The concept of invasive hemodynamic monitoring was first pioneered in the mid-1800s. After that time, various devices and techniques evolved until Swan and Ganz developed the balloon-tipped pulmonary artery catheter (PAC) in 1970.1-3 The “Swan-Ganz catheter” has been used almost exclusively in the intensive care setting ever since, with an estimated 1 million PACs placed annually at a cost of approximately 2 billion dollars.4,5 The use of the PAC has allowed clinicians to measure right atrial, pulmonary artery, and pulmonary capillary wedge pressures at the bedside.6 Although advanced hemodynamic monitoring would seem intuitively to help clinicians in the management of unstable patients, the PAC has not been found to improve survival, and its use has declined significantly over the past 20 years.7 While the utility of the PAC has become less clear, particularly with advances in less invasive monitoring techniques, it is still used in complex cases.8 This chapter focuses on the actual technique of placement of the PAC and is predicated on the ability of the Emergency Physician (EP) to gain central venous access (Chapters 63 and 64).
ANATOMY AND PATHOPHYSIOLOGY
Central access is generally obtained via the right internal jugular or left subclavian vein. Using either of these access points allows the easiest passage of the PAC into the right atrium (RA) from the superior vena cava (SVC) (Figure 67-1). The left internal jugular, right subclavian, or femoral veins may be used but are more technically challenging. Use of the flexible balloon-tipped catheter allows it to “float” with the blood flow through the tricuspid valve into the right ventricle (RV). From there, the catheter travels through the RV outflow tract, through the pulmonic valve, and into the pulmonary artery (PA). Direct measurements of central venous pressure (CVP), right ventricular pressure, pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), and mixed venous saturation can be made.9 The ability to measure the central venous oxygen saturation (ScvO2) provides of the most crucial pieces of information to the EP. This represents the balance of oxygen delivery versus consumption and is critically important in the management of patients in shock.
Cardiac anatomy as it pertains to PAC insertion. The PAC enters the right atrium from the superior vena cava, crosses the tricuspid valve into the right ventricle, and then crosses the pulmonic valve into the pulmonary artery. The catheter tip lies in a branch of the right pulmonary artery.
The balloon of the PAC is inflated and “wedges” into a branch of the PA to occlude blood flow into that segment (Figure 67-2). The catheter, therefore, measures the downstream pressure in the vessel. This PAWP has been shown to correlate closely with left atrial pressure (LAP).7 During ...