Inhriw and Ctifical Carr Nursing ( 1992) 8,2 12-2 16 0 Longman Group UK Ltd 1992
Infection control in the intensive care unit Andrew Kingsley INTRODUCTION Work and research surrounding the issue of infection permits the assumption that the lower the level of health and the higher the level of interventionist care a patient experiences, the greater their increasing level of infection risk. Intensive Care Unit (ICU) patients are thus routinely placed at a high level of risk. Coupled with this is the arguably greater potential impact of infection over many other patient groups. For these reasons it is imperative that infection control practices are of the highest possible standard at all times. In the ICU infection control nurse input is likely to aim at affirming infection control consciousness and the investigation of cases of infection. A clear written research-based infection control strategy on all aspects of patient management, equipment and environmental care, (perhaps in the form of standards) would possibly be the best way to highlight the need for infection prevention in these critical care areas.
INFECTION RISKS FOR ICU PATIENTS An ICU patient is constantly at risk of infection whilst in a dependent state. The following is a list of probably the main types of infections of which a typical ICU patient is at risk: Andrew Kingsley, Infection Control Nurse, East Gloucestershire National Health Service Trust, Cheltenham General Hospital, Sandford Road, Cheltenham GL53 7AN (Requests for offprints to AK) Manuscript 212
accepted 1 September
1992
- Pneumonia - associated with assisted ventilation. - Bacteraemia - associated with intravascular cannulation. - Urinary tract infection - associated with bladder catheterisation. Literature relating to thse conditions will be discussed in this paper. ICU patients are also vulnerable to a whole range of other infections dependent upon their individual circumstances. These are likely to include wound, oral and eye infections.
LITERATURE REVIEW Massanari (1989) highlights the predicament of ICU patients by saying that their vulnerability to infection is augmented by the very interventions employed to keep them alive. He goes on to remark that to understand the cause of infection and its subsequent prevention a conceptual model of three elements must be considered in each case, the host (patient), the environment, and the infectious agent.
Pneumonia Meers et al (1980) discovered that 16.8% of nosocomial infections in the United Kingdom were of the lower respiratory tract. Nosocomial pneumonia is of concern in the ICU because of its high morbidity, mortality and cost (Craven & Kegan, 1989). Inglis et al (1989) noted a key observation from various studies tracking the infection source of the ventilated airway, that it is commonly the patient’s own gastrointestinal flora. Two ways of preventing this have been described, firstly gut decontamination using
INTENSIVE AND CRITICAL CARE NURSING
enteral antibiotics and secondly through maintenance of gastric acidity. Zandstra et al (1988) and Ulrich et al (1989) appeared to show a reduction in respiratory infection rate using the first method; however Inglis et al (1989) urge caution with it due to the risks of antibiotic resistance developing. The second method involves a choice of preparation for stress ulceration prophylaxis. Histamine Hz receptor antagonists such as cimetidine allow an increase in gastric pH to prevent acid ulceration. This however allows a more favourable environment for bacterial growth. An alternative to this is sucralfate which does not disturb pH values. Garcia-Labattut et al (1990) and Driks et al’s study cited by Inglis et al (1989) both showed reduction in infection rates when sucralfate was used. However Maful et al (1990) and Colardyn et al (1990) were not able to demonstrate this. Ventilation circuitry has been shown to be a contamination source. Stucke & Thompson (1980) believed they had demonstrated that tubing condensate revealed contamination earlier than sputum and thus shown the infection route was from ventilator to patient. Studies such as this have probably led to a policy of 24 h tubing change. Interestingly, though, Craven et al (1982) found no significant differences in contamination rates of inspiratory-phase gas or tubing colonisation in circuits changed after 24 as compared with 48 h and Djedaini et al (1990) could show no different pneumonia incidence in groups of patients whose ventilator tubing was changed at 24 or 48 h. However, Malecka-Griggs (1986) and Malecka-Griggs, Kennedy & Ross (1989) demonstrated higher microbial counts in circuits changed at 48 h as opposed to 24 h.
