Abstract
Purpose
Laryngeal tumors can cause significant anatomical distortion, making tracheal intubation challenging. Compared to video laryngoscope (VL), intubation using a Disposcope endoscope (DE) offers flexibility and allows for better navigation around obstructive lesions in the upper airway. This study aimed to compare the clinical performance of DE and VL for anticipated laryngeal tumor related difficult intubation in Ear, Nose, and Throat (ENT) patients undergoing general anesthesia.
Methods
We conducted a prospective, randomized, controlled trial. Eighty patients with anticipated difficult intubation due to laryngeal tumors undergoing elective surgery were included and randomly allocated to either the DE group (n = 40) or the VL group (n = 40). The primary outcome was the first-attempt success rate of tracheal intubation. Secondary outcomes included intubation time, hemodynamic response, and the incidence of complications related to intubation.
Results
A total of 80 subjects (61 male/19 female, 30 to 81 years old) were included in the final analysis. The first-attempt success rate of tracheal intubation was significantly higher in the DE group compared with the VL group (97.5% vs. 77.5%; mean difference [95% CI]: 20% [5.5 to 35.1]; P = 0.007). The intubation time was reduced in the DE group compared to the VL group (28.5 ± 6.7 s vs. 39.0 ± 10.0 s, mean difference [95% CI]: 10.5 s [6.7 to 14.3]; P < 0.001). Compared to DE, VL exhibited a higher heart rate one minute after intubation (71.1 ± 10.9 bpm vs. 78.3 ± 12.8 bpm; mean difference [95% CI]: 7.2 bpm [1.9 to 12.5]; P = 0.008). The incidence of postoperative airway complications was not significantly different between the two groups.
Conclusion
The DE showed a higher first-attempt success rate and a shorter intubation time than the VL for anticipated laryngeal tumor related difficult intubation in ENT patients undergoing general anesthesia.
Trial registration
Chinese Clinical Trials Identifier ChiCTR2300068449.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12871-025-03566-1.
Keywords: Video laryngoscope, Disposcope endoscope, Anticipated difficult intubation, Laryngeal tumors, General anesthesia
Introduction
Tracheal intubation in patients with laryngeal tumors undergoing ear, nose, and throat (ENT) surgery is particularly challenging because tumor-related airway distortion can hinder visualization and tube advancement. Reported first-attempt failure rates reach 28% [1–4], leading to complications such as hypoxia, airway trauma, or even cardiopulmonary arrest [5–7].
Video laryngoscopes (VLs) have become the standard tool for difficult airway management because they provide improved glottic visualization through a camera-equipped blade [8–10]. However, in patients with bulky laryngeal tumors, the glottic view may remain obscured even under video guidance.
The Disposcope endoscope (DE) is a video stylet akin to the Bonfils, Trachway, and Shikani. Unlike the fully rigid Bonfils, the DE has a flexible tip and integrated video display, improving maneuverability and team visualization [11]. Its performance is comparable to the Trachway but with a simpler, self-contained design. Notably, DE is a semi-rigid, adjustable video stylet that allows real-time visual navigation of the endotracheal tube around obstructive lesions [12–14]. In addition, the DE is relatively affordable, widely available, and requires a shorter training curve compared with conventional fiberoptic systems, which enhances its practical utility in various clinical settings. The DE is an effective device for managing difficult airways [11, 15], and previous manikin and case-based studies suggest that DE may facilitate intubation with reduced dental injury and faster tube placement in simulated difficult airways [14, 16].
Despite these promising findings, no randomized controlled trial (RCT) has compared the clinical performance of DE and VL (Fig. 1) in patients with laryngeal tumors. We therefore hypothesized that DE would provide a higher first-attempt success rate than VL in this patient population. The primary aim of this study was to compare the first-attempt success rates of DE versus VL. Secondary outcomes included intubation time, hemodynamic responses, and intubation-related complications.
Fig. 1.
