As simple as possible, but not simpler: estimating the effective arterial elastance at bedside

Excerpt

We have read with interest the recent experimental study performed by Monge Garcia et al. in twelve anesthetized and mechanically ventilated adult pigs [1]. In their conclusion, the authors recommend the clinical use of the mean arterial pressure over stroke volume ratio (MAP/SV) as a robust and preferable estimate of the effective arterial elastance (Ea = ESP/SV, where ESP is the left ventricular end-systolic pressure). Besides the originality of the study results obtained under various experimental conditions, the current article [1] may also be viewed as supporting the use of the MAP/SV ratio as an estimate of Ea in patients with septic shock [2]. Improving the estimation of Ea at the bedside may be an important issue. Indeed, Ea incorporates the main components of arterial load, and the ratio of Ea to left ventricular end-systolic elastance allows quantifying the mechanical coupling between the left ventricle and its load [3‐5]. However, we feel that the oversimplification of the estimation of Ea may hamper the precise evaluation of the left ventricular-arterial coupling, in the saying attributed to Albert Einstein that: “everything should be made as simple as possible, but not simpler”. For sake of clarity for the reader of the Journal of Clinical Monitoring and Computing, we are concerned by the fact the authors [1] do not discuss the role of arterial stiffness in the estimation of Ea. …