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NewsletterLiterature Reviews A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. Sandham JD, Hull RD, Brant RF et al N Engl J Med 2003; 348: 5-14
Reviewer: Rose Christopherson, MD, PhD
Background: Some studies of surgical patients have shown benefit, while others have shown increased mortality to be associated with the use of pulmonary artery catheters (PAC's). Methods: A randomized trial was performed comparing goal-directed therapy based upon measurements from a PAC to standard care without the PAC. Patients enrolled in the study were at least 60 years old, and ASA class III or IV, scheduled for elective or urgent major surgery with recovery in an intensive care unit. The primary outcome was in-hospital mortality. Observers who determined other outcomes were blinded to treatment group assignment. Results:M 1994 patients were randomized. This was 52.4 % of screened patients who were eligible. Baseline characteristics of the 2 groups were similar. Rates of in-hospital death were similar: 7.7 % for those randomized to care without a PAC, 7.8 % for those randomized to the goal directed therapy with the PAC (95 % confidence interval -2.3 to 2.5). The PAC group had a higher rate of pulmonary embolism (8 vs. 0, P = 0.004). Six-month survival rates were 88.1 % in the standard care group and 87.4 in the PAC group (C.I. -3.6 to 2.2). Twelve month survival rates were also similar: 83.9 % in the standard care group and 83.0 % in the PAC group, C.I. -4.3-2.4). In both groups the median hospital stay was 10 days. Conclusions: The authors found no benefit to PAC directed therapy in elderly, high-risk surgical patients. Discussion: Any study that randomizes nearly 2,000 patients to treatment with or without a PAC is worthy of note. However, we should ask two questions about this study: what kind of patients were studied, and how were the PAC's used? With respect to the first question, 47.6 % of screened, eligible patients were not randomized. The non-randomized patients were significantly different from the randomized patients with respect to many baseline variables. Were patients who were likely to need a PAC for their management among those not randomized? Or were patients who clearly were unlikely to benefit from management with a PAC not enrolled in the study? The authors emphasized that crossovers from the standard to the PAC group were strongly discouraged; therefore, enrolling patients whose management might become difficult without a PAC would have been bad both for the patient and for the local politics of the study. With respect to the second question, measurement of central venous pressure was allowed in the standard care group. Goals for the PAC group were: oxygen delivery index of 550-600 ml / minute / square meter of body surface area; cardiac index of 3.5-4.5 L / minute; mean arterial pressure of 70 mm Hg; heart rate less than 120 beats / minute; hematocrit greater than 27 %. Therapeutic maneuvers to achieve these goals were, in order of priority: fluid loading; inotropic therapy; vasodilator therapy; vasopressors for hypotension; blood transfusion for hematocrit less than 27 %. In considering application of the findings of a study such as this, it is important to remember that it was a study of a mixed population having a variety of types of surgeries, and that the goals and maneuvers given above were applied to all of the patients in the PAC group. Many clinicians would accept a lower cardiac index in patients at risk for myocardial ischemia, and would not use fluid loading as a first intervention for patients who have just undergone pulmonary lobectomy. The message of the study may actually be that a subset of patients over 60 years of age having major surgery do not benefit from PAC's, and that PAC's do not benefit patients if the patients are treated the same regardless of their type of surgery and underlying medical diseases. The pulmonary artery catheter allows us to individualize treatment more than we can with a central venous catheter, which only gives right-sided filling pressures. Possibly any protocol that dictates what the hemodynamic goals will be, and how to achieve them for a variety of patients having diverse procedures, will never prove better than use of a central venous catheter. That does not mean that pulmonary artery catheters are not valuable for individualized management of complex, sick patients. Table of Contents:
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