Study devices were used in this study. A The UE video laryngoscope. B The Disposcope endoscope
Methods
Ethics
The study was approved by the Ethical Committee of Shanghai Eye & ENT Hospital of Fudan University on January 19, 2023 (Ethical Committee No. 2023007). The study protocol was registered with the Chinese Clinical Trial Registry (ChiCTR2300068449) before patient enrollment. All methods were performed in accordance with the 1983 Helsinki Declaration. This study was conducted following Good Clinical Practice Guidelines and adhered to the applicable Consolidated Standards of Reporting Trials (CONSORT) guidelines. Written informed consent was obtained from all patients prior to enrollment in the study.
Study design
We conducted a randomized, prospective, parallel-group trial to compare the Disposcope endoscope and video laryngoscope for tracheal intubation in ENT patients undergoing general anesthesia with anticipated difficult intubation due to laryngeal tumors. Patients were blinded to the study intervention. Given the nature of the intervention, the operators who performed the intubation were aware of the group assignments after randomization. However, the researchers and data analysts were blinded to the allocation.
Participants and screening
Participants were recruited from March 1 to July 31, 2023, at a single tertiary teaching hospital (Shanghai Eye & ENT Hospital of Fudan University). Adults (≥ 18 years) with American Society of Anesthesiologists (ASA) physical status I-III who were scheduled for elective otolaryngologic surgery under general anesthesia with planned orotracheal intubation (either could be intubated under VL and DE) were eligible if difficult post-induction intubation attributable to a laryngeal tumor was anticipated. Screening was performed by a senior attending anesthesiologist, with more than 500 cases airway management experience in ENT difficult airways, who reviewed the laryngoscopy report, medical history and conducted a bedside airway assessment. Anticipated laryngeal tumor-related difficult asleep intubation was defined a priori as a laryngeal mass occupying more than 25% of the glottic aperture on preoperative flexible laryngoscopy, indicating likely difficulty with intubation after induction (asleep intubation). This criterion, established through our institutional experience in upper airway management, identifies patients likely to present technical challenges during asleep intubation. Only patients meeting this criterion proceeded to management decisions. For these patients, the anesthesia strategy (awake versus asleep) was determined first; followed by selection of the intubation device (VL, DE, dual‑device approach, or fiberoptic bronchoscope).
To isolate tumor-related difficulty and avoid nontumor confounders, we excluded patients undergoing emergency surgery (including acute laryngeal obstruction requiring emergent airway management or cardiopulmonary arrest); those at high risk of aspiration; those with anticipated difficult mask ventilation; those with a body mass index (BMI) > 40 kg/m², a thyromental distance < 6 cm, or a mouth opening < 3 cm; patients scheduled for awake intubation; and those who declined to participate.
Anatomical classification of laryngeal tumor and study definitions
In the study, tumor locations were defined based on endoscopic findings and classified as follows: (1) Supraglottic tumor: tumors originating from or primarily involving the anatomical structures above the laryngeal ventricle, including the epiglottis, arytenoids, aryepiglottic folds, and false vocal cords. (2) Glottic and subglottic tumor: tumors originating from or primarily confined to the true vocal cords, which is located at glottic and/or subglottic sites. A panel of representative case images (Figure S1) in the supplementary appendix.
Randomization and allocation
Patients were randomly allocated to the video laryngoscope or Disposcope endoscope in a 1:1 ratio using computer-generated blocks of four. The group assignments were written on cards and placed in sealed, opaque, sequentially numbered envelopes. An independent individual prepared the randomization envelopes and generated the allocation sequence. Both devices were available prior to the induction of anesthesia. Due to the inherent differences in the devices, the operators performing the intubation could not be blinded to the group assignment. The envelope was opened after anesthesia induction, following bag-mask ventilation.
Operator experience and training
All intubations were performed by two attending anesthesiologists experienced in both techniques. For videolaryngoscopy, no additional training was provided as it is routinely used in our department. For Disposcope endoscopy, both operators completed a standardized training curriculum prior to study initiation [17], as detailed in Supplementary Methods 1.
