Catheter associated urinary tract infection and
intra-abdominal pressure monitoring via the urinary catheter.
Introduction
– “closed system drainage”:
Our current
CAUTI risk reduction regulations recommend maintaining closed system
urinary drainage because this leads to a reduced risk over
traditional open drainage. Interestingly the traditional open
drainage referred to by the original guidelines that form the basis
for this recommendation was truly open to the environment
continuously – the
Foley catheter actually drained directly into an open jar.[1-3] The
article that this recommendation is based upon was written in 1966 –
when urinary drain tubes and collection bags were introduced and Dr.
Kunin compared this new “sterile closed drainage” system (where a
drain bag was attached to a Foley after it was placed) to drainage
into an open jar. Not surprisingly he found fewer urinary tract
infections with the drain bag than with an open jar.[1] The study
was not a non-randomized, observational trial using historical data
as its control group – a study design that would not be considered
level 1 evidence, only hypothesis generating evidence in today's
evidence based medicine climate.
Since 1966 there have been NO randomized trials demonstrating
strict adherence to closed system drainage results in a reduction in
CAUTI. Not one in 46 years. In fact a plethora of articles suggests
there is no difference between strict closed system maintenance and
use of a simple drain tube and collection bag. This is pertinent to
the concept of abdominal compartment syndrome and intraabdominal
hypertension because the gold standard for non-invasively measuring
abdominal pressure is transduction of the bladder pressure through
the Foley catheter. If “breaking” the Foley drain system is an issue
with CAUTI we would like to know this. Since everything in medicine
is a balance of risk versus benefit we need to understand the risk
of measuring IAP via the Foley – if you read the rest of this web
site you will understand the benefits of measuring IAP. The
literature is pretty clear that there is no risk of CAUTI if careful
technique is maintained, whereas our guidelines suggest otherwise.
This brief discussion will discuss the literature on the topic of
CAUTI in relationship to closed system urinary drainage.
After reading this, the reader can form their own opinion
based on the available evidence.
Why do our guidelines claim any breaking of the “sterile closed drainage” system is a major risk for CAUTI?
To understand
this – we need to read the guidelines and review the supporting
documents. In 1981
closed system drainage became enshrined in the CDC guideline for
prevention of catheter-associate urinary tract infection.[3] This
guideline specifically states: “For patients who require indwelling
urethral catheterization, adherence to the sterile continuously
closed system of urinary drainage is the cornerstone of infection
control. For short term catheterization, this measure alone can
reduce the rate of infection from an inevitable 100% when open
drainage is employed to less than 25%. All other measures can be
viewed as adjunctive measures since none have proven to be as
effective in reducing the frequency of catheter-associated urinary
tract infections.” However, if one looks at the supporting
references for this powerful statement, one might be surprised to
find that they are not what modern research techniques would ever
accept as high levels of evidence.
The three supporting references were:
-
The Kunin study described above (an epidemiologic study that did not actually compare open to closed drainage).[1]
-
Another observational trial (not randomized) by Garibaldi et al that noted a trend towards higher CAUTI rates if the drainage system was opened. However, despite noting a 25% rate of Foley disconnection in this study, they found no statistically significant increase in the incidence of CAUTI in those that were opened.[4]
-
A reference noting that bladder irrigation led to increased rates of CAUTI (the study was not actually designed to investigate open versus closed systems, but found a higher rate in those patients who had bladder irrigation – hence concluding that opening the system must have been the culprit. This may be true, but it also may be the case that irrigation was the culprit).[5]
As stated above, these CDC guidelines were published in
1981 (an update was issued in 2009 – see below) but base their
recommendation on literature from the 1950’s and 1960’s.[2, 3] The
source article supporting closed system drainage in the CDC’s
guideline was published in the New England Journal of Medicine in
1966.[1] In this study the “closed” system consisted of a drain tube
and bag attached to the Foley (no tamper seals, no maintaining
closure, etc). Using this “closed” system the authors found a CAUTI
rate of 23%. Because this was simply an observational study of a new
device, there was no randomization and no direct comparison to prior
methods of drainage. However previous investigations conducted in
the 1950’s and early 1960’s had demonstrated CAUTI rates of 95%
within 4 days when the traditional open system (end of Foley in
glass bottle full of old urine) was used.[6-8] This study did not
claim nor demonstrate that strict maintenance of continuous closed
drainage reduced CAUTI. In fact, the drain tube was not attached
until after the Foley was established, and the authors allowed drain
bag replacement for clinical reasons such as bacterial colonization
detected within the bag.
