- Normal = 6 - 12 mm Hg; (Swan Ganz)
- in absence of pulmonary HTN, > 10 cm PEEP, or mitral valve dz, it reflects left atrial Pressure (Preload), and is measured after inflation of the balloon, which allows the tip of the catheter to wedge in a capillary;
- in absence of obstruction of mitral valve (MS) wedge pressure also approximates the mean left ventricular diastalic pressure;
- however, in presence of elevated left ventricular end diastolic pressure (height of ventricular filling pressure just before ventricular contraction) caused either by an increase in end diastolic volume or a decrease in left ventricular Compliance, the wedge does not accurately reflect the left ventricular end- diastolic pressure, which may significantly exceed mean wedge;
- height of the pulmonary wave or the pulmonary capillary a wave is the most consistent accurate indirect index for sudden changes in actual left ventricular end diastolic pressure;
- nevertheless, the wedge reflects mean left ventricular diastolic pressure and is therefore a useful index to estimate not only the possible risk of the development of pulmonary edma, but also left ventricular Preload;
- in critically ill patients, ventricular Compliance is altered, and there may be no correlation between pressure and volume, making it impossible to estimate left ventricular Preload from the wedge;
- by optimizing the PCWP according to the patients individual Starling curve, opitimal Cardiac Output; - PCWP < 6, think low LVEDP (Preload), in relatively healthy heart, CO may be increased by expanding the volume; PCWP > 12, in absence of severe cardiac dz, means pulmonary congestion due to fluid overload or CHF;
- long standing Cardiac disease may shift the Starling Curve to left;
- consequently, a significantly elevated PCWP may be required to optimize CO;
- patients s/p MI may need PCWP of 16-18 to optimize CO;
- when PCWP is > 12 mm, then CO may be optimized w/ dobutamine and/or dopamine;
- use mean pressure reading to best approx L.A. pressure;
- use the pressure inbetween respirations;
- filling pressures should be read just before Inspiration;
- high PEEP may falsely elevate Wedge Pressure; (subtract 1/3 of PEEP value from wedge for more accurate pressure)
A noninvasive method of predicting pulmonary-capillary wedge pressure