Development of a Bronchoscopy-Radiologic Skills and Task Assessment Tool (BRadSTAT): A Tool for Evaluating the Radiological Skills of Bronchoscopists with Different Experience

BACKGROUND

Competency using radiologic images for bronchoscopic navigation is presumed during subspecialty training, but no assessments objectively measure combined knowledge of radiologic interpretation and ability to maneuver a bronchoscope into peripheral airways.

OBJECTIVES

The objectives of this study were (i) to determine whether the Bronchoscopy-Radiology Skills and Tasks Assessment Tool (BRadSTAT) discriminates between bronchoscopists of various levels of experience and (ii) to improve construct validity using study findings.

METHODS

BRadSTAT contains 10 questions that assess chest X-ray and CT scan interpretation using multiple images per question and 2 technical skill assessments. After administration to 33 bronchoscopists (5 Beginners, 9 Intermediates, 10 Experienced, and 9 Experts), discriminative power was strengthened using differential weighting on CT-related questions, producing the BRadSTAT-CT score. Cut points for both scores were determined via cross-validation.

RESULTS

Mean BRadSTAT scores for Beginner, Intermediate, Experienced, and Expert were 74 (±13 SD), 78 (±14), 86 (±9), and 88 (±8), respectively. Statistically significant differences were noted between Expert and Beginner, Expert and Intermediate, and Experienced and Beginner (all p ≤ 0.05). Mean BRadSTAT-CT scores for Beginner, Intermediate, Experienced, and Expert were 63 (±14), 74 (±15), 82 (±13), and 90 (±9), respectively, all statistically significant (p ≤ 0.03). Cut points for BRadSTAT-CT had lower sensitivity but greater specificity and accuracy than for BRadSTAT.

CONCLUSION

BRadSTAT represents the first validated assessment tool measuring knowledge and skills for bronchoscopic access to peripheral airways, which discriminates between bronchoscopists of various experience levels. Refining BRadSTAT produced the BRadSTAT-CT, which had higher discriminative power. Future studies should focus on their usefulness in competency-based bronchoscopy programs.

Bronchoscopy in Patients With Known or Suspected COVID-19: Results From the Global Pandemic SARS-CoV-2 Bronchoscopy Database (GPS-BD)

BACKGROUND

Amid the Coronavirus Disease 2019 (COVID-19) pandemic, the benefits and risks of bronchoscopy remain uncertain. This study was designed to characterize bronchoscopy-related practice patterns, diagnostic yields, and adverse events involving patients with known or suspected COVID-19.

METHODS

An online survey tool retrospectively queried bronchoscopists about their experiences with patients with known or suspected COVID-19 between March 20 and August 20, 2020. Collected data comprised the Global Pandemic SARS-CoV-2 Bronchoscopy Database (GPS-BD). All bronchoscopists and patients were anonymous with no direct investigator-to-respondent contact.

RESULTS

Bronchoscopy procedures involving 289 patients from 26 countries were analyzed. One-half of patients had known COVID-19. Most (82%) had at least 1 pre-existing comorbidity, 80% had at least 1 organ failure, 51% were critically ill, and 37% were intubated at the time of the procedure. Bronchoscopy was performed with diagnostic intent in 166 (57%) patients, yielding a diagnosis in 86 (52%). and management changes in 80 (48%). Bronchoscopy was performed with therapeutic intent in 71 (25%) patients, mostly for secretion clearance (87%). Complications attributed to bronchoscopy or significant clinical decline within 12 hours of the procedure occurred in 24 (8%) cases, with 1 death.

CONCLUSION

Results from this international database provide a widely generalizable characterization of the benefits and risks of bronchoscopy in patients with known or suspected COVID-19. Bronchoscopy in this setting has reasonable clinical benefit, with diagnosis and/or management change resulting from about half of the diagnostic cases. However, it is not without risk, especially in patients with limited physiological reserve.

Examining patients' preferences for participation in clinical decision-making: the experience in a Latin American chronic obstructive pulmonary disease and cancer outpatient population

BACKGROUND AND AIMS

It is generally accepted that patients prefer to be told the truth by their physicians; however, the practice of partial truth-telling is frequent with an existing 'norm of nondisclosure.' Our primary objective was to determine what patients wanted to be told about their illness, and whether there might be differences between patients with either cancer or advanced chronic obstructive pulmonary disease (COPD). A second objective was to determine how these patients envisioned their participation, or lack thereof, in the treatment decision-making process.

