Pressure-Dependent Pneumothorax and Air Leak: Physiology and Clinical Implications.

Pressure-dependent pneumothorax is a common clinical event, often occurring after pleural drainage in patients with visceral pleural restriction, partial lung resection, or lobar atelectasis from bronchoscopic lung volume reduction or an endobronchial obstruction. This type of pneumothorax and air leak is clinically inconsequential. Failure to appreciate the benign nature of such air leaks may result in unnecessary pleural procedures or prolonged hospital stay. This review suggests that identification of pressure-dependent pneumothorax is clinically important because the air leak that results is not related to a lung injury that requires repair but rather to a physiological consequence of a pressure gradient. A pressure-dependent pneumothorax occurs during pleural drainage in patients with lung-thoracic cavity shape/size mismatch. It is caused by an air leak related to a pressure gradient between the subpleural lung parenchyma and the pleural space. Pressure-dependent pneumothorax and air leak do not need any further pleural interventions.

Association between Drainage-Dependent Prolonged Air Leak after Partial Lung Resection and Clinical Outcomes: A Prospective Cohort Study.

Rationale: Prolonged air leak (PAL) after partial lung resection can occur owing to surgical complications or in the presence of residual thoracic space. The former type results in drainage-independent PAL (DIPAL), whereas the latter type results in drainage-dependent PAL (DDPAL). DDPAL is described after thoracentesis in patients with nonexpandable lung, where the thoracostomy tube can be discontinued safely despite an ongoing air leak. This distinction is clinically relevant, as in the presence of DDPAL, tube thoracostomy can be safely discontinued without the need for further interventions. Objectives: To determine the frequency and clinical relevance of DDAPL and DIPAL in patients with PAL after partial lung resection. Methods: We prospectively identified consecutive patients with PAL after partial lung resection. Pleural manometry was performed 3-5 days after surgery. Pleural pressure was measured for 20 minutes after clamping the thoracostomy tube. DDPAL was diagnosed if the end-expiratory pleural pressure remained stable after plateauing in the absence of respiratory symptoms. Results: Of 225 patients who underwent lung resection, we identified 22 (10%) who had PAL. Twenty patients had adequate pleural manometry readings. The majority, 16/20 (80%), had DDPAL and had lower median hospital length of stay than those with DIPAL (6.9 vs. 11 days; P = 0.02). All patients with DIPAL required reexploration surgery, whereas only one patient with DDPAL underwent reexploration surgery. Conclusions: Most PALs after partial lung resection are DDPAL. Patients with DDPAL have lower hospital length of stay and less need for reexploration surgery than those with DIPAL.

The Relationship of Pleural Manometry With Postthoracentesis Chest Radiographic Findings in Malignant Pleural Effusion.

BACKGROUND: Both elevated pleural elastance (E-PEL) and radiographic evidence of incomplete lung expansion following thoracentesis have been used to exclude patients with a malignant pleural effusion (MPE) from undergoing pleurodesis. This article reports on a cohort of patients with MPE in whom complete drainage was attempted with pleural manometry to determine the frequency of E-PEL and its relation with postthoracentesis radiographic findings. METHODS: Seventy consecutive patients with MPE who underwent therapeutic pleural drainage with pleural manometry were identified. The pressure/volume curves were constructed and analyzed to determine the frequency of E-PEL and the relation of PEL to the postthoracentesis chest radiographic findings. RESULTS: E-PEL and incomplete lung expansion were identified in 36 of 70 (51.4%) and 38 of 70 (54%) patients, respectively. Patients with normal PEL had an OR of 6.3 of having complete lung expansion compared with those with E-PEL (P = .0006). However, 20 of 70 (29%) patients exhibited discordance between postprocedural chest radiographic findings and the pleural manometry results. Among patients who achieved complete lung expansion on the postdrainage chest radiograph, 9 of 32 (28%) had an E-PEL. In addition, PEL was normal in 11 of 38 (34%) patients who had incomplete lung expansion as detected according to the postthoracentesis chest radiograph. CONCLUSIONS: E-PEL and incomplete lung expansion postthoracentesis are frequently observed in patients with MPE. Nearly one-third of the cohort exhibited discordance between the postprocedural chest radiographic findings and pleural manometry results. These findings suggest that a prospective randomized trial should be performed to compare both modalities (chest radiograph and pleural manometry) in predicting pleurodesis outcome.

Defining a Ventilation Strategy for Flexible Bronchoscopy on Mechanically Ventilated Patients in the Medical Intensive Care Unit.

