Intraoperative Unilateral Pulmonary Artery Clamping Test: A First VATS Documentation of a Years Old Technique

This video presents a special case of a fissure last lower bilobectomy after an interoperative unilateral pulmonary artery clamping test. This was necessary because preoperative functional evaluation was inconclusive and intraoperative simulation of bilobectomy by artery clamping was planned to secure functional operability. To the authors’ best knowledge, this is the first documentation of this technique.

This patient is an eighty-five-year-old man suffering from weight loss, severe fatigue, and a permanent feeling of cold. Complete staging with a PET-CT scan, brain MRI, and EBUS-TBNA revealed a large but localized squamous cell cancer in the right lower lobe with infiltration of the middle lobe. The patient had been a smoker with thirty-four pack years and quit immediately after the diagnosis of lung cancer. 

With an FEV1 of 73 percent, DLCO of 36 percent, and a VO2 max of 9.7ml/kg/min, the patient was classified as inoperable. A lung perfusion showed a nearly complete loss of the right lower lobe and part of the middle lobe. There was no curative option such as radiotherapy or oncological treatment, and the patient insisted on having the tumor surgically removed. So, after intensive interdisciplinary discussion among the tumor board, surgeons offered an intraoperative pulmonary artery clamping to perform an oxygenation test to make a final decision on functional operability and a curative resection.

The Surgery

The procedure began by setting up biportal VATS with complete resection of the pulmonary ligament, paraoesophageal, and subcarinal lymph nodes as the first step to gain access to the hilar structures. Lymph node removal between the upper and middle lobe veins created an excellent view of the middle and lower lobe artery. Both arteries were clamped using a snake lymph node dissector, with the tip resting over the intermediate bronchus so that the entire interlobar artery lumen was completely compressed. After five minutes of bilateral ventilation with 100 percent oxygen, the team recorded a PO2 of 380 mmHg in the blood gas analysis, validating a functional operability for lower bilobectomy.

Surgeons proceeded with lower bilobectomy with closure and dissection of the middle and lower lobe veins, the intermediate bronchus, and the interlobar pulmonary artery after removal of interlobar lymph nodes. The remaining parenchymal bridge between upper and lower lobes, as well as upper and middle lobes, were divided with staples.

Postoperatively, there was residual space but no evidence of air leak. Notwithstanding old age, comorbidities, and suffering a COVID-19 infection three weeks postoperatively, the patient exhibited an uneventful recovery. At his follow-up six weeks postoperatively, the patient was nearly fully recovered and was able to carry on with his daily activities and take strolls.

Discussion

A preoperative unilateral pulmonary artery occlusion test is primarily performed with right heart catheterization to simulate pneumonectomy with balloon occlusion of the ipsilateral pulmonary artery. If the mean pulmonary artery pressure after fifteen minutes is 30 mmHg or higher, the cardiopulmonary reserve is considered insufficient for pneumonectomy (1).

Using a similar principle, it is possible to perform intraoperative clamping of the pulmonary artery responsible for supplying the lobe that is to be resected. Reaching a pO2 of 300 mmHg after five minutes of 100 percent oxygen ventilation is proof of functional operability. This is a years-old technique, but to the knowledge of the surgeons, has not yet been published in the scientific community. This procedure was regularly used in the 1990s before dissection of the pulmonary artery when pneumonectomy was necessary. Today, with the use of spirometry, DLCO, perfusion scans, echocardiography, and stair climbing tests, functional operability is usually decided preoperatively (2).

This case demonstrates that minimally invasive surgery can also be used for intraoperative confirmation of functional operability when preoperative evaluation is inconclusive and other therapeutic options are not available.

References

1. Shimohira M, Hashizume T, Ohta K, Suzuki K, Nakagawa M, Ozawa Y, Okuda K, Moriyama S, Nakanishi R, Shibamoto Y. Unilateral pulmonary artery pre-operative occlusion test: technical feasibility and safety prior to pneumonectomy or pleuropneumonectomy for malignancy. Br J Radiol. 2018 Feb;91(1083):20160775. doi: 10.1259/bjr.20160775.
2. Brunelli A, Charloux A, Bolliger CT, Rocco G, Sculier J-P, Varela G, Licker M, Ferguson MK, Faivre-Finn C, Huber RM, Clini EM, Win T, De Ruysscher D, Goldman L; European Respiratory Society and European Society of Thoracic Surgeons joint task force on fitness for radical therapy. ERS/ESTS clinical guidelines on fitness for radical therapy in lung cancer patients (surgery and chemo-radiotherapy). Eur Respir J. 2009 Jul;34(1):17-41. doi: 10.1183/09031936.00184308.

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