Predictors of alveolar air leaks

A nomogram for preoperative prediction of prolonged air leak after pulmonary malignancy resection

Background

Prolonged air leak (PAL) is one of the most common postoperative complications after lung surgery. This study aimed to identify risk factors of PAL after lung resection and develop a preoperative predictive model to estimate its risk for individual patients.

Methods

Patients with pulmonary malignancies or metastasis who underwent pulmonary resection between January 2014 and January 2018 were included. PAL was defined as an air leak more than 5 days after surgery, risk factors were analyzed. Forward stepwise multivariable logistic regression analysis was performed to identify independent risk factors, and a derived nomogram was built. Data from February 2018 to September 2018 were collected for internal validation.

Results

A total of 1,511 patients who met study criteria were enrolled in this study. The overall incidence of PAL was 9.07% (137/1,511). Age, percent forced expiratory volume in 1 second, surgical type, surgical approach and smoking history were included in the final model. A nomogram was developed according to the multivariable logistic regression results. The C-index of the predictive model was 0.70, and the internal validation value was 0.77. The goodness-of-fit test was non-significant for model development and internal validation.

Conclusions

The predictive model and derived nomogram achieved satisfied preoperative prediction of PAL. Using this nomogram, the risk for an individual patient can be estimated, and preventive measures can be applied to high-risk patients.

Effect of Lowest Postoperative Pre-albumin on Outcomes after Robotic-Assisted Pulmonary Lobectomy

Objective:

Lower pre-albumin levels have been associated with increased rates of post-surgical complications, prolonged hospital length of stay (LOS), and death. This study aims to investigate the effect of postoperative pre-albumin levels on perioperative and long-term outcomes following robotic-assisted video thoracoscopic (RAVT) pulmonary lobectomy.

Methods:

We retrospectively reviewed 459 consecutive patients who underwent RAVT pulmonary lobectomy by one surgeon for known or suspected lung cancer. The lowest pre-albumin values during the postoperative hospital stay were recorded. Twenty-three patients with no pre-albumin levels available were excluded from analysis. Patients were grouped as having normal (≥ 15 mg/dL) versus low (< 15mg/dL) pre-albumin. Outcomes and demographics were compared between groups using Pearson χ², Student’s t, or Kruskal-Wallis tests. Univariate and multivariate generalized linear regression, logistic regression, or Cox proportional hazard ratio models were used to assess the association between outcomes and variables of interest. Kaplan-Meier analyses were performed to estimate and depict survival probabilities for each group.

Results:

Our study population comprised 436 patients. Lowest postoperative pre-albumin below 15 mg/dL was associated with more postoperative complications (44.2% vs 24.9%, p < 0.001), longer chest tube duration (6.9 vs 4.6 days, p = 0.001), and longer LOS (7.0 vs. 4.4 days, p < 0.001). In survival analysis, lowest perioperative pre-albumin levels were found to correlate with decreased 1 year (p = 0.012), 3-year (p = 0.001), and 5-year survival (p = 0.001).

Conclusion:

Lower pre-albumin levels postoperatively are associated with more postoperative complications, longer chest tube duration and LOS, and decreased overall survival following robotic-assisted pulmonary lobectomy.

[Establishment of A Clinical Prediction Model of Prolonged Air Leak after Anatomic Lung Resection]

背景与目的

解剖性肺切除术后持续漏气（prolonged air leak, PAL）是胸外科常见并发症，重在准确预测及时预防，但目前国内尚缺少有效的预测模型，本研究旨在建立解剖性肺切除术后PAL临床预测模型。

方法

回顾分析2016年1月-2016年10月安徽医科大学附属省立医院胸外科解剖性肺切除术患者的临床资料和术后漏气情况，其中A组病例359例，通过对患者的年龄（岁）、性别、身体质量指数（body mass index, BMI）、吸烟史、肺功能指数、手术方式（开放或腔镜，肺段、肺叶或其他，如支气管袖式或血管袖式）、手术切除肺叶位置、肺部病灶性质和胸腔粘连情况进行单因素及多因素分析，寻找解剖性肺切除术后PAL的独立预测因子，并建立临床预测模型。随后利用不同时期、不同治疗组完成的112例解剖肺切除患者作为B组，用于验证本模型的诊断效能，并绘制受试者工作特征（receiver operating characteristic curve, ROC）曲线。

结果

多因素Logistic回归分析筛选出BMI、性别、吸烟史、第一秒用力肺活量占用力肺活量的百分比（forced expiratory volume in one second, FEV₁%）、胸腔粘连及是否上叶切除为解剖性肺切除患者术后PAL的独立预测因子。利用筛选出的预测因子建立的诊断模型ROC曲线下面积为0.886（95%CI: 0.835-0.937），最佳临界值P=0.299，对应的诊断敏感性为78.5%，特异性为93.2%。

