion relating to the physical dimensions of the areas involved, infection control or reprocessing of dental instruments.2e7 Later workers described the use of a zone system to reduce cross-infection risks and a ‘centralised’ sterilisation area within the practice, but these papers also lack details on issues such as ideal room requirements, ventilation, segregation of clean and dirty reprocessing areas and throughput capacity calculations needed to estimate decontamination equipment requirements.8,9 The issues involved in dental surgery design to overcome infection control issues have been summarised as challenging in the UK,
0195-6701/$ e see front matter Ó 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2010.06.002
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
due to the nature of the work (aerosol-generating procedures), the legacy of the National Health Service (NHS) remuneration system resulting in high patient throughput, surgery and equipment design and working patterns (multiple processes undertaken in limited space).8,9 The last decade has seen increased interest in the relationship between the built environment and healthcare-associated infections (HCAIs).10 The importance of adequately designed premises, in both the acute and primary care sectors, has been identified as a potential factor in reducing the risk of HCAI although this has been challenged by others.11e13 Within general dental practice, the evidence for the impact of surgery design on infection control is less clear-cut, although issues such as mixing up of clean and used instruments and sharps injuries have been highlighted.9 Dental surgery, with its widespread use of powered tools, provides an ideal aerosol-generating opportunity. There are a number of well-described studies demonstrating the widespread dispersal of oropharyngeal secretions within the dental practice environment and subsequent surface contamination by blood and micro-organisms such as meticillinresistant Staphylococcus aureus.14e18 It is difficult, however, to produce recorded evidence linking the dental surgery environment to cross-infection, although there are reported instances of such episodes in primary care facilities.18e23 The difficulty in providing such evidence may be related to the absence of surveillance data on HCAI associated with dental practice, the subclinical or latent nature of symptoms following treatment as well as other potential confounding variables. Application of basic infection prevention principles, interpretation of in vitro data and good clinical practice, however, dictate that the control of aerosol generation, ease of environmental surface cleaning, segregation of the processing of clean and dirty devices and segregation of instrument decontamination from treatment areas, should be clear priorities. The aim of this study is to report on elements of dental practice design features relevant to instrument decontamination from an observational survey of 179 UK dental surgeries and to describe, in more detail, physical dimensions of surgeries from a number of selected practices, both with and without dedicated instrument decontamination rooms (local decontamination units). Methods Survey methodology This has previously been reported in detail.24 In brief, the study population comprised all general dental practitioners in Scotland with a NHS list number (N ¼ 837). This list was the basis for randomly selecting practitioners to survey. A two-stage proportional stratified random sampling method was used to identify which surgeries were to be surveyed. First, practices were randomly selected in proportion to the distribution of practices within each of the health boards. Then, if there were more than one dentist within a selected practice, simple random sampling was used to identify a single dentist within the selected practice to be approached. The surgery that the dentist worked from and its associated decontamination facilities were the subject of the survey. Data were available from 179 surgeries. Data collection Each surgery was surveyed by a team of two, namely an infection control/decontamination expert and an experienced dental practitioner. The survey team interviewed the dental practitioner and dental nurse, reviewed documentation relevant to the survey and recorded the physical layout of the premises. The decontamination processes, policies and procedures available to the dental
341
surgery staff were viewed directly by a member of the survey team. All relevant information was recorded on to data collection forms prepared for automated reading.24 The form developed for collection of information on the physical layout of the dental surgery was presented as a grid format. For any one room, three grids were completed to scale: one at floor level, one at benchtop level and one detailing ‘above benchtop’ (Figure 1). The key measurements, for example the length and breadth of the room, and the positions and sizes of cupboards and work surfaces were marked clearly on the grids, along with the position of decontamination items such as the sinks and autoclaves. If the decontamination equipment used were located in another surgery or another room, then the layout of that room was also recorded on a second form. Measurements were recorded using a laser measurement device (Stanley tools) or tape measure. The survey visits ran from January 2003 until the end of March 2004. Data analysis Data relating to location of practices, number of rooms, surgeries and ventilation facilities are reported from the 179 surgeries visited. Further data on surgery and instrument decontamination room layouts are reported for 20 surgeries, selected at random from those surveyed; this included 13 surgeries for which instrument decontamination was undertaken within the surgery and seven surgeries for which these processes were undertaken outside the surgery. The room in which instrument decontamination was undertaken in these seven surgeries was also surveyed. The physical attributes of the dental surgeries decontaminating within/outwith the surgery were compared using the ManneWhitney test and corresponding 95% confidence intervals for the difference, using the HodgeseLehmann method. Exact P-values and confidence intervals were calculated given the small sample sizes (StatXact 8.0, Cytel Inc., 2007). Results Location of practices Results from the survey demonstrated that most dental practices (55%) were in converted residential practices, followed by converted commercial premises (29%), usually shop units, whereas 12% were purpose-built. Most practices (91%) did not share premises with other healthcare providers, such as general medical practitioners, pharmacists or podiatrists. Most practices were owned by a single principal (68%). Facilities within dental practices Within the dental practices surveyed, the median number of rooms present in the practice was 8 (range: 2e21) and the median number of dental surgeries within the practices was 3 (range: 1e6). Instrument decontamination areas In 38% of practices there was a dedicated area for decontamination of dental instruments that was physically separated from other work areas. This dedicated area was accessed via a separate entrance in 30% of practices. In 36% of practices the dedicated decontamination area was mechanically ventilated. In areas where instrument decontamination took place, the area was essentially easy to clean in 85% of practices, with 56% having smooth and continuous walls and 86% having smooth floors that were washable with a non-slip finish. However, only 24% had coved junctions between the floors and walls.
