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Reducing the risk of catheter-related urinary tract infection.

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VOL: 101, ISSUE: 12, PAGE NO: 64

Linda Bissett, RN, BN, SPQ Infection Control, is infection control nurse, NHS Tayside, Primary Care Division, Murray Royal Hospital, Perth

The implications for patients of developing a catheter-related UTI range from discomfort to bacteraemia, with resulting morbidity and mortality. It is estimated that 1-4 per cent of catheterised patients with a UTI go on to develop bacteraemia, with a mortality rate of between 13 to 30 per cent among this group (Stamm, 1998). The risk of developing a catheter-related UTI rises by five per cent for each day the catheter remains in place (Tambyah et al, 2002).

Causes of UTIs

Normal micturition eliminates bacteria from the urethral orifice, but when a patient is catheterised there is an increased risk that perineal pathogens can enter the urethra and ascend it, causing infection of urine (Bissett, 2004).

Fader et al (1997) suggest using a catheter valve in catheterised patients to maintain bladder tone. Such valves enable the bladder to fill and empty, allowing a flushing mechanism to occur.

Twenty per cent of Escherichia coli bacteria, a common cause of UTI, are now resistant to the antibiotics used to treat infection, and new resistant E. coli strains are increasing in number. A new lineage of E. coli (clonal group A) has emerged that is resistant to co-trimoxazole (Manges et al, 2001).

Gram-negative bacilli are a common cause of infection in catheterised patients but yeasts can also cause infection, especially if the patient has received antimicrobial therapy (Bronsema et al, 1993). Anti-microbial therapy not only destroys the target bacteria but also reduces the numbers of the natural flora present, allowing other organisms to multiply.

Reducing the risk of infection when a urinary catheter is inserted

Guidelines from the EPIC Project (Pratt et al, 2001) recommend four interventions related to reducing urinary catheter-associated infection:

- Assess the need for catheterisation;

- Select the appropriate catheter type;

- Insert the catheter using an aseptic technique;

- Management of the catheter.

The guidelines also state that catheter-related UTI is associated with the methods and duration of catheterisation, the quality of catheter care and host susceptibility.

Urinary catheterisation is a routine procedure usually carried out by nurses and it is important they are aware of the risk of infection related to the procedure. They must also ensure they have sufficient knowledge and expertise to carry it out (Box 1).

Routes of infection - Because insertion of a urinary catheter carries risk, alternative means of management should be considered before catheterisation takes place. Tambyah and Maki (2001) suggest that infection can occur extraluminally (via the outside of the catheter tube) by direct inoculation when the catheter is inserted.

This is the most common route of infection (Tambyah et al, 1999). It can also be caused by organisms ascending from the perineum using capillary action within the biofilm (a layered culture of microorganisms) that forms on the exterior surface of catheters. Intraluminal infection occurs as a result of a reflux of microorganisms ascending the lumen owing to a breach in the integrity of the closed drainage system or by contamination of urine in the collection bag.

Assessing the need for catheterisation

The reasons for inserting a urinary catheter must always be carefully considered. The cause of incontinence should be assessed before a urinary catheter is inserted to manage the problem (Box 2), and the reasons for catheterisation should always be recorded. If catheterisation is inevitable, a thorough risk assessment should be completed before inserting the catheter.

Consideration must be given to the patient’s views on the insertion of a urinary catheter. This could be influenced by the person’s age, gender, sexual activity, body image and cognitive state.

A patient who does not fully understand the reason for having a catheter inserted may try to remove it and cause trauma to the bladder and urethra.

Any allergy to the materials used to make catheters should also be identified; for example, an allergy to Latex (Damani, 2003).

Choice of catheter

The reasons for catheterising a patient will influence the choice of catheter that is inserted. For example, a short-term indwelling urinary catheter may be used to obtain accurate measurement of urinary output when a patient is seriously ill.

Roadhouse and Wellsted (2004) assessed whether silver alloy/hydrogel-coated catheters reduced catheter-associated UTI. Their results indicated a substantial reduction in this type of infection (60 per cent).

Silver alloy-coated catheters with hydrogel slowly release silver ions that inhibit the formation of biofilm and inhibit the adherence of organisms such as Enterococci, Staphylococci and yeasts (Pratt et al, 2001).

A small-gauge catheter with a 10ml balloon should be the first choice of catheter (Dieckhaus and Garabaldi, 1998).

A 10ml balloon is recommended, as the drainage eye of a catheter is above the balloon and urine below the level of the drainage eye cannot drain out. 

A larger balloon capacity will result in a greater volume of residual urine in the bladder (Roe, 1996).

The measurement that is known as a Charriere (Ch) refers to the outer circumference of a catheter and is equal to three times its diameter.

Therefore, a 12Ch catheter has an external diameter of 4mm. In general, catheters of 12-14Ch are sufficient for both male and female patients if the urine is clear. Thicker catheters can cause bladder spasm. If a thinner catheter is chosen, there is less likelihood of pressure necrosis of the urethral mucosa (Dutch Working Party Infection Prevention, 2004).

Pomfret (1996) recommended that size 12-14Ch should be used for women and 12-16Ch for men, so as to minimise urethral trauma, mucosal irritation and residual urine in the bladder, so helping to reduce the risk of infection.