Outcome parameters
The primary outcome of this study was the first-attempt success rate for tracheal intubation. First-attempt success is defined as the placement of an ETT in the trachea following a single insertion of a VL blade or a DE stylet into the mouth. Success is confirmed by end-tidal carbon dioxide detection.
Secondary outcomes included the intubation time, hemodynamic response, and the incidence of complications related to intubation.
Other parameters recorded included airway evaluation, overall success rate, number of intubation attempts, intubation difficulty, the percentage of glottic opening (POGO) score [18], and view quality.
Detailed airway evaluation was performed before surgery. The modified Mallampati classification, interincisal distance, thyromental distance, neck circumference, cervical spine mobility (normal, reduced, or fixed), and lip bite test (LBT) were all measured. The intubation time was defined as the interval between the insertion and withdrawal of the device from the oral cavity. Overall success was defined as successful intubation with a given device on any attempt. Hemodynamic response, including mean blood pressure (MBP) and heart rate (HR), was recorded just before and 1 min after intubation. The difficulty of intubation was assessed based on the ease of device insertion and tube advancement, graded by the operator using a numeric rating scale (NRS), where zero indicated “easy,” and ten indicated “difficult.” POGO score (0 to 100%, 100%, full view of glottis from anterior commissure to the interarytenoid notch, 0%, even interarytenoid notch is not seen) [18] was used to compare the visual range of tracheal inlet during intubation. The quality of the view was graded as either good or poor by the operator based on the endoscopic visibility when using the video laryngoscope or Disposcope endoscope.
Intubation failure was declared if the tube could not be placed in the trachea after three attempts. The total number of attempts was limited to three. Attempts lasting longer than 60 s were also regarded as failed intubation.
Complications during intubation or immediately following intubation were assessed, including hypoxemia (peripheral oxygen saturation < 90%), severe hypotension (mean blood pressure < 65 mmHg), use of vasopressors, bleeding in the oral cavity, pharyngeal mucosa hemorrhage, laryngospasm, bronchospasm, oesophageal intubation, cardiac arrest, or death. An investigator blinded to the group assignment evaluated postoperative complications, including sore throat and hoarseness. Postoperative assessments were performed 24 h after surgery using the NRS.
Intervention
A brief medical history was taken during the preoperative visit, and the patient was assessed for difficult intubation caused by laryngeal tumors. Eligible patients were given verbal and printed information about the study, and written consent was obtained.
Each subject was fitted with a standard monitor, including an electrocardiogram, noninvasive blood pressure, and pulse oximetry. Anesthesia was induced with 2–2.5.5 mg/kg intravenous propofol and 0.2 µg/kg sufentanil. After confirming the loss of consciousness, 0.6 mg/kg of rocuronium was administered to facilitate tracheal intubation. The tracheal intubation was then performed. Mallinckrodt-reinforced tubes (Medtronic) with an internal diameter of 6.0 mm for women and 6.5 mm for men were used in both groups.
The subjects assigned to the DE group were intubated using the Disposcope endoscope (Kangmin Medical Technology Co., LTD, Changsha, Hunan, China, with a stylet size of 5.0 mm outside diameter and 37 cm length, Fig. 1b). The intubation procedure was similar to that described by QJ Chu [11]. A well-lubricated endotracheal tube (ETT) was preloaded onto the Disposcope endoscope before intubation. After pre-oxygenation and sedation, the jaw thrust maneuver was performed to create space for the stylet tip to gently insert into the vocal cords. Then, the ETT was advanced into the trachea. Successful intubation was confirmed using capnography, as indicated by a sustained wave of exhaled carbon dioxide.