METHODS

Subjects were eligible for this prospective study if they were attending the oncology or pulmonary outpatient consultation services at the British Hospital or the Sanatorio Güemes Private Hospital in Buenos Aires, Argentina between June 2009 and May 2010.

RESULTS

Ninety-nine patients were recruited. Forty-four had a diagnosis of COPD, and 55 patients had cancer. Seventeen of the patients expected their health to improve in the future, but a significantly higher proportion of patients with malignant disorders expected to get better in the near future as compared with those with COPD (98.2% vs 62.8%, P < 0.001). Most study participants expressed a desire to receive all the information available about their condition. A majority of the participants expressed a preference for making treatment decisions in collaboration with their physician (40.4%)

CONCLUSIONS

While they considered the role of their families relevant and wanted information to be shared so that family members might participate in decision-making, they did not want their families to have a right to withhold information, make final decisions.

Role of the pulmonologist in ordering post-procedure molecular markers in non-small-cell lung cancer: implications for personalized medicine

In the growing era of personalized medicine for the treatment of non-small-cell lung cancer (NSCLC), it is becoming increasingly important that sufficient quality and quantity of tumor tissue are available for morphologic diagnosis and molecular analysis. As new treatment options emerge that might require more frequent and possibly higher volume biopsies, the role of the pulmonologist will expand, and it will be important for pulmonologists to work within a multidisciplinary team to provide optimal therapeutic management for patients with NSCLC. In this review, we discuss the rationale for individualized treatment decisions for patients with NSCLC, molecular pathways and specific molecular predictors relevant to personalized NSCLC therapy, assay technologies for molecular marker analysis, and specifics regarding tumor specimen selection, acquisition, and handling. Moreover, we briefly address issues regarding racial and socioeconomic disparities as they relate to molecular testing and treatment decisions, and cost considerations for molecular testing and targeted therapies in NSCLC. We also propose a model for an institution-based multidisciplinary team, including oncologists, pathologists, pulmonologists, interventional radiologists, and thoracic surgeons, to ensure adequate material is available for cytological and histological studies and to standardize methods of tumor specimen handling and processing in an effort to provide beneficial, individualized therapy for patients with NSCLC.

A new instrument to assess physician skill at thoracic ultrasound, including pleural effusion markup

BACKGROUND

To reduce complications and increase success, thoracic ultrasound is recommended to guide all chest drainage procedures. Despite this, no tools currently exist to assess proceduralist training or competence. This study aims to validate an instrument to assess physician skill at performing thoracic ultrasound, including effusion markup, and examine its validity.

METHODS

We developed an 11-domain, 100-point assessment sheet in line with British Thoracic Society guidelines: the Ultrasound-Guided Thoracentesis Skills and Tasks Assessment Test (UGSTAT). The test was used to assess 22 participants (eight novices, seven intermediates, seven advanced) on two occasions while performing thoracic ultrasound on a pleural effusion phantom. Each test was scored by two blinded expert examiners. Validity was examined by assessing the ability of the test to stratify participants according to expected skill level (analysis of variance) and demonstrating test-retest and intertester reproducibility by comparison of repeated scores (mean difference [95% CI] and paired t test) and the intraclass correlation coefficient.

RESULTS

Mean scores for the novice, intermediate, and advanced groups were 49.3, 73.0, and 91.5 respectively, which were all significantly different (P &lt; .0001). There were no significant differences between repeated scores.

CONCLUSIONS

Procedural training on mannequins prior to unsupervised performance on patients is rapidly becoming the standard in medical education. This study has validated the UGSTAT, which can now be used to determine the adequacy of thoracic ultrasound training prior to clinical practice. It is likely that its role could be extended to live patients, providing a way to document ongoing procedural competence.