结论

本研究建立的预测模型能较准确的预测解剖性肺切除术后PAL的发生，对及时有效预防PAL发生有指导作用。

Enhanced recovery after surgery and video-assisted thoracic surgery lobectomy: the Italian VATS Group surgical protocol

Enhanced recovery after surgery (ERAS^®) is a strategy that seeks to reduce patients' perioperative stress response, thereby reducing potential complications, decreasing hospital length of stay and enabling patients to return more quickly to their baseline functional status. The concept was introduced in the late 1990s and was first adopted in patients undergoing open colorectal surgery. Since then, the concept of ERAS has been adopted by multiple surgical specialties. The diffusion of video-assisted thoracic surgery lobectomy (VATS-L) sets also the surgical treatment of lung cancer as a new area for ERAS development. In this paper, we present the Italian VATS Group (www.vatsgroup.org) surgical protocol as part of the ERAS clinical pathway belonging to the VATS-L national database.

Bio-artificial pleura using an autologous dermal fibroblast sheet

Air leaks (ALs) are observed after pulmonary resections, and without proper treatment, can produce severe complications. AL prevention is a critical objective for managing patients after pulmonary resection. This study applied autologous dermal fibroblast sheets (DFS) to close ALs. For sealing ALs in a 44-year-old male human patient with multiple bullae, a 5 × 15-mm section of skin was surgically excised. From this skin specimen, primary dermal fibroblasts were isolated and cultured for 4 weeks to produce DFSs that were harvested after a 10-day culture. ALs were completely sealed using surgical placement of these autologous DFSs. DFS were found to be a durable long-term AL sealant, exhibiting requisite flexibility, elasticity, durability, biocompatibility, and usability, resulting reliable AL closure. DFS should prove to be an extremely useful tissue-engineered pleura substitute.

Quantative computerized tomography assessment of lung density as a predictor of postoperative pulmonary morbidity in patients with lung cancer

BACKGROUND

The aim of this study was to evaluate the pulmonary reserve of the patients via preoperative quantitative computerized tomography (CT) and to determine if these preoperative quantitative measurements could predict the postoperative pulmonary morbidity.

METHODS

Fifty patients with lung cancer who underwent lobectomy/segmentectomy were included in the study. Preoperative quantitative CT scans and pulmonary function tests data were evaluated retrospectively. We compare these measurements with postoperative morbidity.

RESULTS

There were 32 males and 18 females with a mean age of 54.4±13.9 years. Mean total density was -790.6±73.4 HU. The volume of emphysematous lung was (<-900 HU) 885.2±1,378.4 cm(3). Forced expiratory volume in one second (FEV1) (r=-0.494, P=0.02) and diffusion capacity of carbon monoxide (DLCO) (r=-0.643, P<0.001) were found to be correlate with the volume of emphysematous lung. Furthermore FEV1 (r=0.59, P<0.001) and DLCO (r=0.48, P<0.001) were also found to be correlate with mean lung density. Postoperative pulmonary morbidity was significantly higher in patients with lower lung density (P<0.001), larger volume of emphysema (P<0.001) and lower DLCO (P=0.039). A cut-off point of -787.5 HU for lung density showed 86.96% sensitivity and 81.48% specificity for predicting the pulmonary morbidity (kappa =-0.68, P<0.001). Additionally a cut-off point of 5.41% for emphysematous volume showed 84.00% sensitivity and 80.00% specificity for predicting the pulmonary morbidity (kappa =0.64, P<0.001). According to logistic regression analyses emphysematous volume >5.41% (P=0.014) and lung density <-787.5 HU (P=0.009) were independent prognostic factors associated with postoperative pulmonary morbidity.

CONCLUSIONS

In this study, the patients with a lower lung density than -787.5 HU and a higher volume of emphysema than 5.41% were found to be at increased risk for developing postoperative pulmonary morbidity. More stringent precautions should be taken in those patients that were found to be at high risk to avoid pulmonary complications.

Preoperative computed tomography of the chest in lung cancer patients: the predictive value of calcified lymph nodes for the perioperative outcomes of video-assisted thoracoscopic surgery lobectomy

OBJECTIVES

To determine the predictive value of identifying calcified lymph nodes (LNs) for the perioperative outcomes of video-assisted thoracoscopic surgery (VATS).