The findings of
this 1966 nonrandomized uncontrolled observational case series and
supported by a powerful statement in the CDC guidelines have grown
into a perceived “standard” pushed by industry anxious to get you to
buy their newest drain systems despite failure of future studies to
support these recommendations.
Sad as it seems, money talks and the most likely explanation for
this statement persisting as “fact” is likely due to a good
marketing campaign. In fact, Dr. Kunin, the doctor whose article
launched the concept of closed system drainage, specifically
lamented that the “proliferation of gimmicks on drain bags” and
systems are “more fiction that science” warning that very little is
absolutely certain in medicine, that the current recommendations are
soft, based to a large degree on expert opinion and not research,
and that they will need to be changed as new knowledge becomes
available.[9] These warnings did not stop industry from using this
guideline as an effective marketing tool and driving this point deep
into the minds of medical practitioners as fact rather than
hypothesis or guideline. Products were soon developed which had
tamper resistant seals connecting the Foley to the drain tube and
were advertised as infection reducing urinary drain systems,
referencing the CDC guidelines as “proof”.
What does the evidence actually
show about “sterile closed drainage” for Foley catheters and
its impact on CAUTI rates?
Since the 1981
CDC guideline were published, six prospective randomized controlled
clinical trials and one prospective observational study have been
conducted specifically with the intent to compare pre-connected,
sealed tamper resistant closed systems to standard down drain
systems which are connected to the catheter after insertion.[10-16]
[10-17] Of these seven
studies, only one article is mentioned in any of the recent
guidelines – that which purportedly supports their statements, while
the negative findings of the remaining six articles are not
addressed. The single “supporting trial” by Platt was very well
done, but actually does not support the hypothesis that maintenance
of continuously closed drainage reduces CAUTI.[14] Platt et al
conducted a randomized controlled trial comparing closed system
drainage using a tamper resistance seal to closed system drainage
without a seal. In a large cohort of patients (over 1500) randomized
to sealed versus not sealed they found no difference in the
percentage of patients with a CAUTI. However, on retrospective
subgroup analysis of 220 patients not receiving antibiotics they did
identify closed system drainage as a method to reduce CAUTI, whereas
there was no difference in CAUTI in the 1256 patients who were
receiving antibiotics.[14] This finding has never been validated in
a randomized trial for patient not getting antibiotics. In another
randomized controlled trial that entered 153 patients,
Keerasuntonpong et al found no difference the incidence of CAUTI if
urinary drain bags were left in place versus changed every third day
– clearly implying that breaking the seal using aseptic technique
was not a risk.[15] The remaining five prospective
studies entered all patients (regardless of antibiotic use)
either in a randomized fashion, [10-13] or in a before and after
block.[16] A total of
2658 patients were randomized in the five trials – approximately
half into each arm. The studies were all essentially the same –
comparing a simple drain system that connected to the Foley either
before or after catheter placement to a complex system with tamper
resistant seals and antireflux valves. In all 5 studies there were
no differences in rates of CAUTI in either group even in patients
where the drain system was briefly disconnected. The point is than
none of these publications – conducted on over 4000 patients - found
any difference in the rate of CAUTI in patients with continuously
closed system drainage versus patients who had drain systems that
were aseptically opened when clinically indicated.
These
prospective randomized trails constitute what is truly “higher level
of evidence” compared to the CDC expert opinion piece of 1981. The
results clearly demonstrate that pre-connected urinary catheters
with tamper resistant seals have at best very little if any impact
on the risk of CAUTI compared to non-pre-connected drainage systems
that are aseptically disconnected for proper clinical indications.
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.
Guidelines for preventing CAUTI
- updates since 1981 and their comments on closed system drainage
In 2007 the
British updated their guidelines regarding reducing CAUTI,
recommending that the system should remain closed if possible (which
includes avoiding unnecessary accessing of the urinary sampling port
since it is also a method of breaking the system and risking
bacterial entry.)[18] This document admits this is level 3 evidence
but that it seems reasonable unless there is a compelling clinical
reason to break the system (such as obtaining a urine sample, or in
case of this discussion a not mentioned reason – measuring IAP).
