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Theatres Flashcards

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0
Q

What should the theatre be thought in?

A
  • 4 zones
  1. Outer zone - includes rest of hospital and theatre reception
  2. Clean zone - comprises the area from theatre reception up to theatre door
  3. Aseptic zone- anesthetic room, preparation room, scrub up, operating room- see pic
  4. Disposal zone
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1
Q

Where should the operating theatre be located ?

A
  • Near to ae, itu, radiology
  • Away from public circulation and nonessential departments
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2
Q

How is theatre design based around?

A
  • The operating table
  • Lighting, humidity, ventilation, and temperature all controlled carefully
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3
Q

What is the idea, theatre temperature?

Why is this?

A
  • 24-26 oC
  • to prevent pt hypothermia ( paralysis, cool intravenous fluid and open wounds)
  • ideal surgical temp is 19-20 oC
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4
Q

What is created around the patient due to prevent hypothermia?

A
  • A warm microclimate using warming blankets and airflow mattresses
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5
Q

What is the Ideal theatre humidity?

How is this and temp controlled ?

A
  • 40-60 %
  • By alterations made in the ventilation of the theatre
  • important as temperature will effect cement polymerisation
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6
Q

What is the minimum light at the incision sight should be ?

A
  • 40,000 lux
  • HIgh quality ,without shadows
  • direction should be easilt adjustable by surgical team
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7
Q

What should the lights in theatre be able to do?

A
  • Move, easily adjustable
  • high quality without shadows
  • satellite lights can be used but can generate heat and convection currents
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8
Q

What are the 4 Sources of wound contamination in theatre?

A
  • Contamination from the Surgical team
  • Patient
  • Instruments
  • Airborne contamination
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9
Q

Where does the majority of airborne contamination come form?

A
  • Personnel within theatre
  • Accounts for 95% of wound contamination
    • you shed on average 3,000-50,000 microorganisms per minute depending on activity and clothing
  • 90% of all bacteria emissions come from below the neck level
  • Strep/Staphy from URT when talking/coughing
  • Staph from skin
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10
Q

Where do the majority of bacterial emissions come from?

A

Below the neck level

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11
Q

What is the air cleanliness expressed as?

A

Bacteria carrying particles per cubic metre (BCP/m3) or Colony forming units per cubic metre (CFU/m3)

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12
Q

How is this cleanliness most accurately measured?

A

Microbiological volumetric slit sampler -casella slit sampler or settle plates

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13
Q

How do the slit samplers work?

A

Draw in as et volume of air 30-70L/min past culture plates. The plates are incubated for 48hrs at 37oC and the colonies formed are counted.

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14
Q

What is cleanliness in a plenum ventilated operating theatre ?

A

Should be less than 35 CFU of bacteria/m3 of air Less than 180 CFU of clostridium perfinges,staph aureus During surgery there should be less than 180 CFU of bacteria/m3

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15
Q

In ultra clean laminar flow theatres what should the no of CFU be?

A

Less than 20CFU/m3 at the periphery of the enclosure Less than 10CFU/m3 at the centre

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16
Q

Whrer is the source for ventilation in theatres?

A

Taken in at roof level of the theatre suite and drawn in thru a series of fans thru FILTERS capable of removing bacteria carrying particles . Also it is humidified and warmed or cooled

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17
Q

What filters are used To clean the air in theatres?

A

High efficiency particulate air filters - HEPA can filter particles of 0.5 micro is in size with 99.7% efficiency

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18
Q

What are the types of ventilation systems in theatres?

A

Plenum Laminar flow Horizontal laminar flow Vertical laminar flow Ex-flow= Howorth

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19
Q

What is plenum ventilation ?

A

In this system pressure inside the theatre is GREATER than the outside. Clean air is fed via wall or ceiling diffusers and let out of vents placed just above floor level. In theory air from contaminated areas should not enter the septic zones E.g.opening a standard theatre door transfers 2m3 of air across the opening and turbulence created by the activity

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20
Q

What is the no of air changes in a plenum theatre?

A

15-25 per hour

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21
Q

What is laminar flow?

