Recording rates of high-frequency variability index monitoring and use of vasoactive medications in daily clinical practice: A prospective observational study.

Background and Aims: To assess data recording rates of the high-frequency variability index (HFVI), which becomes less reliable with vasoactive medication use, and examine the use of vasoactive medications in daily clinical practice. The hypothesis is that when an HFVI sensor is applied and anaesthesia management is left to the discretion of the anaesthesiologist in charge, HFVI interpretation would be limited. Methods: Patients aged ≥65 years who underwent elective major abdominal surgery for malignant disease under general anaesthesia in those scheduled for surgery for >2 h were eligible. The anaesthesiologists managed patients with HFVI sensors attached at their discretion, without any limitations on vasoactive medication use. The primary outcome was the HFVI data-recording rate. Secondary outcomes were intraoperative bolus and continuous use of vasoactive medications (ephedrine, phenylephrine, atropine, and noradrenaline). The percentage of administration time was calculated by dividing the total administration time by the surgery time. Results: Of 249 eligible patients, HFVI sensors were successfully attached with a mean data recording rate of 73.1% (95% confidence interval: 70.5%, 5.7%). Two hundred and ten patients received at least one administration of vasoactive medications during the assessment period, and ephedrine was dominant. Sixty-one patients received continuous administration of phenylephrine and noradrenaline, and the ratios of continuous administration time to the total surgical time were 77.8% and 84.9%, respectively. Conclusion: The data recording rate of HFVI in routine clinical practice was approximately 70%, and many patients were given vasoactive medications; thus, caution must be taken when interpreting HFVI in routine clinical practice.