Role of TFA-1 adhesive forehead sensors in predicting fluid responsiveness in anaesthetised children

BACKGROUND The TFA-1 adhesive forehead sensor is a newly developed pulse oximeter for the measurement of the plethysmographic variability index (PVI) at the forehead, and for the rapid detection of changes in oxygen saturation during low perfusion. OBJECTIVES We evaluated the ability of the TFA-1 sensor to predict fluid responsiveness in children under general anaesthesia. DESIGN Prospective cohort study. SETTING Single tertiary care children's hospital. PATIENTS Thirty-seven children aged 1 to 5 years under general anaesthesia and requiring invasive arterial pressure monitoring. MAIN OUTCOME MEASURES The baseline PVI of TFA-1 and finger sensors, respiratory variation of aorta blood flow peak velocity (Δ V peak ) and stroke volume index (SVI) obtained using transthoracic echocardiography were assessed. After fluid loading of 10 ml kg −1 crystalloids over 10 min, SVI was reassessed. Responders were defined as those with an increase in SVI greater than 15% from the baseline. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive ability of the PVI of TFA-1 and finger sensors and Δ V peak for fluid responsiveness. RESULTS Seventeen (56.6%) patients responded to volume expansion. Before fluid loading, the PVI of TFA-1 and finger sensors and Δ V peak (mean ± SD) of the responders were 11.2 ± 4.4, 11.4 ± 5.1 and 14.8 ± 3.9%, respectively, and those of the nonresponders were 7.4 ± 3.9, 8.1 ± 3.6 and 11.0 ± 3.3%, respectively. ROC curve analysis indicated that the PVI of TFA-1 and finger sensors and Δ V peak could predict fluid responsiveness. The areas under the curve were 0.8 [ P = 0.00; 95% confidence interval (CI) 0.60 to 0.91], 0.7 ( P = 0.02; 95% CI 0.53 to 0.87) and 0.8 ( P = 0.00; 95% CI 0.59 to 0.91), respectively. The cut-off values for the PVI of TFA-1 and finger sensors and Δ V peak were 6.0, 9.0 and 10.6%, respectively. CONCLUSION The PVI of TFA-1 forehead sensor is a good alternative, but is not superior to the finger sensor and Δ V peak in evaluating fluid responsiveness in mechanically ventilated children under general anaesthesia. CLINICAL TRIAL REGISTRATION www.clinicaltrials.gov, NCT03132480.