METHODS

Fifty-six consecutive patients who underwent VATS lobectomy for lung cancer were included. We evaluated the number and location of calcified LNs on computed tomography (CT). We investigated clinical parameters, including percentage forced expiratory volume in 1 s (FEV1%), surgery duration, chest tube indwelling duration, and length of hospital stay. We performed linear regression analysis and multiple comparisons of perioperative outcomes.

RESULTS

Mean number of calcified LNs per patient was 0.9 (range, 0-6), mostly located in the hilar-interlobar zone (43.8 %). For surgery duration (mean, 5.0 h), FEV1% and emphysema severity were independent predictors (P = 0.010 and 0.003, respectively). The number of calcified LNs was an independent predictor for chest tube indwelling duration (P = 0.030) and length of hospital stay (P = 0.046). Mean duration of chest tube indwelling and hospital stay was 8.8 days and 12.7 days in no calcified LN group; 9.2 and 13.2 in 1 calcified LN group; 12.8 and 19.7 in ≥2 calcified LNs group, respectively.

CONCLUSIONS

The presence of calcified LNs on CT can help predict more complicated perioperative course following VATS lobectomy.

Reverse airflow in certain chest drains may be misinterpreted as prolonged air leakage

BACKGROUND

Prolonged air leakage is common after lung resection. We observed that during deep inspiration some patients were able to empty the water-seal of commercial chest drainage systems and retract air back into the chest tube, which subsequently escaped during the following expiration, mimicking "true" air leakage. This led us to perform in vitro and in vivo pressure measurements in chest tube systems and investigate possible relationships with "false" air.

METHODS

Commercially available one- and three-chamber drainage systems were used as models for large and small water-seals, respectively. Digital pressure measurements were performed in vitro and in ten selected patients with clinical suspicion of reverse airflow.

RESULTS

Repeated measurements in the laboratory demonstrated that in three-chamber chest drainage systems with small water-seals a negative pressure below -30.4 cmH(2)O led to emptying of the water-seal with retrograde flow of air. Retrograde airflow was not possible in one-chamber chest drainage systems. In vivo measurements demonstrated that six of ten highly selected patients were able to create negative pressures below -30.4 cmH(2)O during deep inspiration.

CONCLUSION

During deep inspiration some patients are able to create negative pressure large enough to empty small water-seals in commercial chest drainage systems and retract air back into the chest tube. This excess air escapes during the following expiration and may mislead interpretation of continued air leakage even when there is none, subsequently resulting in prolonged and unnecessary chest tube drainage. Any surgeon who treats patients with chest tubes should be aware of this phenomenon.

Results of a prospective algorithm to remove chest tubes after pulmonary resection with high output

OBJECTIVE

Many patients have their hospital discharge delayed because their chest tube drainage is too high, despite the fact that there are no data to support the commonly used 250 mL/day threshold.

METHODS

A retrospective cohort study was conducted with a prospective database and prospective algorithm from one surgeon. All patients underwent elective pulmonary resection. The last chest tube was removed if there was no air leak and nonchylous drainage of 450 mL/day or less.

RESULTS

The study comprised 8608 operations and 2077 patients who underwent an elective (nonpneumonectomy) pulmonary resection via thoracotomy by one general thoracic surgeon over a 10-year period. Eighty-nine patients went home with a chest tube owing to air leak. The remaining 1988 patients were discharged without a chest tube. Types of pulmonary resection were wedge resection in 729 patients, segmentectomy in 214, lobectomy in 1104, and bilobectomy in 30. The median day of discharge was postoperative day 4. One hundred one (5%) were readmitted to the hospital within 60 days of discharge. The most common reason for readmission was dehydration and fatigue. Only 11 (0.55%) had readmissions owing to recurrent symptomatic effusion and most were treated with video-assisted thoracoscopy. Follow-up was 100% at 4 weeks and 93% at 8 weeks.

CONCLUSIONS

Chest tubes can be removed with up to 450 mL/day of nonchylous drainage after pulmonary resection, and perhaps a higher volume could be accepted. Readmission owing to a recurrent effusion is exceedingly uncommon, and the practice of leaving the tube in longer for drainage less than 450 mL/day is unsupported in the literature.

Dynamic sealing of lung air leaks by the transplantation of tissue engineered cell sheets

Current methods including the use of various biological and synthetic sealants are ineffective in the closure of intraoperative air leaks that often occur during cardiothoracic surgeries, resulting in a decreased quality of life for patients. We present the development of a novel lung air leak sealant using tissue engineered cell sheets. In contrast to previous materials such as fibrin glue, these bioengineered cell sheets immediately and permanently seal air leaks in a dynamic fashion that allows for the extensive tissue contraction and expansion involved in respiration, without any postoperative recurrences. Additionally, we demonstrate that mesothelial cells migrate to cover the transplanted cells sheets, thereby confirming excellent biocompatibility and integration with the host tissues. Finally, we present the use of skin fibroblasts as an effective and readily available autologous cell source that can be easily applied. This study shows for the first time, the development of an immediate and permanent lung air leak sealant, suitable for future clinical applications.

