Thoracoscopic segmentectomy has increased in popularity in recent years, and several methods to identify the intersegmental plane have been proposed [10]. In our hospital, 48 thoracoscopic pulmonary segmentectomies with BJV were performed during a 5-year period. The success rate of BJV was 73%, with the Brinkman index and the location of the target bronchus being significantly related to the success rate.
Okada et al. [6] reported a technique involving selective segmental jet ventilation using a bronchoscope as a new method to detect the intersegmental plane. They completed thoracoscopic segmentectomy in 52 patients with a median operative time of 155 min (range 85-225) and without severe complications, and concluded that BJV provides an obvious intersegmental plane quickly and easily. They described detection of the intersegmental plane by BJV in addition to the path of the intersegmental veins, but did not include intraoperative details of BJV such as the success rate or factors associated with difficulty. In the present study, we found that thoracoscopic segmentectomy by BJV was successful in 35 out of 48 cases, for an acceptable success rate of 73%.
In patients with chronic obstructive pulmonary disease (COPD), it is supposed that the jet ventilation method is difficult because the inflation-deflation line could be obscure or misleading due to collateral ventilation [2]. In the present study, COPD was not related to the failure of BJV. The jet ventilation delivers extremely small tidal volumes that might not be sufficient to inflate the adjacent segment through the collateral respiratory structure. In addition, the surgeon can see the gradual inflation of the targeted segment and stop the jet ventilation upon complete inflation but before air flows into the collateral ventilation. The intersegmental line by BJV was obscure in two patients who had Goddard’s classification 3 severe emphysema in our study. The number of patients who had severe emphysema was relatively small. Further study is needed to investigate the relationship between severe emphysema and BJV success. Our data indicate that BJV is applicable to moderate emphysema, although the small number of patients in this study was a limitation.
Another difficulty with the jet inflation method is secretions remaining in the airway that can interfere with inflation of the targeted lung. In the present study, a higher Brinkman index was significantly related to failure of BJV. Sufficient delineation of the intersegmental plane by BJV could not be achieved in 75% of patients who had a Brinkman index over 1000. Long-term smoking increases mucus production and causes heavy airway secretions, which could be a cause of the lower success rate of BJV. Preoperative intervention to facilitate secretion drainage, such as pulmonary rehabilitation or anticholinergic inhalation with a nebulizer, could improve airway clearance and potentially improve BJV success.
In the present study, the success rate was significantly lower when BJV was applied to the posterior basal segmental bronchus (B10) compared to other regions. B10 is located in a very deep area; it might be difficult to effectively insert the bronchoscope into the deep smaller bronchi. During BJV procedure, surgeons helped an anesthesiologist lead the bronchofiberscope to the targeted bronchus through the light of the tip at the surgical field. According to the operative records, the bronchoscope was positioned in B10 appropriately; however, the inflation-deflation line was not clear enough to identify the segmental plane. It is possible that the deeper bronchus might be more vulnerable to airway secretion. In addition, the anatomy of S10 and adjacent segments such as superior (S6) and medial basal (S7) varies among patients, which might make it difficult to clearly identify the intersegmental plane of the posterior basal segment [11].
The right and left lung anatomy are asymmetrical. The BJV success rate was not different between right and left. There are three segments in the right upper lobe: apical (B1), posterior (B2), and anterior (B3). On the other hand, there are four segments in the left upper lobe: apicoposterior (B1+2), anterior (B3), inferior lingual (B4), and superior lingual (B5). Regarding difficulty reaching the target lesion with the bronchoscope, B1+2 was considered to be the most difficult for insertion because of its sharp angle [12]. During surgery, bronchoscopy may be further complicated by the patient’s lateral decubitus position. In our study, four cases including three B1+2 were not applied BJV because the surgeon found that the target bronchus was anatomically too difficult for bronchoscope insertion. The success rate of BJV was not different between B1+2 and the other regions.
