Pulse pressure variation (PPV) and stroke volume variation (SVV) are dynamic preload variables that can be measured noninvasively to assess fluid responsiveness (FR) in anesthetized patients with mechanical ventilation. Few studies have examined the effectiveness of predicting FR according to the definition of FR, and assessment of inconclusive values of PPV and SVV around the cut-off value (the "grey zone") might improve individual FR prediction. We explored the ability of noninvasive volume clamp derived measurements of PPV and SVV to predict FR using the grey zone approach, and we assessed the influence of multiple thresholds on the predictive ability of the numerical definition of FR.
Ninety patients undergoing general surgery were included in this prospective observational study and received a 500 mL fluid bolus as deemed clinically required by the attending anesthesiologist. A minimal relative increase in stroke volume index (a dagger SVI) was used to define FR with different thresholds from 10-25%. The PPV, SVV, and SVI were measured using the NexfinA (R) device that employs noninvasive volume clamp plethysmography.
The area under the receiver operator characteristic curve gradually increased for PPV / SVV with higher threshold values (from 0.818 / 0.760 at 10% a dagger SVI to 0.928 / 0.944 at 25% a dagger SVI). The grey zone limits of both PPV and SVV changed from 9-16% (PPV) and 5-13% (SVV) at the 10% a dagger SVI threshold to 18-21% (PPV) and 14-16% (SVV) at the 25% a dagger SVI threshold.
Noninvasive PPV and SVV measurements allow an acceptable FR prediction, although the reliability of both variables is dependent on the intended increase in SVI, which improves substantially with concomitant smaller grey zones at higher a dagger SVI thresholds.
|Tijdschrift||Canadian journal of anesthesia-Journal canadien d anesthesie|
|Nummer van het tijdschrift||11|
|Status||Published - nov-2015|