Univent Tube for Thoracoscopic Thymectomy in Myasthenic Patients: an Observational Study

This prospective study was conducted on MG patients who underwent thoracoscopic thymectomy under general anesthesia without NMBAs using Univent tube at Vietnam Military Hospital 103 from January 2016 to December 2019. MG was definitively diagnosed based on clinical features, electromyography results, and/or circulating antibodies against acetylcholine receptors and classified according to the Osserman Classification. Preoperative evaluations included CT scans, pulmonary function tests, and routine exams. The operative risk and airway assessments were evaluated by expert anesthesiologists and excluded patients with preexisting hoarseness or sore throat. This study was approved by Hanoi Medical University's ethics committee (No.168-QĐ/ĐHYHN) and Military Hospital 103. All patients were anesthetized and intubated by one anesthesiologist assigned to the thoracic surgery unit.

Anesthesia procedure

In the operating theatre, the standard monitoring included electrocardiogram (ECG), invasive arterial blood pressure (IABP), peripheral oxygen saturation (SpO2), end-tidal capnography (EtCO2), ventilation peak and plateau pressures, continuous spirometry, and entropy (response entropy-RE and state entropy-SE; Datex Omeda S/5 Advance, GE, USA). Neuromuscular monitoring was recorded in the left forearm using TOF (train-of-four)-WatchsSX (Organons, Oss, the Netherlands).

Patients were pre-oxygenated with 100% oxygen for 5 minutes before induction with sufentanil at 0.5 µg.kg-1 and propofol at 2-3 mg.kg-1. When patients lost their eyelash reflex, lidocaine 10% was initially sprayed in the oral cavity, oropharynx, and upper part of the larynx. Subsequently, lidocaine 2% was administered using The MADgic Laryngo-Tracheal Mucosal Atomization Device (Teleflex, Wayne, Pennsylvania, USA) to cover the oral cavity, oropharynx, larynx, vocal cords, and as deep as possible into the trachea.

Once the SE value reached 50 or lower, a Univent tube (Fuji Systems, Tokyo, Japan) was intubated using conventional direct laryngoscopy. The tube size was standardized based on the patient's sex, with an 8.0-mm inner diameter (ID) used for men and a 7.0-mm ID used for women. Depending on the side of the chest for approaching the anterior mediastinum, the endobronchial blocker was carefully guided into either the right (for a right-sided approach) or left mainstem bronchus (for a left-sided approach) using flexible fiberoptic bronchoscopy. The tracheal and blocker cuffs were gently inflated, ensuring that the intracuff pressure stayed below 30 cmH2O, as measured by a noninvasive manometer. Following the secure positioning of patients in a 45° lateral decubitus orientation for surgery, with their heads firmly fixed, the correct placement of the blocker was reassessed through bronchoscopy.