BACKGROUND: Flexible bronchoscopy (FB) in intubated patients on mechanical ventilation increases airway resistance. During FB, two ventilatory strategies are possible: maintaining tidal volume (VT) while maintaining baseline CO2 or allowing reduction of VT. The former strategy carries risk of hyperinflation due to expiratory flow limitation with FB. The aim of the authors was too study end expiratory lung volume (EELV) during FB of intubated subjects while limiting VT. METHODS: We studied 16 subjects who were intubated on mechanical ventilation and required FB. Changes in EELV were measured by respiratory inductance plethysmography. Ventilator mechanics, EELV, and arterial blood gases, were measured. RESULTS: FB insertions decreased EELV in 64% of cases (-325±371 mL) and increased it in 32% of cases (65±59 mL). Suctioning decreased EELV in 76% of cases (-120±104 mL) and increased it in 16% of cases (29±33 mL). Respiratory mechanics were unchanged. Pre-FB and post-FB, PaO2 decreased by 61±96 mm Hg and PaCO2 increased by 15±7 mm Hg. CONCLUSIONS: There was no clinically significant increase in EELV in any subject during FB. Decreases in EELV coincided with FB-suctioning maneuvers. Peak pressure limiting ventilation protected the subject against hyperinflation with a consequent, well-tolerated reduction in VT, and hypercapnea. Suctioning should be limited, especially in patients vulnerable to derecruitment effect.

Management of Prolonged Pulmonary Air Leaks With Endobronchial Valve Placement.

BACKGROUND: Prolonged pulmonary air leaks (PALs) are associated with increased morbidity and extended hospital stay. We sought to investigate the role of bronchoscopic placement of 1-way valves in treating this condition. METHODS: We queried a prospectively maintained database of patients with PAL lasting more than 7 days at a tertiary medical center. Main outcome measures included duration of chest tube placement and hospital stay before and after valve deployment. RESULTS: Sixteen patients were eligible to be enrolled from September 2012 through December 2014. One patient refused to give consent, and in 4 patients, the source of air leak could not be identified with bronchoscopic balloon occlusion. Eleven patients (9 men; mean age, 65 ± 15 years) underwent bronchoscopic valve deployment. Eight patients had postoperative PAL and 3 had a secondary spontaneous pneumothorax. The mean duration of air leak before valve deployment was 16 ± 12 days, and the mean number of implanted valves was 1.9 (median, 2). Mean duration of hospital stay before and after valve deployment was 18 and 9 days, respectively (P = .03). Patients who had more than a 50% decrease in air leak on digital monitoring had the thoracostomy tube removed within 3-6 days. There were no procedural complications related to deployment or removal of the valves. CONCLUSIONS: Bronchoscopic placement of 1-way valves is a safe procedure that could help manage patients with prolonged PAL. A prospective randomized trial with cost-efficiency analysis is necessary to better define the role of this bronchoscopic intervention and demonstrate its effect on air leak duration.

Pleural Fluid Analysis in Chronic Hemothorax: A Mimicker of Infection.

OBJECTIVES: Timing to video-assisted thoracoscopic surgery (VATS) in hemothorax is based on preventing acute and long-term complications of retained blood products in the pleural space, including pleural space infection. We propose that the persistence of blood in the pleural space induces a proinflammatory state, independent of active infection. METHODS: We identified six patients with a hemothorax by clinical history, radiographic imaging, and pleural fluid analysis from a database of 1133 patients undergoing thoracentesis from 2002 to 2010 at the Medical University of South Carolina. RESULTS: In four of the six patients identified, the time from injury to thoracentesis was one, four, four, and five days, respectively. The fluid pH range was 7.32-7.41. The lactate dehydrogenase (LDH) range was 210-884 IU/L (mean 547 IU/L), and the absolute neutrophil count (ANC) range was 1196-3631 cells/µL. In two patients, the time from injury to thoracentesis was 7 and 60 days. In these two patients, the pH was 7.18 and 6.91, LDH was 1679 and 961 IU/L, and the ANC was 8134 and 5943 cells/µL. Microbiology and pathology were negative in all patients. CONCLUSIONS: The persistence of blood outside the vascular compartment, and within the pleural space, biochemically mirrors infection. We will explore the multiple mechanisms that account for development of pleural fluid acidosis, inflammation, and neutrophil recruitment.

Intrapleural therapy.

