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The routine clinical catheterization of the pulmonary artery was made possible by the pioneering work of H.J.C. Swan and William Ganz. Together they developed the soft, balloon-tipped, flow-directed pulmonary artery catheter (PAC) that bears their names.1 Prior to the work of Swan and Ganz, pulmonary artery catheterization was performed using a stiff catheter that required fluoroscopic guidance and was associated with a high complication rate. The Swan-Ganz PAC allows reliable and continuous measurement of hemodynamic parameters to be performed safely, even in critically ill patients.2–4 While complications are uncommon, they can occur. The optimal application of the PAC, both its insertion and interpretation of the data, requires appropriate training and skill.5–7
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This chapter concentrates on the technique of PAC insertion. Obtaining central venous access is a necessary prerequisite for this technique and is discussed in Chapter 49. A detailed discussion of the interpretation of the abundant variety of data that the PAC may provide is beyond the scope of this chapter.8 The interpretation of data is discussed primarily as it concerns PAC insertion and associated complications.
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The PAC is advanced into the right atrium from a venous access site in the neck, chest, upper extremity, or lower extremity. The balloon near the tip of the catheter is inflated during its insertion. The balloon follows the flow of blood through the right heart—from the right atrium through the tricuspid valve into the right ventricle, then up the right ventricular outflow tract through the pulmonic valve into the pulmonary artery, and from there into a branch of the pulmonary artery (Figure 53-1).
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When the PAC is correctly positioned, inflating the balloon near its tip will occlude the forward blood flow to that arterial segment (Figure 53-2). The lumen opening at the tip of the PAC will therefore measure the downstream pressure in that vessel, rather than pulmonary artery pressure. Because the pulmonary circulation has no valves, the pressure that the PAC tip measures beyond the inflated balloon is equal to the pressure in the pulmonary capillaries. This pressure is, in turn, equal to the pressures in the pulmonary veins and the left atrium. During diastole, when the mitral valve is open, this pressure is equal to the left ventricular diastolic pressure. The left ventricular end-diastolic pressure is a very important parameter because it is the best clinical indicator of preload. Thus, measurement of the pulmonary capillary wedge pressure (or pulmonary artery occlusion pressure, as it is sometimes called) provides ...