VieScope Versus Direct Laryngoscopic Intubation

Endotracheal intubation is required for different surgical procedures for mechanical ventilation and to prevent aspiration of secretions. Endotracheal intubation is usually performed by direct laryngoscopy (DL), i.e. during otorhinolaryngologic or oral and maxillofacial surgery. This technique has limitations and may fail due to insufficient visualization of the larynx. A new device has been introduced that consists of an illuminated straight plastic tube for laryngoscopy (VSC, Vie Scope, Adroit Surgical, Oklahoma City, OK, USA) that enables for indirect intubation over a stylet. So far, the VSC has shown promising results in manikin studies for intubation in normal and difficult airways and was shown to be superior over conventional laryngoscopy during cardiopulmonary resuscitation with providers wearing personal protective equipment. Data in elective patients undergoing otorhinolaryngologic or oral and maxillofacial surgery are not available, so far.

Therefore, we aim to test the VSC in patients compared to conventional techniques in a prospective randomized non-inferiority trial. We aim to test the VSC in predicted non-difficult airway patients.

Patients will be assessed for eligibility in the Anesthesiology Pre-assessment Clinic of the University Medical Center Hamburg-Eppendorf prior to elective surgery. To rule out a difficult airway prior to study inclusion, all patients receive a structured preoperative airway assessment in accordance with standard operating procedure of the Department of Anesthesiology, University Medical Center Hamburg-Eppendorf using the implemented in-house algorithm for the prediction of difficult airway management and the Simplified Airway Risk Index (SARI).

Patients are randomized 1:1 to either intervention or control group. Patients randomized to the intervention group will be intubated with the VSC. Patients randomized to the control group are intubated with a standard MacIntosh type laryngoscope by DL. Anesthesia management, the choice of the blade and tube size, as well as the use of adjuncts like stylets, introducers or forceps or airway optimization maneuvers (e.g. backward upward rightward pressure [BURP] and optimum external laryngeal manipulation [OELM]) will be left to the discretion of the attending physician.

Based on a first attempt success rate of 40%, and a noninferiority margin of 5%, 2x 29 patients are required with errors of α=0.025 and β=0.2 to show non-inferiority for the intervention method (PASS version 08.0.6, NCSS, LLC. Kaysville, UT, USA).

All participating physicians are anesthesiology residents or fellows. To avoid a bias that may occur due to different skills for VSC compared to conventional laryngoscopy, physicians participating in this study take part in a 30 min structured manikin airway training before participating in this study. The age and months of work experience of the participating anesthetists will be assessed within a questionnaire.

Inclusion criteria

• Patients requiring general anesthesia with transoral tracheal intubation for elective surgery
• Age ≥ 18
• Preoperative airway assessment reveals an expected non-difficult airway (rated by the responsible anesthetist in the Pre-assessment Clinic based on the existing in-house algorithm)

Exclusion criteria

• Pregnant or breastfeeding woman
• Confirmed indications for awake fiberoptic intubation especially due to enoral, pharyngeal tumors, abscesses or other processes
• Planned endotracheal intubation without deep anesthesia or neuromuscular blocking agents (e.g. awake videolaryngoscopy)
• Required transnasal tracheal intubation (e.g. for surgical reasons)
• Requirement of special endotracheal tubes such as laser or RAE tubes for surgical reasons
• Patients at risk for pulmonary aspiration who qualify for rapid sequence induction
• Loose teeth
• Denial of consent