90° versus 110° rotation of left double lumen tube for endobronchial intubation: a randomized controlled trial
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Key findings
• The 110° counterclockwise rotation of left double lumen tube (DLT) when the endobronchial cuff passing beyond the glottis, increased the success rate of the first attempt left bronchus intubation and reduced the incidence of postoperative sore throat in adult patients undergoing thoracic surgery, compared with the conventional intubation method of left DLT 90° counterclockwise.
What is known and what is new?
• It is conventional that anesthesiologist rotates the left DLT 90° counterclockwise when the DLT endobronchial cuff crosses beyond the glottis, with which the first attempt success rate of left endobronchial intubation is 75.9%. However, the true inclination angle between the left main bronchus and trachea in the median sagittal is 108.4°.
• We firstly conducted a randomized controlled trial to compare the first attempt left bronchial intubation success rate of left DLT 90° versus 110° counterclockwise rotation when the left DLT endobronchial cuff crossing beyond the glottis.
What is the implication, and what should change now?
• The left DLT 110° counterclockwise rotation increased the success rate of the first left bronchus intubation and reduced the incidence rate of postoperative sore throat. Therefore, the left DLT 110° counterclockwise rotation when the left DLT endobronchial cuff crossing the glottis was superior to the 90° rotation during the left DLT endobronchial intubation.
Introduction
Left double lumen tube (DLT) is a commonly used airway management for achieving one lung ventilation (OLV) in video-assisted thoracic surgery (VATS) (1,2). In terms of left main bronchus anatomy, anesthesiologists tend to prefer the left DLT for VATS except for the surgery involving left main bronchus (3).
Anesthesiologist routinely rotates the left DLT 90° counterclockwise when the left DLT endobronchial cuff crosses the glottis to avoid left DLT sliding into the right main bronchus (4), which the success rate for left DLT first attempt into the left main bronchus is approximately 76% (5). Patel et al. found that the mean anatomic angle between the left main bronchus and trachea in the median sagittal plane is not 90° but 108.4° (6). Therefore, we hypothesized that 110° counterclockwise rotation could increase the first success rate of left DLT into the left main bronchus and reduce intubation complications, so we implemented a randomized controlled study to compare 90° versus 110° counterclockwise rotation left DLT for left endobronchial intubation in adult patients undergoing VATS. Results of the clinical study are reported below. We present this article in accordance with the CONSORT reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-240/rc).
Methods
This was a single-center, single-blind, randomized clinical trial. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of Peking Union Medical College Hospital (No. ZS-2448) and was registered at Chinese Clinical Trial Registry (ChiCTR2100053350) on November 19th, 2021. Written informed consent was obtained from all patients before surgery.
The patients with American Society of Aneshesiologists (ASA) physical I–III, aged 18 years or older, body mass index (BMI) 18–30 kg/m2, and undergoing elective thoracic surgery using left DLT intubation were enrolled into this trial between December 2021 to December 2023 in Peking Union Medical College Hospital. The key excluded criteria were suspected difficult airways management such as Mallampati score ≥III, Cormack-Lehane score ≥III with video laryngoscopy; space occupied lesions in the main trachea, severe cervical spine movement disorder disease, sore throat or hoarseness before surgery.
Randomization, concealment and blinding
Randomization sequence was generated by a statistician not involved in this study otherwise. Using a computer-generated simple randomization sequence, and patients were immediately divided into 90° group and 110° group before intubation. Patients were blinded to grouping, but the outcome assessors were known the grouping.
Intervention
Patients were randomly assigned into two groups depending on the counterclockwise rotating angles of the left DLT, 90° group is counterclockwise rotation left DLT 90° and 110° group is counterclockwise rotation left DLT 110°, and the left DLT rotation between the two groups when the endobronchial cuff passing beyond the glottis was shown on Figure 1 in detail. And we measured the anatomical angle between the left main bronchus and trachea in the median sagittal plane as 112° for example to explain the reason for 110° rotation in Figure 2. The attending anesthesiologists intubated the left DLT (MallinckrodtTM, Covidien LLC, Mansfield, MA, USA) by video laryngoscopy (UE-TD-C, UE Medical Corp, Xianju, China).