Bacteraemia Bacteraemia associated with vascular cannulation is a risk for ICU patients. Just like the endotracheal tube these lines bypass normal body defences. Donowitz et al (1982) reported that 29% of the nosocomial infections in their ICU were bacteraemias in comparison to 12.4% in other areas of the hospital. In an attempt to reduce bacteraemia it is
2 13
common for fluid administration sets to be changed at specified times, often 24 or 48h. However, authors have argued that this period can be increased without any consequent increase in bacteraemia rates. Nystrom et al (1983) in a European multicentre study on surgical patients were unable to demonstrate a correlation between number of catheter days per site for patients with a peripheral intravenous and hospital-acquired bacteraemia. device, Jakobsen et al (1985) concluded there was no benefit of daily replacement of infusion sets rather than changing up to every 5 days, whilst Maki et al (1987) argued that there was no advantage in changing at 48 h rather than 72 h. Arterial lines are another possible site for bacterial contamination and were studied by Shinozak et al (1983). They said that routine changes of arterial line components were not indicated provided that static inline fluid columns were eliminated and proper aseptic precautions in sampling of blood via the stopcock were observed. During their study of 117 patients any individual system parts were replaced if blood clots were visible. With radial artery cannulation bacteraemia related to the catheter or infusate has been found to be unlikely to occur even if the use duration exceeded 4 days (Leroy et al, 1989). Cannula dressings, connecting tubing, stopcocks and infusion solutions were changed daily in this study. It is interesting to note that microparticulateinduced phlebitis is a much more common complication of intravenous therapy than sepsis. Falchuk, Peterson & McNeil (1985) cite Francke (1970) saying that over 10 million patients a year experience this type of phlebitis. Their own studies suggest that by using an in-line filter two-thirds of these cases could be prevented. Only one of the causes postulated for the remaining one-third of cases of phlebitis was bacteria, and these entered the system distal to the filter.
Urinary tract infection Bladder patients
catheterisation is common to many ICU and again this intervention bypasses
214
iNTENSlVEANDCRITI
Infection control in the intensive care unit Andrew Kingsley INTRODUCTION Work and research surrounding the issue of infection permits the assumption that the lower the level of health and the higher the level of interventionist care a patient experiences, the greater their increasing level of infection risk. Intensive Care Unit (ICU) patients are thus routinely placed at a high level of risk. Coupled with this is the arguably greater potential impact of infection over many other patient groups. For these reasons it is imperative that infection control practices are of the highest possible standard at all times. In the ICU infection control nurse input is likely to aim at affirming infection control consciousness and the investigation of cases of infection. A clear written research-based infection control strategy on all aspects of patient management, equipment and environmental care, (perhaps in the form of standards) would possibly be the best way to highlight the need for infection prevention in these critical care areas.
INFECTION RISKS FOR ICU PATIENTS An ICU patient is constantly at risk of infection whilst in a dependent state. The following is a list of probably the main types of infections of which a typical ICU patient is at risk: Andrew Kingsley, Infection Control Nurse, East Gloucestershire National Health Service Trust, Cheltenham General Hospital, Sandford Road, Cheltenham GL53 7AN (Requests for offprints to AK) Manuscript 212
accepted 1 September
1992
- Pneumonia - associated with assisted ventilation. - Bacteraemia - associated with intravascular cannulation. - Urinary tract infection - associated with bladder catheterisation. Literature relating to thse conditions will be discussed in this paper. ICU patients are also vulnerable to a whole range of other infections dependent upon their individual circumstances. These are likely to include wound, oral and eye infections.
LITERATURE REVIEW Massanari (1989) highlights the predicament of ICU patients by saying that their vulnerability to infection is augmented by the very interventions employed to keep them alive. He goes on to remark that to understand the cause of infection and its subsequent prevention a conceptual model of three elements must be considered in each case, the host (patient), the environment, and the infectious agent.