A

Involves the entire body of air within a designated space moving with uniform velocity in a single direction along parallel flow lines Common to be restricted to an area In the centre of the theatre.-a room within a room principle

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22
Q

What is the flow of air in laminar flow? How many exchanges of air take places per hour?

A

0.3m/s not perceptible by the individual 300 changes per hour

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23
Q

What is horizontal laminar flow?

A

HEPA filters are in the wall. Position of scrub team is important and the use of equipment Easier to install than laminar flow- Salvati et al 82 found that although horizontal laminar flow reduced the incidence of deep joint sepsis following thr , sepsis rates increases with TKR

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24
Q

What is vertical laminar flow?

A

What we use in theatre but laminar flow with panels extending form the ceiling usually 2metres. Air passes thru HEPA filters in ceiling and directed towards the operative field In a vertical direction

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25
Q

What is entrainment ?

A

When someone stands on the periphery of vertical laminar flow and deflect comtamination inwards towards the wound

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26
Q

What is ex flow- Howorth enclosure?

A

Howorth in 1980 described a flow of clean air from the operating theatre in the shape of an inverted trumpet- EXOPENETIAL FLOW

27
Q

What is the advantage of Howorth ventilation?

A

Peripheral entrainment cannot occur cf vertical laminar flow More efficient that laminar flow and fewer changes of air.

28
Q

What are the clinical effects of laminar flow?

A

CHARNLEY in 1970 reported a reduction in incidence of infection from 7% to 0.5% Thought to be due to air factors in contamination with better surgical wound closure and surgical apparel

29
Q

What did the mrc trial show?

A

Lidwell in 1982- confirmed a significant reduction in wound contamination and deep joint sepsis in ultraclean air theatres and flux that vertical laminar flow was more efficient than horizontal laminar flow Certain prophylaxis measures reduced joint sepsis Antibiotics loaded cement -11x Systemic antibiotics - 4.8x Ultra clean air- 2.6x Plastic isolators- 2.2x Body exhaust suit 2.2 x

30
Q

What types of clothing are used in theatre?

A

Standard Cotton clothing Ventile Gor-tex Disposable non woven clothing Body exhaust suits

31
Q

What is the name given to the direct migration of bacteria thru a garments that is wet?

A

Moist bacterial strike through

32
Q

What is the standard Cotton clothing?

A

This is comfortable made of Open weave- easy air circulation But pore size is 80 microns and therefore inefficient at preventing migration of bacteria carrying particles Moist bacterial strike through is a problem

33
Q

What is ventile?

A

Cotton product with a close weave giving spore size of 20 microns Effective in reducing bacterial dispersions but uncomfortable to wear as it inhibits circulation Used in front pad on gown to prevent moist bacterial strike thru

34
Q

What is gore -tex?

A

Woven polyester laminated to a film of polytetrafluoroethylene PTE Open structure allows for air exchange Pore size 0.2 microns acts as an effective barrier Dispersion via neck and sleeves

35
Q

What is disposable non woven clothing used for?

A

Frequently surgical gown So Laced fibres are UNWOVEN and appear microscopically as a random mat. Bacteria tend to get trapped In these fibres Open structure airflow is not impeded

36
Q

How do body exhaust suits work?

A

Aim to maintain a negative pressure within the gown- prevent emission of bacteria Disadvantages - claustrophia , can’t use microscope

37
Q

Should everyone in theatre wear mask?

A

Yes Protect wound from direct contamination and in particular talking and breathing. Changed after every operation

38
Q

Why are surgical gloves worn?

A

To protect the surgeon from HAEMATOGENOUS spread of viral diseases Suface contamination during preparation and perforation of glove (40%) suggest double gloving

39
Q

What is the role of ventilatory system in theatres?

A
  • To reduce airborne bacteria to a minimum
40
Q

How is the ventilation system checked for reduction in bacteria?

A
  • Air cleanliness
  • expressed as bacteria carrying particles per cubic metre (BCP/m3) or colony forming units per cubic metre (CFU/m3)
41
Q

WHow are colony forming units per cubic metre (CFU/m3) measured?

