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Pulmonary Artery Pressure Monitoring
Case Synopsis
A 73-year-old woman with known severe mitral regurgitation and a permanent pacemaker is admitted to the surgical intensive care unit with urosepsis and refractory hypotension. Because of her lack of hemodynamic response to fluid boluses, a pulmonary artery catheter (PAC) is placed through her right internal jugular vein and advanced to 53 cm. The recorded pulmonary artery (PA) pressure is 90/30 mm Hg. The next morning, her pulmonary artery pressure is noted to be 76/20 mm Hg, and the waveform display at that time is shown in Fig. 118.1 . The intensivist inflates the balloon of the PAC to record PA occlusion pressure. Within seconds, the patient becomes anxious and tachypneic and coughs bright red blood. Suspecting that the hemoptysis is the result of PA rupture, the intensivist inserts an endotracheal tube. A chest x-ray confirms that the PAC tip is positioned in the distal right PA, and the right lung shows a new infiltrate. A bronchial blocker is inserted into the right mainstem bronchus under fluoroscopic guidance to isolate the right lung and allow unilateral left lung ventilation. As a result of ongoing hypoxemia, venoarterial extracorporeal membrane oxygenation is initiated and results in improved gas exchange and blood pressure. The following day, the patient undergoes successful coil embolization of a proximal branch of the right pulmonary artery.
Acknowledgment
The authors wish to thank Drs. Matthew D. Caldwell and Paul E. Kazanjian for their contributions to the previous edition of this chapter.
Problem Analysis
Definition
PACs are commonly used by anesthesiologists and intensivists to guide hemodynamic management of circulatory shock and monitor surgical patients with severe pulmonary hypertension and/or severe ventricular dysfunction. PAC placement requires the insertion of an introducer sheath into a large vein such as the internal jugular, subclavian, or femoral, but may also be achieved via the axillary vein. The PAC is then placed through the sheath into the lumen of a vein, its balloon is then inflated, and the catheter is advanced with the assistance of the blood flow to and through the right atrium (RA), right ventricle (RV), and proximal PA. Continuous pressure monitoring is used as the PAC is advanced to identify catheter tip location and confirm proper placement. Fluoroscopic guidance can also be used to assist PAC placement. More recently, a technique for transesophageal echocardiography–guided PA catheterization has been described.
Complications of PAC monitoring may occur during or after catheter placement. Insertion-related complications include those that occur during all central venous catheterizations, except that the larger size of the dilator and sheath used for PAC insertion can result in more serious vascular injury (complications related to central venous catheterization are discussed in Chapter 105 ). In addition to central vascular injury, other mechanical injuries described during PAC insertion and monitoring include arrhythmias, tricuspid or pulmonic valve injury, and pulmonary artery perforation. Beyond mechanical complications, PAC monitoring has been associated with central line bloodstream infection, infectious endocarditis, and pulmonary thromboembolism. Finally, and perhaps most importantly, misuse of the pulmonary artery catheter and misinterpretation of catheter-derived data remain important, and perhaps the most common, clinical complications.
Arrhythmias or Bundle Branch Block
As the PAC passes through the RA and RV, both atrial and ventricular arrhythmias are commonly observed. Atrial or ventricular ectopic beats and nonsustained ventricular tachycardia occur commonly (estimates range from 13% to 70% of all PAC placements). Ventricular ectopy can also occur in patients with a PAC in situ and during removal of the catheter. Most atrial and ventricular arrhythmias caused by catheter manipulation are benign and self-limited. However, onset of a supraventricular tachycardia such as atrial fibrillation in some patients may cause severe hypotension and require treatment. Hemodynamically significant sustained ventricular tachycardia or ventricular fibrillation is very infrequent but can develop and may require complete withdrawal of the PAC from the heart.
New right bundle branch block (RBBB) can occur during or shortly after PAC insertion in up to 5% of patients. This is of little consequence except in patients with preexisting left bundle branch block (LBBB). In these patients, complete heart block may ensue, resulting in severe hemodynamic instability requiring emergency cardiac pacing or other standard treatment of severe bradycardia or asystole. Studies suggest that this is uncommon, occurring in fewer than 1% of patients.
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