The subjects assigned to the VL group were intubated using a UE video laryngoscope (Youyi Medical Equipment Co., Ltd., Zhejiang, China, with the TDC-3 Macintosh-style blade, Fig. 1a). After pre-oxygenation and sedation, the blade was inserted into the mouth to visualize the vocal cords and guide the ETT (within a 60°-angled malleable aluminum stylet) into the trachea. Then, confirmation of tube placement was achieved through capnography, as indicated by a sustained wave of exhaled carbon dioxide. At last, the tube was secured.
After successful tracheal intubation, the cuff pressure of the endotracheal tube was measured and maintained at 25 cm H2O using the Posey 8199 Cufflator (Posey Company, Arcadia, CA).
If the attempts failed, other intubation devices would be used at the discretion of the supervised consultant physician. Rescue mask ventilation was applied whenever the pulse oximetry was below 90%.
Sample size determination
In the pilot study, the first-attempt success rates of tracheal intubation using the Disposcope endoscope and video laryngoscope in patients with laryngeal lesions were 97.5% and 75.0%, respectively. The sample size was calculated using the PS (Power and Sample Size Calculations, version 3.0.43), which indicated that 36 patients per group were needed for a 2-tailed χ2 test to obtain 80% power and an α value of 0.05. Considering potential missing data and a 10% dropout rate, a total of 80 patients were planned for enrollment.
Statistical analysis
Quantitative variables were expressed as means ± standard deviation (SD), and qualitative variables as numbers (percentage). For the analysis of continuous parameters, the t-test or the Mann-Whitney U test was used depending on the results of the Kolmogorov-Smirnov test. Two by two contingency tables were analyzed by Fisher’s exact tests and larger contingency tables by Pearson’s Chi-square tests. In addition, the duration of the intubation attempt was analyzed using Kaplan-Meier estimates and a log-rank test [19]. All statistical analyses were performed using SPSS software (version 24.0; IBM Corp, Armonk, NY). In all analyses, P < 0.05 was considered statistically significant.
Results
Of 384 patients assessed for eligibility, 304 were excluded (Fig. 2, CONSORT flow chart). The main reasons were: no laryngeal tumor (n = 87), not anticipated to be a difficult intubation (n = 110), not scheduled for VL or DE intubation (n = 73), and age under 18 years (n = 11). Additional reasons were need for awake intubation (n = 16), thyromental distance < 6 cm (n = 5), and mouth opening < 3 cm (n = 2). No patient declined participation. Eighty patients were enrolled and randomized (40 to VL and 40 to DE), and all were included in the final analysis. The patients’ demographic and airway characteristics are depicted in Table 1.
Fig. 2.
Flow diagram for the study
Table 1.
Baseline Characteristics
| Demographic variables | VL Group (n=40) | DE Group (n=40) | P Value |
|---|---|---|---|
| Age (y), mean ± SD | 56 ± 13 | 56 ± 13 | 0.40 |
| Male, n (%) | 28 (70%) | 33 (82.5%) | 0.24 |
| BMI (kg/m2), mean ± SD | 24.1 ± 2.9 | 25.0 ± 3.3 | 0.60 |
| ASA physical status, n (%) | 0.48 | ||
| I | 14 (35%) | 10 (25%) | |
| II | 24 (60%) | 29 (72.5%) | |
| III | 2 (5%) | 1 (2.5%) | |
| Airway-related parameters | |||
| Mallampati classification, n (%) | 0.86 | ||
| I | 22 (55%) | 21 (52.5%) | |
| II | 14 (35%) | 16 (40%) | |
| III | 4 (10%) | 3 (7.5%) | |
| Interincisor distance ≥ 5cm, n (%) | 37 (92.5%) | 38 (95%) | 1.00 |
| Thyromental distance ≥ 6cm, n (%) | 40 (100%) | 40 (100%) | 1.00 |
| Neck circumference (cm), mean ± SD | 39.3 ± 3.3 | 39.4 ± 3.7 | 0.92 |
