Use of pulmonary artery catheters in cardiac surgery: the evidence-based approach

The use of pulmonary artery catheters (PACs) during cardiac surgery varies considerably depending on local policy, ranging from use in 5–10% of the patient population to routine application. However, as in other clinical fields, recent years have witnessed a progressive decline in PAC use. One of the reasons for this is probably the increasing use of transoesophageal echocardiograpy, even though careful analysis of the information provided by PAC and transoesophageal echocardiograpy indicates that the two tools should be considered subsidiary rather than alternatives. The principal categories of cardiac patients who can benefit from PAC monitoring are those with present and those with possible haemodynamic instability. On this basis we can identify five groups: patients with impaired left ventricular systolic function; those with impaired right ventricular systolic function; those with left ventricular diastolic dysfunction; those with an acute ventricular septal defect; and those with a left ventricular assist device. This review highlights the specific role of PAC-derived haemodynamic data for each category. Introduction Placement of a pulmonary artery catheter (PAC) is an intraoperative right heart catheterization procedure. It therefore provides clinical information on heart chamber pressures, blood flows and vascular resistances – similar to the information obtained during a catheterization laboratory investigation before the operation. Unsurprisingly, since the inception of the PAC cardiac pathology has been its natural ‘battlefield’ [1], and cardiac surgery is the natural setting in which is it applied. By definition, the cardiac surgical patient always has underlying cardiac pathology; such pathology can affect intracardiac pressures and/or myocardial ability to sustain adequate cardiac output. As a consequence of the underlying pathology and/or use of specific drugs, the patient can exhibit changes in systemic and pulmonary resistive state. Moreover, the cardiac surgery itself may result in sudden changes in systolic and diastolic right or left ventricular function, and cardiopulmonary bypass (CPB) may induce release of vasoactive mediators that change flow resistances at the level of the systemic or pulmonary circulation. Finally, the common intraoperative and postoperative use of drugs that act potently on myocardial contractility, and that induce systemic or pulmonary vasodilatation or vasoconstriction permits control of the patient’s haemodynamic profile both during and after the operation. In spite of this, and for several reasons, PACs are not routinely used in all cardiac surgical institutions or in all cardiac surgical patients. The present review addresses the present situation regarding use of PACs in cardiac surgery, and defines those categories of cardiac surgical patients that may truly benefit from PAC placement. Use of pulmonary artery catheters in cardiac surgery: the evidence-based approach In 1997 a consensus conference PACs [2] was convened to address the issue of PAC use in different clinical scenarios. In the setting of cardiac surgery it was agreed that clinical management with PACs does not improve outcome in lowrisk cardiac surgical patients (grade C), plays an uncertain role in high-risk patients (grade C), plays an uncertain role in low-risk patients undergoing aortic surgery (grade B), and improves outcomes in high-risk patients undergoing aortic surgery (grade E). These assertions highlight a clinical scenario that has probably changed since the findings of the consensus conference were reported. They nevertheless offer a good starting point; they do not advocate ‘routine’ use of PACs in cardiac surgery but attempt to define the optimal patient selection. However, the findings of two studies published immediately before [3] and after [4] the consensus conference was held Review Which cardiac surgical patients can benefit from placement of a pulmonary artery catheter?