MATERIALS AND METHODS
This experiment was performed in accordance with Guidelines for Animal Experimentation at St. Marianna University Graduate School of Medicine. In the conventional method, grasping forceps are used to grasp the middle graspable part of the spigot; whereas for the new side-grasping method, rotational forceps are used to grasp the outer edge of the graspable part of the spigot.
On the bench top, the variable angle of the spigot for each method was measured and recorded. Next, 10 bronchoscopists attempted to place 1 spigot into each of the 4 canine bronchi using the conventional and side-grasping methods. The number of bronchoscopists who were able to correctly place their spigots into each bronchus in the stipulated period of 10 minutes was recorded and compared between each method. The following 4 bronchi were used for analysis: (1) cranial branch of the right cranial lobe bronchiole (D1a, red), (2) right middle lobe bronchiole (L1, green), (3) right lateral bronchiole (L2, blue), and (4) cranial branch of the left middle lobe bronchiole (L1a, orange).7 These bronchi were selected as they are similar to the right bronchus segmentalis apicalis (B1), right bronchus segmentalis lateralis (B4), right bronchus segmentalis basalis anterior (B8), and bronchus segmentalis apicoposterior (B1+2) in the human lungs (Fig. 3).
Ten pulmonologists from the Departments of Respiratory Medicine and Respiratory Surgery, with 2 to 28 years experience (median, 11.3) in bronchoscopy, participated in this study. Ten minutes was allocated for placing 1 spigot into the target bronchus for each method, as it is clinically impractical to place 4 bronchi in a subject at 1 time. Bronchoscopists were allowed to use only 1 spigot for each target bronchus, and each method was alternated to eliminate bias.
The number of successful spigot placements for the conventional method within the stipulated period was compared with successful spigot placements for the side-grasping technique using the Fisher exact test. The time needed to place each spigot using both methods was compared using the Wilcoxon signed-rank test, and a P-value of <0.05 was considered statistically significant. All analyses were performed using SPSS software (version 19; IBM, Armonk, NY).
The variable angles for the conventional and side-grasping methods were in a range of 60 degrees (range, −30 to +30 degrees) and 120 degrees (−30 to +90 degrees), respectively.
For bronchoscopists who correctly placed the spigot into the target bronchus within the stipulated 10-minute duration, the side-grasping method was more successful than the conventional method. The total number of bronchoscopists that successfully placed spigots into the target canine bronchi was 15/40 for the conventional method versus 35/40 for the side-grasping method (Table 1). In total, the time to place all EWS was 13±2.2 minutes using the side-grasping method versus 27.8±3.6 minutes for the conventional method. With regard to the time required to place the spigot, the side-grasping method was significantly faster than the conventional method (P<0.01).
In the right D1a, 9 of 10 bronchoscopists successfully occluded the airway with a spigot within the 10-minute period, whereas no bronchoscopists were successful using the conventional technique. In contrast, the median time to place an EWS was 3.2 minutes using the side-grasping method. The time taken to place an EWS into the right D1a and right L1 was significantly different between each method (P<0.01).
In the right L2 and left L1a, the time taken to place an EWS with the side-grasping method was shorter than the conventional method, but not significantly different (Table 2).
Persistent pulmonary air leaks are managed by bronchial occlusion with EWS, which has been found to be effective in stopping air leaks. It is thought that the curative effects of EWS for intractable pneumothorax will increase if it is possible to occlude the affected bronchus more firmly. Our new side-grasping method has shown better placement rates with a shorter time duration, which will have an important impact for intractable pneumothorax patients with respiratory disability and poor general condition.
Shorter placement durations reduce the time of invasive therapy in patients. In addition, if the bronchoscopist can confirm the spigot is placed firmly at the target bronchus, a reduction in complications such as expectoration of the EWS may enhance the outcome of bronchial occlusion.
The right bronchus segmentalis apicalis (B1) in the human lung is notoriously difficult to place. Therefore, it was not surprising that, in this study, no bronchoscopists were able to successfully place the right D1a bronchus in a canine lung within the 10-minute duration using the conventional method. In contrast, the side-grasping method made it possible to correctly place the right D1a bronchus within the stipulated time period (Supplemental Digital Content 1, http://links.lww.com/LBR/A124). In addition, the time needed to place an EWS with the side-grasping method was shorter than that of the conventional method for all bronchi.
One potential reason for the increased effectiveness of the side-grasping method is the larger variable angle. During the process of placing the spigot into the target bronchus, it is important for the tip of the spigot to adjust coaxially with the target bronchus. If the tip of the spigot maneuvers is in the same direction as the target bronchus, placement of the spigot into the target bronchus is very simple. For the conventional method, the variable angle of the spigot was 60 degrees. Therefore, impacting the corner of the spigot against the bronchial wall to change direction is a common approach. This method increases the variable angle of the spigot; however, maneuvering the spigot at certain angles can be difficult. Moreover, this method relies on the bronchial wall to change directions and unfortunately, a satisfactory wall to change the direction of the spigot is not always available. For these aforementioned reasons, the conventional method consumes more time to place the spigot into the target bronchus. In contrast, the variable angle for the side-grasping method was 120 degrees, and the rotational forceps allowed for a full 360 degrees of rotation. With this new method, the tip of the spigot easily adjusts coaxially with the target bronchus at any angle.
The side-grasping method was especially useful in the case of angulated bronchi, implying that the effectiveness of the 2 methods was very similar in the case of straight bronchi (Fig. 2). This may explain why there was no significant difference seen between the 2 methods for the right L2.
For the left L1a, using the new and conventional methods, 7 and 4 bronchoscopists, respectively, performed the placement of the EWS correctly within the stipulated time. However, no significant differences were observed between the 2 methods with regard to the time needed to place the EWS. We believe the reason for this might have been the lack in experience for the side-grasping method.
Although it is generally simple to place an EWS into the middle bronchus of a human; there was a large contrast seen between the 2 methods for the right L1, which is similar to the right B4 in the human lung. This might be due to the anatomic differences between human and canine lungs.8 The angle of branching in a canine bronchi is small compared with that in the human lung, where the right L1 branches off sharply.9,10 It was difficult to place the spigot into the bronchus with the conventional method, which explains why a larger number of bronchoscopists could correctly place the spigot into the bronchus with our new method.
A limitation of this study was that the side-grasping method was only tested in a canine lung. It would be optimal to carry out this study in humans; however, it is not ethical to perform this present study in intractable pneumothorax patients who suffer from poor general condition or respiratory disability.
This present study examines the experience of 10 bronchoscopists placing EWS into target bronchi using both the conventional and side-grasping methods. This is the first study to compare and assess the side-grasping method to the conventional method. If bronchoscopists could enhance the skills required to perform the side-grasping technique, better placement rates and reductions in the time needed to place an EWS may be possible.
Using the side-grasping method, bronchoscopists were able to correctly and rapidly place the EWS into the target bronchus. This study reported superior results with this novel method, and we are convinced that the side-grasping method will yield great benefits in human patients in the future.
The authors would like to thank Mr Jason Tonge from St. Marianna University School of Medicine for reviewing the language of this manuscript.
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endobronchial Watanabe spigot (EWS); bronchial occlusion; EWS placement technique; persistent pulmonary air leaks; pneumothorax; side-grasping method
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