HEMODYNAMICS


I. Normal parameters

  1. Cardiac output = 5-6l/m for men
  2. Normal pressures for different cardiovascular compartments:
  1. RA 0-5mmHg
  2. RV syst 25mmHg; diast 0-5mmHg
  3. PA syst 25mmHg; diast 10mmHg
  4. PCWP 10mmHg
  5. LA 10mmHg
  6. LVsyst 120mmHg diast 10mmHg
  7. Aorta syst 120mmHg diast 80mmHg

II. Calculating resistance of the systemic vasculature

  1. Resist in Dyne.sec.cm-5 =
  2. change in pressure (in mmHg) x 80 flow (in l/min) =
  3. (Mean Art. Press* - RA press) x 80 [syst. vasc. resist

CO

OR

  1. = (Mean PA Press* - PCWP) x 80[pulm. vasc. resist]

CO

*Mean Art. press = DBP + (SBP-DBP)/3; Mean PA press. calculated same way with S-G values

III. "CI"--Cardiac index = CO/Body Surface Area = 3.1 l/min/m2 (for men or women)

  1. CI < 2.2 is a "low-output state"
  2. Clinical signs: Hypotn, tachycard, SOB, diaphoresis, oliguria, and confusion
  3. Frank and Starling decided that a PCWP > 18 mmHg was "elevated"; us. have RALES
  4. This point in the elevation of PCWP is called the "BREAKPOINT" because above it, the F-S curve (contractility vs. chamber volume) levels out, i.e. increased volume (or PCWP) does not bring increased CO
  5. SO, there are four hemodynamic subsets, and ALL CCU PTS MUST BE CLASSIFIED THIS WAY!!!! (though it's not always necessary to put a S-G to do so); The subsets are based on whether pt is above or below CI 2.2 and above or below PCWP 18
  1. CI > 2.2, PCWP < 18; mort post-MI about 1%
  2. CI > 2.2, PCWP >18; "pulmonary congestion" group; mort post-MI about 10%
  3. CI < 2.2, PCWP <18; "vol. depleted" group (absol. or relative); mort post-MI variable, 3-20%

* give 100-200ccNS/h x 1-2h, listen for development of RALES (i.e. conversion to group II)*

  1. CI < 2.2, PCWP > 18; "severe pump failure" group, aka "cardiogenic shock"; mort post-MI about 80%