Use of ventricular stroke work index and ventricular function curves in assessing myocardial contractility

Cardiac output and cardiac index values are traditionally used by critical care nurses as indicators of myocardial contractility. Due to the incidence of compensatory tachycardia in many critically ill patients, however, the value of LVSWI as an indicator of myocardial contractility is enhanced, because the formula for its calculation does not emphasize the variable of heart rate. The advantages of using LVSWI are the following: It is easily calculated at the bedside by using an integrated hemodynamic software package or by using the formula provided. It is readily available to the nurse and indicates sensitive changes in myocardial function. When used in LV function curves in the nursing assessment of myocardial contractility of critically ill adults, its use can direct changes in fluid and pharmacologic interventions. Factors that affect ventricular end-diastolic pressure such as altered myocardial compliance or increased transmural pressure alters PCWP. Although LVSWI is not completely independent of these factors and may be less precise with altered PCWP, the LVSWI does enhance the data base used to manage patients with altered ventricular function. Ideal LVSWI values may not be achievable in patients with poor myocardial contractility; however, tracking the LVSWI provides sensitive and immediate feedback on the efficacy of pharmacologic intervention. Critical care nurses should use the LVSWI for any hemodynamically unstable patient whose myocardial contractility might be compromised. This information allows the nurse to optimize the patient's hemodynamic performance with a more accurate assessment of heart function.