Accuracy of mini-fluid challenge test in predicting fluid responsiveness in elderly patients undergoing surgery in prone position / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the accuracy of mini-fluid challenge test in predicting fluid responsiveness in elderly patients undergoing surgery in prone position.Methods:Forty-eight elderly patients, aged ≥ 65 yr, with body mass index of 18-30 kg/m 2, of American Society of Anesthesiologists physical status Ⅱ or Ⅲ, scheduled for elective spinal surgery, were enrolled.Patients were mechanically ventilated using a volume-controlled mode with a tidal volume of 6 ml/kg of ideal body weight during operation.A radial arterial catheter was inserted and connected to FloTrac/Vigileo system to monitor hemodynamic parameters.At 5 min after prone position, volume expansion was started when the hemodynamics was stable lactated Ringer′s solution 1 ml/kg was intravenously infused over 1 min, 1 min later lactated Ringer′s solution 1 ml/kg was intravenously infused over 1 min, 1 min later lactated Ringer′s solution 1 ml/kg was intravenously infused over 1 min, and 1 min later operation was started.After tracheal intubation and before prone position (T 1), 5 min of prone position (T 2), 1 min after 1st infusion of 1 ml/kg liquid (T 3), and 1 min after 2nd infusion of 1 ml/kg liquid (T 4) and 1 min after infusion of 3 ml/kg fluid (T 5), heart rate, mean arterial pressure, cardiac output, cardiac index, stroke volume, stroke volume index (SVI), stroke volume variability (SVV), pulse pressure variability (PPV), and changes in SVI induced by rapid infusion of 1, 2 and 5 ml/kg crystalloid (ΔSVI 1 ml/kg, ΔSVI 2 ml/kg, ΔSVI 5 ml/kg) were calculated.Positive fluid challenges were defined as an increase in SVI of 10% or more from baseline, and the patients were divided into responder group (R) and non-responder group (NR). Receiver operating characteristic curves predicting fluid responsiveness were generated for ΔSVI 1 ml/kg, ΔSVI 2 ml/kg, SVV and PPV, and areas under the receiver operating characteristic curves (AUC) were calculated. Results:Thirty patients were enrolled in group R and 18 cases in group NR.The AUC of ΔSVI 1 ml/kg in predicting fluid volume responsiveness was 0.87 with a diagnostic threshold of 7%, a sensitivity of 80%, and a specificity of 83%.The AUC of ΔSVI 2 ml/kg in predicting fluid responsiveness was 0.928 with a diagnostic threshold of 8%, a sensitivity of 78%, and a specificity of 89%.The AUC of SVV and PPV in predicting fluid responsiveness was 0.65 and 0.53, respectively. Conclusion:Mini-fluid challenge test guided by ΔSVI can predict fluid responsiveness in elderly patients undergoing surgery in prone position, and rapid infusion of 2 ml/kg crystalloid provides better accuracy than 1 ml/kg.