Tracheal Bronchus: A Case Report

Background: Intubation diculties, hypoxemia, inability to perform a one-lung ventilation, and high airway pressure often occur during double-lumen tube intubation. Tracheal bronchus is a very rare and dicult to nd reason. We present a case of tracheal bronchus accidentally discovered during double-lumen tube intubation in a patient undergoing thoracic surgery. We are the rst one to summarize the one-lung ventilation strategy for patients with tracheal bronchus. Case Presentation: A 53-year-old man underwent a scheduled thoracoscopic left upper lobectomy. After two unsuccessful attempts to pass the right-sided double-lumen tube through the right mainstem bronchus, beroptic bronchoscopy revealed an aberrant tracheal bronchus with an incidence of 0.1%–3%. Finally we used a left-sided DLT to ventilate the right lung. The patient had no airway complications and was discharged 7 days after the operation. Conclusions: This case serves to remind us that preoperative visits must be thorough and careful. Although a computed tomography chest examination we just looked at inspection report and at We also reviewed and summarized the one-lung strategies For either left-sided double-lumen catheter


Background:
Double-lumen tubes (DLTs) are often used in patients who require one-lung ventilation. However, intubation di culties, hypoxemia, inability to perform a one-lung ventilation, and high airway pressure often occur during surgery. An ectopic bronchus arising from the trachea to one or several segments of the bronchus is an uncommon reason [1]. We report a case of the di culty performing a DLT intubation due to a tracheal bronchus (TB). Furthermore, we reviewed the literature and summarized the solutions for one-lung ventilation in cases with TB which has never been previously reported in such detail.

Case Description:
A 53-year-old man (height: 175 cm; weight: 92 kg) was admitted to the hospital for peripheral lung cancer of the left upper lobe. He was scheduled for a thoracoscopic left upper lobectomy. The patient's preoperative examinations were normal, and there was no history of surgical anesthesia. A 37-Fr rightsided DLT was placed blindly. The tube could not be sent further than 27 cm from the incisor. A beroptic bronchoscopy (FOB) examination revealed that there was a view of the three ori ces instead of a clear view of the bronchus intermedius. We retrieved the images of the patient's preoperative imaging examination from the computer, and the patient was con rmed to have a TB with an opening in the upper lobe of the right lung that was not described in the report (Fig. 1). After a discussion with the surgical team, a left 35-Fr DLT was inserted at a depth of 31 cm. Careful examination of the FOB indicated that the cuff of the main lumen of the DLT did not block the TB and did not affect the ventilation of the right upper lobe (Fig. 2). During one-lung ventilation, the right lung breathing sound was normal, and the airway pressure was not high. The patient had no airway complications and was discharged 7 days after the operation.

Discussion:
TB is an abnormal, accessory, or ectopic bronchial branch that directly originates from the tracheal sidewall above the carina, with an incidence of 0.1-3% [2]. It occurs almost exclusively on the right side, involving the upper lobe of the right lung, and usually replaces the right main bronchus or apical bronchus [3].
While the classi cation of TB has not yet been fully uni ed, Conacher [4] proposed a simple classi cation suitable for anesthesiologists, which describes the anatomical relationship between the TB and carina, and is simply divided into three types: Type I TB, ≥ 2 cm from the carina with stenosis of the distal trachea; Type II TB, ≥ 2 cm from the carina with a normal distal trachea diameter; Type III TB, appears at or near the level of the carina. Most adults with TB are asymptomatic. However, it is important for the anesthesiologist to be aware of TB in cases requiring airway management and one-lung isolation.
Pribble et al. [5] reported a case of patient with emergency abdominal trauma with hypoxemia and right upper lung atelectasis during surgery. After bronchoscopy, it was found that that TB was located 3 cm above the carina. This nding suggests that if hypoxemia, abnormally increased airway pressure, and increased end-tidal CO 2 occur when general anesthesia with a single-lumen endotracheal tube is performed, the cause, whether by bronchospasm, secretion blockage, catheter twisting, or bronchial intubation, should rst be identi ed. After considering TB [6,7], intraoperative beroptic bronchoscopy is the most important method for diagnosis.
We reviewed papers in English searched through MEDLINE between 1966 and April 2020 and summarized the literature in Table 1.
For patients requiring left-lung ventilation, there are many methods that can be used, and inserting a leftsided DLT is a good choice. Ho et al.
[8] conducted a retrospective study and found that a left-sided DLT did not affect one-lung ventilation when the TB was located within 2 cm from the carina (type III).
Rosenberg et al. [9] and other researchers have veri ed this. We found that the left-sided DLT can also meet the requirements of intraoperative left-lung ventilation for type TB based on the studies by Ikeno [10] and Peragallo [11]. However, the distance from the TB to carina was just 3 cm. We need more studies to assess the one-lung ventilation strategy for type TB.
The second method is the combined use of a bronchial blocker and a Fogarty artery embolization catheter. Lee et al. [12] reported a case of using a Univent bronchial blocker blocks the right mainstem bronchus, and the Fogarty artery embolization catheter blocks the TB. In the absence of a Univent blocker, combination of a single-lumen tube and a bronchial blocker and a Fogarty artery embolization catheter can be used instead [1]. However, Kin et al. [13] reported that the cuff of the bronchial blocker can also be used to block the TB when the TB is very close to the right mainstem bronchus.
For patients who need right-lung ventilation, a bronchial blocker placed in the left mainstem is a good method based on the study by Conacher [4] for type III TB. We used a different approach by using a leftsided DLT. After ensuring the left bronchial catheter cuff was well positioned, and the tracheal cuff was high enough not to block the TB; the problem of right-lung ventilation was solved by ventilating the trachea. According to the study by Ho et al.[8] this method of lung isolation is safe. Although, when the surgical site involves the left mainstem bronchus, the left DLT should be used with caution.
There have been reports of TB in the past, but for the treatment of such patients during double-lumen endotracheal intubation, only Yoshimura [14] has described the strategy of right lung isolation. We have evaluated more cases and summarized the isolation strategies of the left and right lungs respectively, which has never been previously reported.

Conclusions
In summary, for left-lung ventilation, either a left-sided DLT or a combination of a bronchial blocker and Fogarty artery embolization catheter can be used. For right-lung ventilation, a bronchial blocker or a leftsided DLT is a good choice. In addition, this case demonstrated the importance of careful preoperative evaluations. A chest radiograph or chest computed tomography is necessary. Sometimes you cannot just look at the inspection report, it is better to also look at the preoperative images. Availability of data and materials: All data generated or analyzed during this study are included in this published article. [4] Abbreviations: DLT, double-lumen tube; FOB, beroptic bronchoscopy; SLT, single-lumen tube; TB, tracheal bronchus. Figure 1 Preoperative chest enhanced computed tomography. Note the tracheal bronchus (white arrow).

Figure 2
Seen under the bronchoscope after the left-sided double-lumen tube was xed. Note the tracheal bronchus (white wide arrow) and right mainstem bronchus (dotted white arrow) and left bronchial lumen (thin white arrow).