Catheter lengths vary from 25cm for females to 44cm for males to accommodate the length of the urethra in both sexes. In some cases, a ‘male’ catheter may be selected for a female patient who is confined to a chair to allow for better urine drainage. This illustrates why full assessment of patients’ individual needs is required.

Procedure for the insertion of an indwelling urinary catheter

Local policies and procedures for the insertion of a catheter into a male and female patient should be followed, but the general procedure is as follows:

- Catheters must be inserted using an aseptic technique. Catheter packs should be used to provide a sterile field. If no packs are available, a sterile field should be created using sterile hand-towels, or the area to be used for the procedure should be thoroughly cleaned with a neutral detergent and warm water. The area can then be wiped using an alcohol-impregnated wipe;

- Before starting the procedure the nurse must put on an apron and cleanse her hands thoroughly using an antimicrobial wash;

- Sterile gloves must be worn for the procedure;

- In male patients, the foreskin should be retracted gently and the glans penis cleansed using cotton wool balls or a sterile topical swab and sterile water or according to local policy. Each cotton wool ball should be used only once;

- In female patients, the labia minora should be separated and the urethral opening washed using sterile water and cotton wool balls or a sterile topical swab in a downwards direction. Each cotton wool ball should be discarded after use (Dutch Working Party Infection Prevention, 2004);

- The urethra of both male and female patients should then be lubricated using the complete contents of a single-use syringe of a prescribed anaesthetic gel lubricant. Enough time should be given for the anaesthetic gel to act (approximately 3-5 minutes). The gel dilates the urethral folds in female patients, reducing the risk of trauma (Pomfret, 2004);

- The catheter should then be inserted, ensuring that it does not come into contact with the surrounding area. Once it has been inserted as high as possible into the urethra, inflate the balloon using sterile water. It can then be drawn back until a slight resistance is felt;

- The catheter is attached to a closed drainage system and the bag secured to the patient’s leg. At no time should the bag cause tension on the catheter as this can result in trauma to the bladder sphincter;

- The retracted foreskin on male patients must be gently pushed back into place to prevent paraphimosis. This occurs when the retracted foreskin forms a tight ring of skin round the glans penis and interferes with the blood flow in the glans, causing swelling and pain;

- The date and time of insertion of the catheter, its type and size, the balloon capacity and the volume inserted into the balloon of the catheter should be recorded in the patient’s care pathway, together with the manufacturer’s name, the batch number and expiry date.

Prevention of infection after catheterisation

The reason for the continued use of a urinary catheter should be monitored and recorded on an agreed time scale; for example, daily or weekly. The aim should be to remove the catheter as soon as possible. The patient should be encouraged to shower daily following the insertion of the catheter.

If this is difficult to achieve, the external genitalia should be washed daily with normal soap and water to reduce the amount of colonic flora (National Institute for Clinical Excellence (NICE), 2003).

Emptying the catheter drainage bag - When emptying the catheter drainage bags, staff should wash their hands before applying non-sterile single-use gloves. These must be discarded between patients. Hands must be washed after removing the gloves.

An alcohol-based hand rub or gel may also be used if the hands are not contaminated with organic matter or visibly soiled.

Carers and independent patients should also be taught the importance of handwashing before and after manipulating or emptying the catheter drainage bag (NICE, 2003).

The exterior of the drainage tube and its internal lumen should be cleaned using a 70 per cent alcohol swab before opening and after closing the outlet valve (Wilson, 1996). Care should be taken to prevent the outlet valve from touching the collection receptacle.

Urine bags must be emptied regularly to prevent back-flow into the urethra and bladder. This should be done when the bag is no more than half full.

Urine drainage bags for use at night must never touch the floor, even when a bed is at its lowest level; rather, they should be supported on an appropriate stand to allow for free drainage of urine (Dutch Working Party Infection Prevention, 2004).

Urinary stasis can lead to infection, so patients must be encouraged to drink as much as possible - up to two litres of fluid a day to maintain urine output and to avoid constipation, which can disrupt the free flow of urine.

Urine samples - These should be obtained only by needle aspiration via the sample port in the catheter (Baxter, 2004). This port is especially designed to reseal after withdrawal of the needle.

The port should be cleaned using an isopropyl alcohol 70 per cent wipe and allowed to dry before taking the sample. Needleless sample ports are also available.

Recommendations for practice

It is vital that nurses develop the required skills to allow them to assess patients thoroughly before inserting a urinary catheter and to ensure all other options have been investigated.

Nurses with expertise in urinary catheterisation must share their knowledge with newly qualified staff and nursing students, and ensure that their practice is based on the best evidence available.

New staff members should have their catheterisation skills assessed by a senior member of staff who has the necessary skills before being permitted to carry out the procedure independently (NICE, 2003).

If possible, patients with catheters should be taught catheter care, as this will minimise the risk of urinary tract infection. The carers of dependent patients should be taught the skills required for catheter care, and these patients should be given ongoing support while the catheter is in place.

Conclusion

New evidence-based information becomes available every day on a vast array of subjects. It is vital that all health care workers update their knowledge constantly and are always willing to examine and alter their practice in the light of newly published evidence.

Related article in nursing times

Bond, P., Harris, C. (2005) Best practice in urinary catheterisation and catheter care. Nursing Times; 101: 8, 54-58.

This article describes the development of a best practice statement from NHS Quality Improvement Scotland.

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