PCWP can be measured with a pulmonary arterial catheter (Swan-Ganz catheter). This method helps in differentiating CPE from NCPE; NCPE occurs secondary to injury to the alveolar-capillary membrane rather than from alteration in Starling forces.
A PCWP exceeding 18 mm Hg in a patient not known to have chronically elevated LA pressure indicates CPE. In patients with chronic pulmonary capillary hypertension, capillary wedge pressures exceeding 30 mm Hg are required to overcome the pumping capacity of the lymphatics and produce pulmonary edema.
Large V waves are sometimes observed in the PCWP tracing with acute mitral regurgitation, because large volumes of blood regurgitate into a poorly compliant left atrium. This condition raises pulmonary venous pressure and causes acute pulmonary edema. The pulmonary artery waveform appears falsely elevated because of the large V wave reflected back from the left atrium through the compliant pulmonary vasculature. The Y descent of the waveform is rapid, as the overdistended left atrium quickly empties.
Cardiogenic shock is the result of a severe depression in myocardial function. Cardiogenic shock is hemodynamically characterized by a systolic blood pressure of less than 80mm Hg, a cardiac index of less than 1.8 L/min/m2, and a PCWP of more than 18 mm Hg. This form of shock can occur from a direct insult to the myocardium (large acute MI, severe cardiomyopathy) or from a mechanical problem that overwhelms the functional capacity of the myocardium (acute severe mitral regurgitation, acute ventricular septal defect).
The pulmonary artery catheter is sometimes used in ICU patients with severe acute decompensated CHF; it is not clear whether this technique improves mortality rate and clinical outcome.
The results of the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial showed no mortality benefit or decrease in the number of hospitalized days in the group of patients who underwent PAC insertion. [10] This matter needs further investigation.
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Radiograph shows acute pulmonary edema in a patient who was admitted with acute anterior myocardial infarction. Findings are vascular redistribution, indistinct hila, and alveolar infiltrates.
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Radiograph shows acute pulmonary edema in a patient known to have ischemic cardiomyopathy. Findings are Kerley B lines (1mm thick and 1cm long) in the lower lobes and Kerley A lines in the upper lobes.
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Radiograph demonstrates cardiomegaly, bilateral pleural effusions, and alveolar opacities in a patient with pulmonary edema.
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Radiograph shows interstitial pulmonary edema, cardiomegaly, and left pleural effusion presenting at an earlier stage of pulmonary edema.
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Lateral chest radiograph shows prominent interstitial edema and pleural effusions.
