Clinical Ramifications of Bronchial Kink After Upper Lobectomy

The effect of lobar shifting following right upper lobectomy on postoperative pulmonary function

OBJECTIVES

Lobes occasionally displace after lobectomy, referred to as "lobar shifting". However, the benefits, especially in postoperative pulmonary function, remain controversial. This study aimed to measure the effect of lobar shifting on postoperative pulmonary function especially in the right upper lobe.

METHODS

This retrospective study includes 273 right upper lobectomy patients (lobectomy group) and 24 right upper segmentectomy patients (segmentectomy group) from 2012 to 2021. The lobectomy group was further subdivided based on their Synapse Vincent® image: with their postoperative middle lobe bronchus shifted toward the head (shift group: 176 cases) and without (non-shift group: 97 cases). Several factors were examined to determine the cause of lobar shifting. The rate of measured actual postoperative forced expiratory volume in 1 s (FEV1.0) to predicted postoperative FEV1.0 was analyzed and compared among the three groups.

RESULTS

Factors that correlated with lobar shifting included age (p < 0.001), a relatively small middle lobe volume (p = 0.03), no adhesions (p < 0.001), and good upper/middle and middle/lower lobulation (p = 0.04, p = 0.02). The rate of measured actual postoperative FEV1.0 to predicted postoperative FEV1 for the shift, non-shift, and segmentectomy groups were 112.5%, 107.9%, and 103.1% (shift vs non-shift: p = 0.04, shift vs segmentectomy: p = 0.02, non-shift vs segmentectomy: p = 0.19).

CONCLUSIONS

Lobar shifting after right upper lobectomy is influenced by morphological factors and may have a beneficial impact on postoperative pulmonary function.

Lobar shifting after lobectomy other than left upper lobectomy has a beneficial impact on postoperative pulmonary function

PURPOSE

Occasionally, lobes displace after lobectomy, which is referred to as "lobar shifting". This study aimed to evaluate the effect of lobar shifting on postoperative pulmonary function.

METHODS

We analyzed the records of 761 patients who underwent lobectomy between 2012 and 2022. The patients were categorized based on three-dimensional computed tomography (3D-CT) images into those with (shift group: n = 510) and those without (non-shift group: n = 251) their postoperative subject bronchus shifting toward the head or dorsal side. The preservation rate of forced expiratory volume in one second (FEV1.0) was compared between the two groups. Several factors were investigated to identify the cause of lobar shifting.

RESULTS

FEV1.0 preservation rates, excluding left upper lobectomy, were significantly better in the shift group than in the non-shift group (all patients: 87.9% vs. 84.9%, p < 0.001; right upper lobectomy: 90.1% vs. 85.4%, p = 0.002; right lower lobectomy: 90.0% vs. 84.5%, p = 0.002; left upper lobectomy: 82.0% vs. 83.9%, p = 0.43; left lower lobectomy: 90.0% vs. 85.2%, p = 0.01). Factors that correlated with lobar shifting included age (p < 0.001), adhesions (p < 0.001), and lobulation (p = 0.001).

CONCLUSIONS

Lobar shifting may benefit postoperative pulmonary function, excluding after left upper lobectomy. Morphological factors contribute to lobar shifting.

Pulmonary Function Recovery and Displacement Patterns After Anatomic Segmentectomy vs Lobectomy

BACKGROUND

The functional benefit of segmentectomy compared with lobectomy remains controversial. This ambispective study characterizes the changes in pulmonary function as correlated to displacement patterns of residual lung after segmentectomies vs lobectomies.

METHODS

Patients with normal preoperative pulmonary function and undergoing segmentectomy or lobectomy between 2017 and 2021 were considered. Pulmonary function testing was scheduled preoperatively and at least 3 months postoperatively. Differences in the proportions of the median forced expiratory volume in 1 second (FEV1) reduction between segmentectomy and lobectomy were calculated. Covariance analysis was used to estimate the adjusted postoperative FEV1 (apoFEV1) and compare the difference value (DV) in apoFEV1 between segmentectomy and lobectomy.

RESULTS

The study enrolled 634 patients (334 lobectomies and 300 segmentectomies). Median difference in the proportions of the FEV1 reduction between segmentectomy and lobectomy was 4.58%, with maximal difference observed in right S6 (9.08%) and minimal difference in left S1+2+3 (2.80%). For resections involving the upper lobe, apoFEV1 was significantly higher after segmentectomy than after lobectomy (DV, 0.15-0.22 L), except for left S3 and S1+2+3 segmentectomies (DV, 0.08 L and 0.06 L, respectively). Compared with a lower lobe lobectomy, S6 segmentectomy conferred a higher apoFEV1, whereas S7+8 and S9+10 had a similar apoFEV1 (DV, 0.16-0.18 L, 0.07 L, and 0.00-0.06 L, respectively). Functional recovery after segmentectomy was associated with the number of intersegment planes (P < .01) and the presence of an adjacent nonoperated on lobe (P = .03).

CONCLUSIONS

Basilar and left S3 segmentectomies did not preserve more pulmonary function compared with their corresponding lobectomies, possibly due to the presence of multiple intersegmental resection planes.

Persistent cough after pulmonary resection: Minor issue, major hurdle

Background

Persistent cough is one of the most common complications following pulmonary resection, that impairs patients' quality of life and prolongs recovery time. However, a comprehensive review of persistent cough after pulmonary resection (CAP) has not been performed.

Methods

A literature search of PubMed/MEDLINE, Web of Science, and Embase database was conducted for persistent-CAP up to June 2023. Subsequent qualitative systematic review focused on definition, risk factors, prevention, and treatment of persistent-CAP.

Results

Persistent-CAP stands as a prevalent postoperative complication subsequent to pulmonary resection procedures. with an incidence of 24.4-55.0 %. Although persistent-CAP has a minor impact on survival, this condition is of critical importance because it presents a major hurdle in recovery after surgery. In this review, we proposed a systemic definition for persistent-CAP based on available evidence and our own data. Several assessment tools used to assess severity of persistent-CAP are also introduced. Risk factors associated with persistent-CAP are explored, including surgical approaches, resection extent, surgical site, lymph node dissection, postoperative gastroesophageal acid reflux, tracheal intubation anesthesia, preoperative comorbidity, and sex among others. Surgical and anesthesia preventions targeting risk factors to prevent persistent-CAP are elaborated. A number of studies have shown that a multidisciplinary approach can effectively relieve persistent-CAP.

