Determination of LV contractility is a cornerstone in clinical practice [
6,
12]. Numerous methods for assessing LV contractility have been reported but none have been adequately validated in clinical practice, or require the presence of an intraventricular pressure catheter, prohibiting routine use in clinical practice [
13,
14]. The gold standard method, Ees, requires both ventricular pressure and volume measurements on a beat to beat basis with preload variation [
2]. Single beat analysis has been developed, but requires the whole ventricular pressure waveform [
15]. dP/dt
max can be easily calculated in clinical practice but is sensitive to both LV contractility and preload [
9]. In the present study, we tested whether arterial dP/dt
max, derived from femoral fluid-filled catheter, was accurate for assessing LV contractility. While LV dP/dt
max is considered as a good index of LV contractility despite its preload dependence, little is known about arterial dP/dt
max [
16,
17]. One study performed in perioperative patients found that arterial dP/dt
max and LV dP/dt
max were significantly correlated and concluded that changes in arterial dP/dt
max were accurate for assessing changes LV contractility [
18]. To the best of our knowledge, despite its wide use in critically ill patients, arterial dP/dt
max has never been directly compared with Ees during changes in LV function, at different levels of vascular filling. Our results demonstrated that there was significant correlation between arterial dP/dt
max and Ees. Furthermore, a far better correlation with a good agreement between arterial dP/dt
max and Ees were observed when adequate vascular filling was achieved. Similar improvement was observed between arterial and LV dP/dt
max. However, correlation between LV dP/dt
max and Ees did not significantly change when adequate vascular filling was achieved. Arterial dP/dt
max is an ejection phase index depending on arterial compliance and waves reflections from periphery to aorta. All factors that may affect arterial compliance and waves reflections (vascular filling conditions, vasoactive agents) may also affect arterial dP/dt
max independently of LV contractile function. As a result, the combination of fluid responsiveness and changes in arterial compliance and waves reflections due to endotoxin and/or catecholamines could enhance discrepancies between arterial and LV dP/dt
max and consequently between arterial dP/dt
max and the reference method, Ees [
19]. In this study, fluid administration was directed by PPV.
Adequate vascular filling was defined as PPV ≤ 11%. On the basis of clinical settings, this PPV threshold value allows the best discrimination between responders and nonresponders to intravascular fluid administration [
20‐
23]. In perioperative patients, De Hert et al. showed that changes in femoral dP/dt
max accurately reflected changes in LV dP/dt
max during various interventions. However, absolute values of LV contractility are required for potential ventriculo-arterial interaction analysis [
24]. These authors also found that leg elevation induced significant increase in central venous pressure and LV end-diastolic pressure, but arterial and LV dP/dt
max remained unaltered [
18]. However, it is well recognized that static indices (like central venous pressure or LV end-diastolic pressure) are poor indicators of vascular filling and preload responsiveness [
11]. Masutani et al. showed that LV dP/dt
max can be predicted from aortic dP/dt
max but their method requires aortic impedance which is difficult to calculate in clinical practice [
25]. Therefore, assessing LV contractility from arterial dP/dt
max, when adequate vascular filling is achieved, could be a simple and accurate method with the potential for ventriculo-arterial interaction analysis.
Other methodological issues should be taken into account. First, the use of a fluid-filled catheter could be another source of discrepancy between arterial dP/dt
max and Ees. As pointed out by numerous authors, pressure waves measured with a fluid-filled catheter have to be interpreted cautiously, because the pressure waveform may be distorted by the dynamic response of the catheter. By taking care of a properly flushed catheter system and by filtering out artifacts, the catheter response were optimized in our study [
26]. Secondly, arterial and LV dP/dt
max could also be influenced by heart rate. Heart rate variability was not significant enough to analyze its influence on arterial dP/dt
max in the present observations.