Current opinion holds that a closed urinary drain system is superior to an open system because it reduces catheter associated urinary tract infection risk (CAUTI). This is actually not true. The likely explanation for this myth a review article disseminated by industry that was written in 1983 as the evidence that closed systems are superior.¹ While expert opinions provided in review articles are often the best level of evidence available at the time of publication, one must be careful when using opinions that are 25 years old as “fact.” In actual fact, since the time of that publication three randomized controlled trials and one non-randomized trial have investigated this claim^2-5. These studies all compared commercially available urinary drain systems - one with a separate catheter and low tech drain tube that was connected after catheterization (open system) and one with a pre-connected catheter/drain tube held together with a tamper resistant seal (closed system). In every investigation there was no difference in UTI risk in open versus closed systems. This data clearly shows that the brief disconnection of the catheter from the drain tube is not an infectious risk.

If a closed system does not reduce UTI risk, what risk factors do lead to catheter associated UTI’s? Recent research concludes that UTI risk is not actually related to open versus closed systems, but primarily related to non-modifiable patient factors such as diabetes, malnutrition and female gender.^6-9 However, these studies do note several modifiable factors related to catheter associated UTI: Length of time the catheter is inserted (i.e. take it out as soon as possible), hospital site where the catheter was inserted (insertion in the sterile area of the operating room reduces UTI risk) and drain tube manipulation to measure urine output with improper positioning of the drain tube (large loops of tubing below the drain bag, or lifting the drain tube above the level of the bladder leading to infusion of microbe laden urine back into the bladder increase UTI risk). (See Table) These studies suggest that nurses and doctors should follow the manufactures directions by stretching the drain tube along the entire length of the bed, preventing any loops in the tube will avoid an air-lock. This procedure will eliminate the need to lift the tube above the level of the bladder when assessing hourly urine out-put. By eliminating these loops, the provider can avoid recurrent lifting of the drain tube, reducing the risk of “retrograde reflux of microbe laden urine” into the bladder.⁷

While there is no difference in UTI risk in a closed versus open urinary drain system, this data should not be interpreted to imply that care and protection of the urinary drain system is unimportant. These studies did not purposely expose the internal aspects of the drain tube to contaminants, they did not reopen the system repeatedly and they all provided standard catheter care. The urinary drain system should be treated with respect by using sterile technique at insertion, eliminating manipulation of the drain tube while it is in place and removal of the catheter as soon as it is unnecessary for patient care. Brief tubing disconnection done using sterile technique, on the other hand, is not dangerous and this concern is likely overblown.

Since intra-abdominal pressure monitoring requires access to the urinary drain system to obtain bladder pressure data, it is important to determine if this access leads to an increase in UTI risk. Based on the above data one can surmise that careful access of the urinary catheter should not increase UTI risk, whether this access is via the urinary sampling port or if it involves brief disconnection of the drain tubing. Cheatham et al provide clinical data to support this assumption.¹⁰ They investigated the UTI risk in 122 patients undergoing IAP monitoring and compared it to 2986 other patients in their ICU. There were no differences in UTI risk between the two groups. They conclude that IAP monitoring is safe and does not increase the risk of UTI.

Transvesicular intra-abdominal pressure monitoring carries very little risk of CAUTI, even if the drain system is opened in a thoughtful fashion. However, failure to detect intra-abdominal pressure elevations due to unfounded concerns regarding access to the urinary catheter clearly carry risk to the patient (see outcomes section of this web site) so any unproven risk of UTI is outweighed by the proven benefits of bladder pressure monitoring in high risk patients. The closed system “myth” may have some merit (aseptic technique), but it is not defended by evidence based medicine and he concern is over-blown. Obviously clinicians need to be careful, but not paranoid. Eliminating drain tube loops and recurrent manipulation of the urinary drain tube with repeated dumping of old urine back into the patient’s bladder is probably a modifiable risk we can impact. Neither a brief opening of the urinary drain tube using sterile technique nor recurrent intra-abdominal pressure monitoring increases UTI risk.

References:

1. Wong ES. Guideline for prevention of catheter-associated urinary tract infections. Am J Infect Control 1983; 11:28-36.
2. DeGroot-Kosolcharoen J, Guse R, Jones JM. Evaluation of a urinary catheter with a preconnected closed drainage bag. Infect Control Hosp Epidemiol 1988; 9:72-6.
3. Leone M, Garnier F, Antonini F, Bimar MC, Albanese J, Martin C. Comparison of effectiveness of two urinary drainage systems in intensive care unit: a prospective, randomized clinical trial. Intensive Care Med 2003; 29:551-4.
4. Leone M, Garnier F, Dubuc M, Bimar MC, Martin C. Prevention of nosocomial urinary tract infection in ICU patients: comparison of effectiveness of two urinary drainage systems. Chest 2001; 120:220-4.
5. Wille JC, Blusse van Oud Alblas A, Thewessen EA. Nosocomial catheter-associated bacteriuria: a clinical trial comparing two closed urinary drainage systems. J Hosp Infect 1993; 25:191-8.
6. Leone M, Garnier F, Avidan M, Martin C. Catheter-associated urinary tract infections in intensive care units. Microbes Infect 2004; 6:1026-32.
7. Maki DG, Tambyah PA. Engineering out the risk for infection with urinary catheters. Emerg Infect Dis 2001; 7:342-7.
8. Platt R, Polk BF, Murdock B, Rosner B. Risk factors for nosocomial urinary tract infection. Am J Epidemiol 1986; 124:977-85.
9. Maki DG, Knasinski V, Tambyah PA. Risk factors for catheter-associated urinary tract infection: a prospective study showing the minimal effects of catheter care violations on the risk of CAUTI (Abstract). . Infect Control Hosp Epidemiol 2000; 21:165.
10. Cheatham ML, Sagraves SG, Johnson JL, White MW. Intravesicular pressure monitoring does not cause urinary tract infection. Intensive Care Med 2006; 32:1640-3.