Subjective assessment using still bronchoscopic images misclassifies airway narrowing in laryngotracheal stenosis

OBJECTIVES

Severity of airway narrowing is relevant to management decision-making processes in patients with laryngotracheal stenosis. Airway lumen is frequently assessed subjectively based on still images obtained during airway examinations or objectively using image analysis software applied to radiological or bronchoscopic images. The purpose of this study was to determine whether strictures classified as mild, moderate or severe degrees of airway narrowing based on subjective assessments by a group of experienced bronchoscopists using still images, matched the classifications derived from morphometric bronchoscopy measurements and whether the results of subjective assessments correlated with the level of bronchoscopic experience.

METHODS

Thirty-five bronchoscopic doublet still images of benign causes of laryngotracheal stenosis containing normal and abnormal airway cross-sectional areas were objectively analysed using morphometric bronchoscopy and classified as mild (<50%), moderate (50-70%) or severe (>70%). These images were then subjectively assessed by 42 experienced bronchoscopists participating in an interventional bronchoscopy course. Descriptive statistics were used to explore the accuracy of the participants' classifications. Correlation coefficients were used to study the relationship between participants' subjective assessments and bronchoscopy experience.

RESULTS

Only 47% of strictures were correctly classified by study participants (mean 16.48 ± 2.8). Of the 1447 responses included in this analysis, 755 were incorrect: 71 (9%) were over-classifications of strictures' severity and 684 (91%) were under-classifications. There was no correlation between number of strictures correctly classified and number of lifetime bronchoscopies or number of strictures seen by bronchoscopists in an average month.

CONCLUSIONS

Experienced bronchoscopists often misclassify the degree of airway narrowing when using still bronchoscopic images to subjectively assess strictures of benign aetiology.

Bronchoscopic intervention obviates the need for continued mechanical ventilation in patients with airway obstruction and respiratory failure from inoperable non-small-cell lung cancer

BACKGROUND

Patients with advanced non-small-cell lung cancer (NSCLC) and acute respiratory failure (ARF) from central airway obstruction (CAO) may be offered end-of-life care rather than intensive care treatment and palliative bronchoscopic intervention.

OBJECTIVES

To determine whether bronchoscopic intervention could be immediately successful in restoring airway patency and obviate the need for continued mechanical ventilation in a homogeneous group of inoperable mechanically ventilated patients with ARF and CAO from NSCLC.

METHODS

A retrospective study of 12 consecutive intubated and mechanically ventilated patients with inoperable or unresectable CAO from NSCLC referred for therapeutic bronchoscopic intervention between January 2003 and December 2008. Outcome measures included time-to-postintervention extubation and survival. Procedural success was defined as successful restoration of airway patency, extubation and removal from mechanical ventilation within 24 h after bronchoscopic intervention.

RESULTS

Twelve intubated and mechanically ventilated patients were admitted to the ICU during the 6-year study period. Airway patency was restored in 11/12 (91%) patients. Bronchoscopic intervention resulted in immediate extubation and discontinuation of mechanical ventilation in 9/12 (75%) patients. Overall median survival was 228 days (range 6-927). For the 9 patients extubated within 24 h after intervention, however, median survival was 313 days (range 6-927).

CONCLUSIONS

Intubated patients with respiratory failure caused by CAO from NSCLC can be successfully and rapidly removed from mechanical ventilation after bronchoscopic interventions aimed at restoring airway patency. Median survival greater than 10 months justifies ICU hospitalization and referral for bronchoscopic treatment.

Rigid bronchoscopy for malignant central airway obstruction from small cell lung cancer complicated by SVC syndrome

Central airway obstruction (CAO) and superior vena cava (SVC) syndrome are potentially life-threatening complications in locally advanced lung cancer. Therapeutic rigid bronchoscopy has become an critical component in the treatment of the lung cancer patients with CAO who are not surgical candidates. However, the technique may pose significant risks in patients with coexisting SVC syndrome, especially, and even more so perhaps in patients over the age of eighty. In this case report, we address the potential risks and known benefits of therapeutic bronchoscopic intervention in an 85-year-old man with small cell lung cancer who presented with acute dyspnea secondary to advanced SVC syndrome and CAO involving the lower trachea and right main bronchus. Emergent therapeutic rigid bronchoscopy resulted in a marked improvement, in dyspnea, atelectasis, and postobstructive pneumonia, allowing rapid administration of systemic chemotherapy.

