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Asepsis, Antisepsis and Skin Preparation
INFECTION
most common organism isolated from SSIs. This organism is usually acquired from the hands of HCW. Antisepsis is the removal or destruction of the transient flora.
Asepsis, Antisepsis and Skin Preparation
Hand hygiene The degree of hand cleaning required depends on a number of factors, such as the procedure being performed and the vulnerability of the patient to infection. All hand cleaning should remove visible dirt and it is advisable that rings, watches and bracelets are removed, since they may harbour and protect micro-organisms from removal. The terms used in relation to hand hygiene are varied and lead to confusion. For example, the terms ‘surgical hand scrub’ and ‘anatomical scrub’ both describe the cleaning of hands prior to a surgical procedure. The practice of hand hygiene in the non-surgical setting has numerous terms to describe it, including ‘handwashing’, ‘hand disinfection’ and ‘hand scrub’. The European Standard definitions clarify the situation. The term ‘hygienic hand wash’ is defined as a ‘post-contamination procedure that involves washing hands using a bactericidal product active against transient organisms in order to prevent their transmission’. A ‘hygienic hand rub’ has the same aim, but is a ‘procedure that involves rubbing hands with a bactericidal agent without the addition of water, usually an alcohol-based agent’. ‘Handwashing’ refers to ‘washing hands without bactericidal products’. It removes dirt and some transient flora. Plain soap and water is sufficient. In clinical practice however, hand hygiene is rarely based on handwashing alone. In most countries, antiseptic agents are used either in addition to handwashing or as the single recommended method.
Nicki Hutchinson
Surgical site infections (SSIs) are a common cause of nosocomial infections. They account for 10–16% of all nosocomial infections. Approximately two-thirds of SSIs are confined to the incision, whereas the remainder involve organs or the spaces involved in the surgical procedure. SSIs have a significant morbidity and mortality, as well as increased cost and prolonged postoperative stay. SSIs can occur both peri- and postoperatively, and skin is a major potential source of microbial contamination. Therefore, not only is it important to create and maintain a sterile field operatively, but good hand hygiene is an important component of postoperative care. Asepsis is defined as a process or procedure performed under conditions in which bacterial contamination has been minimized. Historical background In 1847, Semmelweis suggested that surgeon’s hands could be transmitting puerperal sepsis to postnatal women. He reported a dramatic reduction of puerperal fever after the introduction of soaking hands in chlorinated lime after handwashing between treating patients. In 1865, Lister published his theory of asepsis, associating infection with the transfer of bacteria. Prior to this the belief was that bacteria were spontaneously generated when organic tissue was exposed to air. Lister introduced hand antisepsis to surgical practice by pouring carbolic acid over his hands prior to surgery. This brought about a dramatic reduction in surgical infections. It was the reduction of surgical sepsis by hand antisepsis which paved the way for the development of safe surgery.
Hand hygiene in the non-surgical setting The comparison of the indications for hand hygiene show there is no international consensus on situations in which hands should be decontaminated. Hand hygiene is most often recommended before performing invasive procedures and contact with wounds, catheter and drainage sites, and after microbial contamination which can be difficult to determine. The UK has recently produced evidence-based guidelines (Epidemiology and Prevention for Injury Control or EPIC) for hand hygiene and these clarify the matter by recommending the use of some form of hand antisepsis before and after every episode of patient contact. Average compliance with hand hygiene recommendations is below 50% and a large number of barriers have been reported (Figure 1). Studies show that HCW clean their hands far less frequently than they perceive. There have been a number of reported risk factors for lack of adherence to hand hygiene, and these include: • physician status (as opposed to nurse) • male gender • working in an intensive therapy unit • wearing gloves/gowns • performing activities associated with a high risk of crosscontamination. There have been a number of reports which have shown improved hand hygiene after the introduction of alcohol hand gel at the patient bedside. This has been shown to be most effective if combined with continuing education, feedback of infection rates and frequent audit. The hand gel contains an
Bacterial flora The bacterial flora of hands is traditionally divided into 2 groups: resident and transient flora. Resident flora are organisms that are consistently isolated from the hands of most people, and include coagulase-negative staphlyococci, corynebacteria, proprionibacteria, Acinetobacter and sometimes enterobacteriaciae. Transient flora are bacteria that can be isolated from the skin (especially the hands of health care workers (HCW)) but are not consistently present in the normal population. An example of this is Staphylococcus aureus (S. aureus) (and methicillinresistant Staphylococcuc aureus or MRSA). A recent large study in the UK has shown that S. aureus (and especially MRSA) is the
Nicki Hutchinson is Consultant Microbiologist at the Royal Free Hospital, London, UK. She qualified from St George’s Medical School, London, UK and trained in Medical Microbiology in London and on the South coast of the UK. She is also Infection Control Doctor for the Trust. Her research interests include GU and gynaecological infections and infection control.
