Rationale PA catheter and tailored therapy

• Cardiac output (CO) = SV × HR; optimize SV (and thereby CO) by manipulating preload/ LVEDV (w/ IVF, diuretics), contractility (w/ inotropes), & afterload (w/ vasodilators)

• Balloon at catheter tip inflated → floats into “wedge” position. Column of blood extends from tip of catheter, through pulm venous circulation to a point just prox to LA. Under conditions of no flow, PCWP ≈ LA pressure ≈ LVEDP, which is proportional to LVEDV.

• Situations in which these basic assumptions fail:

  (1) Catheter tip not in West lung zone 3 (and ? PCWP = alveolar pressure ≠ LA pressure); clues include lack of a & v waves and if PA diastolic pressure < PCWP

  (2) PCWP >LA pressure (eg, mediastinal fibrosis, pulmonary VOD, PV stenosis)

  (3) Mean LA pressure >LVEDP (eg, MR, MS)

  (4) ∆ LVEDP-LVEDV relationship (ie, abnl compliance, ∴ “nl” LVEDP may not be optimal)