European guidelines have also recently
been updated but they simply quote the 1981 CDC guideline and
fail to provide a single supporting reference whatsoever.[19]
Lastly, in 2009 the CDC finally updated their 30 year old guidelines
for preventing CAUTI.[20] The newest guidelines soften the original
1981 statement regarding maintenance of close system drainage. It
still recommends closed drainage (why not) but state that this is
based on “low quality evidence or accepted practice.” The document
fails to provide additional supporting evidence other than some
conflicting data from risk factor data base studies (several
suggesting closed drainage does not impact infection rates, several
feel it does, none of the listed studies investigated it
specifically).
So how can we modify our
practice to reduce CAUTI?
-
Remove the catheter as soon as possible
-
Eliminate the air lock that prevents urinary drainage
-
Quit lifting the drain to measure urine output
-
Limit unnecessary breaks in the system including accessing the urinary sampling port.
Catheter
associated urinary tract infection risk is not actually related to
variations on our methods of maintaining a closed systems, but
primarily related to patient factors such as diabetes malnutrition
and female gender.[21-25] However, several modifiable factors –
things we can change - relate 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
increase UTI risk). All hospital patients with Foley catheters
should have them removed as soon as possible. Also – methods to
reduce airlock (place the drain tube straight down to the end of the
bed, then off with NO loop) should be implemented to reduce the
“need” to manipulate that drain and risk dumping microbe laden urine
back into the patient.[25] This will not only reduce CAUTI risk, it
will prevent urine from backing up into the bladder – a sensation
that is very uncomfortable for the patient (they are not kidding
when they say they need to go pee after we place a Foley – they
often have retained urine and cannot void against the pressure
within the air lock in the drain tube loop).[25]
Intra-abdominal
pressure monitoring and CAUTI:
How does this data apply to intra-abdominal pressure (IAP) monitoring? First of all, the current reference standard for IAP monitoring is the bladder pressure.[26] Since intra-abdominal pressure monitoring requires access to the urinary drain system to obtain bladder pressure data, there is an obvious concern as to whether this measurement leads to an increase in UTI risk. Based on a careful review the materials presented here 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. (There is actually some concern that the needleless urinary drain access port provides higher risk for infectious complications based on literature from needless access in vascular systems – but this would also need confirmation in a research study before it could be reliably concluded.)[27] Fortunately we have a number of published studies that provide evidence that bladder pressure monitoring does NOT lead to a higher incidence of CAUTI. Cheatham et al investigated the UTI risk in 122 patients undergoing IAP monitoring and compared it to 2986 other patients in their ICU.[28] There were no differences in UTI risk between the two groups. Ejike compared baseline CAUTI risk in patients undergoing routine bladder pressure monitoring to historical controls – noting a CAUTI rate of 0.22/1000 catheter days in those being monitored and a 5.4/1000 in historical controls.[29] Shuster (University Penn) prospectively measured IAP in hundreds of patients for a PhD thesis using a commercial IAP monitoring kit (AbViser) and found no evidence of CAUTI in followup monitoring of the patients.(Melanie Shuster, RN, PhD thesis) Similarly, Kimball et al prospectively collected 7 years of data on over 900 patients undergoing IAP monitoring with the AbViser and also found no increase in CAUTI. All these authors conclude that IAP monitoring is safe and does not increase the risk of UTI.(Kimball et al, In process) (These articles provide strong evidence that aseptic technique used to "break" the urinary drain system and measure IAP does not increase CAUTI risk at all.)
Summary:
Extensive
research involving thousands of patients exposed to urinary drain
systems that can be “broken” and exposed to routine intra-abdominal
pressure monitoring fail to show an increase in CAUTI rates.
The published literature on the topic clearly demonstrates
that neither a brief opening of the urinary drain tube using sterile
technique nor recurrent intra-abdominal pressure monitoring
increases UTI risk. It is reasonable and should be encourage to use
aseptic technique when accessing the urinary drain system –
including when obtaining urine samples or when measuring IAP.
However, failure to measure bladder pressure due to the fear of
CAUTI is unfounded and potentially deleterious to the patient.
References:
1. Kunin, C.M. and R.C. McCormack,
Prevention of catheter-induced urinary-tract infections by sterile
closed drainage. N Engl J Med, 1966. 274(21): p. 1155-61.
2. Wong, E.S.,
Guideline for prevention of
catheter-associated urinary tract infections. Am J Infect
Control, 1983. 11(1): p. 28-36.
3. Wong, E.S. and T.M. Hooton.
Guideline for prevention of catheter-associated urinary tract infections.