Conclusions

Although the mechanisms underlying persistent-CAP are still unclear, existing studies demonstrated that persistent-CAP is related to surgical and anesthesia factors. Therefore, in the future, prevention and treatment should be developed based on risk factors to overcome the hurdle of persistent-CAP.

Longitudinal changes in the volume of residual lung lobes after lobectomy for lung cancer: a retrospective cohort study

It is unclear how the residual lobe volume changes over time after lobectomy. This study aims to clarify the temporal patterns of volume changes in each remaining lung lobe post-lobectomy. A retrospective review was conducted on patients who underwent lobectomy for lung cancer at Yueyang Central Hospital from January to December 2021. Lung CT images were reconstructed in three dimensions to calculate the volumes of each lung lobe preoperatively and at 1, 6, and 12 months postoperatively. A total of 182 patients were included. Postoperatively, the median total lung volume change rates relative to preoperative values were -20.1%, -9.3%, and -5.9% at 1, 6, and 12 months, respectively. Except for the right middle lobe in patients who underwent right upper lobectomy, the volumes of individual lung lobes exceeded preoperative values. The volume growth of the lung on the side of the resection was significantly more than that of the lung on the opposite side. For left lobectomy patients, the right lower lobe's volume change rate exceeded that of the right upper and middle lobes. Among right lobectomy patients, the left lower lobe and the relatively inferior lobe of right lung had higher volume change rates than the superior one. Right middle lobe change rate was more in patients with right lower lobectomy than right upper lobectomy. Six months postoperatively, FEV1% and right middle lobectomy were positively correlated with the overall volume change rate. One year postoperatively, only age was negatively correlated with the overall volume change rate. 75 patients had pulmonary function tests. Postoperative FEV1 change linearly correlated with 1-year lung volume change rate, but not with theoretical total lung volume change rate or segmental method calculated FEV1 change. Time-dependent compensatory volume changes occur in remaining lung lobe post-lobectomy, with stronger compensation observed in the relatively inferior lobe compared to the superior one(s). Preoperative lung function and age may affect compensation level.

Compensatory expansion of the right middle lobe: volumetric and functional analysis of the changes after right upper or lower lobectomy

The right middle lobe often poorly expands after right upper lobectomy. Postoperative pulmonary function may be inferior after right upper lobectomy than after right lower lobectomy due to poor expansion of the middle lobe. This study examined the difference in the postoperative right middle lobe expansion and pulmonary function between right upper and right lower lobectomy. Patients who underwent right upper or right lower lobectomy through video-assisted thoracic surgery (n = 82) were enrolled in this retrospective study. Pulmonary function tests and computed tomography were performed preoperatively and at 1 year postoperatively. Using three-dimensional computed tomography volumetry, the preoperative and postoperative lung volumes were measured, and the predicted postoperative forced expiratory volume in 1 s was calculated. Middle lobe volume ratio (i.e., ratio of the postoperative to the preoperative middle lobe volume) and the postoperative forced expiratory volume in 1 s ratio (i.e., ratio of the measured to the predicted postoperative forced expiratory volume in 1 s) were compared between right upper and right lower lobectomy. Compared with the patients who underwent right upper lobectomy (n = 50), those who underwent right lower lobectomy (n = 32) had significantly higher middle lobe volume ratio (1.15 ± 0.32 vs. 1.63 ± 0.52, p < 0.001) and postoperative forced expiratory volume in 1 s ratio (1.12 ± 0.12 vs. 1.19 ± 0.13, p = 0.010). The right middle lobe showed more expansion and better recovery of postoperative pulmonary function after right lower lobectomy than after right upper lobectomy.

Preservation vs. dissection of inferior pulmonary ligament for thoracoscopic upper lobectomy: a prospective randomized controlled trial

OBJECTIVES

The proper procedure for inferior pulmonary ligament (IPL) during upper lobectomy remains a topic of debate. To address this matter, we carried out a trial comparing the clinical outcomes of IPL preservation versus IPL dissection during thoracoscopic upper lobectomy (TUL).

METHODS

Patients undergoing thoracoscopic left/right upper lobectomy (TLUL/TRUL) were assigned to either the dissection group (Group D) or the preservation group (Group P). Our primary objective was to quantify and compare the alterations in postoperative residual bronchial angle and lung volume changes between the two groups. Our secondary objective encompassed the assessment of various other intraoperative and postoperative outcomes.

RESULTS

Following adherence to the inclusion and exclusion criteria, we enrolled 100 patients (41 left and 59 right) in Group P and 108 patients (41 left and 67 right) in Group D for the study. Our findings revealed that in TLUL, Group P was able to reduce the degree of postoperative residual bronchial angle change (P < 0.05). Conversely, the situation was distinct for TRUL. We found no notable disparity between the two groups (P > 0.05) with regard to alterations in lung volume or the occurrence of postoperative complications-except for the duration of postoperative hospital stay (P < 0.05).

CONCLUSIONS

Our study suggests IPL preservation especially for TLUL when compared to TRUL, which have important implications for the clinical management of patients undergoing upper lobectomy.

Differentiating Imaging Features of Post-lobectomy Right Middle Lobe Torsion

PURPOSE

The purpose of this study was to identify differences in imaging features between patients with confirmed right middle lobe (RML) torsion compared to those suspected yet without torsion.

MATERIALS AND METHODS

This retrospective study entailing a search of radiology reports from April 1, 2014, to April 15, 2021, resulted in 52 patients with suspected yet without lobar torsion and 4 with confirmed torsion, supplemented by 2 additional cases before the search period for a total of 6 confirmed cases. Four thoracic radiologists (1 an adjudicator) evaluated chest radiographs and computed tomography (CT) examinations, and Fisher exact and Mann-Whitney tests were used to identify any significant differences in imaging features (P<0.05).

