Computational fluid dynamics of the airways after left‐upper pulmonary lobectomy: A case study

Abstract

Pulmonary lobectomy is the gold standard intervention for lung cancer removal and consists of the complete resection of the affected lung lobe, which, coupled with the re-adaptation of the remaining thoracic structures, decreases the postoperative pulmonary function of the patient. Current clinical practice, based on spirometry and cardiopulmonary exercise tests, does not consider local changes, providing an average at-the-mouth estimation of residual functionality. Computational Fluid Dynamics (CFD) has proved a valuable solution to obtain quantitative and local information about airways airflow dynamics. A CFD investigation was performed on the airway tree of a leftupper pulmonary lobectomy patient, to quantify the effects of the postoperative alterations. The patient-specific bronchial models were reconstructed from pre-and postoperative CT scans. A parametric laryngeal model was merged to the geometries to account for physiological-like inlet conditions. Numerical simulations were performed in Fluent. The postoperative configuration revealed fluid dynamic variations in terms of global velocity (+23%), wall pressure (+48%), and wall shear stress (+39%). Local flow disturbances emerged at the resection site: a high-velocity peak of 4.92 m/s was found at the left-lower lobe entrance, with a local increase of pressure at the suture zone (18 Pa). The magnitude of pressure and secondary flows increased in the trachea and flow dynamics variations were observed also in the contralateral lung, causing altered lobar ventilation. The results confirmed that CFD is a patient-specific approach for a quantitative evaluation of fluid dynamics parameters and local ventilation providing additional information with respect to current clinical approaches. K E Y W O R D Scomputational fluid dynamics, imaged-based, pulmonary lobectomy, tracheobronchial tree modeling Marta Tullio and Lorenzo Aliboni equally contributed to this study.

Functional analysis of the airways after pulmonary lobectomy through computational fluid dynamics

“…These fluid dynamic alterations are derived from the resection of an entire lung lobe and the geometrical adaptation of the remaining structures, especially for upper lobe lobectomies. Limited to LUL lobectomies, our results are consistent with the two previous studies characterizing this type of lobectomy 23 , 24 . With respect to Gu et al 23 , relatively higher variations of fluid dynamic parameters are observed in our cohort of patients that underwent LUL lobectomy, although this can be possibly ascribed to the higher inlet flow rate considered in the simulations of the presented work.…”

“…With respect to Gu et al 23 , relatively higher variations of fluid dynamic parameters are observed in our cohort of patients that underwent LUL lobectomy, although this can be possibly ascribed to the higher inlet flow rate considered in the simulations of the presented work. The obtained values are indeed in line with Tullio et al 24 , who considered the same inlet flow of the presented study. For upper lobes lobectomies, the increment of pressure, velocity, and wall shear stress can be associated with the severe bronchial stenosis observed and the general re-adaptation of the remaining lower lobes.…”

“…Although present, the structural modifications were less relevant for lower lobe lobectomies and mostly limited to the RML and the lingula shift to the vacant area, in accordance with previous studies 34 . The alterations were also relevant at the trachea and main bronchi level in two subjects, as described by previous studies 24 , 35 . The significant decrement of the cross-section downstream the surgery site is confirmed by studies for the LUL cases 23 , 24 , and the results of the proposed work suggest that this consideration is also verified in the RUL lobectomies cases.…”

“…The alterations were also relevant at the trachea and main bronchi level in two subjects, as described by previous studies 24 , 35 . The significant decrement of the cross-section downstream the surgery site is confirmed by studies for the LUL cases 23 , 24 , and the results of the proposed work suggest that this consideration is also verified in the RUL lobectomies cases. Lower lobe lobectomies, on average, showed lower cross-section variations with the only exception of subject 11.…”

“…The effects on fluid dynamics of congenital anomalies such as the left pulmonary sling have also been studied 22 . Recently, lobectomy effects in patients who underwent left upper pulmonary lobectomy have been investigated 23 , 24 showing significant alterations in the geometry and fluid dynamics between the pre and post-operative models. Although several differences are reported in terms of post-operative changes among lower, middle, and upper lobectomies 3 , 6 , to date, the effects of lobectomy on the fluid dynamics have been analyzed only for the left upper lobectomy.…”