The physiotherapy management of patients undergoing thoracic surgery: a survey of current practice in Australia and New Zealand

BACKGROUND AND PURPOSE

Physiotherapy is considered an essential component of the management of patients after thoracotomy, yet the type of interventions utilized, and evidence for their efficacy, has not been established. The aim of the present study was to ascertain the current physiotherapy management of patients undergoing thoracotomy and the factors influencing practice among different providers.

METHOD

A purpose-designed postal questionnaire was distributed to senior physiotherapists in all thoracic surgical units throughout Australia and New Zealand (n=57).

RESULTS

A response rate of 81% was obtained (n=46). Pre-operatively, 16 respondents (35%) reported assessing all thoracotomy patients. The majority of respondents (n=44; 96%) indicated that all patients were seen by physiotherapists after surgery, with 29 respondents (63%) performing prophylactic physiotherapy interventions to prevent post-operative pulmonary complications. Respondents reported that physiotherapy treatment was usually commenced on day one post-operatively (n=37; 80%) with the most commonly used treatment interventions being deep breathing exercises, the active cycle of breathing techniques, cough, forced expiration techniques and sustained maximal inspirations. Most respondents reported that patients first sat out of bed (n=41; 89%), commenced shoulder range of movement (n=23; 50%) and walking (n=32; 70%) on day one post-operatively. The majority of respondents reported that they offered no post-operative pulmonary rehabilitation (n=25; 54%), outpatient follow-up (n=43; 94%) orpost-thoracotomy pain management (n=40; 87%). Respondents indicated that personal experience, literature recommendations and established practice were the factors which most influenced physiotherapy practice. Conclusion. Most patients after thoracotomy receive physiotherapy assessment and/or treatment in the immediate post-operative period, but only one-third were routinely seen pre-operatively and relatively few were reviewed following discharge from hospital. Further studies are required to guide physiotherapists in determining the efficacy of their practices for patients undergoing thoracotomy.

Mechanical ventilation and air leaks after lung biopsy for acute respiratory distress syndrome

BACKGROUND

Open lung biopsy in acute respiratory distress syndrome (ARDS) may provide a specific etiology and change clinical management, yet concerns about complications remain. Persistent air leak is the most common postoperative complication. Risk factors in this setting are not known.

METHODS

We performed a retrospective analysis of 53 patients who underwent open lung biopsy for clinical ARDS (based on American European Consensus Conference criteria) between 1989 and 2000.

RESULTS

Sixteen patients (30.2%) developed an air leak lasting more than 7 days or died with an air leak. Univariate analyses showed no significant correlation with age, gender, sex, corticosteroid use, diabetes, immunocompromised status, or pathologic diagnosis. A lower risk of air leak was associated with lower peak airway pressure and tidal volume, use of pressure-cycled ventilation, and use of an endoscopic stapling device. In multivariate analyses, only peak airway pressure remained a significant predictor. The risk of prolonged air leak was reduced by 42% (95% confidence interval [CI: 17% to 60%]) for every 5 cm H2O reduction in peak airway pressure.

CONCLUSIONS

The use of a lung-protective ventilatory strategy that limits peak airway pressures is strongly associated with a reduced risk of postoperative air leak after open lung biopsy in ARDS. Using such a strategy may allow physicians to obtain information from open lung biopsy to make therapeutic decisions without undue harm to ARDS patients.

Functional assessment of a new staple line reinforcement in lung resection

BACKGROUND

A major complication of lung resection is prolonged leaking at the staple line. Staple-line reinforcement is performed routinely during these procedures using bovine pericardium (peri-strips) and expanded polytetrafluorethylene. Both materials have been shown previously to increase staple-line durability and reduce the overall incidence of prolonged air leaking after lung resection, specifically in lung volume-reduction surgery. Small intestinal submucosa (SIS) has had many applications in human tissues consequent to its absorption and healing profile, which are well documented in human and animal models. However, it had not been studied in reinforcement of pulmonary staple lines.

MATERIALS AND METHODS

We hypothesized that SIS reinforcement of staple lines in healthy lung tissue would increase durability, as determined by leak rates at increased airway pressures as compared to nonreinforced staple lines. Eight healthy juvenile Yorkshire-cross pigs were subjected to bilateral apical lung resections; one side was reinforced with SIS. The lungs were then inflated to sequentially increase intrabronchial pressures (5-75 cm H2O) for 60-second intervals while the chest was filled with saline under direct visualization monitoring for air leak.