Numerous intrapleural therapies have been adopted to treat a vast array of pleural diseases. The first intrapleural therapies proposed focused on the use of fibrinolytics and DNase to promote fluid drainage in empyema. Numerous case series and five randomized controlled trials have been published to determine the outcomes of fibrinolytics in empyema treatment. In the largest randomized trial, the use of streptokinase had no reduction in mortality, decortication rates or hospital days compared with placebo in the treatment of empyema. Criticism over study design and patient selection may have potentially affected the outcomes in this study. The development of dyspnoea is common in the setting of malignant pleural effusions. Pleural fluid evacuation followed by pleurodesis is often attempted. Numerous sclerosing agents have been studied, with talc emerging as the most effective agent. Small particle size of talc should be avoided because of increased systemic absorption potentiating toxicity, such as acute lung injury. Over the past several years, the use of chronic indwelling pleural catheters have emerged as the preferred modality in the treating a symptomatic malignant pleural effusion. For patients with malignant-related lung entrapment, pleurodesis often fails due to the presence of visceral pleural restriction; however, chronic indwelling pleural catheters are effective in palliation of dyspnoea. Finally, the use of staphylococcal superantigens has been proposed as a therapeutic model for the treatment of non-small lung cancer. Intrapleural instillation of staphylococcal superantigens increased median survival by 5 months in patients with non-small cell lung cancer with a malignant pleural effusion.

The unexpandable lung.

Unexpandable lung is the inability of the lung to expand to the chest wall allowing for normal visceral and parietal pleural apposition. It is the direct result of either pleural disease, endobronchial obstruction resulting in lobar collapse, or chronic atelectasis. Unexpandable lung occurring as a consequence of active or remote pleural disease may present as a post-thoracentesis hydropneumothorax or an effusion that cannot be completely drained because of the development of anterior chest pain. Pleural manometry is useful for identifying unexpandable lung during initial pleural drainage. Unexpandable lung occurring as a consequence of active or remote pleural disease may be separated into two distinct clinical entities termed trapped lung and lung entrapment. Trapped lung is a diagnosis proper and is caused by the formation of a fibrous visceral pleural peel (in the absence of malignancy or active pleural inflammation). The mechanical effect of the pleural peel constitutes the primary clinical problem. Lung entrapment may result from a visceral pleural peel secondary to active pleural inflammation, infection, or malignancy. In these cases, the underlying malignant or inflammatory condition is the primary clinical problem, which may or may not be complicated by unexpandable lung due to visceral pleural involvement. The recognition of trapped lung and lung entrapment as related, but distinct, clinical entities has direct consequences on clinical management. In our practice, pleural manometry is routinely performed during therapeutic thoracentesis and is useful for identification of unexpandable lung and has allowed us to understand the mechanisms surrounding a post-thoracentesis pneumothorax.

Management of pleural effusion in the cancer patient.

The differential diagnosis of a pleural effusion is expanded in the cancer patient. A cancer patient may have a malignant pleural effusion, a pleural effusion indirectly caused by the cancer or its treatment, or a pleural effusion unrelated to the cancer. The approach to the cancer patient with a pleural effusion must take into account the impact of the pleural effusion on quality of life, type and stage of the underlying cancer, impact of biopsy procedures on cancer staging, availability of treatment of the underlying cancer, performance status, and patient preferences. Minimally invasive palliative treatment options for the management of symptomatic malignant pleural effusion, such as chronic indwelling pleural catheters, have not only changed the treatment of the effusion but also require a reassessment of what constitutes an adequate diagnostic evaluation prior to considering such treatment options. Of particular concern to the clinician is the cytologically negative exudative pleural effusion for which a cause could not be established after the initial diagnostic evaluation. The decision to proceed to more invasive diagnostic testing must be individualized and the clinician must consider the limitations of histopathological examination of tissue obtained by invasive procedures.

Dasatinib-induced pleural effusions: a lymphatic network disorder?

Dasatanib, which has been approved for rescue therapy for patients with imatinib-resistant chronic myelogenous leukemia and Philadelphia chromosome positive acute lymphoblastic leukemia, is a novel, orally available multitargeted kinase inhibitor of BCR-ABL and SRC family kinases (Quintas-Cardama et al, J Clin Oncol 2007;25:3908-14). It binds to both active and inactive conformations of the ABL gene and is 325 times more potent than imatinib in inhibiting the growth of BCR/ABL cells in vitro (Morelock and Sahn, Chest 1999;116:212-21; Huggins and Sahn, Clin Chest Med 2004;25:141-53). Although dasatinib is a generally well-tolerated drug in the treatment of Philadelphia chromosome positive hematopoetic malignancies, pleural effusions have been frequently noted and have been reported in up to 35% of patients (Sahn SA. Drug-induced pleural disease. In: Camus P, Rosenow E, editors. Drug-induced iatrogenic lung disease. London: Hodder Arnold; 2009). Although there have been numerous reports of effusions, none have provided complete pleural fluid analysis; therefore, we report 2 patients with dasatinib-induced pleural effusion with complete pleural fluid analysis.