Pneumonia Meers et al (1980) discovered that 16.8% of nosocomial infections in the United Kingdom were of the lower respiratory tract. Nosocomial pneumonia is of concern in the ICU because of its high morbidity, mortality and cost (Craven & Kegan, 1989). Inglis et al (1989) noted a key observation from various studies tracking the infection source of the ventilated airway, that it is commonly the patient’s own gastrointestinal flora. Two ways of preventing this have been described, firstly gut decontamination using
INTENSIVE AND CRITICAL CARE NURSING
enteral antibiotics and secondly through maintenance of gastric acidity. Zandstra et al (1988) and Ulrich et al (1989) appeared to show a reduction in respiratory infection rate using the first method; however Inglis et al (1989) urge caution with it due to the risks of antibiotic resistance developing. The second method involves a choice of preparation for stress ulceration prophylaxis. Histamine Hz receptor antagonists such as cimetidine allow an increase in gastric pH to prevent acid ulceration. This however allows a more favourable environment for bacterial growth. An alternative to this is sucralfate which does not disturb pH values. Garcia-Labattut et al (1990) and Driks et al’s study cited by Inglis et al (1989) both showed reduction in infection rates when sucralfate was used. However Maful et al (1990) and Colardyn et al (1990) were not able to demonstrate this. Ventilation circuitry has been shown to be a contamination source. Stucke & Thompson (1980) believed they had demonstrated that tubing condensate revealed contamination earlier than sputum and thus shown the infection route was from ventilator to patient. Studies such as this have probably led to a policy of 24 h tubing change. Interestingly, though, Craven et al (1982) found no significant differences in contamination rates of inspiratory-phase gas or tubing colonisation in circuits changed after 24 as compared with 48 h and Djedaini et al (1990) could show no different pneumonia incidence in groups of patients whose ventilator tubing was changed at 24 or 48 h. However, Malecka-Griggs (1986) and Malecka-Griggs, Kennedy & Ross (1989) demonstrated higher microbial counts in circuits changed at 48 h as opposed to 24 h.
Bacteraemia Bacteraemia associated with vascular cannulation is a risk for ICU patients. Just like the endotracheal tube these lines bypass normal body defences. Donowitz et al (1982) reported that 29% of the nosocomial infections in their ICU were bacteraemias in comparison to 12.4% in other areas of the hospital. In an attempt to reduce bacteraemia it is
2 13
common for fluid administration sets to be changed at specified times, often 24 or 48h. However, authors have argued that this period can be increased without any consequent increase in bacteraemia rates. Nystrom et al (1983) in a European multicentre study on surgical patients were unable to demonstrate a correlation between number of catheter days per site for patients with a peripheral intravenous and hospital-acquired bacteraemia. device, Jakobsen et al (1985) concluded there was no benefit of daily replacement of infusion sets rather than changing up to every 5 days, whilst Maki et al (1987) argued that there was no advantage in changing at 48 h rather than 72 h. Arterial lines are another possible site for bacterial contamination and were studied by Shinozak et al (1983). They said that routine changes of arterial line components were not indicated provided that static inline fluid columns were eliminated and proper aseptic precautions in sampling of blood via the stopcock were observed. During their study of 117 patients any individual system parts were replaced if blood clots were visible. With radial artery cannulation bacteraemia related to the catheter or infusate has been found to be unlikely to occur even if the use duration exceeded 4 days (Leroy et al, 1989). Cannula dressings, connecting tubing, stopcocks and infusion solutions were changed daily in this study. It is interesting to note that microparticulateinduced phlebitis is a much more common complication of intravenous therapy than sepsis. Falchuk, Peterson & McNeil (1985) cite Francke (1970) saying that over 10 million patients a year experience this type of phlebitis. Their own studies suggest that by using an in-line filter two-thirds of these cases could be prevented. Only one of the causes postulated for the remaining one-third of cases of phlebitis was bacteria, and these entered the system distal to the filter.
Urinary tract infection Bladder patients
catheterisation is common to many ICU and again this intervention bypasses
214
iNTENSlVEANDCRITI
