A Randomized, Controlled Trial of the Use of Pulmonary-Artery Catheters in High-Risk Surgical Patients
This review may be edited
Posted By: A Delaney
Posted Date: 7/1/03
Title: A Randomized, Controlled Trial of the Use of Pulmonary-Artery Catheters in High-Risk Surgical Patients
Authors: James Dean Sandham, M.D., Russell Douglas Hull, M.B., B.S., Rollin Frederick Brant, Ph.D., Linda Knox, R.N., Graham Frederick Pineo, M.D., Christopher J. Doig, M.D., Denny P. Laporta, M.D., Sidney Viner, M.D., Louise Passerini, M.D., Hugh Devitt, M.D., Ann Kirby, M.D., Michael Jacka, M.D., for the Canadian Critical Care Clinical Trials Group
Reference: N Engl J Med 2003;348:5-14.
Link: Click here for a direct link to the paper. A password may be required for access to fulltext.
Abstract: Background Some observational studies suggest that the use of pulmonary-artery catheters to guide therapy is associated with increased mortality.
Methods We performed a randomized trial comparing goal-directed therapy guided by a pulmonary-artery catheter with standard care without the use of a pulmonary-artery catheter. The subjects were high-risk patients 60 years of age or older, with American Society of Anesthesiologists (ASA) class III or IV risk, who were scheduled for urgent or elective major surgery, followed by a stay in an intensive care unit. Outcomes were adjudicated by observers who were unaware of the treatment-group assignments. The primary outcome was in-hospital mortality from any cause.
Results Of 3803 eligible patients, 1994 (52.4 percent) underwent randomization. The base-line characteristics of the two treatment groups were similar. A total of 77 of 997 patients who underwent surgery without the use of a pulmonary-artery catheter (7.7 percent) died in the hospital, as compared with 78 of 997 patients in whom a pulmonary-artery catheter was used (7.8 percent) a difference of 0.1 percentage point (95 percent confidence interval, 2.3 to 2.5). There was a higher rate of pulmonary embolism in the catheter group than in the standard-care group (8 events vs. 0 events, P=0.004). The survival rates at 6 months among patients in the standard-care and catheter groups were 88.1 and 87.4 percent, respectively (difference, 0.7 percentage point [95 percent confidence interval, 3.6 to 2.2]; negative survival differences favor standard care); at 12 months, the rates were 83.9 and 83.0 percent, respectively (difference, 0.9 percentage point [95 percent confidence interval, 4.3 to 2.4]). The median hospital stay was 10 days in each group.
Conclusions We found no benefit to therapy directed by pulmonary-artery catheter over standard care in elderly, high-risk surgical patients requiring intensive care.
Are the Results Valid?
1. Was the assignment of patients to treatments randomized? ( Was allocation concealment maintained?)
Yes, the patients were randomly assigned using a computer generated sequence, stratified according to type of surgery and ASA class, and blocked according to centre. The assignments were concealed in opaque envelopes.
2. Were all patients who entered the trial properly accounted for and attributed at its conclusion?
2a. Was followup complete?
Yes, follow-up was 100% for the primary end point of in-hospital mortality. Follow-up was greater than 90% for all the secondary end points of 6mth and 12mth mortality.
2b. Were patients analyzed in the groups to which they were randomized?
Yes, the analysis was conducted on an intention-to-treat basis. Any patient who was randomized to the standard care arm, who subsequently required a PA catheter as analysed in the group to which they were randomised (standard care arm) or vice versa.
3. Were patients, health workers, and study personnel blind to treatment?
The patients and the health care workers were not able to be blinded. Great care was taken to ensure that all the outcome adjudication (except death) was done in a well defined and blinded fashion by at least two observers
4. Were the groups similar at the start of the trial?
Yes. There were no significant differences between the 2 groups at the start of the trial.
5. Aside from the experimental intervention, were the groups treated equally?
There was no reported difference between the treatment of the 2 groups aside from the experimental intervention.
What are the Results?
1. How large was the treatment effect?
There was no statistically significant difference between the 2 groups with an in-hospital mortality of the control group was 7.7% compared to 7.8% in the PA catheter guided treatment group (P=0.93).
The PA catheter group demonstrated a significant increase in pulmonary embolism rates (0% vs. 0.9%, p=0.004). The standard care group demonstrated a strong trend towards an increase in renal insufficiency (9.8% vs. 7.4%, p=0.07).
2. How precise was the estimate of the treatment effect?
The 95% confidence intervals for mortality extend from -2.3 to 2.5. This means that we can be 95% certain that there is less than a 2.5% difference between these 2 treatment strategies.
Will the Results Help Me In Caring For My Patients?
1. Can the results be applied to my patient care?
Most likely. High risk surgical patients (ASA III and IV) are commonly cared for in ICU's and this study makes it clear that the routine use of PA catheter to guide therapy is not associated with a lowering of mortality in these patients.
2. Were all clinically important outcomes considered?
Yes, multiple secondary end points were assessed. There was an increase in pulmonary embolli detected in the PA catheter guided therapy group (0.9% v's 0%). Apart from this there was no significant differences between the 2 strategies with regards to multiple measures of morbidity, complications, hospital length of stay or mortality at 12 months.
3. Are the likely treatment benefits worth the potential harms and costs?
This study has shown that the routine use of a PA catheter to guide therapy for all patients undergoing high risk urgent or elective surgery (ASA III or IV) is not indicated. However it does not address issues regarding the use of the PA catheter to guide therapy for other patients, for example those with septic or cardiogenic shock. The fact that this well done trial has not shown an increase in mortality due to the use of the PA catheter to guide therapy, as has been suggested in previous less rigorously conducted studies, may be of some comfort to those clinicians who still view the PA catheter as a valuable tool in selected patients. Future studies will need to be performed to clarify the use of the PA catheter in other patient groups.

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