Abstract P111: Cardiac Power Output Accurately Reflects Cardiac Stroke Work Over a Wide Range of Inotropic States
Cardiac power output (CPO) is assessed as the product of cardiac output (liters per minute) and mean aortic pressure, and it predicts mortality in patients with cardiogenic shock. Left ventricular stroke work (LV SW) is represented by the time integral of the LV pressure-volume loop area and measured in the same physical unit as CPO. Whether CPO is correlated to LV SW has not been tested yet. Data from an ongoing resuscitation study in anaesthetized pigs (n=8, 64±9 kg) were analysed. CPO was derived from a Swan-Ganz catheter and an aortic pressure line. LV SW was calculated from LV pressures and dimensions assessed by a LV conductance catheter. Data are reported from control measurements and at 10 min, 1h and 6h after return of spontaneous circulation (ROSC) after 5 min of electrically induced ventricular fibrillation and defibrillation. Heart rate ranged from 51 to 157 bpm, maximum LV pressure from 67 to 168 mmHg, mean aortic pressure from 52 to 141 mmHg, cardiac output from 2,1 to 9,3 l/min, and systemic vascular resistance from 8.7 to 26.4 mmHg*min/l. There was a strong correlation between LV SW and CPO (graph). We conclude that under conditions representative for an intensive care unit setting, CPO is an excellent measure of LV stroke work. These data further recommend the use of CPO to monitor the success of inotropic therapy in patients with depressed cardiac function.