[Humanitarian ethics and the concept of justice]

The bases of humanitarian assistance, beyond a legal norm--which appears to be essential given the inalienable obligations that result for all participating bodies--are influenced by philosophical and political conceptualizations framed in an ethics of justice. Actors in the humanitarian field who adhere to the Rawlsian social contract model their actions based on a philosophy that assistance is a noble and desirable option that remains in the hands of those who offer aid, and who can freely choose to not offer such assistance. Peter Singer and Thomas Pogge propose nuances to the understanding of the duty of assistance. Not assisting would be bad, basically tantamount to killing. Assistance is no longer a caring act deserving of praise, but rather a moral obligation. The financial imperatives of associations, the growing complexity of activities and the development of an important element of communication lead to a professionalization of humanitarian medicine. A modern vision of humanitarian assistance requires an understanding of justice and solidarity and global outreach. We believe that ethics need to be embedded firmly in humanitarian actions that have clear political implications.

In vivo three-dimensional imaging of normal tissue and tumors in the rabbit pleural cavity using endoscopic swept source optical coherence tomography with thoracoscopic guidance

The purpose of this study was to develop a dynamic tunable focal distance graded-refractive-index lens rod-based high-speed 3-D swept-source (SS) optical coherence tomography (OCT) endoscopic system and demonstrate real-time in vivo, high-resolution (10-microm) imaging of pleural-based malignancies in an animal model. The GRIN lens-based 3-D SS OCT system, which images at 39 fps with 512 A-lines per frame, was able to capture images of and detect abnormalities during thoracoscopy in the thoracic cavity, including the pleura, chest wall, pericardium, and the lungs. The abnormalities were confirmed by histological evaluation and compared to OCT findings. The dynamic tunable focal distance range and rapid speed of the probe and SS prototype OCT system enabled this first-reported application of in vivo 3-D thoracoscopic imaging of pleural-based malignancies. The imaging probe of the system was found to be easily adaptable to various sites within the thoracic cavity and can be readily adapted to other sites, including rigid airway endoscopic examinations.

Multimodality bronchoscopic [corrected] imaging of tracheopathica osteochondroplastica

Results of a commercial optical coherence tomography system used as part of a multimodality diagnostic bronchoscopy platform are presented for a 61-year-old patient with central airway obstruction from tracheopathica osteochondroplastica. Comparison to results of white-light bronchoscopy, histology, and endobronchial ultrasound examination are accompanied by a discussion of resolution, penetration depth, contrast, and field of view of these imaging modalities. White-light bronchoscopy revealed irregularly shaped, firm submucosal nodules along cartilaginous structures of the anterior and lateral walls of the trachea, sparing the muscular posterior membrane. Endobronchial ultrasound showed a hyperechoic density of 0.4 cm thickness. optical coherence tomography (OCT) was performed using a commercially available, compact time-domain OCT system (Niris System, Imalux Corp., Cleveland, Ohio) with a magnetically actuating probe (two-dimensional, front imaging, and inside actuation). Images showed epithelium, upper submucosa, and osseous submucosal nodule layers corresponding with histopathology. To our knowledge, this is the first time these commercially available systems are used as part of a multimodality bronchoscopy platform to study diagnostic imaging of a benign disease causing central airway obstruction. Further studies are needed to optimize these systems for pulmonary applications and to determine how new-generation imaging modalities will be integrated into a multimodality bronchoscopy platform.

Development of a rabbit pleural cancer model by using VX2 tumors

Primary and secondary pleural cancer remains an important clinical problem, with research progress limited by the lack of a suitable moderate- to large-sized (3 to 4 kg) animal model of pleural cancer. Many potential pleura-based imaging and treatment modalities cannot be investigated sufficiently by using currently available small murine animal models because their pleural space is not comparable to that of humans and therefore does not allow for the use of standard thoracoscopic techniques. Here we describe the development of a reproducible model of pleural malignancy in moderate-sized immunocompetent rabbits. Under thoracoscopic guidance, 9-15 x 10(6) VX2 carcinoma cells were inoculated into the plural space of 3 to 4 kg New Zealand white rabbits that had undergone gentle pleural abrasion. Malignant tumor involvement developed on the visceral and parietal pleural surfaces in an average of 2 to 4 wk. This novel pleural tumor model induction method likely will facilitate a broad range of investigations of pleural cancer diagnostics and therapeutics.