RESULTS

Staple lines reinforced with porcine small intestinal submucosa had significantly better durability as determined by Kaplan-Meier survival calculations with respect to leak rate as a function of pressure.

CONCLUSION

Reinforcement of staple lines with SIS allows pulmonary staple lines to tolerate significantly higher intrabronchial pressures without demonstrating air leak at the staple line.

Lung Resection in Patients With Preoperative FEV 1 < 35% Predicted

OBJECTIVES

To determine the morbidity, mortality, and feasibility of lung resection in patients with tumors and preoperative FEV1 < 35% predicted.

DESIGN

Retrospective review.

SETTING

A 734-bed, tertiary care, academic hospital with a dedicated general thoracic surgery unit performing > 2,000 operations per year.

PATIENTS

One hundred consecutive patients with discrete lung tumors and with preoperative FEV1 < 35% predicted undergoing lung resection between September 1997 and May 2003. Only operations with curative intent were included. Average preoperative predicted FEV1 was 26%. Sixteen percent of the patients were oxygen dependent prior to the operation.

RESULTS

Open and thoracoscopic wedge resections, segmentectomies, lobectomies, and combined lung resections with lung volume reduction were performed. Sixty-six of the lesions were malignant, and 57 were primary lung cancers. Only one patient left the operating room with positive margins. There was one in-hospital or 30-day mortality. Thirty-six percent of the patients had one or more complications. Twenty-two percent of the patients had prolonged air leaks requiring a chest tube for > 7 days. One patient left the hospital ventilator dependent, 3 additional patients required intubation > 48 h, and 11 patients were discharged with a new oxygen requirement. There were four pneumonias, one myocardial infarction, and two reoperations for bleeding. Male gender (p = 0.003), preoperative oxygen dependence (p = 0.03), and pack-year history (p = 0.006) were associated with a higher overall incidence of complications, while age, incision, diabetes, coronary artery disease, duration of smoking cessation, amount of lung resected, size of lesion, and preoperative percentage of predicted FEV1 did not correlate with the overall incidence of complications.

CONCLUSIONS

In a large academic center, minimally invasive surgical techniques, intensive pulmonary care, and advanced anesthetic techniques allow for curative lung tumor resections in patients with very low preoperative FEV1 with a very low mortality and very low incidence of ventilator dependence. Other serious complications such as pneumonia, myocardial infarction, and bleeding are uncommon. An extended hospital stay and a high incidence of prolonged air leak should be expected, especially in patients with preoperative FEV1 < or = 20% predicted.

Characterization and Importance of Air Leak After Lobectomy

BACKGROUND

Air leak after pulmonary resection is a common occurrence that is incompletely characterized. Our objectives were to determine prevalence of air leak and identify its risk factors, characterize its duration and discover its correlates, and evaluate its clinical importance.

METHODS

Air leak was studied in 319 patients undergoing isolated anatomic lobectomy between January 1998 and July 2001. Risk factors for air leak were identified by logistic regression of patient characteristics, indications for lobectomy, lobe resected, and fissure management. Factors associated with air leak duration were sought by time-related analysis. Association of complications with air leak was evaluated by propensity-matched pairs analysis.

RESULTS

Prevalence: Air leak prevalence was 58% (186 patients). It occurred less frequently after left lower lobectomy (p < 0.0001) and later in the series (p = 0.008). It was surgeon dependent (p = 0.007) but not associated with forced expiratory volume in 1 second.

DURATION

The 10th, 50th, and 90th percentiles of air leak duration were 1.6, 3, and 7 days, respectively. No factors, including fissure management, were reliably associated with air leak duration.

IMPORTANCE

Air leak was associated with more complications (30% vs 18%, p = 0.07) and protracted hospital course (p = 0.02).

CONCLUSIONS

Postoperative air leak is a common occurrence after lobectomy, but fortunately it is self-limiting in most patients. Air leak is independently associated with longer hospital stay and other postoperative complications. Surgical technique is important and may be the only modifiable factor.

Centromere DNA, proteins and kinetochore assembly in vertebrate cells

The centromere is a specialized region of the chromosome that is essential for faithful chromosome segregation during mitosis and meiosis in eukaryotic cells. It is the site at which the kinetochore, the functional nucleoprotein complex responsible for microtubule binding and chromosome movement, is assembled through complex molecular mechanisms. Herein, I review recent advances in our understanding of centromeric DNAs as sites for kinetochore assembly and the mechanisms underlying kinetochore assembly in vertebrate cells.