The Nexfin device estimates arterial pressure by the volume clamp method through a finger pneumatic cuff. It also allows to estimate cardiac index (CI noninv) by pulse contour analysis of the non-invasive arterial pressure curve. We evaluated the ability of the device to track changes in cardiac index induced by a fluid challenge.
We included 45 patients for whom a volume expansion (500 mL of saline infused over 30 min) was planned. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution (CI inv, PiCCO device) and in CI noninv were recorded.
In seven patients, the Nexfin could not record the arterial curve due to finger hypoperfusion. Considering both the values obtained before and after volume expansion (n = 76 pairs of measurements), the bias (lower and upper limits of agreement) between CI inv and CI noninv was 0.2 (-1.8 to 2.2) L/min/m 2. The mean change in CI noninv was 10 ± 11%. The percentage error of CI noninv was 57%. The correlation between the changes in CI inv and CI noninv observed during volume expansion was significant ( P = 0.0002) with an r 2 = 0.31.