Glossopharyngeal Nerve Block for Awake Intubation
Condition: Morbid Obesity
MeSH terms: Obesity, Morbid
Study type: Interventional

Summary: 
      Endotracheal intubation of the morbidly obese is often performed awake. This is performed
      after topical anesthesia of the patient's pharynx and larynx. There are many techniques used
      to perform topical anesthesia of the patient's airway, which include aerosolization of local
      anesthesia, topical application of local anesthesia, and nerve blockade using needles and
      local anesthesia. Reasons for failure of any awake tracheal intubation technique is excess
      gagging. The most effective method to adequately anesthetize the airway to decrease the
      amount of gagging is unknown. The investigators wish to assess if the instillation of local
      anesthesia soaked gauze next to the peritonsillar pillars will decrease the number of gagging
      episodes during awake video laryngoscopy assisted tracheal intubation of the morbidly obese.
    

Detailed description: 
      Research design 1.1 Study design Prospective randomized control trial. 1.2 Patients All
      morbidly obese patient presenting for bariatric surgery at the Royal Victoria Hospital are
      eligible.

      1.3 Exclusions We will exclude any patient with

        -  moderate to severe systemic illness, i.e. American Society of Anesthesiologists (ASA)
           score of 4 or higher

        -  inability to communicate in English or French

        -  contraindications to the drugs used in the study 1.4 Recruitment Eligible patients
           admitted to Royal Victoria Hospital who do not have any of the exclusion criteria will
           be approached by one of the investigators in the recovery room, or in the preoperative
           clinic before the scheduled surgery. The study protocol will be explained and a consent
           form will be given to the patients. Patients will have time and opportunity to ask any
           questions before the consent will be signed.

      1.5 Study protocol Patients will be prepared for surgery according to the routine guidelines
      established by the Departments of Surgery and Anesthesia at the Royal Victoria Hospital.

      They will have an IV and peripheral arterial line inserted, and will have Canadian Anesthesia
      Society standard monitors placed. Glycopyrrolate 0.4 mg iv will be given to decrease
      secretions. Using a computer generated randomization table, patients will be assigned to a
      group that receives standard airway anesthesia with 20 ml of aerosolized 2% lidocaine and
      peritonsillar instillation of gauze soaked in normal saline (Control Group) or that receives
      20 ml of aerosolized 2% lidocaine and peritonsillar instillation of gauze soaked with 2%
      lidocaine (Glossopharyngeal Group). Sedation will be administered using a remifentanyl
      intravenous infusion of 0.05 /min with an initial bolus of 0.4µg/kg, and intravenous
      midazolam 0.05 mg/kg. We will review the chart to obtain patient demographic data including
      patient age, height, weight, medications, and past medical histories. Baseline blood
      pressure, heart rate, will be recorded, and a blood sample will be drawn for lidocaine level.

      Once the airway is topicalized and sedation has taken effect, the anesthesiologist will
      insert the video laryngoscope into the patient's oropharynx. Once the ideal view of the vocal
      cords is obtained, an endotracheal tube fitted with a stylet will be introduced into the
      pharynx, and then slid through the vocal cords into the trachea. During the intubation
      attempt, a blinded observer will record the blood pressure and heart rate at every minute,
      and the best view obtained with the laryngoscope. The observer will assign the patient a
      reaction score (4) at three time points: the insertion of the video laryngoscope, the
      pharyngeal insertion of the tracheal tube, and the tracheal insertion of the tracheal tube.
      This score will be:

        1. No reaction

        2. Single change in facial expression

        3. Grimacing facial expression

        4. Severe facial grimace, no reflex head movements

        5. Severe facial grimace with head movements

        6. Severe facial grimace with head and limb movements The observer will also record the
           time from the insertion of the video laryngoscope, and the first evidence of endtidal
           carbon dioxide from the tracheal tube. If the intubation attempt results in a reaction
           score of 6, or in an inadequate laryngeal view, the treating anesthesiologist may secure
           the airway in any way they see fit, which may include addition of more topical
           anesthesia, more sedation, or the use of another airway technique. The number of
           attempts at intubation, and any other techniques used for intubation will be recorded.
           We will measure lidocaine levels in blood samples every 10 minutes for 40 minutes after
           the commencement of the airway anesthesia, using the mass spectrometry method previously
           used for similar studies at the Royal Victoria Hospital.
    

Intervention name(s): 2% Lidocaine; placebo
Intervention type(s): Drug; Drug
Intervention description(s): 2% lidocaine and peritonsillar instillation of gauze soaked with 2% lidocaine (Glossopharyngeal Group).
Intervention MeSH terms: Lidocaine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Health Services Research
Keywords: Glossopharyngeal nerve block; Airway anesthesia; Awake intubation