Masataro Hayashi

Computed tomography-defined functional lung volume after segmentectomy versus lobectomy.

OBJECTIVE Lung segmentectomy reduces the extent of resection required for lobectomy, but its resulting clinical benefits remain controversial. METHODS Forty patients who underwent segmentectomy for stage I lung cancer over a 5-year period were matched to 40 patients who underwent lobectomy, using nearest available matching method with the estimated propensity score. We compared the functional volume of the ipsilateral lung to be resected, the ipsilateral lung to be preserved and the contralateral lung before, and 6 months after the operation, between the groups. Functional lung volume was defined as the lung volume representing normal attenuation (-600 to -910 Hounsfield units (HUs)) on computed tomography. We also compared the volumetric parameters to the spirometric parameters in 42 other patients, who underwent major lung resection for stage I lung cancer. RESULTS We removed 11.6% of the functional lung volume by segmentectomy and 24.5% by lobectomy (P<0.001). However, the loss of the functional lung volume after segmentectomy was only 8.3% and that after lobectomy was 9.2%: this difference was not significant (P=0.7). Both the ipsilateral residual lung and the contralateral lung increased in functional volume more extensively after lobectomy than after segmentectomy. Increased postoperative functional lung volume was significantly correlated with improvement in postoperative pulmonary function (R=0.6, P<0.001). CONCLUSION Although lung segmentectomy can reduce the extent of lung resection, it may not contribute to preserving postoperative functional lung volume because lobectomy promotes postoperative expansion of the bilateral residual lung, which compensates postoperative pulmonary functional loss to a greater extent than segmentectomy.

Compensation of pulmonary function after upper lobectomy versus lower lobectomy

OBJECTIVE Major lung resection may induce expansion of the remaining lung, accompanied by some gain in the function of this lung; however, the impact of the site of resection on this compensatory response remains unclear. METHODS We measured computed tomography-based functional lung volume, representing normal lung attenuation (-600 to -910 Hounsfield units), and spirometry-based lung function (forced expiratory volume in 1 second) preoperatively and 6 months postoperatively in patients with lung cancer and compared them between patients undergoing upper lobectomy (n = 34) and patients undergoing lower lobectomy (n = 26). RESULTS We removed 17% ± 4% of the functional lung volume by upper lobectomy and 27% ± 5% by lower lobectomy (P < .001). Postoperatively, the residual lung expanded by various degrees, accompanied by a proportionate gain in the residual lung function (R = 0.6, P < .001). This anatomic and functional compensation of the residual lung was more remarkable after lower lobectomy than after upper lobectomy (P <.05). Consequently, the percentage loss of the functional lung volume after upper lobectomy (10% ± 10%) did not differ significantly from that after lower lobectomy (9% ± 12%, P = .6). Likewise, the percentage loss of lung function after upper lobectomy (12% ± 16%) did not differ significantly from that after lower lobectomy (14% ± 17%, P = .6). CONCLUSIONS Although the lower lobectomy implies greater resection than the upper lobectomy, lung function after lower lobectomy was not inferior to that after upper lobectomy because the compensatory response appeared more robust after lower lobectomy.

Omitting chest tube drainage after thoracoscopic major lung resection

OBJECTIVES Absorbable mesh and fibrin glue applied to prevent alveolar air leakage contribute to reducing the length of chest tube drainage, length of hospitalization and the rate of pulmonary complications. This study investigated the feasibility of omitting chest tube drainage in selected patients undergoing thoracoscopic major lung resection. METHODS Intraoperative air leakages were sealed with fibrin glue and absorbable mesh in patients undergoing thoracoscopic major lung resection. The chest tube was removed just after tracheal extubation if no air leakages were detected in a suction-induced air leakage test, which is an original technique to confirm pneumostasis. Patients with bleeding tendency or extensive thoracic adhesions were excluded. RESULTS Chest tube drainage was omitted in 29 (58%) of 50 eligible patients and was used in 21 (42%) on the basis of suction-induced air leakage test results. Male gender and compromised pulmonary function were significantly associated with the failure to omit chest tube drainage (both, P < 0.05). Regardless of omitting the chest tube drainage, there were no adverse events during hospitalization, such as subcutaneous emphysema, pneumothorax, pleural effusion or haemothorax, requiring subsequent drainage. Furthermore, there was no prolonged air leakage in any patients: The mean length of chest tube drainage was only 0.9 days. Omitting the chest tube drainage was associated with reduced pain on the day of the operation (P = 0.046). CONCLUSIONS The refined strategy for pneumostasis allowed the omission of chest tube drainage in the majority of patients undergoing thoracoscopic major lung resection without increasing the risk of adverse events, which may contribute to a fast-track surgery.