Clinical implications of unexpandable lung due to pleural disease.

Unexpandable lung due to pleural disease may manifest itself as a hydropneumothorax after pleural drainage procedure or as an inability to completely drain a pleural effusion due to chest pain. The condition is a mechanical complication of a variety of pleural disorders. Of these, malignant lung entrapment and inflammatory lung entrapment are considered complications of active pleural disease, and management is primarily dependent on the nature of the active process. Trapped lung is a sequela of remote inflammation of the pleural space. Trapped lung is usually asymptomatic but may be the cause of dyspnea in some patients. The only available treatment of symptomatic trapped lung is surgical decortication. Surgical decortication should only be considered after other causes of dyspnea have been excluded.

Real-time endobronchial ultrasound-guided transbronchial lymph node aspiration.

BACKGROUND: Accurate staging of lung cancer requires noninvasive and pathologic examination of intrathoracic lymphadenopathy, which determines both the treatment options and prognosis. The gold standard for mediastinal staging has been mediastinoscopy. Other options include video-assisted thoracoscopic surgery, blind transbronchial needle aspiration, and endoscopic ultrasound-guided fine-needle aspiration. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has recently been introduced. Here we report the use of EBUS-TBNA as a diagnostic modality for mediastinal adenopathy and staging modality for lung cancer. METHODS: This was a retrospective analysis of 152 consecutive patients who underwent EBUS-TBNA with undiagnosed intrathoracic adenopathy or cancer staging as the primary indications. The procedures occurred between January 2005 and June 2006 at a single academic medical center. Of the 152 patients, 117 were included in the final statistical analysis after excluding those with benign disease diagnosed by EBUS-TBNA. Rapid on-site cytopathologic examination was used in all cases. RESULTS: Malignancy was identified in 113 patients, of which 67 (59.3%) had non-small cell lung carcinoma, and 20 (17.7%) underwent surgical resection. Four patients had benign diagnoses at surgical pathology. Only 1 surgical patient was found to have nodal metastasis at a lymph node station previously biopsied by EBUS-TBNA (negative predictive value, 97%). Compared with radiologic staging, EBUS-TBNA down-staged 18 of 113 (15.9%) and up-staged 11 (9.7%). Sensitivity was 98.7%, with 100% specificity. No major complications were associated with the procedure. CONCLUSIONS: EBUS-TBNA is useful in accessing mediastinal and hilar lymph nodes for the diagnosis and staging of non-small cell lung cancer and other disorders of the mediastinum. Thoracic surgeons and pulmonologists are well positioned to use this tool in everyday practice.

Endobronchial ultrasound for the diagnosis of pulmonary sarcoidosis.

BACKGROUND: The diagnosis of pulmonary sarcoidosis can be established by a variety of techniques. Transbronchial lung biopsy is often the preferred approach, but it is frequently nondiagnostic and carries a risk of pneumothorax and bleeding. Mediastinoscopy is often suggested as the next diagnostic step but entails significant cost and associated morbidity. Endobronchial ultrasound (EBUS) with transbronchial needle aspiration (TBNA) is emerging as a safe, minimally invasive tool for the primary diagnosis of mediastinal and hilar lymphadenopathy. The purpose of this study was to assess the utility of EBUS-TBNA for pulmonary sarcoidosis. METHODS: Fifty consecutive patients who had been referred for EBUS-TBNA for suspected pulmonary sarcoidosis were included in the study. On-site cytology was used to assess the adequacy of the samples. The presence of noncaseating granulomas without necrosis in the appropriate clinical setting was deemed to be adequate for the diagnosis of pulmonary sarcoidosis. Patients with a negative EBUS-TBNA underwent further histologic biopsy or clinical follow-up to determine the final diagnosis. RESULTS: Eighty-two lymph nodes with a median size of 16 mm (range, 4 to 40 mm) were punctured. EBUS-TBNA demonstrated noncaseating granulomas without necrosis in 41 of 48 patients (85%) with a final diagnosis of sarcoidosis. EBUS-TBNA, therefore, has a sensitivity of 85% for the primary diagnosis of pulmonary sarcoidosis. CONCLUSIONS: EBUS-TBNA is a safe, minimally invasive tool for the primary diagnosis of pulmonary sarcoidosis that has a high diagnostic yield. EBUS-TBNA should be considered an appropriate alternative diagnostic technique for patients with suspected pulmonary sarcoidosis.