Anaesthesia
The patient entered the operating room, and monitored by arterial pressure, electrocardiogram, pulse oximetry, and given 100% oxygen. General anesthesia was induced with 0.03 mg/kg midazolam, 2 mg/kg propofol, 2 µg/kg fentanyl, 0.9 mg/kg rocuronium. Then, we marked the DLT rotation angle around the patient’s mouth with the marker pen. Then, the attending anesthesiologists intubated the left DLT by video laryngoscopy. When the left DLT’s endobronchial cuff passing beyond the glottis, we removed the stylet, rotated the left DLT counterclockwise, and continued to intubate the tube until resistance is encountered. After the left DLT into bronchus, we used the fiberoptic bronchoscopy to examine whether the left DLT into the left bronchus. If the left DLT slide into the right main bronchus, the attending anesthesiologists reintubated the left DLT by fiberoptic bronchoscopy. The attending anesthesiologists guided the fiberoptic bronchoscopy into the left bronchus in visualization, and then the left DLT intubated into the left bronchus under the fiberoptic bronchoscopy. The patients were given sevoflurane, fentanyl and rocuronium during anesthesia. The left DLT were removed when the operation was completed.
Outcome measures
The primary outcome in the trial was the first attempt intubation success rate of the left DLT into the left main bronchus. The secondary outcomes were the overall intubation success rate, carina mucosal injuries, sore throat and hoarseness.
The anesthesiologist who was unaware of the group assignment evaluated every patient’s DLT intubation related injuries. Within 30 min from the starting of surgery, fiberoptic bronchoscopy was used to evaluate the carina mucosal injuries. The types of injuries were divided into 3 levels, namely: 1, redness as the red color in the mucosa without surrounding swelling; 2, oedema as swollen mucosa; 3, hematoma as mucosa bleeding (7,8). The anesthesiologist blinded to group assignment assessed sore throat and hoarseness 24 h after surgery. The sore throat and hoarseness severity were evaluate by the numerical rating scale (NRS): the 0 was no sore throat; the 10 was the worst imaginable pain for the sore throat NRS, and the 0 was no hoarseness; the 10 was the worst hoarseness for the hoarseness severity NRS (9).
Statistical analysis
Minimal sample size estimation was determined using power analysis based on the following assumptions: (I) the first attempt intubation success rate is 76% in 90° group (5); (II) a clinically meaningful increased in success rate by 10% (to 86% in the 110° group); (III) two-sided α of 0.05, and power (1 − β) of 0.9; (IV) a dropout rate of 5%. The calculation yielded 556 patients.
In this study, SPSS (version 20.0; IBM, Chicago, IL, USA) statistical software were used. Data were expressed as mean ± standard deviation (SD) or number (%). Differences in parametric values, used Student’s t-test; and differences in categorical variables, used the χ2 test. All reported P value were two-side and P<0.05 was considered statistically significant.
Results
A total of 610 patients were assessed for this study between December 2021 to December 2023 in Peking Union Medical College Hospital, and 54 patients were excluded (Figure 3). The 556 patients were randomly divided into two groups, the 90° group (n=275) and the 110° group (n=281). There were no significant differences between the two groups with demographic and baseline characteristics (Table 1).
