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Cardiac output

- See:
- Afterload
- Frick method 
- 3.5-5.5 L/min; Cardiac Index: 2.8-3.2 L/min/m sqd;
- average normal cardiac index is 3.5 l/min/m sq, and 95% of normal individuals have indices in the range of 2.1 to 4.9 l/min/m sq;
- determinants of cardiac output:
- HR: in general should be maintained between 80-110
- for slower rates may use low dose: Dopamine or Isoproterenol
- Preload: w/ incr Preload, CO will rise on the Starling Curve;
- usually PCWP may be increased to 18-20 mm Hg to optimize CO; (most hearts, even sick hearts, will tolerate this pressures)
- it is not necessary to increase filling press. if CO is OK; (many relatively healthy Post Op hearts may pump well at 10-15)
- for the sick heart (prior infarcts and extensive heart surgery)
- filling pressures greater than 18 to 20 mm Hg may be required;
- for these hearts, individual Starling Curve must be determined and volume administration must be turned off as curve flattens;
- note: w/ overdistension, tension (and O2 consumption) increases dramatically; tension is major determinant of O2 consumption