RESULTS

A reversed halo sign was more frequent for all readers (P=0.001) in confirmed RML torsion than patients without torsion (83.3% vs. 0% for 3 readers, one the adjudicator). The CT coronal bronchial angle between RML bronchus and bronchus intermedius was larger (P=0.035) in torsion (121.28 degrees) than nontorsion cases (98.26 degrees). Patients with torsion had a higher percentage of ground-glass opacity in the affected lobe (P=0.031). A convex fissure towards the adjacent lobe on CT (P=0.009) and increased lobe volume on CT (P=0.001) occurred more often in confirmed torsion.

CONCLUSION

A reversed halo sign, larger CT coronal bronchial angle, greater proportion of ground-glass opacity, fissural convexity, and larger lobe volume on CT may aid in early recognition of the rare yet highly significant diagnosis of lobar torsion.

The impact of dissection of station 9 on survival and the necessity of pulmonary ligament division during upper lobectomy for lung cancer

BACKGROUND

We conducted this study to investigate the need for dissection of station 9 lymph nodes during upper lobectomy for non-small-cell lung cancer (NSCLC) and to find out the operative results of inferior pulmonary ligament division.

METHODS

A total of 840 patients who underwent upper lobectomy for NSCLC between January 2007 and June 2020 were evaluated retrospectively. The patients were separated into two groups - those having undergone lymph node dissection of station 9 and inferior pulmonary ligament dissection (Group I) and those who did not (Group II). In these groups, the prognostic value of station 9 lymph nodes and postoperative effects (drainage time, prolonged air leak, dead space and length of hospital stay) of ligament division or preservation were analyzed.

RESULTS

The number of patients with station 9 lymph node metastasis was only one (0.1%) and that was multi-station pN2 disease. Station 9 lymph nodes were found in 675 (80.4%) patients, while 22 (2.6%) patients had no lymph nodes in the dissected material. In the other 143 (17%) patients, the inferior pulmonary ligament and station 9 were not dissected. While 5-year survival was 64.9% in 697 patients of Group I, it was 61.3% in 143 patients of Group II (p = 0.56). There was no statistically significant difference between the groups in postoperative effects of ligament division or preservation.

CONCLUSIONS

In upper lobectomies, status of station 9 does not have a significant impact on patients' survival and lymph node staging. Additionally, preservation or division of the inferior pulmonary ligament has no significant advantage or disadvantage.

Right middle lobe syndrome after upper lobectomy: Role of the bronchial angle

BACKGROUND

Right middle lobe syndrome is part of a spectrum of relatively rare but serious conditions that may occur following right upper lobectomy. We aimed to assess whether the preoperative middle lobe bronchial angle on CT predicted patients at risk of developing middle lobe syndrome.

METHOD

All patients who had a complete upper lobectomy over 4 years were retrospectively reviewed for clinical and imaging findings of middle lobe syndrome. Patients with previous lung surgery, preoperative chemo- or radiation therapy, or more extensive surgical resection were excluded. Patient demographics and symptoms, the surgical, pathologic and bronchoscopy reports, and pre- and post-operative chest imaging, to include 3D CT reconstructions and measurements of the middle lobe angles in a subset of patients, were retrospectively reviewed.

RESULT

One hundred and twenty-eight patients met inclusion criteria. Ten (8%) had middle lobe syndrome based on symptoms and imaging features. Eight had severe middle lobe consolidation. Two had postoperative onset of wheezing, with middle lobe bronchial abnormality on CT. The pre- and postoperative middle lobe bronchial angles of 14 patients without middle lobe syndrome were compared to 10 patients with middle lobe syndrome. The middle lobe bronchus was completely obliterated postoperatively and could not be determined in 1 patient. There was no significant difference between the pre- and postoperative angles in patients with or without middle lobe syndrome.

CONCLUSION

Middle lobe syndrome occurred in 8% of patients with right upper lobectomy. The preoperative middle lobe bronchial angle did not predict patients at risk for developing middle lobe syndrome.

A comparative analysis of segmentectomy-aswere medicated withinsociated factors influencing bronchial tortuosity in early-stage left upper lung cancer

BACKGROUND

Several studies of early-stage non-small cell lung cancer (NSCLC) have reported a notable therapeutic effect of segmentectomy. However, the secondary benefits of lung volume preservation remain unclear. This study aimed to investigate the potential benefits of segmentectomy, in terms of its impact on postoperative bronchial change.

METHODS

Patients who underwent left-sided upper lobectomy and upper division segmentectomy for pStage 0-IA2 NSCLC, were retrospectively analyzed. Degree of the left main bronchial deviation was measured by the curvature index (CI), determined using computed tomography. Variables, including CI value and postoperative rate of change in CI were compared for postoperative cough management the lobectomy and segmentectomy groups.

RESULTS

Sixty-seven patients were reviewed. Thirty-seven and 30 patients underwent lobectomy and segmentectomy, respectively, without any significant differences in baseline and surgical variables. The 5-year overall survival rates in the lobectomy and segmentectomy groups were 86.7 and 95.2%, respectively (p = 0.437). While there was no significant difference in postoperative complications, the rate of change in CI was significantly higher in the lobectomy group than in the segmentectomy group (113 vs. 106%, p = 0.005). In addition, the analysis based on postoperative cough reveals the rate of change in CI to be significantly higher in patients requiring medical treatment (p = 0.005). Conclusions Left upper division segmentectomy provides satisfactory treatment and relief of postoperative bronchial tortuosity. Our study suggests that there is a possibility the mitigation of environmental changes in the thoracic cavity may reduce symptoms, thus contributing to an improved quality of life.