Table 1
| Variables | 90° group (n=275) | 110° group (n=281) | P value |
|---|---|---|---|
| Age (years) | 56.7±12.1 | 56.1±12.6 | 0.57 |
| Female | 168 (61.1) | 154 (54.8) | 0.15 |
| BMI (kg/m2) | 23.9±3.1 | 24.3±3.4 | 0.19 |
| ASA physical status | 0.28 | ||
| I | 68 (24.7) | 79 (28.1) | |
| II | 184 (66.9) | 192 (68.3) | |
| III | 23 (8.4) | 10 (3.6) | |
| DLT size | 0.15 | ||
| 35F | 168 (61.1) | 154 (54.8) | |
| 37F | 107 (38.9) | 127 (45.2) | |
| Mallampati grade | 0.24 | ||
| I | 181 (65.8) | 198 (70.5) | |
| II | 94 (34.2) | 83 (29.5) | |
| Cormack-Lehane grade | 0.16 | ||
| I | 167 (60.7) | 154 (54.8) | |
| II | 108 (39.3) | 127 (45.2) | |
| Type of surgery | 0.76 | ||
| Wedge resection | 78 (28.4) | 72 (25.6) | |
| Segmentectomy | 59 (21.5) | 64 (22.8) | |
| Lobectomy | 138 (51.1) | 145 (51.6) |
Data are shown as mean ± SD or n (%). ASA, American Society of Anaesthesiologists; BMI, body mass index; DLT, double lumen tube; SD, standard deviation.
The first attempt success rate of left bronchial intubation was 87.9% in the 110° group versus 80.7% in the 90° group (odds ratio =1.734; 95% confidence interval: 1.083–2.800; P=0.02, Table 2). The reintubation success rate by using fiberoptic bronchoscopy was 100% in both groups.
Table 2
| Variables | 90° group (n=275) | 110° group (n=281) | P value | OR (95% CI) |
|---|---|---|---|---|
| First intubation success | 222 (80.7) | 247 (87.9) | 0.02 | 1.734 (1.083–2.800) |
| First intubation time (s) | 17.3±4.7 | 16.9±4.4 | 0.35 | – |
Data are shown as mean ± SD or n (%). Student’s t-test was used for first intubation time, and the χ2 test was used for first intubation success rate. CI, confidence interval; DLT, double lumen tube; OR, odds ratio; SD, standard deviation.
The frequency of carina mucosal injuries was 16.4% (45/275) in the 90° group and 13.9% (39/281) in the 110° group (P=0.41, Table 3). Two patients in 90° group and one patient in 110° group unexpectedly backed to the intensive care unit (ICU) after surgery and was not suitable for evaluating of sore throat and hoarseness at 24 h.
Table 3
| Variables | 90° group (n=275) | 110° group (n=281) | P value |
|---|---|---|---|
| Mucosal injury | 45 (16.4) | 39 (13.9) | 0.41 |
| Grade 1 | 37 (13.5) | 29 (10.3) | |
| Grade 2 | 8 (2.9) | 10 (3.6) | |
| Grade 3 | 0 (0.0) | 0 (0.0) |
Data are shown as n (%). The χ2 test was used for the rate. DLT, double lumen tube.
Within 24 h after surgery, the incidence rate of sore throat was 45.8% (125/273) in the 90° group and 33.9% (95/280) in the 110° group (P=0.005, Table 4). Meanwhile, the incidence rate of hoarseness was 22.0% (60/273) in the 90° group and 20.4% (57/280) in the 110° group (P=0.68, Table 4).
Table 4
| Variables | 90° group (n=273) | 110° group (n=280) | P value |
|---|---|---|---|
| Sore throat | 125 (45.8) | 95 (33.9) | 0.005 |
| NRS severity | 3.2±1.2 | 3.2±1.1 | 0.96 |
| Hoarseness | 60 (22.0) | 57 (20.4) | 0.68 |
| NRS severity | 1.9±0.8 | 1.8±0.8 | 0.71 |
Data are shown as mean ± SD or n (%). The χ2 test was used for the rate, and Student’s t-test was used for the NRS severity. DLT, double lumen tube; NRS, numerical rating scale; SD, standard deviation.
Discussion
This randomized clinical study demonstrated that the left DLT 110° rotation increased the success rate of the first left bronchus intubation in adult patients during VATS by left DLT. The left DLT 110° rotation for left bronchial intubation decreased the rate of postoperative sore throat after surgery 24 h as well.
Brodsky et al. enrolled 1,170 patients who underwent anesthesia for thoracic procedures and intubated the left DLT by rotating 90° counterclockwise, which the success rate of the first intubation was 75.9% (5). In our current trial, the first intubation success rate of the 90° group was 80.7%, which the discrepancy may be due to the using the video laryngoscope for left DLT intubation in our study (10,11).
