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The ICU and hemodynamic monitoring: Part 2

(BQ) Continued part 1, part 2 of the document The ICU and hemodynamic monitoring has contents: Hemodynamic monitoring techniques, monitoring the adequacy of oxygen supply and demand, echocardiography, preload dependency dynamic indices, perspectives Invite you to refer. | Hemodynamic Monitoring Techniques 3 3.1 Measurement of Pulmonary Artery Occlusion Pressure by the Pulmonary Artery Catheter 3.1.1 Principle Pulmonary arterial pressure PAP is measured at the distal end of the Swan-Ganz catheter. A transient occlusion of blood flow is performed during inflation of the distal balloon in a large caliber pulmonary artery. Beyond the balloon the pressure drops in the pulmonary artery to a pressure called the pulmonary artery occlusion pressure PAOP Fig. 3.1 . This pressure is the same throughout the pulmonary vascular segment in which the balloon is occluded. This segment behaves as an open downstream static column of blood in the pulmonary venous segment. In this regard the PAOP is a reflection of the pulmonary venous pressure. Because the artery occluded by the balloon is rather large in size the PAOP is the pressure of a pulmonary vein of the same caliber. Because the resistance of the pulmonary venous segment flowing into the left atrium is considered to be low the PAOP is a good reflection of the pressure of the left atrium and by extension the diastolic pressure of the left ventricle provided that there is no mitral stenosis. Notably the PAOP does not match the pulmonary artery wedge pressure. The wedge pressure corresponds to the pressure in relation to the occlusion of a pulmonary vessel of a smaller caliber obtained without inflating the balloon. Thus the wedge pressure reflects the pulmonary venous pressure in an area with a lower rating and is greater than the PAOP. Finally the pulmonary capillary pressure cannot be directly measured. It can only be estimated in two ways from the decay curve upon balloon inflation or from the Gaar equation as follows Pulmonary capillary pressure PAOP 0.4 PA . - PAOP Unfortunately this formula is only relevant if the venous resistance is homogeneously distributed. Pulmonary capillary pressure is rarely used in clinical practice due to the difficulty of measurement even though it reliably .