Seat belt-induced chylothorax: a cause of idiopathic chylothorax?

Chylothoraces are associated with multiple etiologies including non-Hodgkin lymphoma and surgical trauma, representing 50% and 25% of all chylothoraces, respectively. Intrathoracic operations such as repair of coarctation of the aorta and esophagectomy are commonly associated with surgical trauma. Idiopathic chylothoraces may account for up to 15% of all chylothoraces. When a thorough evaluation finding is negative, further history to identify possible blunt, nonpenetrating trauma to the chest is warranted.

Characteristics of trapped lung: pleural fluid analysis, manometry, and air-contrast chest CT.

STUDY OBJECTIVES: To review the pleural fluid characteristics, pleural manometry, and radiographic data of patients who received a diagnosis of trapped lung in our pleural diseases service. DESIGN: Retrospective case series. METHODS: The procedure records of 247 consecutive patients who underwent pleural manometry at the Medical University of South Carolina between October 2002 and November 2005 were reviewed. Eleven patients in whom a diagnostic pneumothorax was introduced were identified. Manometry data, radiographic findings, pleural fluid analysis, final clinical diagnosis, and information regarding the initial pleural insult were retrieved from the medical record. RESULTS: All 11 patients had a clinical diagnosis of trapped lung. The causes of trapped lung were attributed to coronary artery bypass graft surgery, uremia, thoracic radiation, pericardiotomy, spontaneous bacterial pleuritis and repeated thoracentesis, and complicated parapneumonic effusion. Mean pleural fluid pH was 7.30, pleural fluid lactate dehydrogenase (LDH) was 124 IU/L, and pleural fluid total protein was 2.9 g/dL. Pleural fluid was paucicellular with mononuclear cell predominance. Pleural space elastance was increased in all cases and ranged from 19 to 149 cm H(2)O/L of pleural fluid removed. All demonstrated abnormal visceral pleural thickness on air-contrast chest CT. CONCLUSIONS: Trapped lung is a clinical entity characterized by the presence of a restrictive visceral pleural peel that was first described in 1967. The pleural fluid is paucicellular, LDH is low, and protein may be in the exudative range. The elevated total pleural fluid protein may be related to factors other than active pleural inflammation or malignancy and does not exclude the diagnosis.

Effect of thoracentesis on respiratory mechanics and gas exchange in the patient receiving mechanical ventilation.

BACKGROUND: This study reports the effect of thoracentesis on respiratory mechanics and gas exchange in patients receiving mechanical ventilation. STUDY DESIGN: Prospective. SETTING: University hospital. PATIENTS: Eight patient receiving mechanical ventilation with unilateral (n = 7) or bilateral (n = 1) large pleural effusions. INTERVENTION: Therapeutic thoracentesis (n = 9). MEASUREMENTS: Resistances of the respiratory system measured with the constant inspiratory flow interrupter method measuring peak pressure and plateau pressure, effective static compliance of the respiratory system (Cst,rs), work performed by the ventilator (Wv), arterial blood gases, mixed exhaled Pco2, and pleural liquid pressure (Pliq). RESULTS: Thoracentesis resulted in a significant decrease in Wv and Pliq. Thoracentesis had no significant effect on dynamic compliance of the respiratory system; Cst,rs; effective interrupter resistance of the respiratory system, or its subcomponents, ohmic resistance of the respiratory system and additional (non-ohmic) resistance of the respiratory system; or intrinsic positive end-expiratory pressure (PEEPi). Indices of gas exchange were not significantly changed by thoracentesis. CONCLUSIONS: Thoracentesis in patients receiving mechanical ventilatory support results in significant reductions of Pliq and Wv. These changes were not accompanied by significant changes of resistance or compliance or by significant changes in gas exchange immediately after thoracentesis. The reduction of Wv after thoracentesis in patients receiving mechanical ventilation is not accompanied by predictable changes in inspiratory resistance and static compliance measured with routine clinical methods. The benefit of thoracentesis may be most pronounced in patients with high levels of PEEPi.