| Lip bite test, n (%) | 0.79 | ||
| I | 18 (45%) | 15 (37.5%) | |
| II | 21 (52.5%) | 24 (60%) | |
| III | 1 (2.5%) | 1 (2.5%) | |
| Difficult airway characteristics present | 0.59 | ||
| Supraglottic tumor, n (%) | 8 (20%) | 10 (25%) | |
| Glottic and Subglottic tumor, n (%) | 32 (80%) | 30 (75%) | |
| Surgical approach, n (%) | 1.00 | ||
| Intra-oral | 38 (95%) | 37 (92.5%) | |
| open | 2 (5%) | 3 (7.5%) | |
| Anesthesia time (min), mean ± SD | 34.0 ± 24.7 | 47.0 ± 41.0 | 0.04 |
| Induction-to-Incision Timea (min), mean ± SD | 5.4 ± 1.3 | 5.6 ± 1.2 | 0.53 |
| Operation time (min), mean ± SD | 24.2 ± 22.8 | 36.1 ± 39.0 | 0.05 |
| Recovery time (min), mean ± SD | 31.9 ± 3.8 | 31.4 ± 3.9 | 0.81 |
VL Video laryngoscope, DE Disposcope endoscope, SD Standard deviation, BMI Body mass index
aThe time from the start of induction to the start of surgery
The first-attempt success rate for tracheal intubation was significantly higher in the DE group (97.5%; 95% CI: 87.1–99.9%) than in the VL group (77.5%; 95% CI: 62.5–87.7%), with an absolute difference of 20% (95% CI: 5.5–35.1), corresponding to an odds ratio of 11.32 (P = 0.007). In the VL group, one intubation took 67 s. According to our definition, this was classified as a failed intubation as it exceeded the 60-second threshold. All 80 patients were successfully intubated within three attempts.
The DE group demonstrated a 10.5-second reduction in mean intubation time compared to the VL group (28.5 ± 6.7s vs. 39.0 ± 10.0s, the mean difference [95% CI]: 10.5s [6.7 to 14.3], P < 0.001; Table 2; log-rank P < 0.001; Fig. 3], with a large effect size (Cohen’s d = 1.23). Compared to DE, VL exhibited a higher heart rate one minute after intubation (71.1 ± 10.9 bpm vs. 78.3 ± 12.8 bpm; mean difference [95% CI]: 7.2 bpm [1.9 to 12.5]; P = 0.008), with a moderate effect size (Cohen’s d = 0.60).
Table 2.
Comparisons of Intubation-Related variables between the VL group and DE group
| Variables |
VL Group
(n=40) |
DE Group
(n=40) |
Mean Difference
(95% CI) |
P Value |
|---|---|---|---|---|
| First-attempt success rate, n/total N (%) | 31 (77.5%) | 39 (97.5%） | 20% (5.5 to 35.1) | 0.007 |
| Overall success rate, n/total N (%) | 39 (97.5%)c | 40 (100%) | 2.5% (-2.4 to 7.3) | 1.000 |
| Number of intubation attempts, n (%) | 0.025 | |||
| 1 | 31 (77.5%) | 39 (97.5%) | NA | |
| 2 | 8 (22.5%) | 1 (2.5%) | ||
| 3 | 1 (2.5%) | 0 | ||
| Intubation time (s), mean ± SD | 39.0 ± 10.0 | 28.5 ± 6.7 | 10.5 (6.7 to 14.3) | < 0.001 |
| POGO score, mean ± SD | 69.3 ± 23.7 | 73.9 ± 27.9 | 4.5 (-7.0 to 16.1) | 0.437 |
| External laryngeal manipulation, n (%) | 4 (10%) | 0 | NA | 0.124 |
| Difficulty of intubation (NRSa), mean ± SD | 2.0 ± 1.0 | 2.2 ± 1.2 | 0.2 (-0.7 to 0.3) | 0.405 |
| Quality of image, n (%) | NA | 0.002 | ||
| Bad | 2 (5%) | 13 (32.5%） | ||
| Good | 38 (95%) | 27 (67.5%） | ||
| Mean blood pressure (mmHg), mean ± SD | ||||
| Before intubation | 82.2 ± 12.0 | 85.1 ± 14.4 | 2.9 (-8.8 to 3.0) | 0.336 |
| 1 min after intubation | 87.9 ± 13.6 | 83.6 ± 14.8 | 4.3 (-2.0 to 10.6) | 0.180 |
| Heart rate (bpmb), mean ± SD | ||||
| Before intubation | 73.4 ± 10.8 | 73.9 ± 9.5 | 0.5 (-5.0 to 4.0) | 0.826 |
| 1 min after intubation | 78.3 ± 12.8 | 71.1 ± 10.9 | 7.2 (1.9 to 12.5) | 0.008 |
VL Video laryngoscope, DE Disposcope endoscope, CI Confidence interval, NA Not applicable, SD Standard deviation, POGO Percentage of glottic opening
aNRS Numeric rating scale
bbpm: beats per minute; cIn the VL group, one intubation took 67 seconds. According to our definition, this was classified as a failed intubation as it exceeded the 60-second threshold
Fig. 3.
Kaplan-Meier estimates the time until successful intubation using the video laryngoscope or Disposcope endoscope. There was a significant difference in intubation times between VL Group and DE Group (log-rank P < 0.001)
There were no significant differences in the mean blood pressure between the two groups. The image quality of the VL scope view was significantly better than that of the DE (P = 0.002; Table 2). The VL provided a good view in 38 out of 40 cases (95%), compared to only 27 cases (67.5%) with DE.Pharyngeal mucosal bleeding was observed in 3 (7.5%) and 1 (2.5%) patients in the VL and DE groups, respectively; this difference was not statistically significant (P > 0.5; Table 3 ). The rate of other postoperative airway complications did not differ between the two groups. No serious adverse events, including hypoxemia or death, occurred during the intubation period (Table 3).
Table 3.
Comparisons of postoperative complications between the 2 Groups
| Variables |
VL Group
(n=40) |
DE Group
(n=40) |
Statistics | P value |
|---|---|---|---|---|
| Any complicationsa, n (%) | 21 (52.5%) | 17 (42.5%) | 0.80 | 0.37 |
| Lip or Dental trauma, n (%) | 2 (5%) | 0 | 2.05 | 0.49 |
| Pharyngeal mucosa hemorrhage after intubation, n (%) | 3 (7.5%) | 1 (2.5%) | 1.05 | 0.62 |
| Postoperative 24 h sore throat, n (%) | 20 (50%) | 17 (42.5%) | 0.45 | 0.50 |
| Postoperative Throat pain (NRS), mean ± SD | 0.6 ± 0.1 | 0.5 ± 0.1 | 1.22 | 0.27 |
VL Video laryngoscopy, DE Disposcope endoscope, NRS Numeric rating scale, SD Standard deviation
aAny complications refer to the number of patients experiencing at least one complication in the category
Two operators participated. Operator 1 had 8 years of ENT airway management experience and had performed 803 VL and 452 DE intubations. Operator 2 had 7 years of experience and had performed 678 VL and 401 DE intubations.
Discussion
In this randomized trial, we compared the DE and VL for tracheal intubation in ENT patients undergoing general anesthesia with anticipated difficult intubation due to laryngeal tumors. The tracheal intubation with DE demonstrated clear advantages over VL, achieving a higher first-attempt success rate and shorter intubation time. Although the VL provided superior image quality, it was associated with a greater hemodynamic response during intubation. Importantly, no serious adverse events occurred, and the incidence of intubation-related complications was similar between the two groups. These findings support DE as an effective and efficient option for asleep tracheal intubation in patients with laryngeal tumors.
Laryngeal tumors can obstruct glottic exposure, narrow the airway, or cause bleeding, making intubation more challenging. In these patients, advanced airway management strategies could be considered, including awake fiberoptic intubation, video laryngoscope, and optical stylet techniques. Institutional experience, operator expertise, and preparation for immediate rescue with fiberoptic equipment ensured procedural safety. According to Gómez-Ríos et al. structured assessment and cognitive aids should guide airway planning [20, 21].
In our study, DE demonstrated superior intubation performance, likely related to its design features. Because the camera view is aligned with the endotracheal tube, the DE facilitates passage through narrowed or distorted airways and reduces tissue trauma [22]. In contrast, the indirect view of a video laryngoscope (VL) may not align with the tube trajectory when tumors distort the glottic axis. This likely explains the higher success and faster intubation with the DE in our population compared with reports in patients with normal anatomy [16, 23].
Although VL produces clearer images, this did not improve intubation efficiency. Our findings reaffirm that glottic visualization alone does not ensure successful tube passage [24, 25]. For nasotracheal intubation and other scenarios, DE may serve as a reliable alternative to fiberoptic bronchoscopy. While the Macintosh-blade VL can fail to elevate the epiglottis when tumor distortion prevents full lift, the DE conforms to the airway’s curvature, enabling intubation without needing epiglottic elevation. These properties likely contributed to DE’s shorter intubation times, which could help minimize hypoxemia risk in patients with limited respiratory reserve [26]. However, operator experience, device familiarity, and setup time may also affect success and intubation speed.
The DE’s advantage primarily arises from its tip alignment and flexibility, which may also extend to other challenging airway scenarios such as an anterior larynx, subglottic stenosis, or airway narrowing from radiation fibrosis. In appropriately selected borderline cases where awake intubation might otherwise be considered, these same characteristics could allow the DE to serve as a feasible alternative for asleep intubation under experienced supervision.
The higher first-attempt success and shorter intubation time observed with DE may have implications beyond elective ENT practice. Our findings align with prior reports of effective DE performance in other difficult airway phenotypes, including patients with restricted neck mobility, cervical spine pathology, and maxillofacial trauma [14, 15, 27]. Nevertheless, generalization to emergency department or intensive-care settings should be regarded as a future research question rather than an inference from our data. In these time-critical environments, differences in urgency, physiologic instability, and operator expertise could alter device performance. Targeted multicenter studies in such settings are therefore warranted to verify external validity.
VLs remain valuable in certain conditions, for example, contaminated airways with copious secretions or minor bleeding, where a wide field of view can improve landmark identification, or in bulky pharyngeal or transglottic tumors where additional working space aids tube delivery. In those cases, VL can be paired with adjuncts such as a bougie or flexible endoscope to navigate around lesions [28]. Device selection should thus be individualized based on anatomy, operator familiarity, and environmental context.
In our VL group, the first-attempt success rate (77.5%) likely reflects the use of a standard-geometry (Macintosh-style) blade rather than a limitation of VLs as a class. Blade angulation, curvature, and length vary considerably among VL designs and can influence both glottic visualization and tube delivery. We used a Macintosh-style VL to ensure internal consistency and reflect the common practice in our institution, where standard-geometry blades are routinely used. However, hyperangulated VLs (HAVLs) may offer advantages in anterior or anatomically distorted airways, such as retrognathia, limited neck extension, or mass occupied pharyngolaryngeal spaces, where a more acute viewing angle can facilitate tube guidance. Therefore, our results primarily apply to standard-geometry VLs, and outcomes may differ when using hyperangulated designs.
Limitations
Our study has several limitations. First, this was a single-center trial restricted to patients with laryngeal tumors appropriate for asleep intubation; those requiring awake intubation were excluded. Airway lesion size and location influence difficulty and success [29], so results should not be extrapolated to critically obstructed airways where awake fiberoptic intubation remains recommended. Second, operator blinding was not possible due to evident device differences. Although objective endpoints and standardized scoring scales were used, performance and detection bias cannot be fully excluded. Third, all intubations were conducted by anesthesiologists highly experienced with both techniques. This expertise likely represents an optimal scenario and may limit generalizability to less-experienced users; future studies should analyze outcomes across varied operator skill levels [30]. Fourth, procedural factors such as device flexibility, maneuverability, ergonomics, learning curves, and cost-effectiveness were not evaluated; these warrant assessment in future bench and clinical investigations. Finally, postoperative follow-up was limited to 24 h, possibly underdetecting delayed airway symptoms or complications. Longer-term evaluations using validated patient-reported measures at 7–30 days would strengthen understanding of clinical impact.
Conclusion
The Disposcope endoscope demonstrated higher first-attempt success and shorter intubation time than the video laryngoscope for anticipated laryngeal tumor related difficult intubation, with similar safety and less hemodynamic stress. These findings position DE as an effective option for asleep intubation in ENT patients with tumor related difficult airways. Confirmation in emergency, awake, and critical-care settings is needed to define its broader clinical role. From a clinical standpoint, these results suggest that the DE could be incorporated into difficult airway training programs and institutional airway algorithms as an intermediate option between videolaryngoscopy and fiberoptic bronchoscopy. Its distinct advantages in tumor related airway narrowing may inform updates to cognitive aids and future guideline development, supporting structured, evidence-based decision-making in anticipated difficult intubation management.
Supplementary Information
Acknowledgements
None.
Abbreviations
- VL
Video Laryngoscope
- DE
Disposcope Endoscope
- ENT
Ear, Nose, and Throat
- ChiCTR
Chinese Clinical Trials Registration
- RCT
Randomized Controlled Trial
- SpO2
Peripheral Oxygen Saturation
- CONSORT
Consolidated Standards of Reporting Trials
- ASA
American Society of Anesthesiologists
- BMI
Body Mass Index
- ETT
Endotracheal Tube
- POGO
Percentage of Glottic Opening
- LBT
Lip Bite Test
- MBP
Mean Blood Pressure
- HR
Heart Rate
- SD
Standard Deviation
- CI
Confidence Interval
- HAVL
Hyperangulated Video Laryngoscope
Authors’ contributions
Author Wenxian Li and author Yuan Han designed and joined to supervise the study. Authors Hongyan Xiao, Yanan Xiao, Ji’e Jia, Yirong Cai, Yilei Shen, Liu Han, Peixia Wu and Lili Feng contributed to the acquisition, analysis, and interpretation of the data.Author Hongyan Xiao and author Yingjie Wang participated in drafting the manuscript, and author Yuan Han revised it critically. All authors read and approved the final version of the manuscript.
Funding
This work was supported by the Natural Science Foundation of Shanghai [grant number 23ZR1409300] to Wenxian Li; 2023 Shanghai leading talent project, Fudan University Shanghai Medical College -Young Clinical Distinguished Physicians Training Program to Yuan Han; Shanghai Municipal Health Commission [grant number 202240315] to Yirong Cai. The sponsors have no involvement in study design, data collection and interpretation, writing of the manuscript, and the decision to submit the manuscript for publication.
Data availability
Not applicable.The datasets used in this study are not publicly available due to [ethical/legal restrictions], but anonymized subsets may be provided by the corresponding author upon reasonable request and with permission of the institutional review board.
Declarations
Ethics approval and consent to participate
Ethical approval was obtained from the Institutional Review Board of Shanghai Eye & ENT Hospital of Fudan University on January 19, 2023 (Approval No. 2023007).The study protocol was prospectively registered with ChiCTR prior to patient enrollment.Written informed consent was obtained from all patients prior to enrollment in the study.
Consent for publication
Written informed consent was obtained from all participants (or their legal guardians) for participation in the study. The manuscript contains no personally identifiable information. A Chinese-language sample consent form is provided as additional file.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Hongyan Xiao and Yanan Xiao are contributed equally.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
Not applicable.The datasets used in this study are not publicly available due to [ethical/legal restrictions], but anonymized subsets may be provided by the corresponding author upon reasonable request and with permission of the institutional review board.