Evaluation of the necessity of Pulmonary Ligament Lymph Node Dissection for Upper Lobe Stage IB NSCLC: A Propensity Score-matched Study

Objective: The purpose of this study was to explore whether the resection of pulmonary ligament lymph nodes would affect the prognosis of patients with stage IB non-small cell lung cancer (NSCLC). Methods: We retrospectively analyzed 341 patients with upper lobe stage IB NSCLC who underwent radical surgery for lung cancer at Sun Yat-Sen University Cancer Center from 1999 to 2009. The Cox proportional hazard regression model was used to analyze the prognostic factors. After propensity score matching (PSM), 204 cases were selected. The Kaplan-Meier method and log-rank test were applied to compare overall survival (OS) and recurrence-free survival (RFS). Results: Among the 341 cases included in the study, 217 had no pulmonary ligament lymph nodes resected, and 124 had pulmonary ligament lymph nodes resected. They were divided into two groups according to whether the pulmonary ligament lymph nodes were resected; there were significant differences between the two groups in laterality, resected lymph node stations, and resected lymph node numbers (P<0.05). Univariate and multivariate analyses by the Cox proportional hazards model showed that age and family history of malignant tumors were prognostic factors for OS, and no variables were prognostic factors for RFS (P<0.05). Resection of the pulmonary ligament lymph node was not associated with OS or RFS. After propensity score matching (PSM), survival analysis was performed again using the Kaplan-Meier method and log-rank test; the results suggested that resection of the pulmonary ligament lymph node is not statistically associated with OS and RFS (P>0.05). Conclusions: For stage IB NSCLC, resection of the pulmonary ligament lymph nodes was not statistically associated with OS or RFS. Pulmonary ligament lymph node resection is not necessary for early-stage NSCLC.

Impact of counterclockwise rotation of the right middle lobe following right upper lobectomy

OBJECTIVES

Following right upper lobectomy, the right middle lobe may shift towards the apex and rotate in a counterclockwise direction with respect to the hilum. This study aimed to investigate the incidence and clinical impact of middle lobe rotation in patients undergoing right upper lobectomy.

METHODS

From January 2014 to November 2018, 82 patients underwent right upper lobectomy at our institution for lung cancer using a surgical stapler to divide the minor fissure. Postoperative computed tomography scans evaluated the counterclockwise rotation of the middle lobe, in which the staple lines placed on the minor fissure were in contact with the major fissure of the right lower lobe (120° counterclockwise rotation). Clinicoradiological factors were evaluated and compared between patients with and without middle lobe rotation. We also reviewed surgical videos in patients with middle lobe rotation to evaluate the position of the middle lobe at the end of surgery.

RESULTS

Nine patients had a middle lobe rotation (11%), where 1 patient required surgical derotation. Patients with middle lobe rotation were significantly associated with more frequent right middle lobe atelectasis and severe postoperative complications compared with those without rotation. A surgical video review detected potential middle lobe rotation at the end of the surgery.

CONCLUSIONS

Middle lobe rotation without torsion following right upper lobectomy is not rare, and it is associated with adverse postoperative courses. Careful positioning of the right middle lobe at the end of surgery is warranted to improve postoperative outcomes.

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

Pulmonary lobectomy, which consists of the partial or complete resection of a lung lobe, is the gold standard intervention for lung cancer removal. The removal of functional tissue during the surgery and the re-adaptation of the remaining thoracic structures decrease the patient's post-operative pulmonary function. Residual functionality is evaluated through pulmonary function tests, which account for the number of resected segments without considering local structural alterations and provide an average at-the-mouth estimation. Computational Fluid Dynamics (CFD) has been demonstrated to provide patient-specific, quantitative, and local information about airways airflow dynamics. A CFD investigation was performed on image-based airway trees reconstructed before and after the surgery for twelve patients who underwent lobectomy at different lobes. The geometrical alterations and the variations in fluid dynamics parameters and in lobar ventilation between the pre and post-operative conditions were evaluated. The post-operative function was estimated and compared with current clinical algorithms and with actual clinical data. The post-operative configuration revealed a high intersubject variability: regardless of the lobectomy site, an increment of global velocity, wall pressure, and wall shear stress was observed. Local flow disturbances also emerged at, and downstream of, the resection site. The analysis of lobar ventilation showed severe variations in the volume flow rate distribution, highlighting the compensatory effects in the contralateral lung with an increment of inflow. The estimation of post-operative function through CFD was comparable with the current clinical algorithm and the actual spirometric measurements. The results confirmed that CFD could provide additional information to support the current clinical approaches both in the operability assessment and in the prescription of personalized respiratory rehabilitation.

Bronchial morphological changes are associated with postoperative intractable cough after right upper lobectomy in lung cancer patients

BACKGROUND

To date, postoperative intractable cough (PIC) has not received adequate attention, and the complex perioperative factors when performing pulmonary resection often prevent researchers from addressing this issue. This study aimed to investigate the clinicopathological and radiographic indicators related to PIC in lung cancer patients.

METHODS

In all, 112 patients who had had right upper lobectomy for primary lung cancer from January 2019 to December 2020 were retrospectively reviewed. We collected data via the electronic medical database of our department. Bronchial morphological features were investigated comprehensively via three-dimensional chest computer tomography reconstruction images.

RESULTS

During outpatient follow-up visits, 41 (36.6%) patients complained about persistent dry cough after surgery. Compared with the non-cough group, patients in the refractory cough group showed significant differences in smoking history, right upper lobe stump length, changes of right bronchus intermedius (RBI) diameter, changes of right lower lobe (RLL) basal bronchus diameter, changes of RBI/RLL bronchial angle, and bronchial kink. However, according to multivariable regression analysis, stump length, bronchial kink, and diameter change of the right lower lobe basal bronchus were independently associated with postoperative refractory cough. A nebulization drug was prescribed for the 41 patients diagnosed with PIC, and 33 (80.5%) patients had improved by the next visit.

CONCLUSIONS

After right upper lobectomy, the morphology of the remaining bronchial tree in the residual lung changed significantly. The bronchial morphological alterations were independent risk factors for PIC.

Changes in Forced Expiratory Volume in 1 Second after Anatomical Lung Resection according to the Number of Segments

Background

Although various methods are already used to calculate predicted postoperative forced expiratory volume in 1 second (FEV₁) based on preoperative FEV₁ in lung surgery, the predicted postoperative FEV₁ is not always the same as the actual postoperative FEV₁. Observed postoperative FEV₁ values are usually the same or higher than the predicted postoperative FEV₁. To overcome this issue, we investigated the relationship between the number of resected lung segments and the discordance of preoperative and postoperative FEV₁ values.

Methods

From September 2014 to May 2020, the data of all patients who underwent anatomical lung resection by video-assisted thoracoscopic surgery (VATS) were gathered and analyzed retrospectively. We investigated the association between the number of resected segments and the differential FEV₁ (a measure of the discrepancy between the predicted and observed postoperative FEV₁) using the t-test and linear regression.