[Autonomy and practical identity. Cornerstones to ethical physician behavior]

Three frequent problems of daily medical practice are analyzed: (1) a physician's perceived obligation to provide medical services regardless of whether one's health care institution provides monetary compensation for the medical act, (2) increasing pressures to obtain informed consent in a national context where paternalistic physician-patient interactions have been customary, and (3) a physician's professional responsibility to offer internationally recognized standard of care even if this means allocating expensive tertiary healthcare resources to a small number of patients in spite of one's knowledge that national governments are unable to provide primary care to millions of their citizens. These problems are discussed from the point of view of the ethical principle of respect for patient autonomy. Potential limiting factors (cultural, financial, religious or disease-related influences) on autonomy of patients and doctors are identified. The functions of patient autonomy in the framework of four different patient-doctor interaction models (paternalist, informative, interpretative and deliberatibe) are described. Physician leaders, health care institutions, and professional organizations are responsible for creating an environment in which doctors can discuss ethical issues as comfortably and as frequently as they discuss biological matters. Health care providers should do their best to recover the human side of medical practice which, undoubtedly, would create a greater likelihood that appropriate decisions will be made when facing complex ethical dilemmas.

Evaluation of Tracheal Imaging by Optical Coherence Tomography

BACKGROUND

Optical coherence tomography (OCT) is a new technology capable of generating high resolution cross-sectional images of complex tissue in real time. Analogous to ultrasound, OCT measures backscattered light intensity using coherence interferometery to construct topographical images of complex tissue. Since OCT uses infrared light rather than acoustic waves, its spatial resolution is exceptionally high (2-10 microm). Recent advances in data acquisition, analysis, and processing enable real-time imaging, and make OCT a potentially valuable tool for pulmonary airway diagnostic applications, including assisting directed airway biopsies.

OBJECTIVE

This study evaluates feasibility of OCT for delineating proximal airway microstructures in various animal as well as human tracheas.

METHODS

Excised trachea samples from New Zealand white rabbits, Duroc pigs, and human trachea were imaged using a compact, 1,300-nm broad-band superluminescent-diode-based prototype fiber OCT device we constructed. The resulting structural OCT images were compared to conventional hematoxilin and eosin (HE) stained histological sections from the same samples.

RESULTS

OCT was able to delineate microstructures such as the epithelium, mucosa, cartilage, and glands in all samples.

CONCLUSION

These findings suggest that integration of OCT with flexible fiberoptic bronchoscopy could enhance pulmonary diagnostic medicine and detection of pathologic tissue changes in various respiratory diseases.

Two-dimensional and 3-dimensional optical coherence tomographic imaging of the airway, lung, and pleura

BACKGROUND

Methods for obtaining real-time in vivo histologic resolution by means of noninvasive endoscopic optical imaging would be a major advance for thoracic surgical diagnostics and treatment. Optical coherence tomography is a rapidly evolving technology based on near-infrared interferometry that might provide these capabilities. The purpose of this study is to investigate the feasibility of real-time 2- and 3-dimensional optical coherence tomographic imaging of airway, pleural, and subpleural lung tissues in normal, inflammatory, and malignant animal models and patients with known or suspected airway malignancy.

METHODS

Freshly excised lungs and pleural tissue obtained from rabbits with inhalation lung injury and induced empyema, metastatic sarcomas, and pleural sarcomas and from patients with airway disease were imaged by using 2- and 3-dimensional optical coherence tomography with a prototype superluminescent diode optical coherence tomographic system constructed in our laboratory. Lungs and pleural tissue were subsequently processed for standard hematoxylin and eosin histology for comparison with optical coherence tomography.

RESULTS

Optical coherence tomographic imaging achieved an ex vivo resolution of 10 microm and an in vivo resolution of about 30 microm with a depth penetration of 1 to 2 mm with 2- and 3- dimensional reconstruction capabilities. Tumors as small as 500 microm were detectable with optical coherence tomography. The acquired images closely matched histologic images, demonstrating details at the level of mucosal layers, glands, alveoli, and respiratory bronchioles.

CONCLUSIONS

Optical coherence tomography with near-infrared interferometric methods enables near real-time in vivo near-histologic resolution optical imaging. With further advances, optical coherence tomography has the potential for real-time accurate and early pleural and subpleural diagnostics by using small-diameter flexible fiberoptic endoscopic probes for a wide range of thoracic surgical applications.

