Confirmatory Study of HFVI Guided Analgesic Administration in Surgical Subjects

Overview

The current study is intended to be a prospective clinical performance validation study designed to confirm the clinical utility of HFVI-guided fentanyl administration during sevoflurane anesthesia. The overall objective of this study is to confirm the safety and efficacy of HFVI-guided analgesic administration in comparison to standard clinical practice. The primary efficacy endpoint will be the amount of postoperative pain reported in the PACU, as measured using a nurse administered Numerical Rating Scale (NRS) pain score.

HFVi was designed to provide a standardized measure of the parasympathetic component (p∑) of the Autonomous Nervous System (ANS). It tracts changes of the p∑ tonus induced by each respiratory cycle (spontaneous or artificial) to measure the relative balance of parasympathetic and sympathetic tone as reflected in the EKG signal. These rapid changes of the p∑ tonus express themselves at the sinus node level by changes of the time interval separating two R waves of the electrocardiogram. The following normal RR intervals constitute the tachogram (displayed as respiratory pattern on the monitor). The p ∑ component is evaluated after filtering, standardization and re-sampling of the R-R series, by measuring the surface generated by respiratory cycles on the tachogram. Higher p∑ tonus is reflected as a larger measured surface area. In contrast, the measured surface decreases when the p∑ decreases. HFVi, a measure of the surface area, is expressed in the form of a dimensionless index ranging from 0 to 100. This index reflects the relative activity of the parasympathetic nervous system. It expresses the relative quantity of the present p∑ tonus compared to the Para and sympathetic tonus. The measure of HFVi displayed represents the average of a sequence of measurements: each elementary measure is realized on 64 seconds of data, updated each second using a sliding window. During development, a probabilistic interpretation of the HFVi was used to relate index values to a clinical state in an anesthetized subject. A significant hemodynamic response (increase of the heart rare or blood pressure of 20% compared to the baseline) within 10 minutes was used as an indicator of nociception/inadequate analgesia. As a measure of parasympathetic tone, HFVi may be influenced by many factors and thus be difficult to interpret in many of the following situations: * arrhythmia * no breathing (ex : apnea due to intubation) * Respiratory rate lower than 9 cycles/min * Tidal volume variable on the measuring time, thus 64 seconds * Irregular breathing (when the patient speaks, laugh or cough) * pace maker (some types) * heart transplantation * Drug use having a significant effect on the sinus cardiac activity

Conditions

Interventions

Eligibility

Locations (1)

Outcomes