Results

Information on 238 patients who underwent VATS anatomical lung resection at Kyung Hee University Hospital at Gangdong and by DH. Kim for benign and malignant disease was collected. After applying the exclusion criteria, 114 patients were included in the final analysis. In the multiple linear regression model, the number of resected segments showed a positive correlation with the differential FEV₁ (Pearson r=0.384, p<0.001). After adjusting for multiple covariates, the differential FEV₁ increased by 0.048 (95% confidence interval, 0.023–0.073) with an increasing number of resected lung segments (R²=0.271, p<0.001).

Conclusion

In this study, after pulmonary resection, the number of resected segments showed a positive correlation with the differential FEV₁.

Inferior Pulmonary Ligament Division May Be Unnecessary during Left Upper Lobectomy: Effects on Lung Volume, Bronchial Angle and Bronchial Tortuosity

The benefits of dissecting inferior pulmonary ligament (IPL) during upper lobectomy using video-assisted thoracoscopic surgery (VATS) for early-stage lung cancer remains controversial. This study evaluates the effect of IPL dissection by comparing the lung volume, bronchial angle, and bronchial tortuosity of the left lower lobe (LLL) during VATS upper lobectomy. Medical records of all patients who underwent VATS left upper lobectomy for early-stage lung cancer were evaluated. Patients were divided into group P (preservation) and group D (dissection). Pre- and post-surgery lung volumes, bronchial angles (angle 1: axial angulation; angle 2: vertical angulation), and bronchial tortuosity (curvature index of the left main bronchus) were measured using computed tomography images for comparison. Forty patients were included in each group. Patient characteristics such as age, gender, body mass index, and smoking status, and preoperative lung volume, bronchial angles, and tortuosity were not significantly different between the two groups, and there was no statistically significant difference in the axial and vertical angulations; however, the change in pre- and postoperative bronchial tortuosity (0.03 ± 0.03 vs. 0.06 ± 0.03) and lung volume (-558.1 ± 410.0 mL vs. -736.3 ± 382.7 mL) showed a significant difference (p < 0.001 and p = 0.04, respectively). Preservation of IPLs during left upper lobectomy may be beneficial for LLL expansion and induces less movement and positional change in the left main bronchus.

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

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 left-upper 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.

Risk factors of middle lobe bronchus kinking following right upper lobectomy

Background

The incidence rate of kinking of the middle lobe bronchus following right upper lobectomy is higher compared to that with residual lung bronchus following other lobectomies. Bronchial kinking was presumed to be caused by the displacement of the residual lung lobes, but its etiology is unclear. Moreover, prevention methods and effective treatments have not yet been established. The purpose of this study was to investigate the risk factors and etiology of middle lobe bronchus kinking and discuss prevention methods.

Methods

Patients who underwent right upper lobectomy in our hospital were retrospectively evaluated. Patient clinical characteristics, lung function, and lung lobe volume, surgical procedure were analyzed in association with the incidence of middle lobe bronchus kinking. The association between the displacement of residual lung lobes after operation and the incidence of middle lobe bronchus kinking was analyzed to assess the etiology.

Results

A total of 175 patients were enrolled in the risk analysis. Middle lobe bronchus kinking was observed in 5 patients (2.9%). The low percentage of forced expiratory volume percentage in 1 second (P=0.021), the low volume ratio of the right middle lobe (RML) to the right thoracic cavity (RTC) (P=0.016), and the low volume ratio of RML to right upper lobe (RML/RUL) (P=0.006) were significant risk factors of middle lobe bronchus kinking. In the patients who underwent CT at 6 months after surgery, the degree of the cranial displacement of RML was associated with the incidence of middle lobe bronchus kinking (P=0.025).

Conclusions

The risk of middle lobe bronchus kinking could be assessed preoperatively by calculating the volume ratio of RML/RTC and RML/RUL. The displacement of RML could be associated with the incidence of middle lobe bronchus kinking.

Predictive factors of cough after uniportal video-assisted thoracoscopic pulmonary resection

Background

Cough is one of the shared complications after lung surgery. In this study, a prospective analysis was conducted for exploring the risk factors of persistent cough after uniportal video-assisted thoracoscopic pulmonary resection.

Methods

One hundred thirty-five patients with pulmonary nodules who underwent surgical treatment in the same surgical group from November 2019 to January 2020 were enrolled in this prospective study. The severity of cough and its impact on patients’ quality of life before and after surgery were assessed by the Mandarin Chinese version of the Leicester cough questionnaire (LCQ-MC), and postoperative cough was tested by the cough visual analog scale (VAS) and cough symptom score (CSS). Risk factors of cough after pulmonary resection (CAP) were determined by univariate and multivariate logistic regression analysis.

Results

The incidence of postoperative cough was 24.4% (33 of 135 patients). Univariate analysis showed that gender (female), the surgical site (upper right), the resection (lobectomy), subcarinal lymph node dissection, postoperative acid reflux, length of hospitalization contributed to the development of CAP resection. Multivariate logistic regression analysis showed that the resection (lobectomy) (OR 3.590, 95% CI: 0.637–20.300, P=0.017), subcarinal lymph node dissection (OR 4.420, 95% CI: 1.342–14.554, P=0.001), postoperative acid reflux (OR 13.55, 95% CI: 3.186–57.633, P<0.001) and duration of anesthesia (over 153 minutes, OR 0.987, 95% CI: 0.978–0.997, P=0.011) were independent risk factors for postoperative cough.

Conclusions

The application of uniportal video-assisted thoracoscopic techniques to several types of lung surgery are conducive to enhanced recovery after surgery (ERAS). Postoperative cough is related to an ocean of factors, the resection (lobectomy), subcarinal lymph node dissection, postoperative acid reflux, and duration of anesthesia (over 153 minutes) are independent high-risk factors for CAP resection.

Trial registration

This study was registered on ClinicalTrials.gov (NCT04204148).

Intermediate bronchial kinking after right upper lobectomy for lung cancer

BACKGROUND

Bronchial kinking after lung lobectomy is likely, whereas that of the intermediate bronchus after right upper lobectomy is often not recognized. The aim of this study was to examine the clinical implications of this condition.

