Sensitivity of the left ventricle outflow resistance

In this study, linear regression slopes relating changes in stroke volume (SV) and systemic vascular resistance (SVR) were determined as an indication of LV function. The findings of the study are at some variance with conclusions of Cohn and others Left ventricules with good LV function proved load sensitive during anesthesia and surgery, and in two such patients the regression slopes of SV vs SVR were steep. In patients with poor LV function there was a range of regression slopes. In patients with less steep slopes, SV was relatively fixed and changed little with increase or decrease of SVR; vasodilator therapy was of limited application and ionotropic support sometimes required. At the other extreme of the range, a markedly steep regression slope indicated a hazardous sensitivity to change in SVR. These findings have important clinical implications for anesthesia management and indicate the value of regression slope analysis of SV vs SVR in clinical evaluation of LV funcion.