asepsis in surgery

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ASEPSIS IN SURGERYBASHIR BIN YUNUS

Surgery AKTH

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DEFINITIONS• Asepsis is the process that reduces the risk of bacterial contamination of surgical

wounds.• Antisepsis is the removal of transient organisms from skin and reduction in

resident flora.• Aseptic techniques: These are various standard measures employed in surgery to

ensure that only sterile materials make contact with wounds and operative sites. • Sterilisation is the process that destroys viable micro-organisms including spores

and viruses.• Disinfection destroys vegetative forms of micro-organisms but spares spores. The

application of antimicrobial agent on in-animate objects to prevent infection.• Cleaning: A process that physically removes contamination but does not

necessarily destroy micro-organims.

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AIM OF ASEPSIS & ANTISEPSIS•Prevention & Elimination of wound infection(& its

sequelae) in surgical patient.

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DISINFECTIONA reduction in the number of viable organisms. Can be achieved by: • Physical methods;

Heat • Low-temperature steam• Boiling water

UV- light • Chemical disinfectants

Low-temperature steam; • Most bacteria and viruses are killed by exposure to moist heat.• Usually achieved with dry saturated steam at 73 °C for greater than 10 minutes.• Effective and reliable and suitable for instrument with a lumen.• Unsuitable for heat-sensitive items

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Chemical disinfectants• Destroys microorganisms by chemical or physicochemical means

• Different organisms vary in their sensitivity • Gram-positive - highly sensitive• Gram-negative - relatively resistant• Clostridial & mycobacterial species - very resistant• Slow viruses - highly resistant

• Disinfectants are suitable for heat-sensitive items• Less effective than heat• chemicals used include:

• Cetrimide• Chlorhexidine • Clear soluble phenolics• Hypochlorites• Alcohols• Quaternary ammonium compounds

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STERILIZATIONCan be achieved by: Physical method

• Autoclaves• Hot air ovens• Irradiation• Filtration

Chemical method • Ethylene oxide• Low-temperature steam and formaldehyde• Sporicidal chemicals• Gas plasma

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AUTOCLAVES• Steam under pressure has a higher temperature than 100 C• To be effective against viruses and spore forming bacteria need to• Have steam in direct contact with material• Vacuum has to be created• Need to autoclave for 3 min at 134 °C or 15 min at 121 °C• Check performance by colour changes on indicator tape• Autoclaves are highly effective and inexpensive• Unsuitable for heat-sensitive objects

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Hot ovens• Inefficient compared to autoclaves• Requires temperatures of 160 °C for 2 hours or 180 °C for 30 min

Irradiation•Gamma rays and accelerated electrons are excellent at sterilization•Used as an industrial rather than hospital based method

Ethylene oxide•Highly-penetrative and active against bacteria, spores and viruses•Also flammable, toxic and expensive•Leaves toxic residue on sterilised items•Instruments therefore need to be stored for prolonged period before use•Suitable for heat-sensitive items

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• FILTRATION• used in sterilization of air in the theatre• also used by microbiologists to sterilize fluids containing

sera and aas denatured by heat• commonly used filters: seitz filters – made of asbestos

discs• sintered-glass filters – made of finely-ground glass

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Sporicidal chemicals• Often used as disinfectants but can also sterilise instruments if

used for prolonged period• Inexpensive and suitable for heat-sensitive items• Toxic and irritants• 2% Gluteraldehyde is most widely used liquid sporicidal chemical•Most bacteria and viruses killed within 10 minutes• Spores can survive several hours

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Peri- operative antiseptic techniquePRE-OPERATIVETreatment of active infections at site of surgical incision.Pre-Operative stay as short as possible.Good bath with antibacterial preparationBowel preparationPatient to wear a clean gown Shaving(on table) in OR

- Depilatory creams- Electric chippers- Scalpal blade*

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•Washing of surgical site• Skin preparation is the most important method of

decreasing infection.•Pre-op antibiotics at induction.

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Skin preparationSkin shaving• Aesthetic and makes surgery, suture and dressing removal easier•Wound infection rate lowest when performed immediately prior to

surgery• Infection rate increased from 1% to 5% if performed more than 12

hours prior to surgery• Abrasions can cause colonisation which can lead to wound

infection• Clippers or depilatory creams reduce infection rates to less than

1%.

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Skin preparation70% Isopropyl alcohol

• Acts by denaturing proteins• Is bactericidal but short acting• Effective against gram-positive and gram-negative organisms• Also fungicidal and virucidal

0.5% Chlorhexidine • Quaternary ammonium compound• Acts by disrupting the bacterial cell wall• Bactericidal but does not kill spore forming organisms• It is persistent and has a long duration of action (up to 6 hours)• More effective against gram-positive organisms

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70% Povidone - iodine • Acts by oxidation / substitution of free iodine• Bactericidal and active against spore forming organisms• Effective against both gram-positive and gram-negative

organisms• Rapidly inactivated by organic material such as blood• Patient skin sensitivity is occasionally a problem• No evidence that one is superior to any other

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• In skin preparation, begin with the area where the incision is to be made outwards in ever increasing circles. The surgeon never returns the cleansing sponge to the incision site from the periphery.• He also should never return the sponge to the cleansing

solution.

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Theatre Design:• The 1° source of perioperative infection is the patient & the 2° sources are

the OR Team. OR.• - Should provide an environment that is as free of bacterial

contamination as possible• Strict control of human traffic• Minimum size:• - 20 x 20 feet, (temp = 20-22°C, 60%humidity)• - should be spacious for gowning of operating team, draping of

patient & allow for free movmt of members of the surgical team.• Very low concn of air borne particulate matter & bacteria which is

achieved by: -

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•Changing room air 20-25 times per hr•Passing air through High –efficiency particulate Air (HEPA)

Filter.•Pattern of air flow must be adequate•All OR doors should remain closed•Positive air pressure in the OR to prevent air entry.•OR Team: -• The preparation & conduct of the OR Team are of

paramount importance in the aseptic treatment of the surgical patient.

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• Good personal hygiene• Scrub hands & arms to elbow with antiseptic solution before each

operation• Sterile gowns• caps• Face masks• Surgical gloves• Use of reinforced gowns• Move face-to-face or back-to-back

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• Draping of patient: -• Sterile drapes to define and preserve the sterile field of operation.• Drapes should be made of re-usable or disposable fabrics that has

been shown to be nearly impermeable to bacteria even when wet.• In draping, materials should be held above waist level in a compact

position.• Drape from the operative site to the periphery.• Once placed in position drapes should never be moved or lifted. • Monitor drapes• Drapes cables.

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• Use Of Sterilized Equipment/materials• Surgical equipment• Prosthesis/implants• Xenografts etc.

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• INTRA OPERATIVE•Halstedian Teaching: -• 1. Gentle handling of tissues• 2. Careful haemostasis• 3. Appropriate irrigation.• These principles remain valid till today

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• Incision• Atraumatic handling of tissues• Dissection• Changing of torn gloves • Debridement• Haemostasis• Electocautery• Wound closure (Do not close the skin in contaminated case !)• Suturing• Draining• Irrigation• Dressing• Control of sweating.

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POST OPERATIVE• Dirty & biologically contaminated materials are subjected to regulated

disposal• Immobilization• Prophylactic antibiotics• Removal of sutures.• Timely removal of drains

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Conclusion • Asepsis and antisepsis are an imperative in surgery.• The patient is the most important source of infection, then followed

by members of the surgical team and, of course the condition of the OR.• Therefore, sterilization of instruments & equipment; adequate skin

preparation & draping; preparation, clothing & techniques of the surgical team must not be compromised.