ASIGN Trial- Angulated Versus Standard Video-laryngoscope Blade in Nasal Intubation

ASIGN is a prospective, single-blinded randomized single-center study to be conducted at Mount Sinai Hospital comparing hyperangulated blades versus Macintosh style videolaryngoscope blades for nasal intuba-tion The study will aim to enroll 220 patients, 110 on each treatment arm.

Patients who meet the inclusion criteria will be identified on the day of surgery and consent will be ob-tained from these patients. Once eligibility is confirmed, the research coordinator will randomize the pa-tient to one of two groups: C-MAC© Videolaryngoscope D-Blade or the C-MAC© Videolaryngoscope Mac-intosh blade.

All study participants will receive the same perioperative management which will include nasal vasoconstriction with xylometazoline 0.05% nasal spray. Three sprays will be given in each nostril prior to the patient entering the operating room. The choice of nostril for the nasal intubation will be made according to the pre-assessment with the patient and radiology imaging available.

To minimize the risk of operator-related bias during the procedure, the data collection will be collected by a member of the research team. All intubations will be performed by an anesthesiologist with more than 3 years of experience in using Macintosh videolaryngoscope, hyperangulated videolaryngoscope, nasal intubation and adjunct maneuvers.

Standard monitoring of vital signs will be used, including non-invasive blood pressure, pulse oxygen saturation, cardioscope, end-tidal carbon dioxide waveform, and neuromuscular transmission (NMT). Additional monitoring will be left to the criteria of the attending anesthesiologist. All subjects will be preoxygenated to an end-tidal oxygen fraction above 80%. The head will be supported in a headgel pillow in the extended position in a way that the patient is comfortable prior to the induction and head elevation between 5 to 10 cm.

Polar® North Polar Tubes (Smiths Medical, Minneapolis, USA), internal diameter 6.0 or 7.0 millimetre, are available and pre-warmed in the operation room. After the induction of general anesthesia, the anesthesiologist will nominate their first choice of size for the nasal endotracheal tube based on the weight and height of the patient. Once the NMT shows a train-of-four (TOF) = 0, the nostril will be lubricated with a water-based solution and the nasal tube will be advanced over until the tip is present in the oropharynx. After the insertion of the tube through the nostril, the anesthesiologist will use the de videolaryngoscope assigned for each group.

The patients allocated to the hyperangulated videolaryngoscope group will have C-MAC D-BLADE© (Karl Storz SE & Co. KG, Tuttlingen, Germany) as the tool for nasal intubation. Whereas the Macintosh-style videolaryngoscopy group will have a C-MAC© size 3 or 4 Macintosh blade (Karl Storz SE & Co. KG).

In case of hypoxemia, defined as pulse oxygen saturation < 90%, the intubation attempt will be interrupted, and mask ventilation will be reinitiated. If tracheal intubation fails after the third attempt, intubation with an alternative device would be attempted. If intubation is not possible, the patient will be awakened.

The study will be stopped early in the occurrence of any of the following: arterial active epistaxis bleeding, bronchospasm and laryngospasm that create difficulty ventilation even after deepen the anes-thesia and the use of muscle relaxant medication, refractory hypotension regardless the use of vasopres-sors, bradycardia below forty heart beats per minute with no response from anticholinergic medication, sustained hypertension regardless the use of vasodilators, sustained cardiac arrhythmia, - allergic reac-tion, failed facemask ventilation after using oropharyngeal airway plus two-hand seal mask technique, or rescuing the airway with a supraglottic device or front of neck access surgical airway.

The study will be interrupted in one of the following situations: nasal intubation is not possible due to size of the tube, necessity for intubation with nasal RAE (Ring-Adair-Elwyn) tube or necessity of oral endotracheal intubation.

Inclusion criteria

• Patients 18 years old or above

Exclusion criteria

• Patients requiring awake fiber optic intubation
• Emergency cases
• High risk of aspiration
• Bleeding diathesis
• Abnormal nasal anatomy
• Chronic Epistaxis
• Severe cardiorespiratory disease
• Basilar skull fracture