SURGERY
190
© 2002 The Medicine Publishing Company Ltd
INFECTION
Barriers to good hand hygiene • • • • • • • • • • • • • • •
Essential components of a surgical scrub
Hand hygiene agents cause irritation and drying Shortage of sink or bad location Lack of soap and paper towels Surgeon is too busy Understaffing/overcrowding Other patient needs take priority Hand hygiene interferes with HCW–patient relationship Low level of risk of acquiring infection from patient Using gloves as substitute Lack of knowledge of guidelines Forgetfulness No role model from colleagues or superiors Scepticism of effectiveness Disagreement with guidelines Lack of awareness of improved hand hygiene on hospitalacquired infections
HCW, Health care worker Source: D Pittet. Compliance with hand disinfection and its impact on hospital acquired infections. J Hosp Infect 2001; 48 (suppl A): S40–S46.
Comments A short pre-scrub wash loosens surface debris and transient micro-organisms
Subungual areas should be cleaned under running water using a nail cleaner
Poorly cleaned subungal areas can harbour organisms
An antimicrobial agent should be applied with friction to the wet hands and forearms
Vigorous rubbing is required to remove dirt, transient organisms and some resident bacterial flora
Fingers, hands and arms should be visualized as having four sides, each requiring scrubbing
A scrub is effective only if all surfaces are cleaned
Hands should be held higher This prevents contamination than the elbows and away from and allows water to run from the surgical attire to the arm cleanest area down
1
emollient which prevents drying of the skin, is fast-acting and easy to use. Surgical scrub The purpose of the surgical hand scrub is to: • remove debris and transient micro-organisms from the nails, hand and forearms • reduce the resident flora to a minimum • inhibit rapid rebound growth of bacteria. The antimicrobial hand scrub agent should significantly reduce micro-organisms on intact skin, be non-irritating, broad-spectrum, fast-acting and have a residual effect. Organisms proliferate in the moist environment produced by wearing gloves, and gloves frequently become damaged during surgical procedures. For this reason, it is desirable that the antimicrobial agent used has persistent chemical activity to suppress microbial growth. Agents such as chlorhexidine gluconate, iodophors and triclosan demonstrate such residual activity. This is achieved by the agent binding to the stratum corneum. Across the world, there is much variation in: • the type of surgical scrub, i.e. with or without the use of brushes • the duration of surgical scrub (this usually varies between 2 and 6 minutes) • the antimicrobial agent used. In Europe, alcohol-based agents are preferred, whilst in the USA, chlorhexidine or iodophors are used. Figure 2 describes the basis of a surgical scrub.
Brushes or sponges should be discarded appropriately
This prevents cross contamination. Re-usable brushes should be decontaminated and sterilised before re-use
Avoid splashing water onto surgical attire
If a sterile gown is worn over damp surgical attire, contamination of the gown will occur by strikethrough moisture
Subsequent hand scrubs should follow the same procedure, as bacteria rapidly multiply in the moist, warm environment of a gloved hand
Although studies show a reduction in micro-organisms for a long time after the initial scrub and a cumulative effect after several scrubs, this effect may not be consistent and depends on the antiseptic agent used and the diligence of the HCW.
2
fingertip increase the risk of tearing gloves. Recent studies have shown that freshly applied nail varnish is not related to increased microbial growth. However, nail varnish that has been worn for more than 4 days or is chipped has a tendency to harbour greater numbers of bacteria. Artificial nails should not be worn, as higher numbers of Gram-negative bacteria have been cultured from the fingertips of people wearing them. It has also been shown that fungal growth occurs frequently under artificial nails due to moisture being trapped between the natural and artificial nail.
Fingernails Fingernails should be kept short, clean and healthy, since the subungual region harbours the majority of organisms found on the hand. Dirt from fingernails should be removed using a nail cleaner under running water. Fingernails extending past the
SURGERY
Action Thoroughly moistened hands and forearms should be washed using an approved surgical scrub agent and rinsed before the surgical scrub
191
© 2002 The Medicine Publishing Company Ltd
INFECTION
Activity of antiseptic agents Mode of action Denaturation of protein Chlorhexidine Disruption of cell wall Alcohols
Triclosan Iodine/ Iodophores
Disruption of cell wall Oxidation/ substitution of free iodine
Gram +ve bacteria +++
Gram -ve bacteria +++
Fungi
Viruses
++
++
+++
++
+
++ +++
+/++ ++
_ ++
++ enveloped ? ++
Rapidity of action +++
Residual activity _
Affect of organic material Minimal
++
+++ 6 hours +++ +
Minimal
++ ++
Minimal Yes, above pH 4
Source: Larson E. Skin Cleansing. In: Wenzel R P, ed. Prevention and Control of Nosocomial Infections. 2nd edition. Baltimore: Williams and Wilkins, 1992: 450–7.
3
Antiseptic agents It is important to consider a number of factors when choosing an antiseptic agent, including: • the properties of the agent (e.g. spectrum and rapidity of action and degree of persistence) • safety • acceptability to staff (i.e. presence of emollients, perfume, absorption and degree of irritation). Products should always be used in accordance with the manufacturer’s instructions and HCW should be given clear guidelines for use. The activity of antiseptic agents is described in Figure 3.
Patient preparation The length of time a patient is in hospital preoperatively is directly related to the risk of SSIs. This is probably due to the patient becoming heavily colonized with hospital flora such as MRSA and multi-resistant Gram-negative organisms. It is for this reason some authorities (such as the Centers for Disease Control and Prevention) recommend that patients shower or bath with an antiseptic agent (such as hexachlorophane) preoperatively. Preoperative hair removal, if necessary, should be done by depilatory, as this is associated with a reduced SSIs risk. If shaving or clipping of hair is required, this should be done immediately prior to the procedure to reduce bacterial colonization of nicks to the skin which occur during shaving. The patients skin should be treated at the time of surgery with an effective antiseptic. These are usually either 1% iodine in 70% alcohol or 0.5% chlorhexidine in 70% alcohol. The antiseptic should be generously applied to the surgical site and allowed to dry. It is important to take care with the use of diathermy and alcohol solutions in order to prevent burns.
Other factors • Damage to skin: the antiseptic agents used to prepare the surgeon’s and patient’s skin can cause drying, cracking and dermatitis. Regular users of latex gloves may also develop an allergy to the latex, thereby destroying the integrity of the skin. Any damage to the skin puts the HCW at increased risk if they are exposed to blood-borne viruses. Bacteria proliferate in cracks in the skin and it is difficult to clean adequately. It is important that surgeon ensure that their skin is kept in the best possible condition and this includes the use of hand lotions, with should be freely available in all clinical areas. Lotions containing oils or petroleum jelly may damage latex gloves. For those who suffer an allergy to latex cotton and vinyl, under-gloves or latex-free gloves are available. • Glove use: gloves are no substitute for good hand hygiene and inappropriate use can put both patients and HCW at risk. Gloves are used to provide a barrier against microbial transmission between HCW and patient. If gloves are used, they should be changed frequently and hands cleaned after use, since bacterial transmission has occurred even when gloves are used. • Product containers: the containers in which antiseptic agents are stored should be small and disposable as large containers are liable to contamination. If it is necessary to use large containers, then they must be cleaned thoroughly before refilling. u
Drapes Sterile drapes are almost universally used to establish a sterile field. The function of surgical drapes is to establish an aseptic barrier that minimizes the passage of micro-organisms between non-sterile and sterile areas. The drapes should be placed on the patient, furniture and equipment that is to be included in the sterile field. The drapes should be handled infrequently and rapid movements avoided, as this creates air currents on which particles (e.g. dust) can migrate and contaminate the surgical site. The type of drape (i.e. cotton versus disposable) depends on a number of factors, including cost. Cotton drapes are inexpensive and can be used many times before discarding. However, they require careful laundering and autoclaving between each use and they may absorb blood and moisture, which provides an ideal culture medium. Disposable, prefabricated, single-use drapes are more expensive. However, they do not require laundering and can be coated with a water repellent. Higher postoperative SSIs have been associated with the use of a plastic adhesive strip attaching the drapes to the surgical site. This has been thought to be due to the sweating that occurs under the occlusive plastic strips, which provides an ideal medium for bacteria to flourish.
SURGERY
FURTHER READING Beyea S C. Preventing surgical site infections—guiding practice with evidence. AORN J 2000; 72(2): 305–7.