Various methods have been proposed to identify intersegmental planes during thoracoscopic pulmonary segmentectomy [10, 13]. In the slip knot method, a specific ligation (slip knot) is applied to the target segment bronchus followed by bilateral ventilation, and then the knot is slipped to close the bronchus [14,15,16]. This method does not require a jet ventilator and anesthesiologist who manipulate bronchoscope; however, in some cases, it takes time to obtain lung collapse in the preserved segments. Other methods use indocyanine green (ICG), which is a green dye visible under regular white light and visible as fluorescence by near-infrared light. Misaki et al. reported intravenous ICG injection after clamping the pulmonary arteries perfusing the target segment [17,18,19]. Under fluorescence thoracoscopy, the target segment is visualized as a dark area while the lung perfused with ICG appears as a bright area. Limitations of this method are that the duration of intravascular ICG visualization is short because ICG is rapidly washed out, and that fluorescence thoracoscopy is not yet widely available. The BJV method needs a skillful anesthesiologist and a jet ventilator. A jet ventilator provides high-frequency jet ventilation (HFJV) for laryngeal surgery and management of the difficult airway which have potential hazards to cause barotrauma [20]. In the BJV method, a jet ventilator is used to send small volume of air into the targeted segment through a bronchoscope, not for respiration (gas exchange). Therefore, inspiratory driving pressure and frequency is much less than HFJV. Driving pressure setting for HFJV is 1–3 bar [20], whereas pressure needed for BJV is less than 0.6 bar. A jet ventilator enables an anesthesiologist to increase driving pressure gradually and stop inflation immediately with one hand while he/she holds a bronchoscope with the other hand. Surgeons who can monitor the lung directory from the operative field warn hyperinflation during BJV. Close collaboration between the anesthesiologist and the surgeon is essential to safely complete the procedure.
Although there were thirteen unsuccessful BJV cases, neither operative time nor intraoperative bleeding was higher in these cases compared to the successful cases. We consider this was because alternative approaches were promptly applied. Typical difficulties encountered during BJV are insertion of the bronchoscope to the targeted bronchus and inflation of the targeted segment with jet ventilation. Proper insertion can be quickly confirmed from the surgical field by the bronchoscope tip light, and surgeons can also directly see the targeted bronchus and estimate the anatomical feasibility of inserting the bronchoscope. Inflation of the targeted segment can also readily be confirmed. During jet ventilation, the surgeon can see the gradual inflation of the targeted segment and either clear visualization of the intersegmental line or failure to create the inflation-deflation line owing to collateral ventilation or airway secretion. These features of BJV help the operator to make a judgment on whether the BJV method is feasible or not, and to promptly change tactic when necessary.
Incidence of postoperative complications was not different between BJV success cases and BJV failed cases. In the present study, air leaks and pulmonary fistula were the most common issue. In BJV failed cases, adjacent non-anatomic wedge resection was performed; however, persistent air leaks did not occur except one case. Smoking, pleural adhesion, stapling length, and early postoperative drainage were reported to be a significant risk factors for persistent air leaks after pulmonary resection [21, 22]. These factors might play a dominant role on incidence of the postoperative air leaks. Direct inflation into the bronchus by puncturing with a needle has been reported to cause massive air embolism, most likely resulting from direct injection of air into an adjacent pulmonary vein [14, 16]. Although we did not have any complication with the alternative method, great care is essential as this approach. Among those who had surgery except segmentectomy (n = 21) and those who were not applied BJV (n = 4), postoperative complications were seen in 5 patients. Incidence of postoperative complications was not different between BJV cases and non-BJV cases (11/44, 25% vs 5/25, 20%, P = 0.636).
There were some limitations in this study. The BJV technique might depend on the skill of the anesthesiologist; however, BJV was not performed by a single anesthesiologist in the present study. Ten anesthesiologist performed BJV during the 5-years study period and there was not obvious individual difference in the BJV success rate. All anesthesiologist had more than 4 years of experience and more experienced anesthesiologist supervised them if they needed. Although bronchoscopy is the widespread practice, the BJV method requires a clear knowledge of tracheobroncial anatomy with the fiberoptic bronchoscope. A video screen monitor to allow sharing the views was used whenever possible in the present study. Enhanced bronchoscopic view and communication between anesthesiologists and surgeons helped us succeeded BJV technique.
Another limitation is the small number of the cases. Although we included all patients scheduled for pulmonary segmentectomy during 5 years, there were only two patients with severe CT-diagnosed emphysema. Confounding may also exist in the present study because data were gathered retrospectively. Statistical adjustments were not performed due to the small sample size. The observed relationships between difficulty of BJV and long-term smoking or deep bronchus seem clinically reasonable. Further research including larger numbers of patients is needed.
