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Duke Orthopaedics
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Wheeless' Textbook of Orthopaedics

Pulmonary capillary wedge pressure


- 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



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, May 22, 2012 1:02 pm