Intrapleural Staphylococcal Superantigen Induces Resolution of Malignant Pleural Effusions and a Survival Benefit in Non-Small Cell Lung Cancer

BACKGROUND

Malignant pleural effusion (MPE) may occur in up to 50% of patients with non-small cell lung cancer (NSCLC). The majority of these patients have a poor performance status and a dismal prognosis, with survival duration ranging from 2 to 3 months. Since these patients are typically symptomatic from their MPE, prompt treatment is required. Patients with symptomatic MPE from NSCLC and poor performance scores (Eastern Cooperative Oncology Group [ECOG] score >/= 2, Karnofsky performance status [KPS] score < 50) are generally not offered systemic chemotherapy. Treatment is palliative and includes intrapleural catheter drainage or chemical pleurodesis with talc, doxycycline, or bleomycin. None of the latter modalities prolong survival.

OBJECTIVE

Our goal was to investigate the toxicity and therapeutic effect of a new therapeutic agent, Staphylococcus aureus superantigen (SSAg), a powerful T-cell stimulant administered intrapleurally to unselected, consecutive patients with MPE from NSCLC (stage IIIb with pleural effusion) and a poor performance status. By providing direct access of the SSAg to the bronchial and mediastinal lymphatics, we predicted that intrapleural administration of SSAg would induce resolution of MPE and prolong survival in this population with advanced NSCLC and a limited prognosis.

METHODS

Fourteen consecutive, unselected patients with MPE from NSCLC and a median pretreatment KPS score of 40 (range, 10 to 60) received pleural instillation of SSAg, 100 to 400 pg, once or twice weekly (mean, 3.7 +/- 1.3 treatments [+/- SD]) until the pleural effusions resolved. They were evaluated for drug toxicity, resolution, duration of MPE, and survival.

RESULTS

Other than mild fever (maximum grade 2), toxicity of SSAg treatment was trivial and notably devoid of respiratory distress or hypotension. Eleven patients had a complete response (CR), and 3 patients had a partial response of their MPE. In 12 patients, the response endured for > 90 days, with a median time to recurrence of 5 months (range, 3 to 23 months). The median survival for the SSAg-treated group was 7.9 months (range, 2 to 36 months; 95% confidence interval [CI], 5.9 to 11.4 months), compared to a median survival of 2.5 months (range, 0.1 to 57 months; 95% CI, 1.3 to 3.4 months) for 18 consecutive, unselected patients with MPE from NSCLC (stage IIIb) treated with talc poudrage (p = 0.044). Survival duration of all 14 SSAg-treated cases and 13 talc-poudrage-treated patients with comparable pretreatment KPS (range, 10 to 60; median, 40 and 30, respectively), and distribution (p = 0.5) was 7.9 months (95% CI, 5.9 to 11.4 months) and 2.0 months (95% CI, 0.4 to 2.9 months), respectively (p = 0.0023). Nine of 14 patients treated with SSAg survived > 6 months, 4 patients survived > 9 months, and 3 patients survived > 350 days. One of the patients in the CR group has survived 36 months. None of the 13 talc-treated patients survived > 6 months.

INTERPRETATION

In 14 unselected, consecutive patients with MPE from NSCLC and poor pretreatment performance (median KPS of 40), the intrapleural administration of SSAg was efficacious in resolving the MPE without any clinically important adverse effects. SSAg-treated patients with a median KPS of 40 (range, 10 to 60) had a median survival that exceeded that with talc poudrage, and was comparable to current systemic chemotherapy used in patients with KPS >/= 70 status. SSAg treatment is simple to perform, minimally invasive, and does not require hospital time. It may be an attractive alternative to existing palliative modalities for stage IIIb patients with MPE and poor performance who are not candidates for systemic chemotherapy.

Innovative approaches to lung volume reduction for emphysema

The 10 years of resurgent interest in lung volume reduction surgery (LVRS) and recent National Emphysema Treatment Trial findings for emphysema have stimulated a range of innovative alternative ideas aimed at improving outcomes and reducing complications associated with current LVRS techniques. Concepts being actively investigated at this time include surgical resection with compression/banding devices, endobronchial blockers, sealants, obstructing devices and valves, and bronchial bypass methods. These novel approaches are reaching the stage of clinical trials at this time. Theory, design issues, methods, potential advantages and limitations, and available results are presented. Extensive research in the near future will help to determine the potential clinical applicability of these new approaches to the treatment of emphysema symptoms.