342
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
A
B
C
0
D
E
F
H
G
I
J
K
L
D+C D+C
M N D
O
P Key
D
1
Door BT
2
C
4
C
5
O
D
3.1m
3
DESK
6 7 8
Window Cupboards
C
Drawer units
D
Cupboard and drawers
C&D
Dental chair
CHAIR
Stool Sterilized instr storage
D
9
D+C
10 11
D+C
D
Sharp bin on floor
12
SIS
Ultrasonic cleaner
UC
WD
WD
Sterilizer
ST
Additions Bracket table
13 46438
Floor level
BT
4.9 m
14
Please note that each square on this grid represents 300mm (approx 1 foot)
15
Serial number 29 04 37
AD3/29/04 Layout of relevant rooms© University of Glasgow 2002
Figure 1. Example of data collection form used to record physical layout of dental surgery environment at floor level.
Ventilation In terms of mechanical ventilation, 18% of surgeries had ventilation for the patient treatment waiting area, 19% for the patient treatment area and 19% for the instrument decontamination area. Extract ventilation over the manual instrument washing sink, to minimise aerosol dispersion, was present in 4% of surgeries. In 25% of surgeries a benchtop fan was used to provide ventilation in areas where decontamination was occurring. Surgery and decontamination room dimensions The median area (physical room size) of surgeries that undertook instrument decontamination within the surgery was 15.8 m2 (range: 7.3e23.9), with the same median room area of surgeries that undertook instrument decontamination outwith the surgery (15.8 m2; range: 9.7e19.8). The seven dedicated rooms in which instrument decontamination took place (local decontamination units) had a median area of 7.6 m2. There was a wide range in size of
the dedicated decontamination rooms, with the smallest being 2.9 m2 and the largest 16.0 m2 (Table I). The work surface area is also summarised in Table I. The median physical area comprising work surfaces for surgeries decontaminating instruments within the surgery was 2.9 m2 compared with 3.4 m2 in surgeries decontaminating instruments outwith the surgery. For both scenarios the work surface took up, on average, 20% of the room area. In the dedicated rooms used to decontaminate instruments, the median work surface area was 4.8 m2, representing, on average, 63% of the room area. Other activities associated with these areas included beverage preparation, radiograph processing, preparation of filling materials and housing of air compressors. No statistically significant differences were detected in any of the physical attributes between surgeries decontaminating instruments within or outwith the surgery. Discussion There have been a few studies investigating the physical space requirements for the set-up of instrument decontamination
Table I Summary of physical attributes of dental surgeries and instrument decontamination rooms
Room area (m2) 2
Work surface area (m ) % of room covered by work surfaces
Decontamination within surgery (N ¼ 13)
Decontamination outwith surgery (N ¼ 7)
P-valuea
95% CI for differenceb
Decontamination room (N ¼ 7)
15.8 (7.3, 23.9) 2.9 (1.8, 6.2) 20.4 (10.7, 27.2)
15.8 (9.7, 19.8) 3.4 (1.4, 4.7) 21.0 (11.6, 30.9)
0.862
(3.4 to 4.1)
0.892
(1.2 to 0.9)
0.924
(5.2 to 5.8)
7.6 (2.9, 16.0) 4.8 (1.0, 10.2) 63.2 (34.5, 71.1)
CI, confidence interval. a Exact P-value from ManneWhitney test comparing decontamination within surgery versus decontamination outwith surgery. b Exact 95% confidence interval (HodgeseLehmann method) for difference decontamination within surgery minus decontamination outwith surgery.
