McGrath Videolaryngoscopy and Direct Laryngoscopy in Morbidly Obese Patients
Condition: Morbid Obesity
MeSH terms: Obesity; Obesity, Morbid
Study type: Interventional

Summary: 
      Our goal is to compare conventional direct laryngoscopy using a Macintosh blade with the
      McGrath videolaryngoscope for endotracheal intubation in very morbidly obese patients
      undergoing non-cardiac surgery. Specifically, we propose to test the primary hypotheses that
      videolaryngoscopy improves visualization of the vocal cords, defined with modified Cormack
      and Lehane classification, compared to direct laryngoscopy.
    

Detailed description: 
      In the preoperative period, patient's airway data will be recorded by a research coordinator
      or anesthesia provider (Table 1). Patients will be positioned supine and in a standardized
      ramped position on the OR table. Patients will be pre-medicated with midazolam 0-2 mg IV, as
      clinically appropriate. All patients will be pre-oxygenated until the fraction of expired
      oxygen exceeds 80%. General anesthesia will be induced as preferred by the attending
      anesthesiologist, usually with a combination of lidocaine 1 mg/kg, propofol 2-5 mg/kg,
      fentanyl 1-3 µg/kg, and rocuronium 0.6-1.2 mg/kg or succinylcholine 1.5 mg/kg.

      Manual bag-mask ventilation will be initiated, with no restriction on the use of oral
      airways, nasal airways, laryngeal masks. Complete muscle relaxation will be confirmed by
      absence of palpable twitches in response to supra-maximal train-of-four stimulation of the
      ulnar nerve at the wrist. After confirming adequate bag mask manual ventilation, patients
      will be randomized 1:1, stratified for BMI >50 kg/m2, to:

        -  Direct laryngoscopy using an appropriately sized Macintosh blade (usually size 3 or 4);

        -  McGrath videolaryngoscopy in an appropriate size (usually blade size 3 or 4).
           Randomization will be based on computer-generated codes accessed from the Redcap system
           shortly before anesthetic induction. Allocation will thus be concealed until the last
           possible minute.

      Intubations will be performed with a regular endotracheal tube of adequate diameter, usually
      7.5 mm or 8.0 mm. Endotracheal tubes will be equipped with a hockey-stick-shaped stylette,
      which will be prepared by the anesthesiologist in advance.

      The McGrath or the Macintosh blade will be introduced into oral cavity according to
      manufacturer recommendations and clinical practice. Minor airway manipulation procedures
      including BURP or Sellick maneuvers will be allowed to improve visualization of the vocal
      cords.

      If initial intubation attempts fails, the endotracheal tube will be removed and manual bag
      mask ventilation will resume. Minor adjustments of patient's position and/or tube stylette
      are allowed as clinically appropriate. Up to three intubation attempts will be made as
      necessary. Further airway management will follow clinical assessment of the anesthesiologist.
      Additionally, throughout the procedure, the anesthesiologist could terminate the study
      participation.

      Once intubation is achieved, the endotracheal tube will be connected to the anesthesia
      circuit. Mechanical ventilation with O2 and air will be adjusted to maintain end-tidal PCO2
      between 32 and 35 mmHg as clinically necessary. Maintenance of general anesthesia will be
      provided, as clinically indicated.

      At the end of the surgical procedure, patients will be extubated and transferred to the post
      anesthesia care unit (PACU). Patients will then be assessed for postoperative complications 2
      hours following extubation, either in the PACU or surgical ward.

      Measurements Table 1. Demographic and morphometric characteristics will be collected from
      electronic medical records.

        1. Age

        2. Gender

        3. Race

        4. BMI

        5. ASA status

        6. Charlson score

        7. Smoking status

        8. Airway examination

             1. History of obstructive sleep apnea (yes/no)

             2. History of snoring (yes/no)

             3. History of CPAP (yes/no)

             4. History of difficult airway (yes/no)

             5. Mobility of cervical spine (cm)

             6. Mouth opening (cm)

             7. Inter-incisor gap (cm)

             8. Mandibular protrusion test

             9. Thyro-mental distance (cm)

            10. Sterno-mental distance (cm)

            11. Neck circumference (cm)

            12. Upper lip bite test (Class I, II, III)

            13. Mallampati score (1/2/3/4)

            14. Teeth status, Gap/missing teeth, Denture (n)
    

Intervention name(s): McGrath videolaryngoscopy; Direct laryngoscopy
Intervention type(s): Device; Device
Intervention description(s): Intubations will be performed with a regular endotracheal tube of adequate diameter, usually 7.5 mm or 8.0 mm. Endotracheal tubes will be equipped with a hockey-stick-shaped stylette, which will be prepared by the anesthesiologist in advance.
The McGrath or the Macintosh blade will be introduced into oral cavity according to manufacturer recommendations and clinical practice. Minor airway manipulation procedures including BURP or Sellick maneuvers will be allowed to improve visualization of the vocal cords.; Intubations will be performed with a regular endotracheal tube of adequate diameter, usually 7.5 mm or 8.0 mm. Endotracheal tubes will be equipped with a hockey-stick-shaped stylette, which will be prepared by the anesthesiologist in advance.
The McGrath or the Macintosh blade will be introduced into oral cavity according to manufacturer recommendations and clinical practice. Minor airway manipulation procedures including BURP or Sellick maneuvers will be allowed to improve visualization of the vocal cords.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment