The Effect of Neuromuscular Blockade on the Composite Variability Index (CVI) During Laryngoscopy
Condition: Anesthesia; Neuromuscular Blockade
Study type: Interventional

Summary: 
      The Bispectral Index (BIS) monitor is used in many operating rooms to provide information to
      the anesthesiologist about a patient's level of consciousness. The Composite Variability
      Index (CVI) is a new index that may provide the anesthesiologist with more information about
      the condition of the patient. The CVI is a measure of the combined variability in BIS
      (bispectral index) and frontal electromyography (EMG) activity that may be useful in
      assessing the nociception/anti-nociception balance for patients under general anesthesia.The
      purpose of this study is to determine if a commonly used anesthetic drug (rocuronium) affects
      the CVI measurement differently with different doses. Rocuronium is a neuromuscular blocking
      agent (NMBA) routinely used during surgery. It is expected that the group given the highest
      dose of rocuronium will have diminished CVI values.

      This study will randomize patients to one of four doses of rocuronium: no rocuronium, 0.2,
      0.4, and 0.6 milligrams per kilo of body weight; the last dose is the standard amount for
      adults. It is expected that the group given the highest dose of rocuronium will have
      diminished CVI values. By including intermediate doses, information about the function of CVI
      in states of less than full muscle relaxation, or paralysis, will be obtained. This
      information is critically important for the development of the composite variability index,
      because during general anesthesia patients are usually maintained in a state of less than
      full paralysis. If the CVI response to stimulation in the intermediate groups is similar to
      the group receiving no rocuronium, the monitor may find wide clinical applicability. If the
      response is similar to the maximal rocuronium group, the index may only be reliable in states
      with no muscle relaxant, which will greatly limit clinical utility.
    

Detailed description: 
      Consented subjects randomized to one of four doses of rocuronium will be transported to the
      operating room and be connected to routine monitors that included a BIS (Covidien), M-Entropy
      sensor (GE Healthcare) and TOF (train of four) monitor. Following preoxygenation, general
      anesthesia will be induced with propofol and remifentanil using traditional syringe pumps.
      The induction doses given and subsequent infusion rates will be determined by utilizing
      pharmacokinetic (Pk) models (Marsh model for propofol, Minto model for remifentanil).
      Unconsciousness will be confirmed by performing the usual clinical assessments and by
      obtaining a BIS value between 40 and 50. Once the subject is unconsciousness, they will be
      given the assigned dose of rocuronium, after which the study anesthesiologist will perform a
      laryngoscopy. The anesthesiologist performing the laryngoscopy will not know what dose of
      rocuronium the subject received. Neuromuscular blockade (NMB) will be monitored by a
      train-of-four twitch monitor (TOF Watch-SX) at the adductor pollicis muscle (2 HZ, 50mAmp)
      every 15 seconds.

      At three minutes after the rocuronium administration, a standardized 20-second laryngoscopy
      will be applied. The CVI, entropy, and hemodynamic responses (heart rate, blood pressure
      measurement each minute) and train-of-four measurements will be monitored for three minutes
      before and after the laryngoscopy.
    

Intervention name(s): Saline 0.06 ml/kg; Rocuronium 0.2 mg/kg; Rocuronium 0.4 mg/kg; Rocuronium 0.6 mg/kg
Intervention type(s): Drug; Drug; Drug; Drug
Intervention description(s): IV Infusion x1 prior to laryngoscopy; IV Infusion x1 prior to laryngoscopy; IV Infusion x1 prior to laryngoscopy; IV Infusion x1 prior to laryngoscopy
Other intervention name(s): Normal Saline; Rocuronium bromide: Zemuron; Rocuronium bromide: Zemuron; Rocuronium bromide: Zemuron
Intervention MeSH terms: Bromides; Rocuronium
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science