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
facilities in dental practice.25,26 It has been suggested that the linear space requirements for a decontamination facility would measure approximately 2.4 0.6 m, although the author does stress that size of the sterilisation facility would also be determined by the size and number of steriliser units and no method for the calculation of throughout capacity, treatment activity and number of sterilisers was given.26 Interestingly, noise from the instrument cleaning and sterilising equipment was quoted as a major determining factor for removal of these items out of the treatment area.26 In addition, until relatively recently, guidelines from professional societies have outlined general principles, for example, ‘where possible, instruments should be decontaminated away from the surgery’, with little detail on surgery and equipment layout, services, ventilation and space requirements.27,28 Similarly, no detailed work has been undertaken investigating the different decontamination processes used, work flow, management, economics and facility design (including comparison with off-site reprocessing at a sterile service department) all of which would prove insightful and informative for today’s debate on local reprocessing of dental surgical instruments. This study has highlighted that dental practices have several limitations to overcome in order to comply with recent detailed guidelines.29e31 Since the majority of dental practices are located in residential properties it will prove difficult to meet many of these requirements and in some listed buildings the options may be even more tightly constrained. Interestingly, our survey of practices with and without in-surgery instrument decontamination showed little difference in the dimensions of the rooms used for treatment and this probably relates to the standard room dimensions found in residential properties. Regarding the separate instrument decontamination rooms, few were dedicated solely to the function of instrument decontamination and the larger percentage of the room taken up by bench space reflects this multi-purpose role and maximal use of space in small rooms. A review of design guidance for new build and major refurbishment of facilities for the provision of primary dental care has recommended more detailed guidance on this subject and a minimally designed treatment area.32 Guidance on the requirements for equipment, facilities and management of local decontamination units has been recently published in Scotland, accompanied by a separate publication providing detailed information on materials, layout, space requirements and capacity planning issues in relation to patient throughput.29,30 This document provides three options for instrument decontamination facilities, ranging from a single room to two rooms with ante-rooms, the latter being the preferred option.30 These documents stress the need for careful planning and optimisation of equipment that is customised for each practice with projected patient throughput and treatment types; for example, matching washer-disinfector capacity with steriliser throughput. In light of these individual practice requirements, practitioners should take care not to extrapolate directly plans from the schematics that are found in a range of publications. In addition, the highly technical and specialist nature of the guidance documents underlines the importance of appropriate and timely support for dental practitioners upgrading their premises. Within England, separate guidance has been published with schematics for a single room or two room options, with the removal of decontamination facilities from within the treatment area viewed as a priority.31 An example of the challenges ahead relates to ventilation requirements where the provision of extract ventilation over areas undertaking ‘dirty’ activities such as used for manual cleaning and rinsing of contaminated instruments are unlikely to be adequately controlled by general room ventilation. Standards concerning observations on ventilation were based on requirements contained in Health Technical Memorandum 2025, specifying that for dirty activities
343
a foul extract system should be used to ensure that the room is maintained at negative pressure while in use to prevent egress of potentially contaminated air.33 This guidance has now been updated in Scottish Health Planning Note 13 part 2 and Health Technical Memorandum 03 part A in England and Wales.30,34 In conclusion, the intention to remove instrument reprocessing activities outwith the dental treatment area has been suggested and recommended for several decades. However, few in-depth research studies have been undertaken investigating the design of dental surgeries, layout of decontamination facilities, throughput capacity and ventilation requirements. The impact of working with biological aerosols in an inadequately ventilated environment merits further study from the occupational health perspective.35e37 Many of the surgeries surveyed had attempted to remove instrument reprocessing outwith the treatment area but were compromised by multiple activities in the instrument reprocessing areas and lack of space, suggesting a willingness for compliance but a lack of sufficient technical support. The current arrangement of dental practice location within converted residential properties will severely restrict optimal decontamination facility design and best value for money could be obtained by incorporating recent design guidance into new builds and the pooling of resources for different groups of health workers in purpose-built healthcare facilities. Alternatively, consideration should be given to partial or full outsourcing of instrument decontamination to sterile service departments. Conflict of interest statement None declared. Funding sources Study supported by a grant from the Scottish Executive Health Department. References 1. Gee AM. Basic elements of dental office design. J Can Dent Assoc 1966;32:642e648. 