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March
1997
Outcome
assessment and pulmonary artery catheterization: why does the debate continue?
[editorial]
Tuman KJ, Roizen MF.
Anesth Analg 1997;84:1-4.
[ no abstract ]
Readers will doubtless recall the disturbing report on the SUPPORT study
in JAMA last fall which found that the use of the pulmonary artery catheter
is associated with increased mortality (1), and the controversial editorial
(2) that accompanied it in which suggested that the FDA apply a moratorium
on its use (Dr. Lubarsky reviewed
this article (Abstract
available in the December 1996 edition of AnesthesiaWeb.)
The ramifications of these articles have already been felt by many anesthesiologists
in increased anxiety and uncertainty about the use of pulmonary artery
catheterization (PAC). In the January issue of anesthesia & analgesia,
Tuman and Roizen write an editorial which brings a refreshing tonic of
common sense to the issue of PAC, and provides useful logic for the defense
of continuing judicious use of PAC by anesthesiologists in the OR and
ICU.
The SUPPORT study (Study to Understand Prognoses and Preferences for Outcome
and Risks of Treatment) was an observational study conducted on 5735 critically
ill patients (of whom 2184 had PAC) in 15 ICUs in five medical centers.
Based on matched pairs of patients with and without PAC, the authors reported
an increased 30 day mortality rate (37.5% vs. 33.8%), greater mean hospital
cost ($49.3 k vs. $35.7 k) and longer ICU and hospital stays (1).
Tuman and Roizen point out a number of limitations in the SUPPORT study
that challenge the conclusions reached by the authors (1)
and the exhortations against PAC by Dalen and Bone (2).
By many parameters, patients who received PAC were sicker but the indications
for PAC were neither defined nor controlled. Outcomes differed at different
study sites, but no treatment algorithms are provided, and there is no
evidence of uniform patient management. In perhaps one of their most trenchant
caveats to the reasoning of Dalen and Bone, they point out that in the
case of coronary artery disease a failure to account for differences in
disease severity and interventions "..might result in the dangerous conclusion
that a moratorium should be placed on cardiac catheterization and coronary
angiography since application of this technology ..is associated with
poorer outcome when compared with noninvasive testing alone".
Interventions were greater in the PAC group, but it is unclear whether
this was prompted by PAC or because patients with PAC were intrinsically
sicker. Tuman and Roizen also remind us that it is not the insertion of
catheters and measurement of hemodynamic data which affect outcome, but
the therapy based on these measurements. They conclude that the editorial
calling on the NIH to direct an immediate prospective controlled study
on PAC, or failing that an FDA-initiated moratorium on the use of PAC,
is unwarranted based on the SUPPORT or any other data: "...and highlight(s)
the problem of permitting editorial writers with conflicting interests
to opine in a prominent forum".
With regard to the increased cost associated with PAC, Tuman and Roizen
point out that the real question is not the acquisition or monitoring
cost of PAC but whether sufficient incremental value (i.e. by faster ICU
discharge, avoidance of organ system failure) is obtained by expending
additional costs. That is, the value of PAC is highly dependent on how
well the data obtained are interpreted and applied.
Tuman and Roizen further point out the difficulties that await one in
conducting a large scale prospective study on PAC. These include rapidly
changing anesthetic, medical and surgical management over the time course
required for such a study, and learning contamination bias of physicians
not using PAC but who may manage patients differently based on what they
have learned from PAC. The Ontario Intensive Care Group study - a previous
attempt to evaluate outcome with PAC - had to be abandoned because of
poor recruitment and because many physicians considered it unethical to
withhold PAC from their sickest patients (3)
.
Nonetheless, Tuman and Roizen do acknowledge the need for more careful
case selection in the use of PAC, and for "properly designed, adequately
powered randomized trials on the effectiveness of PAC".
This editorial will do much to calm the Brownian motion and jangled nerves
induced by the Connors' data (1) and
Dalen and Bone's editorial (2). It will
also help to emphasize the importance of constructive questioning of dogma
and ritual, and of conclusions based on careful, scientific reasoning.
For example, in the Surgical Intensive Care Unit at Duke University Medical
Center we embarked several months ago on a continuous prospective audit
of our PAC usage, indications, management and outcome in the hope that
the information gathered would help us to address some of these questions
in our own institution. Clearly there is no dispute that we must jettison
unquestioning application of PAC to all patients as a virtual treatment
in itself, but we should balance that with the preservation of PAC-derived
hemodynamic data as a keystone to the rational management of the sickest
patients in the OR and ICU.
References:
- Connors
AF, Jr., Speroff T, Dawson NV, et al. The effectiveness of right
heart catheterization in the initial care of critically ill patients.
SUPPORT Investigators. JAMA 1996;276:889-97. (Commentary by Dr. Lubarsky
in the December 1996 issue of AnesthesiaWeb: http://www.anesthesiaweb.com/new_direction/lit/dl-96dec.shtml.
Abstract: http://www.anesthesiaweb.com/new_direction/lit/dl-96dec-connors.shtml)
- Dalen
JE and Bone RC. Is it time to pull the pulmonary artery catheter?
[editorial] JAMA 1996;276:916-8. (Commentary by Dr. Lubarsky in the
December 1996 issue of AnesthesiaWeb: http://www.anesthesiaweb.com/new_direction/lit/dl-96dec.shtml.)
- Guyatt
G and Group. OIC. A randomized control trial of right-heart catheteriaztion
in critically ill patients. J Intensive Care Med 1991;6:91-5.
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