192
© 2002 The Medicine Publishing Company Ltd
most common organism isolated from SSIs. This organism is usually acquired from the hands of HCW. Antisepsis is the removal or destruction of the transient flora.
Asepsis, Antisepsis and Skin Preparation
Hand hygiene The degree of hand cleaning required depends on a number of factors, such as the procedure being performed and the vulnerability of the patient to infection. All hand cleaning should remove visible dirt and it is advisable that rings, watches and bracelets are removed, since they may harbour and protect micro-organisms from removal. The terms used in relation to hand hygiene are varied and lead to confusion. For example, the terms ‘surgical hand scrub’ and ‘anatomical scrub’ both describe the cleaning of hands prior to a surgical procedure. The practice of hand hygiene in the non-surgical setting has numerous terms to describe it, including ‘handwashing’, ‘hand disinfection’ and ‘hand scrub’. The European Standard definitions clarify the situation. The term ‘hygienic hand wash’ is defined as a ‘post-contamination procedure that involves washing hands using a bactericidal product active against transient organisms in order to prevent their transmission’. A ‘hygienic hand rub’ has the same aim, but is a ‘procedure that involves rubbing hands with a bactericidal agent without the addition of water, usually an alcohol-based agent’. ‘Handwashing’ refers to ‘washing hands without bactericidal products’. It removes dirt and some transient flora. Plain soap and water is sufficient. In clinical practice however, hand hygiene is rarely based on handwashing alone. In most countries, antiseptic agents are used either in addition to handwashing or as the single recommended method.
Nicki Hutchinson
Surgical site infections (SSIs) are a common cause of nosocomial infections. They account for 10–16% of all nosocomial infections. Approximately two-thirds of SSIs are confined to the incision, whereas the remainder involve organs or the spaces involved in the surgical procedure. SSIs have a significant morbidity and mortality, as well as increased cost and prolonged postoperative stay. SSIs can occur both peri- and postoperatively, and skin is a major potential source of microbial contamination. Therefore, not only is it important to create and maintain a sterile field operatively, but good hand hygiene is an important component of postoperative care. Asepsis is defined as a process or procedure performed under conditions in which bacterial contamination has been minimized. Historical background In 1847, Semmelweis suggested that surgeon’s hands could be transmitting puerperal sepsis to postnatal women. He reported a dramatic reduction of puerperal fever after the introduction of soaking hands in chlorinated lime after handwashing between treating patients. In 1865, Lister published his theory of asepsis, associating infection with the transfer of bacteria. Prior to this the belief was that bacteria were spontaneously generated when organic tissue was exposed to air. Lister introduced hand antisepsis to surgical practice by pouring carbolic acid over his hands prior to surgery. This brought about a dramatic reduction in surgical infections. It was the reduction of surgical sepsis by hand antisepsis which paved the way for the development of safe surgery.
Hand hygiene in the non-surgical setting The comparison of the indications for hand hygiene show there is no international consensus on situations in which hands should be decontaminated. Hand hygiene is most often recommended before performing invasive procedures and contact with wounds, catheter and drainage sites, and after microbial contamination which can be difficult to determine. The UK has recently produced evidence-based guidelines (Epidemiology and Prevention for Injury Control or EPIC) for hand hygiene and these clarify the matter by recommending the use of some form of hand antisepsis before and after every episode of patient contact. Average compliance with hand hygiene recommendations is below 50% and a large number of barriers have been reported (Figure 1). Studies show that HCW clean their hands far less frequently than they perceive. There have been a number of reported risk factors for lack of adherence to hand hygiene, and these include: • physician status (as opposed to nurse) • male gender • working in an intensive therapy unit • wearing gloves/gowns • performing activities associated with a high risk of crosscontamination. There have been a number of reports which have shown improved hand hygiene after the introduction of alcohol hand gel at the patient bedside. This has been shown to be most effective if combined with continuing education, feedback of infection rates and frequent audit. The hand gel contains an
Bacterial flora The bacterial flora of hands is traditionally divided into 2 groups: resident and transient flora. Resident flora are organisms that are consistently isolated from the hands of most people, and include coagulase-negative staphlyococci, corynebacteria, proprionibacteria, Acinetobacter and sometimes enterobacteriaciae. Transient flora are bacteria that can be isolated from the skin (especially the hands of health care workers (HCW)) but are not consistently present in the normal population. An example of this is Staphylococcus aureus (S. aureus) (and methicillinresistant Staphylococcuc aureus or MRSA). A recent large study in the UK has shown that S. aureus (and especially MRSA) is the
Nicki Hutchinson is Consultant Microbiologist at the Royal Free Hospital, London, UK. She qualified from St George’s Medical School, London, UK and trained in Medical Microbiology in London and on the South coast of the UK. She is also Infection Control Doctor for the Trust. Her research interests include GU and gynaecological infections and infection control.
