Elisabeth Pepperell, RN.
Critical Care Outreach Nurse, ITU, Whittington Hospital, LondonUrinary catheterisation is now regarded as a commonplace procedure in both the hospital and community setting, with up to 12% of hospital patients requiring catheterisation during their stay (Mullhall et al, 1988).
Urinary catheterisation is now regarded as a commonplace procedure in both the hospital and community setting, with up to 12% of hospital patients requiring catheterisation during their stay (Mullhall et al, 1988).
Although indications for catheterisation (Table 1) are well documented, guidelines to aid nurses in the assessment of the appropriateness of urinary catheterisation are virtually nonexistent. In fact, it was observed by the author that, in general practice, there was no continuity concerning the point at which patients with oliguria (low urine output) were catheterised. Some patients were catheterised prematurely without other options being explored, while others may have benefited from being catheterised earlier than they were.
A common example is the catheterisation of patients with a low urine output postoperatively when they had not really been encouraged to void. Urinary catheterisation increases the risk of infection. One survey of hospital infection in 1980 revealed that 21% of catheterised patients developed a urinary tract infection compared to only 2% of patients without a catheter (Ayliffe et al, 1981). Therefore catheterisation should be undertaken only if appropriate.
Aim and method
The aim was to produce guidelines on catheterisation in the event of acute oliguria. A literature search was performed on the Cinahl and Medline databases using the words 'catheterisation', 'oliguria' and 'urinary catheters'. No papers were found that focused on when it was appropriate to catheterise the oliguric patient, although some did discuss indications for catheterisation. Other papers focused on the primary causes of decreased urine output and a discussion of catheterisation in such cases.
From the literature it emerged that the two main reasons for an acute low urine output were either acute urinary retention or a critical illness resulting in acute renal failure. The literature also noted the complications of catheterisation.
Acute urinary retention
Acute urinary retention is classed as a sudden inability to void, despite the presence of urine in the bladder and the desire to urinate (Gray, 2000a). It can also be very painful (Emberton and Anderson, 1999). Failing to catheterise a person in acute urinary retention can result in acute renal failure or rupture of the bladder (Gray, 2000b). Men in their seventies have a one-in- ten chance of going into acute urinary retention within the next five years and that risk increases with age (Emberton and Anson, 1999). The reasons why urinary retention occurs are still not fully understood, but the theories are either an obstruction such as a foreign body or lesion, interruption of the nerve supply to the bladder or a bladder which has been allowed to become over-distended (Gray, 2000a). This final theory may account for the many episodes which occur after surgery performed under general anaesthetic (Emberton and Anson, 1999). It is also commonly acknowledged that epidurals can also increase the risk of acute urinary retention (Cox, 2001).
Acute renal failure
Acute renal failure (ARF) can be defined as a sudden impairment of the kidneys' ability to remove the body's waste products of metabolism (Short and Cumming, 1999). It is usually associated with oliguria. The reasons for developing ARF are categorised as pre-renal, intra-renal or post-renal failure. These are summarised in Table 2.
The most common type of ARF in critically ill patients is pre-renal failure. There are several clinical situations that can lead to reduced kidney perfusion. Included are any cause of a reduced cardiac output (for example myocardial ischaemia, tamponade or valvular disease) and severe hypotension or a depletion in intravascular volume (for example haemorrhagic or septic shock). The primary intervention in the prevention of the development of ARF is to quickly restore and then maintain the intravascular volume while also treating the initial insult (Bellomo, 1997).
The complications that are typically associated with ARF include the development of a uraemic state. Metabolic toxins are retained and accumulate in the blood and hyperkalemia (high serum potassium levels) can develop. This is a potential life-threatening situation and prompt treatment is required. The retention of sodium and water leads to peripheral oedema and in some cases pulmonary oedema. Metabolic acidosis can occur because acid excretion is inadequate (Bellomo, 1997). Catheterisation of patients who are in ARF or at risk of developing ARF allows for accurate measurement of urine output and therefore enables staff to determine the effectiveness of any treatment given. Testing any urine produced by means of a urine dipstick test can aid in the diagnosis of primary renal disease as positive haematuria and proteinuria results are significant (Short and Cumming, 1999).
Complications of catheterisation
The most common complication of catheterisation is urinary infection (Winson, 1997). There are a number of reasons for this. First, the insertion of a catheter exposes the bladder to organisms present on the catheter itself. In addition, while inserting the catheter, organisms from the urethra can be pushed into the bladder (Sanderson, 1995). Bacteria can also be introduced via the catheter lumen from contaminated drainage bags or catheter outlet connections (Winson, 1997).
Inadequate infection control practices could also lead to infection. Following local infection control policies may help reduce the risk of infection. These should include aseptic insertion of the catheter, scrupulous attention to handwashing by all health professionals and avoidance of urinary stasis by placing the drainage bag below the level of the bladder (Patel and Arya, 2001). Urinary catheters should be removed as soon as possible to limit the potential risk of developing an infection (Patel and Arya, 2001). The risk of infection increases proportionately with the length of duration of catheterisation (Table 3).
The algorithm was devised based on the two causes of oliguria already described, acute urinary retention and acute renal failure. A draft copy of this algorithm was then sent to senior nurses and medical staff of a north London hospital to gain multidisciplinary feedback. Changes were made according to the feedback given and the final algorithm developed (Figure 1).
To encourage use of the algorithm it was decided that it had to be easy to use, simple in design and relevant to everyday practice. Use of medical jargon was avoided as much as possible.
It comprises two paths. On the left-hand side, a patient becomes critically unwell and could develop acute renal failure. The hospital in which this algorithm was developed has an established critical care outreach team and the algorithm was written with this in mind. If the patient's symptoms fall into this side of the algorithm, his or her condition is deteriorating and the algorithm suggests informing both medical and outreach teams.
The right-hand side of the algorithm covers acute urinary retention. It includes simple prompts that can sometimes be overlooked, including encouraging someone to void and palpating for a full bladder. Again it recommends seeking medical advice, this time if urine output is low but there are no indications of urinary retention. The use of closed questions resulting in either a 'Yes' or 'No' answer ensures objectivity and prevents any need for subjective interpret-ation on the part of the nurse.
Implications for nurses - a summary
- Using an agreed protocol takes the guesswork out of knowing when catheterisation is appropriate
- With a high risk of infection, catheterisation should be undertaken only if necessary and when other options have already been considered
- Catheterising someone in acute urinary retention prevents bladder rupture and acute renal failure
- Encouraging someone with a full bladder to void may prevent the need for catheterisation
- In acutely unwell patients, catheterisation can help determine the extent of their illness and the effectiveness of treatment.
Urinary catheterisation should not be done on an ad hoc basis and clear guidelines are required if continuity and consistency are to be achieved. This algorithm has only recently been introduced in the hospital in which it was written and its effectiveness has yet to be assessed. However, with indwelling catheterisation accounting for a substantial number of hospital-acquired infections, it will not only be the nurses, but patients as well, who should benefit from comprehensive, practical guidelines that encourage best practice.
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