METHODS

One-hundred cases of right upper lobectomy for primary lung cancer were reviewed. The cases were divided into groups with intermediate (group A) and non-intermediate (group B) bronchial kinking, and the patient characteristics and postoperative outcomes were compared. The remaining lower lobe deformation was also evaluated using the angle formed by the intrathoracic tracheal line and posterior fissure on reconstructed sagittal computed tomography.

RESULTS

There were 23 cases in group A which had a higher rate of bronchial calcification, older age, and female sex, whereas and smoking and pulmonary emphysema were less frequent. Three cases in group A had respiratory symptoms such as wheezing and respiratory noise, while only one case of middle lobe atelectasis was found in group B. In multivariate analysis, upper mediastinal lymph node dissection was an independent factor for non-intermediate bronchial kinking. The lower lobe was significantly more expanded in group A than in group B.

CONCLUSIONS

Intermediate bronchial kinking correlates with postoperative respiratory symptoms and was less likely after upper mediastinal lymph node dissection.

Development of Miniature Y Stent for Treatment of Postoperative Bronchial Stenosis

Bronchial stenosis after chest surgery is a rare event. In upper lobectomy it is likely due to the upward movement of the remaining lobes with torsion of the bronchus and edema. This case report describes the use of existing tools and prosthesis to create a novel miniature Y stent for a stenotic lobar bronchus that rapidly bifurcates, not allowing the insertion of a standard bronchial stent.

Effect of inferior pulmonary ligament division on residual lung volume and function after a right upper lobectomy

OBJECTIVES

The requirement to divide an inferior pulmonary ligament (IPL) during an upper lobectomy has not been standardized. We evaluated the influence of the division of an IPL after a lobectomy of the right upper lobe.

METHODS

We evaluated 52 patients with lung cancer who underwent a video-assisted thoracoscopic lobectomy of the right upper lobe at Asan Medical Center between January 2011 and April 2014. These cases were stratified by division of the IPL or not, i.e. a preservation group (group P, n = 21) and a division group (group D, n = 31). The angle between the bronchus intermedius and the right middle lobe bronchus and the lung volume were measured using computed tomography. The results of the pulmonary function tests and the prevalence of complications were also reviewed.

RESULTS

The prevalences of atelectasis (P = 0.538), dead space (P = 0.084) and pleural effusion (P = 0.538) were not statistically different. The postoperative volumetric change of the right middle lobe (group P, -27 ± 97 ml; group D, -29 ± 111 ml; P = 0.950) and of the right lower lobe (group P, 397 ± 293 ml; group D, 335 ± 294 ml; P = 0.459) did not show statistical differences. The change in the bronchial angle was not statistically different between the groups (group P, -26.3 ± 13.7°; group D, -26.7 ± 13.6°; P = 0.930). The patients in group D experienced a greater loss in forced vital capacity than those in group P (group P, -0.16 ± 0.26 l; group D, -0.42 ± 0.33 l; P = 0.007), but the loss in the forced expiratory volume in 1 s was not significant (P = 0.328).

CONCLUSIONS

An IPL division does not produce significant differences in lung volume, bronchial angle change or prevalence of complications other than loss of forced vital capacity.

Structural and functional alterations of the tracheobronchial tree after left upper pulmonary lobectomy for lung cancer

Background

Pulmonary lobectomy has been a well-established curative treatment method for localized lung cancer. After left upper pulmonary lobectomy, the upward displacement of remaining lower lobe causes the distortion or kink of bronchus, which is associated with intractable cough and breathless. However, the quantitative study on structural and functional alterations of the tracheobronchial tree after lobectomy has not been reported. We sought to investigate these alterations using CT imaging analysis and computational fluid dynamics (CFD) method.

Methods

Both preoperative and postoperative CT images of 18 patients who underwent left upper pulmonary lobectomy are collected. After the tracheobronchial tree models are extracted, the angles between trachea and bronchi, the surface area and volume of the tree, and the cross-sectional area of left lower lobar bronchus are investigated. CFD method is further used to describe the airflow characteristics by the wall pressure, airflow velocity, lobar flow rate, etc.

Results

It is found that the angle between the trachea and the right main bronchus increases after operation, but the angle with the left main bronchus decreases. No significant alteration is observed for the surface area or volume of the tree between pre-operation and post-operation. After left upper pulmonary lobectomy, the cross-sectional area of left lower lobar bronchus is reduced for most of the patients (15/18) by 15–75%, especially for 4 patients by more than 50%. The wall pressure, airflow velocity and pressure drop significantly increase after the operation. The flow rate to the right lung increases significantly by 2–30% (but there is no significant difference between each lobe), and the flow rate to the left lung drops accordingly. Many vortices are found in various places with severe distortions.

Conclusions

The favorable and unfavorable adaptive alterations of tracheobronchial tree will occur after left upper pulmonary lobectomy, and these alterations can be clarified through CT imaging and CFD analysis. The severe distortions at left lower lobar bronchus might exacerbate postoperative shortness of breath.

Postoperative Imaging After Lobectomy: Predicting the Displacement and Change in Orientation of Nonresected Lung Nodules

OBJECTIVES

The objective of this study was to determine the effect of a lobectomy to the location and orientation of nonresected lung nodule and its corresponding airway.

METHODS

We reviewed preoperative and postoperative computed tomography of patients who underwent lobectomies and have a separate nonresected nodule in the ipsilateral lung. Displacement of the nonresected nodule and angulation of its corresponding segmental bronchus were measured.

RESULTS

Fifty nodules from 40 patients (30 females, 10 male; mean ± SD age, 67 ± 7 years) were assessed. Nodules are displaced clockwise after right upper, right middle, and left lower lobectomies and counterclockwise after right lower and left upper lobectomies. Displacement of the remaining nodules was greater in the craniocaudal plane, followed by anteroposterior and transverses planes (mean, 3.7, 2.5, and 1.9 cm, respectively).

CONCLUSIONS

Remaining ipsilateral nodules and their associated segmental airways are displaced in a predictable fashion after lobectomy. This may help in the assessment of follow-up imaging.

Ventilation failure after lateral jackknife positioning for robot-assisted lung cancer surgery in a patient after lingula-sparing left upper lobectomy

BACKGROUND

Ventilation failure commonly occurs when a standard left-sided double-lumen tube is used in patients after left upper lobectomy having remarkable angulation of the left main bronchus. We present a female without remarkable angulation, in whom ventilation failure occurred after lateral jackknife positioning.