SURGERY
190
© 2002 The Medicine Publishing Company Ltd
INFECTION
Barriers to good hand hygiene • • • • • • • • • • • • • • •
Essential components of a surgical scrub
Hand hygiene agents cause irritation and drying Shortage of sink or bad location Lack of soap and paper towels Surgeon is too busy Understaffing/overcrowding Other patient needs take priority Hand hygiene interferes with HCW–patient relationship Low level of risk of acquiring infection from patient Using gloves as substitute Lack of knowledge of guidelines Forgetfulness No role model from colleagues or superiors Scepticism of effectiveness Disagreement with guidelines Lack of awareness of improved hand hygiene on hospitalacquired infections
HCW, Health care worker Source: D Pittet. Compliance with hand disinfection and its impact on hospital acquired infections. J Hosp Infect 2001; 48 (suppl A): S40–S46.
Comments A short pre-scrub wash loosens surface debris and transient micro-organisms
Subungual areas should be cleaned under running water using a nail cleaner
Poorly cleaned subungal areas can harbour organisms
An antimicrobial agent should be applied with friction to the wet hands and forearms
Vigorous rubbing is required to remove dirt, transient organisms and some resident bacterial flora
Fingers, hands and arms should be visualized as having four sides, each requiring scrubbing
A scrub is effective only if all surfaces are cleaned
Hands should be held higher This prevents contamination than the elbows and away from and allows water to run from the surgical attire to the arm cleanest area down
1
emollient which prevents drying of the skin, is fast-acting and easy to use. Surgical scrub The purpose of the surgical hand scrub is to: • remove debris and transient micro-organisms from the nails, hand and forearms • reduce the resident flora to a minimum • inhibit rapid rebound growth of bacteria. The antimicrobial hand scrub agent should significantly reduce micro-organisms on intact skin, be non-irritating, broad-spectrum, fast-acting and have a residual effect. Organisms proliferate in the moist environment produced by wearing gloves, and gloves frequently become damaged during surgical procedures. For this reason, it is desirable that the antimicrobial agent used has persistent chemical activity to suppress microbial growth. Agents such as chlorhexidine gluconate, iodophors and triclosan demonstrate such residual activity. This is achieved by the agent binding to the stratum corneum. Across the world, there is much variation in: • the type of surgical scrub, i.e. with or without the use of brushes • the duration of surgical scrub (this usually varies between 2 and 6 minutes) • the antimicrobial agent used. In Europe, alcohol-based agents are preferred, whilst in the USA, chlorhexidine or iodophors are used. Figure 2 describes the basis of a surgical scrub.
Brushes or sponges should be discarded appropriately
This prevents cross contamination. Re-usable brushes should be decontaminated and sterilised before re-use
Avoid splashing water onto surgical attire
If a sterile gown is worn over damp surgical attire, contamination of the gown will occur by strikethrough moisture
Subsequent hand scrubs should follow the same procedure, as bacteria rapidly multiply in the moist, warm environment of a gloved hand
Although studies show a reduction in micro-organisms for a long time after the initial scrub and a cumulative effect after several scrubs, this effect may not be consistent and depends on the antiseptic agent used and the diligence of the HCW.
2
fingertip increase the risk of tearing gloves. Recent studies have shown that freshly applied nail varnish is not related to increased microbial growth. However, nail varnish that has been worn for more than 4 days or is chipped has a tendency to harbour greater numbers of bacteria. Artificial nails should not be worn, as higher numbers of Gram-negative bacteria have been cultured from the fingertips of people wearing them. It has also been shown that fungal growth occurs frequently under artificial nails due to moisture being trapped between the natural and artificial nail.