2. Scott MJ. A purpose-built dental surgery in a new town. Br Dent J 1967;17:69e70. 3. Willard PJ. Building a dental practice: Part 1. Br Dent J 1981;151:157e160. 4. Willard PJ. Building a dental practice: Part 2. Services. Br Dent J 1981;151:195. 5. Willard PJ. Building a dental practice: Part 3. Detailed planning of surgeries. Br Dent J 1981;151:231e233. 6. Mayhew B. Tray systems, colour coding and storage/sterilisation area. Dent Update 1974;8:417e421. 7. Paul E. The design of the dental surgery and its equipment. Br Dent J 1974;137:269e277. 8. Rothwell PS, Dinsdale RCW. Cross-infection control in dental practice. Part 1: The practicability of a zone system to reduce cross-infection risks in conventionally-designed dental surgeries. Br Dent J 1988;10:185e187. 9. Worthington LS, Rothwell PS, Banks N. Cross-infection control in dental practice. Part 2: A dental surgery planned with cross-infection control as the design priority. Br Dent J 1988;165:226e228. 10. NHS Estates. Infection control in the built environment. London: Department of Health; 2002. 11. Gould DJ. Infection control: the environment and service organisation. Nurs Stand 2005;20:57e65. 12. Wilson APR, Ridgway GL. Reducing hospital-acquired infection by design: the new University College London Hospital. J Hosp Infect 2006;62:285e299. 13. Dettenkofer M, Seegers S, Antes G, Motschall E, Schumacher M, Daschner FC. Does the architecture of hospital facilities influence nosocominal infection rates? A systemic review. Infect Control Hosp Epidemiol 2004;25:21e25. 14. Prospero E, Savini S, Annino I. Microbial aerosol contamination of dental healthcare workers’ faces and other surfaces in dental practice. Infect Control Hosp Epidemiol 2003;24:139e141. 15. Bennett AM, Fulford MR, Walker JT, Bradshaw DJ, Martin MV, Marsh PD. Microbial aerosols in general dental practice. Br Dent J 2000;189:664e667. 16. McColl E, Bagg J, Winning S. The detection of blood on dental surgery surfaces and equipment following dental hygiene treatment. Br Dent J 1994;176:65e67. 17. Edmunds LM, Rawlinson A. The effect of cleaning on blood contamination in the dental surgery following periodontal procedures. Aust Dent J 1998;43:349e353. 18. Kurita H, Kurashina K, Honda T. Nosocomial transmission of methicillinresistant Staphylococcus aureus via the surfaces of the dental operatory. Br Dent J 2006;201:297e300.
344
A.J. Smith et al. / Journal of Hospital Infection 76 (2010) 340e344
19. Autio KL, Rosen S, Reynolds NJ, Bright JS. Studies in cross-contamination in the dental clinic. J Am Dent Assoc 1980;100:358e361. 20. Martin MV. The significance of the bacterial contamination of dental unit water systems. Br Dent J 1987;163:152e154. 21. Martin MV, Hardy P. Two cases of oral infection by methicillin-resistant Staphylococcus aureus. Br Dent J 1991;170:63e64. 22. Scottish Executive Health Department. NHS Scotland Safety Action Notice SAN (SC)03/23: re-usable stainless steel vaginal speculae: risk of cross infection. Edinburgh: SEHD; 2003. 23. Keene WE, Markum AC, Samadpour S. Outbreak of Pseudomonas aeruginosa infections caused by commercial piercing of upper ear cartilage. JAMA 2004;291:981e985. 24. Smith A, Hurrell D, Bagg J, McHugh S, Mathewson H, Henry MA. A method for surveying instrument decontamination procedures in general dental surgery. Br Dent J 2005;8:1e6. 25. Cash RG. Sterilization and disinfection. Considerations in office design. J Clin Orthod 1988;22:170e175. 26. Hamula W. Orthodontic Office design: planning a sterilization area. J Clin Orthodont 1991;25:375e381. 27. British Dental Association. Advice sheet A12 e infection control in dentistry. London: BDA; 2003. 28. Kohn WG, Collins AS, Cleveland JL, et al. Centers for Disease Control and Prevention. Guidelines for infection control in dental healthcare settings. Morb Mortal Weekly Rep 2003;52:21e22.
29. NHS National Services Scotland. Local Decontamination Units e Guidance on the requirements for equipment, facilities and management. Glasgow: Health Protection Scotland; 2007. 30. Health Facilities Scotland. Scottish Health Planning Note 13: Part 2. Decontamination facilities: local decontamination units. Glasgow: HFS; 2008. 31. Department of Health. Health Technical Memorandum 01-05. London: Department of Health; 2008. 32. Morganstein SI, Glanville R. Design guidance for new build and major refurbishment of facilities for the provision of primary dental care. London: Department of Health; 2007. 33. Department of Health. Health Technical Memorandum 2025. Ventilation in healthcare premises. London: HMSO; 1994. 34. Department of Health. Health Technical Memorandum 03-01 e ‘Specialised ventilation in healthcare premises’. Part A Design and installation of ventilation systems. London: Department of Health; 2007. 35. Hamula W. Orthodontic office design: sick building syndrome. J Clin Orthodont 1991;25:725e734. 36. Grenier D. Quantitative analysis of bacterial aerosols in two different dental clinic environments. Appl Environ Microbiol 1995;61:3165e3168. 37. Pankhurst CL, Wilson C, Philpott-Howard JN, Surman-Lee S, Warburton F, Challacombe S. Evaluation of the potential risk of occupational asthma in dentists exposed to contaminated dental unit waterlines. Primary Dental Care 2005;12:53e63.