It is found that the angles between the left main bronchus and the median sagittal plane was not 90°, and the true inclination angles is 108.4° (109.7°±10.1° in females and 107.0°±10.5° in males) (6). Therefore, the success rate upon the first intubation attempt of the left DLT into the left bronchus was 87.9% in the 110° group, was higher than the 90° group (87.9% versus 80.7%). We consider that 110° rotating of the left DLT could more accurately slide into the left main bronchus during the left DLT intubation, so 110° rotating of the left DLT was superior to the 90° rotating during the left DLT endobronchial intubation. As for the only 20° gap for between 90° and 110° rotation, we must carefully rotate the left DLT 110° for the accuracy and more slippery sliding into the left main bronchus. We may be lacking precise measurement tools in the routine working. So, we could make a 110° angle card in the thoracic operating room for convenience.
The intubation success rate of individualized rotation of the left DLT according to the angle between the left main bronchus and the trachea in the median sagittal plane was 91.4%, owing to the sex difference and the age which affect the inclination angle of the left main bronchus (12). However, based on the fact that average angle of the left main bronchus in American is 108°, rotation of left DLT 110° improved the left DLT intubation success rates, which was less than the left DLT intubation success rates of individualized rotation (12). So, further clinical trials are needed to validate whether the rotation of left DLT 110° could substitute for the individualized rotation of left DLT for left endobronchial intubation, which is our next study direction. In summary, the 110° rotation of the left DLT improved clinical efficiency of operations compared with the the left DLT of individualized rotation according to the angle of the left main bronchus and maint trachea in routine setting.
The incidence rate of postoperative sore throat can reach as high as 60% after the tracheal intubation (13,14). In our trial, the incidence of sore throat at postoperatively 24 h was 45.8% in the 90° group, which possibly because of the using of video laryngoscopy during the left DLT intubation. Meanwhile, the incidence of sore throat at postoperatively 24 h was lower in the 110° group (33.9% versus 45.8%), and we consider that left DLT could more accurately into the left main bronchus by rotating the left DLT 110° with less resistance, so 110° rotation the left DLT had lower rate of the intubation complications (15,16). However, there was no statistically significant difference in terms of carina mucosal injury and hoarseness between the two groups. The incidence rate of postoperative hoarseness in our trial was consistent with the others research (17,18). When the left DLT’s endobronchial cuff passing beyond the glottis, anesthesiologists removed the stylet, rotated the left DLT counterclockwise 90° or 110°, the increasing 20° counterclockwise rotation of the smooth left DLT did not increase the vocal cords trauma, so there was no statistically significant difference in the incidence rate of postoperative hoarseness between the two groups in our trial. The Hsu et al. trial had proved that the incidence rate of carina mucosal injury was 19%, which was higher than our study of carina mucosal injury (19), perhaps it is because different anesthesiologist has different intubation techniques and skills. Although there was no statistical difference, the carina mucosal injury rate of 110° group was lower than 90° group (13.9% versus 16.4%), maybe rotation left DLT 110° and then intubation the left DLT forward had less resistance, so had lower rate of carina mucosal injury.
There are several limitations in this study. First, this was a single-centre trial. The conclusions need to be verified by multicenter trials with large samples in further. Second, the success rate of left DLT rotation 110° was higher than the success rate of left DLT rotation 90° but was lower than the left DLT intubation success rates of individualized rotation. So, clinical trials are needed to validate whether the individualized rotation of left DLT is significantly better than rotation of left DLT 110° for left endobronchial intubation.
Conclusions
In conclusion, the left DLT 110° rotation increased the success rate of the first left bronchus intubation and reduced the incidence of sore throat in adult patients undergoing VATS using left DLT.
Acknowledgments
None.
Footnote
Reporting Checklist: The authors have completed the CONSORT reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-240/rc
Trial Protocol: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-240/tp
Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-240/dss
Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-240/prf
Funding: This work was supported by an internal grant of
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-240/coif). The authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of Peking Union Medical College Hospital (No. ZS-2448) and written informed consent was obtained from all individual participants.
Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
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