Fingernails Fingernails should be kept short, clean and healthy, since the subungual region harbours the majority of organisms found on the hand. Dirt from fingernails should be removed using a nail cleaner under running water. Fingernails extending past the
SURGERY
Action Thoroughly moistened hands and forearms should be washed using an approved surgical scrub agent and rinsed before the surgical scrub
191
© 2002 The Medicine Publishing Company Ltd
INFECTION
Activity of antiseptic agents Mode of action Denaturation of protein Chlorhexidine Disruption of cell wall Alcohols
Triclosan Iodine/ Iodophores
Disruption of cell wall Oxidation/ substitution of free iodine
Gram +ve bacteria +++
Gram -ve bacteria +++
Fungi
Viruses
++
++
+++
++
+
++ +++
+/++ ++
_ ++
++ enveloped ? ++
Rapidity of action +++
Residual activity _
Affect of organic material Minimal
++
+++ 6 hours +++ +
Minimal
++ ++
Minimal Yes, above pH 4
Source: Larson E. Skin Cleansing. In: Wenzel R P, ed. Prevention and Control of Nosocomial Infections. 2nd edition. Baltimore: Williams and Wilkins, 1992: 450–7.
3
Antiseptic agents It is important to consider a number of factors when choosing an antiseptic agent, including: • the properties of the agent (e.g. spectrum and rapidity of action and degree of persistence) • safety • acceptability to staff (i.e. presence of emollients, perfume, absorption and degree of irritation). Products should always be used in accordance with the manufacturer’s instructions and HCW should be given clear guidelines for use. The activity of antiseptic agents is described in Figure 3.
Patient preparation The length of time a patient is in hospital preoperatively is directly related to the risk of SSIs. This is probably due to the patient becoming heavily colonized with hospital flora such as MRSA and multi-resistant Gram-negative organisms. It is for this reason some authorities (such as the Centers for Disease Control and Prevention) recommend that patients shower or bath with an antiseptic agent (such as hexachlorophane) preoperatively. Preoperative hair removal, if necessary, should be done by depilatory, as this is associated with a reduced SSIs risk. If shaving or clipping of hair is required, this should be done immediately prior to the procedure to reduce bacterial colonization of nicks to the skin which occur during shaving. The patients skin should be treated at the time of surgery with an effective antiseptic. These are usually either 1% iodine in 70% alcohol or 0.5% chlorhexidine in 70% alcohol. The antiseptic should be generously applied to the surgical site and allowed to dry. It is important to take care with the use of diathermy and alcohol solutions in order to prevent burns.
Other factors • Damage to skin: the antiseptic agents used to prepare the surgeon’s and patient’s skin can cause drying, cracking and dermatitis. Regular users of latex gloves may also develop an allergy to the latex, thereby destroying the integrity of the skin. Any damage to the skin puts the HCW at increased risk if they are exposed to blood-borne viruses. Bacteria proliferate in cracks in the skin and it is difficult to clean adequately. It is important that surgeon ensure that their skin is kept in the best possible condition and this includes the use of hand lotions, with should be freely available in all clinical areas. Lotions containing oils or petroleum jelly may damage latex gloves. For those who suffer an allergy to latex cotton and vinyl, under-gloves or latex-free gloves are available. • Glove use: gloves are no substitute for good hand hygiene and inappropriate use can put both patients and HCW at risk. Gloves are used to provide a barrier against microbial transmission between HCW and patient. If gloves are used, they should be changed frequently and hands cleaned after use, since bacterial transmission has occurred even when gloves are used. • Product containers: the containers in which antiseptic agents are stored should be small and disposable as large containers are liable to contamination. If it is necessary to use large containers, then they must be cleaned thoroughly before refilling. u
Drapes Sterile drapes are almost universally used to establish a sterile field. The function of surgical drapes is to establish an aseptic barrier that minimizes the passage of micro-organisms between non-sterile and sterile areas. The drapes should be placed on the patient, furniture and equipment that is to be included in the sterile field. The drapes should be handled infrequently and rapid movements avoided, as this creates air currents on which particles (e.g. dust) can migrate and contaminate the surgical site. The type of drape (i.e. cotton versus disposable) depends on a number of factors, including cost. Cotton drapes are inexpensive and can be used many times before discarding. However, they require careful laundering and autoclaving between each use and they may absorb blood and moisture, which provides an ideal culture medium. Disposable, prefabricated, single-use drapes are more expensive. However, they do not require laundering and can be coated with a water repellent. Higher postoperative SSIs have been associated with the use of a plastic adhesive strip attaching the drapes to the surgical site. This has been thought to be due to the sweating that occurs under the occlusive plastic strips, which provides an ideal medium for bacteria to flourish.
SURGERY
FURTHER READING Beyea S C. Preventing surgical site infections—guiding practice with evidence. AORN J 2000; 72(2): 305–7.
192
© 2002 The Medicine Publishing Company Ltd