Confirmatory Study of HFVI Guided Analgesic Administration in Surgical Subjects
Condition: Analgesia
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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
    

Intervention name(s): HFVI
Intervention type(s): Device
Intervention description(s): Subjects in the HFVI intervention group will be monitored in the same manner as the control group, but the HFVI monitor display will also be available to the anesthesia provider in real time. Bolus doses of 25ug or 50 ug of fentanyl will be recommended to be administered when the HFVI values begin to decrease below 50, and as needed based on the judgment of the clinician responsible for the case. All anesthetic medications that are given, patient events, and vital sign recordings will be included in the anesthetic record and data collection forms.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: A Prospective, Randomized, PACU Blinded, Clinical Utility Study to Confirm the Safety and Efficacy of HFVI-Guided Analgesic Administration in Surgical Subjects Receiving Balanced Sevoflurane-Fentanyl Anesthesia
Masking: Double (Participant, Care Provider)
Primary purpose: Supportive Care
Keywords: Sevoflurane-Fentanyl Anesthesia