Detecting Intersegmental Plane in Thoracoscopic Segmentectomy Using Infrared Thermography
Segmentectomy is a surgical procedure that has gained recognition as an effective method for treating early-stage lung cancer. This technique is designed to preserve pulmonary function to the greatest extent possible while maintaining a post-operative survival rate comparable to that of more extensive resections. However, the successful implementation of segmentectomy is influenced by several factors, including the surgeon’s experience, familiarity with lung anatomy, and the ability to accurately identify the intersegmental plane during the operation. The identification of the intersegmental plane is a critical step in lung segmentectomy, as it determines the precise boundaries for resection.
Traditionally, surgeons have relied on two primary methods to identify the intersegmental plane. The first method, known as the “inflation-deflation” technique, involves inflating the lung after occluding the target segmental bronchus. This creates a visible border between the inflated and deflated segments. However, this method requires approximately 10 to 15 minutes of intraoperative time, which can reduce surgical efficiency and increase patient risk. The second method involves the injection of indocyanine green, either intravenously or intrabronchially, to highlight the intersegmental plane. While this technique is effective, it carries risks of toxicity and allergic reactions associated with the dye.
Given the limitations of these existing methods, there is a need for safer, faster, and more reliable techniques to identify the intersegmental plane during lung surgery. Recent advancements in infrared thermography have provided a promising alternative. Infrared thermography is a non-invasive imaging technique that detects temperature differences on the surface of tissues. Based on the principles of pulmonary circulation, it has been hypothesized that the surface temperature of lung segments would decrease after the ligation of the corresponding pulmonary arteries. This temperature difference can be visualized using infrared thermography, allowing surgeons to identify the boundary between the ligated segments and the normal lung tissue.
The feasibility of this approach has been demonstrated in animal studies, which showed that the temperature of non-perfused lung tissue is significantly lower than that of perfused tissue, with a temperature difference of approximately 1.5 to 2°C. Building on these findings, a pilot study was conducted to evaluate the use of infrared thermography for identifying the intersegmental plane during human lung segmentectomy.
The study involved two patients who underwent thoracoscopic segmentectomy for early-stage lung cancer. The first patient had a microinvasive adenocarcinoma located in the apical segment of the right upper lobe (S1), while the second patient had an adenocarcinoma in situ located in the apical-posterior segment of the left upper lobe (S1+2). Preoperative three-dimensional lung reconstruction models were created to visualize the tumor location and plan the surgical approach.
During the surgery, the segmental arteries corresponding to the target lung segments were ligated. One to two minutes after ligation, a customized infrared thermography detector was inserted through an endoscopic trocar to obtain thermal images of the lung surface. The detector, which was specifically designed for use in minimally invasive thoracic surgery, captured high-resolution images that displayed temperature differences in color-coded formats. In both cases, the temperature of the ligated regions decreased significantly, from 36.8°C to 34.7°C in the first patient and from 37.5°C to 35.3°C in the second patient. These temperature changes were observed within three minutes of artery ligation. When the lung was inflated before thermographic imaging and a waiting period of approximately five minutes was allowed, the temperature differences became even more pronounced.
The infrared thermography images clearly delineated the boundaries between the ligated segments and the normal lung tissue. These boundaries were three-dimensional, providing surgeons with precise visual guidance for the resection. The technique offered several advantages over traditional methods. First, it eliminated the need for the injection of indocyanine green, thereby avoiding the risks of drug-related adverse effects. Second, it reduced the waiting time associated with the inflation-deflation method, improving surgical efficiency. Third, the three-dimensional visualization of the intersegmental plane enhanced the accuracy of the resection. Fourth, the infrared thermography equipment was easy to use in the operating room and did not require extensive training for surgeons. Finally, the key steps of the procedure, such as artery ligation, were already part of the standard surgical protocol, making the technique safe and convenient to implement.
The study also compared the boundaries identified by infrared thermography with those obtained using the inflation-deflation method. It was observed that the boundaries were not entirely overlapping. The inflation-deflation boundary was slightly larger than the thermographic boundary, which may be attributed to the ventilation effects caused by the pores of Kohn between pulmonary alveoli. Additionally, the thermographic boundary appeared smoother and more precise than the inflation-deflation boundary.
Despite these promising results, the study had limitations. The small sample size of only two cases prevented a comprehensive evaluation of the advantages, accuracy, and consistency of infrared thermography in identifying the intersegmental plane. Further studies with larger sample sizes are needed to validate these findings and establish the clinical utility of this technique.
The use of infrared thermography in lung surgery represents a significant advancement in the field of thoracic surgery. By providing a non-invasive, efficient, and accurate method for identifying the intersegmental plane, this technology has the potential to improve the outcomes of segmentectomy procedures. Future research should focus on optimizing the technique, expanding its application to a broader range of cases, and comparing its performance with other existing methods.
In conclusion, infrared thermography offers a novel and effective approach to detecting the intersegmental plane during thoracoscopic segmentectomy. Its ability to provide real-time, three-dimensional visualization of tissue temperature differences enhances surgical precision and efficiency. As the technique continues to evolve, it is expected to play an increasingly important role in the management of early-stage lung cancer, ultimately benefiting patients through improved surgical outcomes and preserved pulmonary function.
doi.org/10.1097/CM9.0000000000001806
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