CASE PRESENTATION

A 73-year-old female after lingula-sparing left upper lobectomy without remarkable angulation was scheduled for robot-assisted right upper lobectomy. Ventilation failure with a standard left-sided double-lumen tube occurred when she was placed not in the lateral position but in the lateral jackknife position required for robotic surgery. After replacement by the Silbroncho® left-sided double-lumen tube, adequate one-lung ventilation became possible.

CONCLUSIONS

Ventilation failure with a standard tube may occur more easily when patients with bronchial angulation are placed in the lateral jackknife than lateral position due to posture-induced exacerbations of bronchial angulation. The Silbroncho® tube seems useful in such situations.

Computed tomography detection of stapled interlobar fissure facilitates diagnosing postoperative lobar torsion: A case report

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The position of staples should be evaluated by CT for postoperative middle lobe atelectasis.

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Patency of the pulmonary artery does not rule out the possibility of lobar torsion.

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If the aeration maneuver for atelectasis fails, rethoracotomy should be considered.

Introduction

Atelectasis of the right middle lobe following right upper lobectomy may result from lobar torsion, bronchial kink, or impacted mucus plug. Although clinical consequence of lobar torsion could be serious, differentiating it from bronchial kink is occasionally challenging.

Presentation of case

A 39-year old man with non-small cell lung cancer of cT1aN0M0 stage IA underwent right upper lobectomy. On postoperative day 1, we identified middle lobe atelectasis on the chest X-ray and performed bronchoscopy, which showed an obstruction of the right middle lobe bronchus without mucoid impaction. We injected air using a bronchoscope to the middle lobe, which re-expanded it. However, on postoperative day 2, chest X-ray showed a slightly collapsed and opacified middle lobe. Although enhanced computed tomography showed a patent middle lobe pulmonary artery, we noticed that a staple placed in the horizontal fissure was in contact with the lower lobe, implying the possibility of lobar torsion. Rethoracotomy on postoperative day 2 revealed a 240° clockwise rotation of the congested middle lobe. Therefore, we performed simple detorsion. The patient was discharged 10 days after rethoracotomy without further adverse events.

Discussion

In our case, patency of the pulmonary artery and temporary improvement of the atelectasis using a bronchoscopic aeration maneuver could not rule out the possibility of lobar torsion.

Conclusion

The position of the staple placed on the interlobar fissure should be evaluated using computed tomography in postoperative middle lobe atelectasis. If the aeration maneuver for middle lobe atelectasis using bronchoscope fails, rethoracotomy should be considered.

Pleural Hypercarbia After Lung Surgery Is Associated With Persistent Alveolopleural Fistulae

BACKGROUND

Persistent air leak (PAL) > 5 days due to alveolopleural fistulae is a leading cause of morbidity following surgical resection. Elevated CO2 levels reportedly inhibit alveolar epithelial cell proliferation and impair wound healing in vitro. Because the injured lung surface is in direct communication with the pleural cavity, we investigated whether the pleural gaseous milieu affected lung healing.

METHODS

Oxygen and CO2 levels in pleural gas were determined prospectively in consecutive patients (N = 116) undergoing lung resection by using an infrared spectroscopy-based analyzer. Poisson and logistic regression analyses were used to determine the relationship between time to resolution of air leaks and pleural oxygen and CO2. In addition, patients with pleural CO2 concentrations ? 6% on postoperative day 1 (n = 20) were alternatively treated with supplemental oxygen and extrapleural suction to reduce the pleural CO2 levels.

RESULTS

Poisson analyses revealed that every 1% increase in CO2 was associated with a delay in resolution of air leak by 9 h (95% CI, 7.1 to 10.8; P < .001). Linear regression showed that every 1% increase in CO2 increased the odds of PAL by 10-fold (95% CI, 2.2 to 47.8; P = .003). In patients with pleural CO2 ? 6%, a reduction in CO2 promoted resolution of air leak (6.0 ± 1.2 vs 3.4 ± 1.1 days; P < .001).

CONCLUSIONS

Pleural hypercarbia seems to be associated with persistent alveolopleural fistulae following lung resection. Analysis of pleural gases could allow for better chest tube management following lung resection. Patients with intrapleural hypercarbia seem to benefit from supplemental oxygen and suction, whereas patients who do not have hypercarbia can be maintained on water seal drainage.

Perioperative outcomes of upper lobectomy according to preservation or division of the inferior pulmonary ligament

BACKGROUND

The aim of this study was to investigate the relationship between inferior pulmonary ligament division and postoperative complications.

METHODS

Medical records of 72 non-small cell lung cancer (NSCLC) patients who underwent video-assisted thoracic surgery (VATS) upper lobectomy between March 2012 and November 2013 performed by a single thoracic surgeon at our center were reviewed retrospectively. Patients were categorized into two groups: the division group, who underwent division of the inferior pulmonary ligament, and the preservation group, who did not. The division group included 43 patients (27 right, 16 left), while the preservation group included 29 (11 right, 18 left). Postoperative outcomes such as the presence of pleural effusion, chest tube duration, and changes in the angle and diameter of remnant bronchus were compared; bronchial diameter and angle were measured on three-dimensional (3D) reconstruction chest CT images.

RESULTS

Chest tube duration, duration of chest tube drainage >200 mL, and the presence of pleural effusion on chest X-rays taken 1 month after surgery were not significantly different between the two groups (P=0.07, 0.33, and 1.00, respectively). There were also no significant differences between groups in the presence of apical dead space or in change in bronchial angle (P=0.22 and 0.74, respectively). In 3D reconstruction images, changes in the diameter of the right middle, right lower, and left lower lobar (LLL) bronchi were similar between groups (P=0.72, 0.12 and 0.29, respectively). Change in the angle between the right bronchus intermedius (RBI) and the right middle lobar (RML) bronchus and between the RBI and the right lower lobar (RLL) bronchus were significantly different between the division and preservation groups (P=0.02 and 0.05, respectively).

