Noninvasively derived stroke volume variation by finger volume clamping can reliably predict fluid responsiveness

Abstract

Background and Goal of Study: Dynamic preload variables derived from the arterial pressure waveform have been shown to accurately predict fluid responsiveness in mechanically ventilated patients. One of these variables, stroke volume variation (SVV), can also be obtained noninvasively by the finger volume clamp method using the Nexfin® device (Edwards Lifesciences BMYE, Amsterdam, Netherlands). In patients undergoing general surgery, we explored the ability of noninvasive SVV to predict fluid responsiveness defined at multiple thresholds. We also studied the limits of the so-called grey zone, indicating the area of doubt.1 Materials and Methods: After local IRB approval, 81 patients undergoing general surgery were included. SVV and stroke volume index (SVI) were measured using the noninvasive volume clamp method (Nexfin®). All patients received a 500 ml colloid bolus for routine clinical care and the attendinganaesthetist was blinded for Nexfin®- derived variables. A minimal increase in Stroke Volume Index (↑SVI) was used to define fluid responsiveness with thresholds of 10, 15, and 20%. Areas under the ROC curve (AUROC) were calculated to assess the ability of SVV to predict fluid responsiveness and to calculate the grey zone limits (i.e. values for which sensitivity and specificity are < 90%). Results and Discussion: Mean (SD) SVI increased from 40 (11) to 45 (10) ml/m². For all thresholds, the number of fluid responders / non-responders, AUROC’s and the associated limits of the grey zone are shown in table 1. Sensitivities and specificities are shown in figure 1. Conclusion: Advanced noninvasive haemodynamic monitoring using the volume clamp method to measure SVV can adequately predict fluid responsiveness in patients undergoing general surgery. Its ability to assess fluid responsiveness is dependent on the intended increase in SVI and improves for higher ↑SVI thresholds. Reference: 1. Cannesson M, et al. Anesthesiology 2011; 115: 231-41