The "PAC" was designed in an effort to quantify and therefore manipulate haemodynamic parameters ie:
Pulmonary artery occlusion pressure (or PCWP Pulmonary Capillary Wedge Pressure)
Under conditions described in the clinical procedure section of this guideline the PA catheter is inserted into a central vein.
The PA catheter is introduced into a segmental pulmonary artery using a flow directed technique described below.
Swan Ganz Haemodynamic Waveforms
Pressure trace during Pulmonary Artery Catheterization. RA; Right Atrium, RV; Right Ventricle, PA; Pulmonary Artery and PAOP; Pulmonary Artery Occlusion Pressure.
The premise behind the use of this catheter is that PAOP is determined by left atrial pressure which bears a relationship to left ventricular end diastolic pressure and this in turn relates to left ventricular end-diastolic volume as the final arbiter of pre-load.
This relationship does not hold true if:
There is not a continuous column of fluid between sensor and left atrium.
There is mitral regurgitation
The compliance characteristics of the left ventricle are abnormal.
Given the above, it is not surprising that the PAOP has proven to be an unreliable predictor of preload in clinical practice.
Complications of Pulmonary Artery Catheterization
Time spent inserting the catheter may distract from resuscitating the patient
Insertion and mechanical problems, thrombosis and infection are similar to those observed with central access cannulation
Balloon induced problems: