Hyperangulated vs Standard Videolaryngoscopy vs Direct Laryngoscopy for Double-Lumen Endobronchial Tube Intubation

Evaluation of Efficacy and Safety of Hyperangulated and Standard Curvature Blade Video Laryngoscopy Versus Direct Laryngoscopy for Double-Lumen Endobronchial Tube Intubation

This is a prospective, randomized, single-center, three-arm, open-label, low-risk medical device clinical study conducted at the Department of Anesthesiology and Reanimation, Trakya University Medical Faculty.

The study aims to compare the efficacy, safety, and clinical usability of three laryngoscopy methods for double-lumen endotracheal tube (DLT) intubation in patients undergoing elective thoracic surgery requiring one-lung ventilation: (i) C-MAC hyperangulated (D-blade) videolaryngoscopy, (ii) C-MAC Macintosh blade videolaryngoscopy, and (iii) direct Macintosh laryngoscopy.

The primary outcome is the total time to successful DLT placement (in seconds), defined as the interval from the end of mask ventilation to fiberoptic bronchoscopic confirmation of correct tube position. Secondary outcomes include glottic visualization quality (POGO score and Cormack-Lehane grade), intubation difficulty (Intubation Difficulty Scale), number of intubation attempts, need for auxiliary maneuvers, intubation-related complications, malposition rate, and postoperative airway symptoms (sore throat, dysphonia) assessed at 1, 6, and 24 hours postoperatively.

Eligible patients are adults (≥18 years), ASA class I-III, scheduled for elective thoracic surgery requiring one-lung ventilation. Patients with anticipated difficult airway, emergency surgery, pregnancy, or prior upper airway surgery are excluded. A total of 180 patients will be enrolled and randomized 1:1:1 into three groups (60 per group) using computer-generated block randomization.

Study Overview

• Status: Not yet recruiting
• Conditions: Thoracic Surgery; Endobronchial Intubation; One Lung Ventillation (OLV); Double Lumen Tube Intubation
• Intervention / Treatment: Device: C-MAC Hyperangulated D-Blade Videolaryngoscopy; Device: C-MAC Macintosh Blade Videolaryngoscopy; Device: Direct Macintosh Laryngoscopy

Detailed Description

Background and Rationale:

Double-lumen endobronchial tubes (DLTs) are the primary airway device for one-lung ventilation (OLV) in intrathoracic surgery. Their use enables lung isolation, which is essential for surgical exposure in procedures such as lobectomy, pneumonectomy, esophagectomy, and thoracoscopic interventions. Despite their widespread use, DLT placement is technically more demanding than standard single-lumen endotracheal intubation due to the tube's larger outer diameter, greater length, increased rigidity, and the presence of a distal bronchial cuff. These structural characteristics make laryngoscopy and tube advancement through the glottis considerably more challenging and are associated with a higher incidence of oropharyngeal, laryngeal, and tracheobronchial trauma compared to standard intubation.

Airway injuries related to DLT placement span a wide spectrum, ranging from minor mucosal lacerations of the lips, tongue, and pharynx to temporary or permanent vocal cord damage. In rare but serious cases, tracheobronchial perforation has been reported, a potentially life-threatening complication. The increased structural difficulty of DLT intubation translates into a higher likelihood of multiple intubation attempts, each of which independently increases the risk of airway trauma, hemodynamic instability due to prolonged laryngoscopy, and desaturation. Minimizing the number of attempts and the total intubation time is therefore of direct clinical importance in this patient population.

Videolaryngoscopy (VL) has become increasingly integrated into routine and difficult airway management over the past two decades. By providing an indirect, magnified view of the glottis transmitted via a camera mounted at the tip of the blade, VL improves glottic visualization compared to direct laryngoscopy (DL), particularly in patients with anticipated or unanticipated difficult airways. Multiple meta-analyses and randomized controlled trials have demonstrated the superiority of VL over DL in terms of first-attempt success rate, Cormack-Lehane grade, and rate of esophageal intubation in both routine and difficult airway scenarios.

The Storz C-MAC system is one of the most widely studied videolaryngoscopes and is available in two blade configurations relevant to this study: the Macintosh-geometry blade (C-MAC M-blade), which allows both direct and indirect laryngoscopy and preserves familiar hand mechanics, and the hyperangulated D-blade (C-MAC D-blade), which provides a more acute viewing angle and is specifically designed for cases where standard geometry blades fail to achieve adequate glottic exposure. Both blades transmit a high-resolution image to an external monitor, and the C-MAC system has been shown to improve first-attempt success rates and glottic visualization in a range of clinical settings.

In the context of DLT intubation, the choice of laryngoscope blade is further complicated by the need to shape the DLT stylet to match the blade curvature. A hyperangulated blade requires a correspondingly acute stylet bend, which may facilitate or hinder tube advancement depending on the operator's experience and the patient's anatomy. While several studies have compared videolaryngoscopy systems with direct laryngoscopy for DLT placement - including the GlideScope, C-MAC, and other platforms - the existing literature remains limited in volume and inconsistent in its conclusions. No adequately powered prospective randomized trial has directly compared the C-MAC D-blade, C-MAC M-blade, and standard direct Macintosh laryngoscopy head-to-head for DLT intubation in thoracic surgery patients. The present study is designed to address this gap.

Objectives and Hypotheses:

The primary objective of this study is to compare three laryngoscopy techniques for DLT intubation - (i) C-MAC hyperangulated D-blade videolaryngoscopy (HCMAC), (ii) C-MAC Macintosh blade videolaryngoscopy (MCMAC), and (iii) direct Macintosh laryngoscopy (DL) - with respect to intubation time, glottic visualization quality, procedural difficulty, and intubation-related complications in adult patients undergoing elective thoracic surgery requiring one-lung ventilation.

The secondary objective is to provide prospective, randomized clinical evidence to guide the selection of the most appropriate laryngoscopy method for DLT intubation in routine thoracic anesthesia practice and to contribute to standardization of airway management in this surgical context.

Primary hypothesis: Total DLT placement time is shorter with videolaryngoscopy, particularly with the C-MAC hyperangulated D-blade, compared to direct Macintosh laryngoscopy.

Secondary hypotheses: (1) Videolaryngoscopy groups will demonstrate superior glottic visualization as measured by POGO score and Cormack-Lehane grade. (2) Intubation difficulty as assessed by the Intubation Difficulty Scale (IDS) and the need for auxiliary maneuvers will be lower in videolaryngoscopy groups. (3) The overall incidence of intubation-related complications, including mucosal trauma, dental or lip injury, and hemodynamic perturbations associated with laryngoscopy, will be lower in videolaryngoscopy groups compared to direct laryngoscopy.

Study Design:

This is a prospective, randomized, single-center, three-arm, open-label, low-risk medical device clinical study. The study is conducted at the Department of Anesthesiology and Reanimation, Trakya University Medical Faculty, Trakya University Health Research and Application Center Hospital, Edirne, Turkey. The study is classified as a low-risk medical device clinical investigation, as all procedures are performed within the scope of routine clinical care and no additional investigational drugs or invasive interventions beyond standard practice are introduced.

Patients fulfilling eligibility criteria are randomized in a 1:1:1 ratio to one of three study arms (HCMAC, MCMAC, or DL) using a computer-generated block randomization sequence. Allocation concealment is maintained using sequentially numbered, opaque, sealed envelopes that are opened in the operating room immediately prior to the intubation attempt.

Eligibility Criteria:

Inclusion criteria: age ≥18 years; written informed consent obtained prior to surgery; ASA physical status class I, II, or III; scheduled for elective thoracic surgery requiring one-lung ventilation and double-lumen endobronchial intubation.

Exclusion criteria: age <18 years; refusal or inability to provide informed consent; ASA physical status class IV or above; emergency surgery; anticipated difficult airway defined by any of the following - Mallampati score 4, thyromental distance <6.5 cm, restricted mouth opening, or BMI >30 kg/m²; history of upper airway surgery; significant upper airway obstruction or stridor; pregnancy.

Interventions and Procedures:

All patients receive standard intraoperative monitoring per ASA guidelines, including continuous ECG, peripheral oxygen saturation (SpO₂), and non-invasive blood pressure (NIBP). Following induction of general anesthesia, mask ventilation is performed until conditions for intubation are achieved. DLT size is selected according to a validated sex- and height-based sizing scale. The intubation is then performed using the laryngoscopy device assigned by randomization.

Glottic visualization is assessed by the operator immediately upon laryngoscope insertion and recorded as Cormack-Lehane grade and POGO score. Intubation time is defined as the interval from cessation of mask ventilation to fiberoptic bronchoscopic confirmation of correct DLT positioning, and is recorded in seconds. The number of intubation attempts and any auxiliary maneuvers employed - including BURP (backward-upward-rightward pressure), Sellick maneuver, shoulder elevation, 90° or 270° tube rotation during bronchial advancement, and external tracheal pressure - are documented. Where applicable, the number of tube size changes, the sizes attempted, and the size ultimately used for successful placement are recorded.

Correct DLT placement is defined as positioning of the tube in the target bronchus without proximal or distal migration, confirmed by fiberoptic bronchoscopy. Malposition is classified as: deep bronchial migration, contralateral bronchial placement, or proximal (tracheal) positioning, and is corrected under fiberoptic guidance. If three intubation attempts fail, the institution's established difficult airway management algorithm is activated and the case is classified as intubation failure. All devices used in this study are CE-marked and are used strictly in accordance with their intended purpose as specified by the manufacturer.

Hemodynamic parameters (SpO₂, heart rate, NIBP) are recorded at baseline, immediately before intubation, and at 0, 1, 3, 5, and 10 minutes after intubation. Where available, subglottic diameter and left main bronchial diameter are measured from preoperative CT imaging and recorded. Postoperative assessment includes evaluation for sore throat, dysphagia, and dysphonia at 1, 6, and 24 hours after surgery, as well as documentation of any signs of airway trauma observed intraoperatively or in the postoperative care unit.

Sample Size and Statistical Analysis:

Sample size was estimated based on a power analysis using data from previous reference studies (linked at "references" section). Cohen's effect size f was calculated as 0.235. With 80% statistical power and a two-sided type I error rate of 5%, a minimum of 60 patients per group is required, yielding a total enrollment target of 180 patients across three groups.

Normality of continuous variables will be assessed using the Shapiro-Wilk test. For normally distributed variables, between-group comparisons will be performed using one-way analysis of variance (ANOVA); for non-normally distributed variables, the Kruskal-Wallis test will be used. Relationships between categorical variables will be analyzed using chi-square tests. Correlations between continuous variables will be assessed using Pearson or Spearman correlation analysis as appropriate. Continuous variables will be reported as mean ± standard deviation or median (interquartile range) according to distribution; categorical variables will be reported as frequency and percentage. The threshold for statistical significance is set at p < 0.05 for all analyses.

• Study Type: Interventional
• Enrollment (Estimated): 180
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: havva suheyla akin uzan, medical doctor; Phone Number: +905079516118; Email: shylaakin@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 18 years or older
• Written informed consent obtained prior to surgery
• ASA physical status class I, II, or III
• Scheduled for elective thoracic surgery requiring one-lung ventilation and double-lumen endobronchial intubation

Exclusion Criteria:

• Age under 18 years
• Refusal or inability to provide informed consent
• ASA physical status class IV or above
• Emergency surgery
• Anticipated difficult airway, defined by any of the following: Mallampati score 4, thyromental distance less than 6.5 cm, restricted mouth opening, or BMI greater than 30 kg/m²
• History of upper airway surgery
• Significant upper airway obstruction or stridor
• Pregnancy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Hyper-angulated blade C-MAC videolaryngoscopy; HCMAC: DLT intubation performed using the Storz C-MAC hyperangulated D-blade videolaryngoscope. The D-blade provides an acutely angled geometry and transmits a high-resolution glottic image to an external monitor. The DLT stylet is shaped to match the hyperangulated blade curvature prior to intubation. Glottic view, intubation time, number of attempts, auxiliary maneuvers, and intubation-related complications are recorded. Correct tube placement is confirmed by fiberoptic bronchoscopy.	Device: C-MAC Hyperangulated D-Blade Videolaryngoscopy; Double-lumen endotracheal tube intubation performed using the Storz C-MAC hyperangulated D-blade videolaryngoscope. The D-blade provides an acutely angled viewing geometry with high-resolution video transmission to an external monitor. The DLT stylet is shaped to match the D-blade curvature prior to intubation. All devices are CE-marked and used in accordance with the manufacturer's intended purpose.
Experimental: Macintosh-type blade C-MAC videolaryngoscopy; MCMAC: DLT intubation performed using the Storz C-MAC Macintosh blade videolaryngoscope. The Macintosh geometry blade allows both direct and indirect (video-assisted) laryngoscopy and preserves standard hand mechanics familiar to the operator. The DLT stylet is shaped to match the Macintosh blade curvature prior to intubation. Glottic view, intubation time, number of attempts, auxiliary maneuvers, and intubation-related complications are recorded. Correct tube placement is confirmed by fiberoptic bronchoscopy.	Device: C-MAC Macintosh Blade Videolaryngoscopy; Double-lumen endotracheal tube intubation performed using the Storz C-MAC Macintosh blade videolaryngoscope. The Macintosh geometry blade enables both direct and video-assisted laryngoscopy while preserving standard hand mechanics. The DLT stylet is shaped to match the Macintosh blade curvature prior to intubation. All devices are CE-marked and used in accordance with the manufacturer's intended purpose.
Active Comparator: Direct laryngoscopy; DL: DLT intubation performed using a standard direct Macintosh laryngoscope without video assistance. This arm serves as the active comparator representing current standard clinical practice for DLT intubation in thoracic surgery. The DLT stylet is shaped to match the Macintosh blade curvature prior to intubation. Glottic view, intubation time, number of attempts, auxiliary maneuvers, and intubation-related complications are recorded. Correct tube placement is confirmed by fiberoptic bronchoscopy.	Device: Direct Macintosh Laryngoscopy; Double-lumen endotracheal tube intubation performed using a standard direct Macintosh laryngoscope without video assistance. This represents current standard clinical practice for DLT intubation in thoracic surgery and serves as the active comparator. The DLT stylet is shaped to match the Macintosh blade curvature prior to intubation. All devices are CE-marked and used in accordance with the manufacturer's intended purpose.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total time to successful double-lumen endotracheal tube placement-seconds	Total intubation time in seconds, defined as the interval from cessation of mask ventilation to the appearance of the first complete end-tidal CO2 waveform confirming successful endotracheal tube placement. Final tube position is verified by fiberoptic bronchoscopy. If the tube is not placed properly, fiberoptic bronchoscopy is used to correct the position. Time is recorded continuously for each participant using a stopwatch. In cases requiring multiple intubation attempts, cumulative time across all attempts is recorded. Cases requiring activation of the difficult airway algorithm after three failed attempts are classified as intubation failure and analyzed separately.	Intraoperative (from cessation of mask ventilation to appearance of the first complete end-tidal CO2 waveform confirming successful DLT placement, assessed immediately after intubation)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glottic visualization quality - POGO score	Percentage of Glottic Opening (POGO) score assessed by the operator immediately upon laryngoscope insertion, expressed as a percentage from 0% (no glottic structures visible) to 100% (entire glottic opening visible).	Intraoperative (assessed immediately upon laryngoscope insertion)
Glottic visualization quality - Cormack-Lehane grade	Cormack-Lehane laryngoscopic grade (I, II, III, IV) assessed by the operator immediately upon laryngoscope insertion and recorded as an ordinal variable.	Intraoperative (assessed immediately upon laryngoscope insertion)
Intubation difficulty - Intubation Difficulty Scale (IDS)	Intubation Difficulty Scale (IDS) score calculated after each intubation, incorporating number of attempts, number of operators, number of techniques used, Cormack-Lehane grade, lifting force, laryngeal pressure, and vocal cord position. Higher scores indicate greater intubation difficulty.	Intraoperative (assessed immediately after intubation)
Number of intubation attempts	Total number of intubation attempts required for successful DLT placement, defined as each insertion of the tube past the teeth. Cases requiring more than three attempts are classified as intubation failure and managed according to the institutional difficult airway algorithm.	Intraoperative (recorded during the intubation procedure)
Rate of need for auxiliary maneuvers	Incidence, type and number of auxiliary maneuvers required during DLT intubation, including BURP (backward-upward-rightward pressure), Sellick maneuver, shoulder elevation, 90° or 270° tube rotation during bronchial advancement, and external tracheal pressure.	Intraoperative (recorded during the intubation procedure)
Rate of intubation-related complications	Incidence of intraoperative intubation-related complications including mucosal bleeding, dental, lip or tongue trauma, and oxygen desaturation (SpO2 <92%) during laryngoscopy. Assessed by direct visualization intraoperatively and in the post-anesthesia care unit.	Intraoperative and immediately postoperative (up to 1 hour after surgery)
Rate of DLT malposition confirmed by fiberoptic bronchoscopy	Incidence and classification of DLT malposition confirmed by fiberoptic bronchoscopy, categorized as deep bronchial migration, contralateral bronchial placement, or proximal (tracheal) positioning. All malpositions are corrected under fiberoptic guidance.	Intraoperative (assessed immediately after intubation by fiberoptic bronchoscopy)
Postoperative sore throat assessed by a Numerical Analog Scale	Severity of postoperative sore throat assessed using a Numerical Analog Scale (NAS) at 1, 6, and 24 hours after surgery.	Postoperative 1, 6, and 24 hours
Postoperative dysphonia and cough assessed by a 4-point scale (0-3=	Presence and severity of voice change (dysphonia) and cough assessed at 1, 6, and 24 hours after surgery 0=none, 1=mild, 2=moderate, 3=severe	Postoperative 1, 6, and 24 hours
Rate of dental and oral mucosal injury detected post-operatively	Presence of dental injury and oral mucosal injury assessed at 1, 6, and 24 hours after surgery, recorded as present or absent by direct clinical evaluation.	Postoperative 1, 6, and 24 hours

Collaborators and Investigators

• Sponsor: Trakya University

Publications and helpful links

Helpful Links

• Related Info
• Related Info

Study record dates

Study Major Dates

• Study Start (Estimated): May 15, 2026
• Primary Completion (Estimated): November 15, 2028
• Study Completion (Estimated): January 15, 2029

Study Registration Dates

• First Submitted: May 11, 2026
• First Submitted That Met QC Criteria: May 28, 2026
• First Posted (Actual): May 29, 2026

Study Record Updates

• Last Update Posted (Actual): May 29, 2026
• Last Update Submitted That Met QC Criteria: May 28, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: one-lung ventilation; direct laryngoscopy; videolaryngoscopy; double-lumen endotracheal tube; C-MAC; thoracic anesthesia
• Other Study ID Numbers: 2607A07; DLT-VL 2026 (Other Identifier: Trakya University Clinical Research Ethics Committee)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No