A
  • using a **volumetric slit sampler **
    • e.g. Casella slit sampler
  • or settle plates
42
Q

How do the volumetric slit sampler work?

A
  • They draw in a set volume of air per minute (30-70L/min) past culture plates
  • the plates are incubated for 48hrs at 37oC and the colonies formed are counted
43
Q

When air sampling recommended?

A
  • According to british standards in Plenum ventilated operating rooms at Comission or after refurbishment
  • in ultra-clean operating theatres, air sampling is recommended on a regular basis several times a year ( standard every 3/12) done inside and outside the enclosed area
44
Q

Define the number of colony forming units in a plenum theatre is non use (clean), working ?

A
  • Lying empty = < 35 CFU of bacteria/m3 of air
  • less than 1 CFU/m3 of clostridium perfringes and staphy aureus
  • During operating
    • < 180 CFU of bacteria/m3
45
Q

Define the number of colony forming units in a ultra-clean laminar flow theatre ?

A
  • <20 CFU/m3 at periphery
  • <10 CFU/m3 at centre
46
Q

where is source of air for ventilation?

A
  • Roof level of theatre suite
47
Q

What happens to the air in the theatre ventilation?

A
  • It is drawn by a series of fans through filters capable of removing bacteria carrying particles
  • It is humidified and warmed or cooled
48
Q

What filters are used in the ventilation system and what size particles are removed?

A
  • High-efficiency particulate air ( HEPA)
  • Capable of filtering particles of 0.5microns in size with 99.97 efficiency
49
Q

Describe the different types of ventilation systems?

A
  • Plenum
  • Laminar Flow
    • horizontal
    • Vertical
    • Ex-Flow = Howarth enclosure
50
Q

What is plenum ventilation?

A
  • Pressure inside the theatre is greater than outside
  • clean air is fed via wall or ceiling diffusers and let out of vents placed just above floor level
  • air also passed out around the doors and other openings
  • ideally air from contaminated areas should not enter aseptic zone but opening doors/ movement of personel makes this less efficient
  • opening door transfers 2m3 of air across the opening and turbence created
51
Q

how many exchanges of air per hour occur in plenum ventilation?

A
  • 15-25
52
Q

What is laminar flow?

A
  • characteristically involves the entire body of air within a designated space moving with uniform velocity in a single direction along parallel flow lines
  • true laminar flow is not achieved unless 100 % HEPA filter coverage of ceiling grid system
  • **horizontal **
  • **vertical **
  • ex-flow
  • common for laminar flow to be restricted to a roomwithin a room in the center of op room- flow of air is 0.3m/s and not perceived by person within it
  • Air changes = 400 x per hour, 20 x per hour in entire room
53
Q

What is horizontal laminar flow?

A
  • HEPA filters from a wall
  • position of scrub team and equipment important
  • easier to install than vertical
  • Salvati et al found although horizontal laminar flow reduced the incidence of deep joint sepsis following THR, sepsis rates following TKR increased- probably die ot difficulties with intra-op personnel placment
54
Q

What is vertical laminar flow?

A
  • An enclosure is formed with panels extending from ceiling to within 2m of the floor
  • Air is passed through HEPA filters in the ceiling and directed towards the operative field in a vertical direction
  • entrainment can occur from personnel moving within the periphery of the laminar flow area
  • such entrainment can deflect contamination inwards towards the wound
  • full enclosures are free of this problem
55
Q

What is ex-flow laminar flow?

A
  • Howorth described a flow of clean air form the operating theatre in the shape of an inverted trumpet- ex-flow or exponential flow
  • Air moves downwards and out
  • Peripheral entrainment therefore cannot occur as with vertical laminar flow systems
  • More efficient that laminar flow as requires fewer changes of air per hour
56
Q

What are the clinical effects of laminar flow?