1981 [cited 2008
December 1]; Available from: http://www.cdc.gov/ncidod/dhqp/gl_catheter_assoc.html.
4. Garibaldi,
R.A., et al., Factors predisposing to bacteriuria during indwelling urethral
catheterization. N Engl J Med, 1974. 291(5): p. 215-9.
5. Warren, J.W.,
et al., Antibiotic irrigation
and catheter-associated urinary-tract infections. N Engl J Med,
1978. 299(11): p. 570-3.
6. Kass, E.H.,
Asymptomatic infections of the
urinary tract. Trans Assoc Am Physicians, 1956. 69: p. 56-64.
7. Gillespie,
W.A., et al., Prevention of catheter infection of urine in female patients. Br Med
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8. Gillespie,
W.A., et al., Prevention of Urinary Infection in Gynaecology. Br Med J, 1964.
2(5406): p. 423-5.
9. Kunin, C.M., A.J. Yost, and L.P.
Christel, Guideline for
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Comments. Am J Infect Control, 1983. 11(1): p. 33-36.
10.
DeGroot-Kosolcharoen, J., R. Guse, and J.M. Jones,
Evaluation of a urinary
catheter with a preconnected closed drainage bag. Infect Control
Hosp Epidemiol, 1988. 9(2): p. 72-6.
11. Leone, M., et al.,
Comparison of effectiveness of
two urinary drainage systems in intensive care unit: a prospective,
randomized clinical trial. Intensive Care Med, 2003. 29(4): p.
551-4.
12. Wille, J.C., A. Blusse van Oud Alblas, and
E.A. Thewessen, Nosocomial
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closed urinary drainage systems. J Hosp Infect, 1993. 25(3): p.
191-8.
13. Huth, T.S., et al.,
Clinical trial of junction
seals for the prevention of urinary catheter-associated bacteriuria.
Arch Intern Med, 1992. 152(4): p. 807-12.
14. Platt, R., et al.,
Reduction of mortality
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15. Keerasuntonpong,
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16. Leone, M., et al.,
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of two urinary drainage systems. Chest, 2001. 120(1): p. 220-4.
17. Burke, J.P., R.A. Larsen, and L.E. Stevens,
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closed sterile urinary drainage. Infect Control, 1986. 7(2 Suppl):
p. 96-9.
18. Pratt, R.J., et al.,
epic2: National evidence-based
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hospitals in England. J Hosp Infect, 2007. 65 Suppl 1: p. S1-64.
19. Tenke, P., et al.,
European and Asian guidelines
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infections. Int J Antimicrob Agents, 2008. 31 Suppl 1: p.
S68-78.
20. Gould, C.V., et al.,
Guideline for prevention of
catheter-associated Urinary Tract Infections 2009. CDC and Dept
of Health and Human Services - HealthCare Infection Control
Practices Advisory Committee, 2009: p. 1-67.
21. Leone, M., et al.,
Catheter-associated urinary
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6(11): p. 1026-32.
22. Maki, D.G. and P.A. Tambyah,
Engineering out the risk for
infection with urinary catheters. Emerg Infect Dis, 2001. 7(2):
p. 342-7.
23. Platt, R., et al.,
Risk factors for nosocomial
urinary tract infection. Am J Epidemiol, 1986. 124(6): p.
977-85.
24. Maki, D.G., V. Knasinski, and P.A. Tambyah,
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: p. 165.
25. Garcia, M.M.,
et al., Traditional Foley
drainage systems--do they drain the bladder? J Urol, 2007.
177(1): p. 203-7.
26. Cheatham, M.L.,
et al., Results from the
International Conference of Experts on Intra-abdominal Hypertension
and Abdominal Compartment Syndrome. II. Recommendations.
Intensive Care Med, 2007. 33(6): p. 951-62.
27. Rupp, M.E., et al.,
Outbreak of bloodstream
infection temporally associated with the use of an intravascular
needleless valve. Clin Infect Dis, 2007. 44(11): p. 1408-14.
28. Cheatham, M.L.,
et al., Intravesicular
pressure monitoring does not cause urinary tract infection.
Intensive Care Med, 2006. 32(10): p. 1640-3.
29. Ejike, J.C., K. Bahjri, and M. Mathur,
What is the normal intra-abdominal pressure in critically ill children
and how should we measure it? Crit Care Med, 2008. 36(7): p.
2157-62.