A pilot study of expiratory flow limitation and lung volume reduction surgery

STUDY OBJECTIVES

To examine the relationships between changes in expiratory flow limitation (FL) during anesthesia and postoperative responses to lung volume reduction surgery (LVRS).

DESIGN

Prospective consecutive case comparison.

SETTING

University medical center.

PATIENTS

Eight patients with severe emphysema.

INTERVENTIONS

General anesthesia with muscle paralysis and thoracic epidural analgesia were provided for LVRS via median sternotomy.

MEASUREMENTS

FEV(1), functional residual capacity (FRC), and total lung capacity (TLC) were measured preoperatively and 3 months postoperatively. Tidal volume (VT) flow/volume (F/V) curves were obtained with a Pitot-type spirometer. VT, expiratory flow rate at 0. 25 x VT (V'VT,25% ), and peak expiratory flow rate (V'VT,MAX) were obtained from VT F/V curves to derive V'VT,25%/V'VT,MAX ratio as a measure of FL.

RESULTS

Closed chest VT F/V curves during anesthesia pre-LVRS showed four patients with FL (group A) whose V'VT,25%/V'VT, MAX ratio was 0.38 +/- 0.06 (mean +/- SD) and four patients without FL (group B) whose V'VT,25%/V'VT,MAX ratio was 0.82 +/- 0.06 (p = 0. 0001). Closed chest post-LVRS V'VT,25%/V'VT,MAX ratio during anesthesia increased by 0.48 +/- 0.08 in group A, compared with a 0. 19 +/- 0.16 reduction in group B (p = 0.0001). Preoperative FEV(1) was 0.57 +/- 0.10 L for group A vs 0.82 +/- 0.13 L for group B (p = 0.02). Postoperative FEV(1) increased by 67 +/- 40% for group A (p = 0.03) vs 29 +/- 21% for group B (not significant). FRC decreased by 33 +/- 3% for group A vs 17 +/- 5% for group B (p = 0.0007), and FRC/TLC decreased by 0.14 +/- 0.05 for group A vs 0.01 +/- 0.07 for group B (p = 0.026). Post-LVRS V'VT,25%/V'VT,MAX ratio change during anesthesia correlated with postoperative reduction in FRC (r(2) = 0. 89, p = 0.0004) and FRC/TLC (r(2) = 0.52, p = 0.045).

CONCLUSION

Post-LVRS change in V'VT,25%/V'VT,MAX ratio during anesthesia showed a linear relationship with 3-month postoperative improvement in dynamic hyperinflation. Thus, V'VT,25%/V'VT,MAX ratio may help provide valuable insights into the interactions between chest wall recoil, dynamic hyperinflation, and VT flow rates in patients with severe COPD and LVRS.

A patient-like human malignant pleural mesothelioma nude-mouse model

Human malignant pleural mesothelioma is an aggressive cancer with no effective treatment. A relevant animal model is required to study the biology and to develop effective treatment. To meet this need we have developed an orthotopic transplant model for malignant mesothelioma in nude mice. Fresh specimens derived from four patients with malignant mesothelioma were implanted on the parietal pleura of nude mice. All xenografted tumors gave rise to locally growing tumors in the mice. The transplanted mice presented with symptoms of malignancy such as decrease in physical activity and signs of tumor-related respiratory distress. These animals were shown to have extensive tumor spread in the ipsilateral and contralateral pleural cavity as well as mediastinal lymph nodes. When the lesions were confined to the ipsilateral parietal pleura, the implanted animals were in good physical condition. The macroscopic features usually found in the patients were also found in the implanted animals such as nodules, masses and pleural thickness. Histologic examination revealed malignant mesothelioma similar to that from which the original tumor specimen was derived. Orthotopic parietal-pleura implantation of fresh histological human malignant mesothelioma thus allows mesothelioma growth in an animal model that mimics the clinical spread of the human disease. This model provides for the first time a useful human model for biological studies of this disease and for developing effective treatment.