CONCLUSIONS

Inferior pulmonary ligament division had no clear benefits. Complications related to excessive dislocation of remnant bronchi might be associated with inferior pulmonary ligament division, but further research is needed to elucidate this relationship.

Dividing inferior pulmonary ligament may change the bronchial angle

BACKGROUND

Whether dissecting the inferior pulmonary ligaments (IPLs) during superior video-assisted thoracoscopic (VATS) lobectomy for early stage lung cancer remains controversial. This study aimed to evaluate the influence of dissecting the IPLs during VATS superior lobectomy on bronchial distortion and recovery of pulmonary function.

MATERIALS AND METHODS

This was a retrospective study of 72 patients with non-small cell lung cancer who underwent VATS superior lobectomy from March 2012-August 2013 at the First People's Hospital of Yunnan Province. Patients were grouped according to IPLs preservation (group P) or dissection (group D). The preoperative and postoperative pulmonary function and the postoperative complications were analyzed. The changes in bronchi angles and pulmonary capacity were measured using computed tomography.

RESULTS

There were no significant differences in the complication rate and volume of chest drainage between the two groups. The changes in bronchus angle in group P were significantly smaller than those in group D after left lung operation (P = 0.046 at 3 mo; P = 0.038 at 6 mo); in the right lung, the changes were not significant between the two groups (P = 0.057 at 3 mo; P = 0.541 at 6 mo). The forced expiratory volume of 2% and forced expiratory volume in 1 s (FEV1%) were significantly better in group P than those in group D at 3 and 6 mo (P < 0.05). The pulmonary capacity in group P was significantly larger than that in group D at 6 mo (P = 0.002).

CONCLUSIONS

Preservation of IPLs during VATS lobectomy might have an impact on the bronchus angle, lung function, and lung volume.

Prediction of postoperative dyspnea and chronic respiratory failure

BACKGROUND

Even among patients considered to be functionally eligible for major lung resection, some experience postoperative dyspnea. Based on our previous study with quantitative computed tomography (CT), we hypothesized that postoperative dyspnea is associated with the collapse of the remaining lung, and thus, prediction of the postoperative lung volume may contribute to risk assessment for postoperative dyspnea.

METHODS

We measured the emphysematous lung volume and functional lung volume (FLV) separately on whole lung CT using an image analysis software in 290 patients undergoing major lung resection for cancer between January 2006 and December 2012. The postoperative FLV was predicted by a stepwise multiple regression analysis.

RESULTS

Fourteen patients complained of postoperative dyspnea (complicated group), five of them presented with chronic respiratory failure. The postoperatively measured FLV was significantly lower in the complicated group than in the control group (P < 0.01). The postoperative FLV could be calculated using preoperative variables, including the forced vital capacity, number of resected segments, FLV, and emphysematous lung volume. The predicted postoperative FLV was significantly lower in the complicated group than in the control group (P < 0.01, area under the curve = 0.78; sensitivity 86%; specificity 73%). The predicted postoperative FLV was also useful in distinguishing complicated patients from matched-control patients who had similar preoperative pulmonary function (P = 0.02).

CONCLUSIONS

Postoperative dyspnea is likely accompanied by a collapse of the remaining lung. Quantitative assessment of the lung morphology on preoperative CT is useful to screen for patients at risk of postoperative dyspnea.

Reverse v-shape kinking of the left lower lobar bronchus after a left upper lobectomy and its surgical correction

A 76-year-old male underwent a left upper lobectomy with wedge resection of the superior segment of the left lower lobe using video-assisted thoracoscopic surgery (VATS) for non-small-cell lung cancer of the left upper lobe. He presented with shortness of breath, fever, and leukocytosis. Chest radiography showed atelectasis at the remaining left lower lobe. Bronchoscopy revealed narrowing of the left lower bronchus with purulent secretion, and computed tomography showed downward kinking of the left lower lobar bronchus. He underwent exploratory VATS, and intraoperative findings showed an inferiorly kinked left lower lobar bronchus with upward displacement of the left lower lobe. After adhesiolysis, the kinked bronchus was straightened, and bronchopexy was performed to the pericardium to prevent the recurrence of bronchial kinking. Also, the inferior pulmonary ligament was reattached to prevent upward displacement. Postoperative follow-up bronchoscopy revealed no evidence of residual bronchial obstruction, and chest radiography showed no atelectasis thereafter.

The effect of postoperative change in bronchial angle on postoperative pulmonary function after upper lobectomy in lung cancer patients

OBJECTIVES

Upper lobectomy inevitably leads to an upward displacement of the remaining lower lobe. Such displacement may result in bronchial angulation, thereby narrowing the airway. We hypothesized that the degree of displacement of the bronchus is associated with the degree of exacerbation of postoperative pulmonary dysfunction. This study investigated whether bronchial angulation affects postoperative pulmonary function.

METHODS

Patients undergoing upper lobectomy for lung cancer were retrospectively evaluated. A check for the presence of dyspnoea, pulmonary function test, chest X-ray and chest computed tomography (CT) were performed at 3 and 12 months postoperatively in these patients. The angle formed by the main bronchus and the bronchus intermedius on the right side and that by the main bronchus and the lower lobar bronchus were measured using the coronal view of the chest CT. We analysed the relationship between the change in bronchial angle and pulmonary function.

RESULTS

Ninety-nine patients were enrolled in this study. Among these patients, 50 underwent left upper lobectomy (LUL) and 49 underwent right upper lobectomy (RUL). Nine patients who underwent LUL showed worsening symptoms, and among them, 8 presented an increase in the angle. However, among the 9 patients with worsening symptoms after RUL, only 4 presented an increase in the angle. Decreased forced expiratory volume in 1 s (FEV1) from 3 to 12 months after surgery was observed in 16 patients in the LUL group and 14 in the RUL group. Exacerbation of pulmonary dysfunction was associated with an increase in the bronchial angle (P = 0.04 for LUL and P = 0.02 for RUL). The degree of angle change was also associated with the extent of FEV1 reduction (P = 0.02 for LUL and P = 0.02 for RUL).

CONCLUSIONS

Although the change in the bronchial angle is a physiological condition, it can reduce postoperative pulmonary function. The measurement of the change in the angle using the coronal view of a chest CT is a useful screening tool for predicting the postoperative reduction in FEV1.