The Effect of Neuromuscular Blockade on the Composite Variability Index (CVI) During Laryngoscopy

Condition(s) targeted: Anesthesia; Neuromuscular Blockade

Intervention: Dose 1a (Drug); Dose 2a (Drug); Dose 3a (Drug); Dose 4a (Drug); Dose 1b (Drug); Dose 2b (Drug); Dose 3b (Drug); Dose 4b (Drug)

Phase: N/A

Status: Completed

Sponsored by: Medtronic - MITG

Official(s) and/or principal investigator(s):
Donald M Mathews, MD, Principal Investigator, Affiliation: University of Vermont

The Bispectral Index monitor is used in many operating rooms to provide information to the anesthesiologist about a patient's level of consciousness. The Composite Variability Index, or Composite Variability Index (CVI), is a new index that may provide the anesthesiologist with more information about the condition of the patient. 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 muscle relaxant routinely used during surgery. It is expected that the group given the highest dose of rocuronium will have diminished CVI values.

Official title: The Effect of Rocuronium on the Response of Composite Variability Index (CVI) to Laryngoscopy

Study design: Allocation: Randomized, Intervention Model: Single Group Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Basic Science

Primary outcome: The difference between the mean CVI value prior to laryngoscopy to the maximal CVI reading following laryngoscopy.

Secondary outcome: The average CVI level during the maintenance phase of surgery.

Detailed description: 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. Subjects will receive propofol and remifentanil infusions during the case. These are commonly used medications for anesthesia. The subjects will also be randomized to two additional groups. One group will receive a remifentanil infusion of 2ng ml-1 and the other group will receive a 8ng ml-1 remifentanil infusion. Both doses are acceptable and often used during standard clinical care. The propofol infusion will be adjusted to keep the BIS number between 45-60. The anesthesiologist will not be able to see the CVI value. The times of certain intraoperative events, such as intubation and incision, will be recorded. All subjects will receive a morphine bolus (0. 10-0. 15 mg/kg) towards the end to reduce post-operative pain, as per standard clinical care. As the subject wakes up, time to eye opening and orientation will be recorded. The subject will rate their pain on a numerical pain scale and the quality of emergence will be assessed. Upon arrival in the post anesthesia care unit (PACU), subjects will be asked to rate their pain again using the same pain scale. The pain score will be evaluated every 10 minutes for half an hour, then every hour until they are discharged from PACU.

Minimum age: 18 Years. Maximum age: 75 Years. Gender(s): Both.

Criteria:

Inclusion Criteria:

- Presence of ASA physical status class I or II. (This will exclude subjects with

significant medical problems).

- Body mass index between 18 and 35 kg m-2.

- No use of psychotropic or neuropsychiatric medications.

- A airway assessment with no indication of a difficult intubation including a class I

or II Mallampati airway and a mandible-to-hyoid distance of greater than three fingerbreadths.

- Age between 18-75 years.

Exclusion Criteria:

- Does not meet inclusion criteria.

Fletcher Allen Health Care, Burlington, Vermont 05405, United States

Starting date: September 2011
Last updated: February 2, 2015