Clinical Ramifications of Bronchial Kink After Upper Lobectomy

BACKGROUND Bronchial kink is caused by upward displacement of the remaining lower lobe of the lung after upper lobectomy, which can cause an intractable cough or shortness of breath. However, bronchial kink is often overlooked because of the difficulty in the simultaneous diagnosis of bronchial curvature and narrowing. METHODS Screening for bronchial kink with three-dimensional computed tomography (CT)-based bronchography was done on 50 patients who had undergone hemilateral upper lobectomy for cancer. Bronchial kink was confirmed if there was airway angulation and resultant stenosis exceeding 80%. We compared postoperative changes in spirometry-based ventilatory capacity with CT-based functional lung volume (FLV) in patients with and without bronchial kink. RESULTS Bronchial kink was confirmed in 21 patients (42%). Postoperative FLV and ventilatory capacity were significantly greater in patients without than in those with bronchial kink (p<0.05 for both measures). Postoperative FLV and ventilatory capacity were also significantly greater than the estimated postoperative values for both measures in patients without bronchial kink (both, p<0.05), representing favorable compensatory adaptation of the remaining lung, whereas this was not the case in patients with bronchial kink (both, p>0.1). Patients with bronchial kink complained more often than those without bronchial kink of an intractable cough and shortness of breath (76% vs 21%, respectively, p<0.01). CONCLUSIONS Bronchial kink after upper lobectomy is a common and functionally unfavorable condition that can exacerbate postoperative shortness of breath. Computed tomography-based bronchography is a useful tool in screening for bronchial kink. Strategies for preventing bronchial kink should be explored in the clinical setting.

Clinical application of an ultrasonic scalpel to divide pulmonary vessels based on laboratory evidence.

The Harmonic Ace ultrasonic scalpel (Ethicon Endo-Surgery, Inc, Cincinnati, Ohio), has been widely used in endoscopic surgery to divide systemic vessels, but not pulmonary vessels. We describe our initial clinical experience of using it for pulmonary vessel division. The Harmonic Ace was used to divide pulmonary vessels 5 mm or less in diameter, secured with a proximal single ligation, in 20 patients who underwent video-assisted major lung resection between September 2007 and April 2008. We also evaluated the sealing potential of this device in a pig model. We divided 43 pulmonary arteries and 13 pulmonary veins (PV) by the device. The diameter of the divided vessels ranged from 2 to 5 mm. Vascular sealing was successful in all except two early procedures: several subsegmental arteries were held at once, and vessels positioned near the distal end of the blade jaw bled intraoperatively. There was no postoperative bleeding. In the pig model, the bursting pressure of sealed pulmonary arteries (PA) was >75 mmHg. Pulmonary vessels can be safely divided using the Harmonic Ace with proximal single ligation unless multiple or large pulmonary vessels are held within the blade jaw.

Long-term pulmonary function after major lung resection

The function of the remaining lungs after major lung resection may be a determinant of the early postoperative outcome, as well as the late postoperative quality of life of the patient. Thus, extensive efforts have been made to accurately estimate the postoperative pulmonary function using a variety of methods: the segment counting method is utilized in patients without parenchymal diseases, while the functional lung imaging technique may be useful in patients with heterogeneous anatomical lung diseases. The postoperative pulmonary function is influenced not only by the extent of parenchymal resection, but also by various other factors, such as the site of resection, the mode of thoracotomy, the severity of pulmonary emphysema and/or the postoperative progression of pulmonary fibrosis. Although thoracoscopic surgery or segmental resection can lessen the extent of chest wall damage or the extent of parenchymal resection compared with conventional operations, the resulting functional benefits do not last. Interestingly, the postoperative pulmonary function continues to improve during the first postoperative year as if the remaining lungs grow, although the cause(s) of this compensatory response of the remaining lungs remains unclear. Such an ability of the remaining lung to compensate for the lost lung function may eventually determine the late postoperative pulmonary function.

Mesh-Based Pneumostasis Contributes to Preserving Gas Exchange Capacity and Promoting Rehabilitation After Lung Resection

BACKGROUND We recently introduced a technique of sutureless, mesh-based pneumostasis for preventing alveolar air leaks after lung resection. To verify the clinical usefulness of this technique, we examined if it can contribute to preserving gas exchange capacity and promoting postoperative rehabilitation. METHODS We prospectively collected perioperative data, including arterial oxygen saturation on postoperative day (POD) 1 and the length of postoperative rehabilitation in 100 patients undergoing elective, video-assisted major lung resection for cancer. Before April, 2006, intraoperative air leaks were sealed with the conventional method (control group), and thereafter, with bioabsorbable mesh and glue, without suturing, (treated group). To reduce the bias in comparison of the nonrandomized control group, we paired the treated group with the control group using the nearest available matching method on the estimated propensity score. RESULTS Thirty-five patients in the control group were matched to 35 patients in the treated group based on the estimated propensity score. The length of both chest tube drainage and postoperative rehabilitation were significantly shorter in the treated group than in the control group (median, 1 versus 1 d, P = 0.03; 2 versus 3 d, P = 0.01, respectively). The arterial oxygen saturation on POD 1 was significantly higher in the treated group than in the control group (median, 94.0 versus 92.5 %, P = 0.03). CONCLUSION Mesh-based pneumostasis during video-assisted major lung resection enabled early chest tube removal, preserved postoperative oxygenation capacity, and promoted postoperative rehabilitation, which may facilitate fast-track surgery for patients undergoing video-assisted major lung resection for cancer.

Assessment of volume reduction effect after lung lobectomy for cancer

BACKGROUND Lung lobectomy results in an unexpected improvement of the remaining lung function in some patients with moderate-to-severe emphysema. Because the lung function is the main limiting factor for therapeutic decision making in patients with lung cancer, it may be advantageous to identify patients who may benefit from the volume reduction effect, particularly those with a poor functional reserve. METHODS We measured the regional distribution of the emphysematous lung and normal lung using quantitative computed tomography in 84 patients undergoing lung lobectomy for cancer between January 2010 and December 2012. The volume reduction effect was diagnosed using a combination of radiologic and spirometric parameters. RESULTS Eight patients (10%) were favorably affected by the volume reduction effect. The forced expiratory volume in one second increased postoperatively in these eight patients, whereas the forced vital capacity was unchanged, thus resulting in an improvement of the airflow obstruction postoperatively. This improvement was not due to a compensatory expansion of the remaining lung but was associated with a relative decrease in the forced end-expiratory lung volume. According to a multivariate analysis, airflow obstruction and the forced end-expiratory lung volume were independent predictors of the volume reduction effect. CONCLUSIONS A combined assessment using spirometry and quantitative computed tomography helped to characterize the respiratory dynamics underlying the volume reduction effect, thus leading to the identification of novel predictors of a volume reduction effect after lobectomy for cancer. Verification of our results by a large-scale prospective study may help to extend the indications for lobectomy in patients with oncologically resectable lung cancer who have a marginal pulmonary function.

Similar radiopathological features, but different postoperative recurrence rates, between Stage I lung cancers arising in emphysematous lungs and those arising in nonemphysematous lungs

OBJECTIVES The aim of the present study was to clarify the differences between lung cancer arising in emphysematous lungs and that arising in nonemphysematous lungs with regard to radiopathological features and the postoperative recurrence rate. METHODS We retrospectively reviewed a prospective database of 212 patients who underwent major lung resection for clinically diagnosed Stage I primary lung cancer. Emphysematous lungs were identified on the basis of quantitative computed tomography (CT). The biological features of the primary tumour were diagnosed according to the presence or absence of a ground-glass component on high-resolution CT and the maximum standardized uptake value in [(18)F]-fluorodeoxyglucose positron emission tomography, in addition to conventional characteristic factors. RESULTS The risk factors for postoperative recurrence were underlying emphysema, a high maximum standardized uptake value, the absence of a ground-glass component, the pathological grade and lymph node metastasis, whereas the risk factors for lymph node metastasis were a high maximum standardized uptake value, the absence of a ground-glass component and the pathological grade. Surprisingly, these risk factors were entirely matched between patients with and without emphysematous lungs, regardless of the fact that patients with emphysematous lungs had a higher recurrence rate. CONCLUSIONS Similar clinicopathological features, but different postoperative recurrence rates, were found between Stage I lung cancers arising in emphysematous lungs and those arising in nonemphysematous lungs. It may be valuable to search for underlying molecular mechanisms that promote metastasis from primary tumours arising in emphysema, such as paracrine effects between the tumour and pulmonary emphysema.

Role of inhaled tiotropium on the perioperative outcomes of patients with lung cancer and chronic obstructive pulmonary disease.

BACKGROUND Tiotropium, a long-acting bronchodilator, can be used perioperatively in patients with lung cancer and airway obstruction, although its benefits for the perioperative outcome remain unclear. METHODS We prospectively collected the perioperative data of 44 patients with resectable lung cancer and untreated airway obstruction. Tiotropium was not used before September 2007 (control group, n = 24) but was used routinely thereafter (treated group, n = 20). We estimated a propensity score to adjust comparisons between the groups. RESULTS Tiotropium improved preoperative global pulmonary function significantly, especially in four patients. Postoperative outcomes in these major responders were significantly better than those in the remaining minor responders. However, postoperative outcomes were not significantly different between the treated group (n = 15) and the control group (n = 15) matched by a propensity score. CONCLUSION Regardless of its favorable effects on preoperative pulmonary function, we could not establish a significant benefit of tiotropium for postoperative outcomes overall. Nonetheless, our data suggested that tiotropium might have improved the postoperative outcomes of major responders.