A
  • after the intro of laminar flow
  • Charnley 1972 reported a reduction in the incidence of deep infection from 7% to 0.5% in the period 1960-70 during which time the 5800 hip arthroplasties were preformed
  • Charnley attributed decreaseed incidence due to air factors in combination with better surgical wound closure and surgical apparel
  • MRC ( medical research council) prospective randomised trial by Lidwell et al 1982 confirmed a significant reduction in wound contamination and deep joint sepsis in ultra-clean air theatres and found the found that vertical laminar flow was more effective than horizontal laminar flow
  • they also found certain prophylatic measures were also effective in reducing joint sepsis- (factor by which deep joint sepsis was reduced)
    • Antibtiotic loaded cement - (11)
    • Systemic antibiotics ( 4.8)
    • Ultra clean air ( 2.6)
    • Plastic isolators (2.2)
    • Body exhaust suits ( 2.2)
57
Q

What are the different types of theatre clothing

A
  • standard balloon- cotton clothing
  • Ventile
  • Gore-tex
  • Disposable non woven clothing
  • Body exhaust systems
58
Q

Describe balloon clothing?

A
  • Comfortable
  • made of open weave- allows for easy air circulation
  • pore size is 80 microns so inefficient at preventing migration of bacteria -carrying particles
  • Moist bacterial strike through is a particular problem
59
Q

what is ventile clothing?

A
  • Cotton product with close weave
  • pore size of 20 microns
  • effective at reducing bacterial dispersial but uncomfortable to wear as inhibits air circulation
  • employed as a front pad to prevent moist bacterial strike through from abdominal and lower thoracic areas of the surgeon
60
Q

What is goretex clothing?

A
  • Woven polyester laminated to a film of polytetrafluroethylene (PTFE)
  • the open structure allow for exhange
  • pore size is 0.2 microns acts as a effective barrier
  • Dispersion via neck and arm apertures still occurs so goretex suits have seals at arms and neck-> uncomfortable in prolonged proceedures
61
Q

What is disposable non woven clothing?

A
  • Most common used surgical gown
  • spun laced fibres are unwoven and appear microscopically as a random mat
  • bacteria tend to get entrapped within fibres
  • because of open structure, air circulation is not impeded
  • single use only so expensive
  • but overall costs may be benefical cf resuseable cotton gowns
62
Q

How do body exhaust suits work?

A
  • maintaining a negative pressure within the gown which prevents the admission of bacteria-carrying particles by the wearer
  • as the gown-helmet is impermeable , air is drawn in adn around the operators legs and passes over the body cooling the operator
  • disadv: claustrophia, inablity to use microscope
  • a variation of the charnley body exahust suit is the neck lace and mandarin gown which exclude the head of the operator- this system works on the basis that 90% if bacteria-carrying particles are admitted below neck level
63
Q

What are the clinical effects of clothing?

A
  • MRC trial showed a 50% reduction in deep joint sepsis in operations performed in ultra-clean -air theatres
  • a further 25% reduction was achieved by combining ultra-clean operating theatres with body exhaust systems
  • lowest incidence 0.06% was with ultra-clean operating theatres with body exhaust systems and antibiotics
64
Q

What are the different types of surgical drapes?

A
  • used with skin prep of antiseptics
  1. Body drapes
    • disposable
    • non woven drapes
    • bacteria entrapped
    • open structure so air circulation occur
  2. Incisional Drapes
    • used to hold down surgical drapes
    • no evidence to show reduced wound infection
    • must remaiin adherent to wound edge throughout operaton
  3. Wound -edge drapes
    • ​​these cover the incised wound
    • bacteria persisting in the wound edge may lead to subsequent wound contamination
    • not currently used in orhto
65
Q

What is the purpose of surgical masks?

A
  • Prevent direct contamination - projectile effects of talking or breathing
  • masks changed after each operation as easily contaminated
  • no evidence to suggest non scrubbed personell should wear masks but BOA recommend that they do
66
Q

What is the purpose of surgical gloves?

A
  • Protect the surgical wound from contamination by any resisdual bacteria remaining after surgical scrub
  • protect surgeon from haematogenous spread of viral diseases
  • Glove perforation reported to be 40%
  • Suface colonization of gloves during arthroplasty has been noted so double gloving and changing of top glove before implantation is advocated
  • significant contamination after prep- change gloves

Basic Science (31 decks)

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