The findings of this research demonstrate a high concordance between the intersegmental planes formed by BFBM and MIDM. The elapsed time required to expose these intersegmental planes using either method showed no significant difference. However, one notable advantage of using BFBM is that it saved an average of 13.8 minutes in operative time. This is because the operation could continue while waiting for the formation of the intersegmental plane, potentially speeding up patient recovery. Thus, considering these results, we propose that BFBM could effectively replace MIDM in the execution of segmentectomies.
In this study, we employed a self-control method to mitigate individual variances, enhancing the reliability of the results. Despite the smaller sample size of just 12 patients, we were able to obtain satisfactory results using the Open Sequential Test. The 12 segmentectomies performed during the study included six cases from the right lung, six from the left lung; five from the upper lung, and seven from the lower lung. The operations comprised six simple segmentectomies (S6, S4 + 5, S1 + 2+3, S2), alongside six complex segmentectomies (S7 + 8, S8, S10, S9 + 10, S3, S9) (20), This encompassed a broad range of common segmentectomy types. The decision to limit the sample size was based on the fact that all cases yielded concordant results. In line with our study design, the research was concluded once the test line intersected with the effective line at the 12th case.
The identified improvement in surgical methods has the potential not only to save operation time, but also, more importantly, to simplify complex segmental resections that involve two or more borderlines with adjacent segments. By utilizing the BFBM approach, the intersegmental plane can be effectively formed approximately 13 minutes after ligating the arteries or veins of the targeted lung segment. Typically, this stage corresponds to approximately one-third of the entire surgical process. Dealing with the trachea and remaining vessels in the segment hilum can prove challenging in complex segmentectomies due to limited exposure. However, with the intersegmental plane visible, one side of the plane can be prioritized, thereby enhancing the exposure of the segment hilum and potentially simplifying the surgical procedure. Our team had gained extensive experience in simplifying complex segmentectomies using this enhanced approach, and we intend to determine its effectiveness in forthcoming studies.
The BFBM method is reliant on blood vessels, making accurate recognition of these vessels essential for effectively obtaining intersegmental planes. Thus, 3D reconstruction should be performed prior to the surgery when using BFBM.
Apart from segmentectomy, we postulate that BFBM could potentially be employed in combined subsegmental resection, aligning with the underlying logic of BFBM coupled with our accrued experience. Additionally, BFBM might be suitable for lesion positioning in wedge resection. Generally, this involves ligating only one vessel, the drainage area of which contains the targeted lesion.
However, BFBM may not be suitable for all patients; specifically, those with severe emphysema and pleural adhesions. For these patients, the formation of the intersegmental plane may take a longer duration, and the resultant plane may not be as distinct. In such scenarios, we favor the peripheral intravenous injection of indocyanine green(18). However, this approach necessitates a fluorescent display, a resource that is unavailable in many county hospitals in China.
Hong-Hao Fu(21) proposed the arterial-ligation-alone method, which aligns closely with ours except in the handling of vein parts. He conducted a retrospective study demonstrating a high level of concordance between the intersegmental planes formed by the arterial-ligation-alone method and the MIDM. However, his method—restrictively involving only artery ligation—fails to cater to all types of segmentectomies such as S9 (anterior-basal segment)or S10 (posterior-basal segment༉segmentectomies, which typically require initial vein handling. We argue that the crux of delineating the intersegmental plane resides in blocking the targeted segment's blood flow, which can be effectively achieved via ligation of either arteries or veins.
In 2013, Hisashi Iwata(17) introduced a surgical technique that demonstrated the formation of intersegmental planes. This method was later refined by Wang, J(15) evolving into what we now call the MIDM technique, which is widely employed in China. Iwata's methodology is based on the understanding that the arteries and veins of a lung segment facilitate the process of gas exchange. Ligation of these arteries and veins inhibits this gas exchange within the segment, thereby creating a plane between the segments that can and cannot facilitate gas exchange. In Iwata's original method, the first step is to ligate the segmental pulmonary arteries and veins. Following this, the entire lung lobe is inflated with pure oxygen. Then, the segmental bronchus is immediately stapled, and the medical team waits for the plane to appear. The MIDM procedure is similar, with one vital difference: the segmental bronchus is ligated before the lung is inflated. This change effectively represents the progression of this surgical technique from Iwata's original method to the improved MIDM. To validate Hisashi Iwata's theory, we performed an experiment wherein an isolated lobe was expanded using pure carbon dioxide gas. It was observed that the lung tissue turned dark red several minutes after excision from a patient requiring lobectomy due to lung cancer. However, after inflating the isolated lobe with pure carbon dioxide gas, the tissue turned pink. Upon deflation, the tissue returned to its dark red color. This experiment suggested that the color change in the lung tissue was not influenced by the nature of the gas but by the volume of air within the alveoli. Furthermore, we discovered that the formation of the intersegmental plane could occur regardless of whether or not the segmental bronchus was ligated. This finding suggests that the formation of the intersegmental plane depends on the blood circulation in the lung segment, which aids in gas exchange. Thus, an intersegmental plane can be formed by merely halting blood circulation in the pulmonary segments, i.e., by ligating either the arteries or veins in the pulmonary segments. This reasoning forms the basis of the BFBM method, indicating that BFBM, MIDM, and Iwata's approach share a common scientific rationale. Although they all operate under the same principle, our method enhances the process through procedural improvements.