A new self-designed “tongue root holder” device to aid fiberoptic intubation

The study was conducted in accordance with the Declaration of Helsinki. It took place at The First Affiliated Hospital of Nanjing Medical University, after receiving approval from the institute’s ethics committee and was registered at ClinicalTrials.​gov. Written informed consent was obtained from all patients. Three hundred patients, scheduled to receive general anesthesia for elective surgery and requiring orotracheal intubation between 2016 and 2018, were considered for enrollment. Inclusion criteria were (1) aged 18–75 years old, (2) American Society of Anaesthesiologists Physical Status (ASA PS) class I or II, and (3) presence of one or more of the following risk factors for difficult airway (difficult mask ventilation and difficult intubation): age older than 55 years, BMI > 26 kg/m², lack of teeth, history of snoring, presence of beard [7], Mallampati grades III–IV, interincisor gap < 3 cm, mental-thyroidal distance < 6 cm [8], receding mandible, buck teeth [9], reduced temporomandibular joint motility (upper lip bite test class III) [10‐12], and atlanto-occipital joint extension <35° (Table 1). Exclusion criteria: (1) awake intubation is required; (2) with a risk of aspiration; (3) with a previous failed tracheal intubation history; (4) with airway lesions and tracheobronchial injuries; (5) with trachea stenosis, compression, or malformations; (5) history of laryngopharyngeal or tracheobronchial surgery (including history of metallic stenting implantation); (6) those requiring emergency surgery; and (7) BMI < 18.5 kg/m².

Anesthetic monitoring included electrocardiogram (ECG), heart rate (HR), blood oxygen saturation (SpO2), respiration rate (RR), and non-invasive blood pressure (Bp). These indexes were measured using a Mindray T6 monitor (Mindray Inc., Shenzhen, China). After cannulation of a large forearm vein, lactated Ringer’s solution was given. The patients were randomly assigned to one of two groups at a 1:1 ratio: group L, FOI with tongue root holder, or group C, standard FOI. The jaw thrust maneuver was applied to all patients in both groups to facilitate advancement of the fiberoptic bronchoscope. After pre-oxygenation with 100% oxygen, anesthesia was induced with a standardized regimen, using intravenous midazolam (0.05 mg/kg) and etomidate (0.3 mg/kg). When patients lost consciousness, standard face mask ventilation was achieved. After we made sure that face mask ventilation was effective, a neuromuscular-blocking agent was provided (cisatracurium, 0.15 mg/kg). Fentanyl (3 μg/kg) was administered to attenuate hemodynamic response.

Three fellow anesthesiologists participated in this study. All FOI were performed by one senior anesthesiologist (A) with more than 10 years of experience in FOI. A flexible fiberscope was used through the oral approach. The patients’ head was positioned in a neutral position to establish the airway. The jaw thrust maneuver was performed by grasping and lifting the angles of the lower jaw with both hands, one on each side, while displacing the mandible forward [13]. This was performed by an experienced anesthesiologist (B) with both groups (L and C), who stood facing the patient from the patient’s left side. After the jaw thrust maneuver was performed, with the mouth open, the tongue root holder was inserted into the midline of the oral pharynx and placed on the dorsum of the tongue (Fig. 2). The handle was then lifted with an upwards and forward motion, pulling the tongue anteriorly and away from the soft palate and the posterior pharynx. This was done by a third anesthesiologist (C) with group L who stood facing the patient from the patient’s right side. An endotracheal tube (Shiley™; Covidien, Mansfield, MA, USA) with an internal diameter (ID) of 7.0 mm for female patients, and 7.5 mm for male patients, was threaded over a fiberoptic bronchoscope (LF-2; Olympus, Tokyo, Japan). Lubrication was applied to ease the advancement. The scope was advanced past the open vocal cords and then navigated all the way to the carina. Finally, the tube was advanced over the scope and into the trachea.

Successful FOI on the first attempt was defined as placement of the tracheal tube with a single insertion [14]. Successful intubation was confirmed by end-tidal carbon dioxide and auscultation of lungs and stomach [15]. If the vocal cords and the carina were not visible within 60 s, or SpO₂ was below 90%, a further attempt was made after 3 min of mask ventilation with 100% oxygen. If FOI has not yet been successful after three attempts, it was recorded as a failure. In failure cases of group C, we attempted to use tongue root holder. Of course, other techniques, including video-assisted laryngoscopy, lighted stylets, laryngeal mask airway (LMA), or a combination of these, may have been used for intubation after mask ventilation with 100% oxygen for 3 min.

Before anesthesia induction in the operating room, each patient received a clinical assessment of anatomical variables, including interincisor gap, thyromental distance, atlanto-occipital joint extension [16], modified Mallampati score, and the upper lip bite test (Table 1).

The primary endpoint was feasibility of intubation. The secondary endpoints included the number of intubation attempts, airway clearance, and intubation-related times. Airway clearance at the soft palate and glottis levels was graded according to previous reports (Table 1) [17, 18]. Airway clearance was defined as the percentage of grade I. The intubation times included the time to view the glottis (from the insertion of fiberoptic bronchoscope into the oral cavity to the visualization of the glottis), the time to view the carina (from the insertion of fiberoptic bronchoscope into the oral cavity to the visualization of the carina), and the total time to achieve tracheal intubation (from the insertion of the fiberoptic bronchoscope into the oral cavity to the confirmation of successful intubation). These times were only analyzed in patients with successful intubation on first attempt.

Statistical analysis was performed using SPSS version 19 (IBM Corporation, Armonk, NY, USA). Data are expressed as mean  ± standard deviation for continuous variables or as n of patients (%) for categorical data. Variance analysis between groups was compared using the two-sample Student’s t test for continuous variables. Non-parametric data were analyzed using the two-sample Mann–Whitney U rank-sum test. Pearson’s chi-squared test or Fisher exact test was used to compare categorical data. Differences were considered statistically significant when P < 0.05.