ICU echocardiography and noninvasive hemodynamic monitoring: The integrated approach

Abstract

Optimal cardiovascular function requires appropriate coupling of the left ventricle and the arterial system and good interaction of its components. To appreciate the pathophysiology of cardiovascular function, we need a diagnostic and monitoring modality that can represent left ventricular-arterial coupling or the matching of ventricular elastance (E ES) with arterial elastance (EA). EES(ventricular function) indicates the variations of left ventricular end-systolic volume (ESV) (and indirectly the variations of stroke volume, SV) in response to the variations of end-systolic pressure (ESP) (arterial pressure) (ESP/ESV), and EA(arterial mechanical properties) indicates the variations of arterial pressure (ESP) in response to the variations of SV (ESP/SV). It has been suggested that the EA/EESratio is the left ventricular-arterial coupling parameter and that when EA/EES = 1, that is, when the EAslope is equal to the EESslope, the external work (mechanical work) is optimized, whereas for EA/EES = 0.5, that is, the EAslope is lower than the EESslope, cardiac efficiency is maximal. There are multiple potential sources of error in the noninvasive assessment of left ventricular-arterial coupling (EA/EESratio). However, this integrated monitoring approach (ESP, SV, ESV) gives appropriate attention to the concept of left ventricular-arterial coupling and it demonstrates the feasibility of monitoring the EA/EESratio throughout the noninvasive echocardiographic assessment.