Positive End-Expiratory Pressure, Pleural Pressure, and Regional Compliance during Pronation: An Experimental Study.

Rationale: The physiological basis of lung protection and the impact of positive end-expiratory pressure (PEEP) during pronation in acute respiratory distress syndrome are not fully elucidated. Objectives: To compare pleural pressure (Ppl) gradient, ventilation distribution, and regional compliance between dependent and nondependent lungs, and investigate the effect of PEEP during supination and pronation. Methods: We used a two-hit model of lung injury (saline lavage and high-volume ventilation) in 14 mechanically ventilated pigs and studied supine and prone positions. Global and regional lung mechanics including Ppl and distribution of ventilation (electrical impedance tomography) were analyzed across PEEP steps from 20 to 3 cm H2O. Two pigs underwent computed tomography scans: tidal recruitment and hyperinflation were calculated. Measurements and Main Results: Pronation improved oxygenation, increased Ppl, thus decreasing transpulmonary pressure for any PEEP, and reduced the dorsal-ventral pleural pressure gradient at PEEP < 10 cm H2O. The distribution of ventilation was homogenized between dependent and nondependent while prone and was less dependent on the PEEP level than while supine. The highest regional compliance was achieved at different PEEP levels in dependent and nondependent regions in supine position (15 and 8 cm H2O), but for similar values in prone position (13 and 12 cm H2O). Tidal recruitment was more evenly distributed (dependent and nondependent), hyperinflation lower, and lungs cephalocaudally longer in the prone position. Conclusions: In this lung injury model, pronation reduces the vertical pleural pressure gradient and homogenizes regional ventilation and compliance between the dependent and nondependent regions. Homogenization is much less dependent on the PEEP level in prone than in supine positon.

Pleural Pressure Differences Before Removal Are Greater in Patients Who Develop Residual Pneumothorax Post Chest Drain Removal.

Aim of study: We aimed to investigate whether the difference in pleural pressures (ΔP) is wider among patients who develop a residual pneumothorax after chest tube removal following lung resection surgery. Materials and methods: Ninety-eight patients who underwent lung resection were included in the study over a period of 12 months. The ΔP prior to chest tube removal in patients who developed a residual pneumothorax after chest tube removal was compared with that of patients who did not develop this complication. The receiver operating characteristic (ROC) curve analysis was performed to identify cutoff values of ΔP for the prediction of residual pneumothorax. Logistic regression analysis was used to formulate a prediction model for the occurrence of residual pneumothorax based on ΔP. Results: Thirteen patients who developed a residual pneumothorax were compared with 85 patients without this complication. The ΔP in the residual pneumothorax group was significantly higher (10.8 versus 4.2 cm H2O, p < 0.01). The ΔP in patients who required intervention was also significantly higher (14.8 versus 4.2 cm H2O, p < 0.01). A ΔP cutoff value of 8 cm H2O was predictive of the occurrence of residual pneumothorax (sensitivity 85.6%, specificity 84.6%) and a value of 12 cm H2O was predictive of intervention (sensitivity 84%, specificity 85%). Increasing ΔP was an independent predictor of the occurrence of residual pneumothorax (p = 0.008) on the multivariate logistic regression model. Conclusion: Patients with wide ΔP before chest drain removal may be complicated with residual pneumothorax.

[Risk factors for aerostasis failure in case of lung resection].

The results of risk factors analysis of aerostasis failure in 141 patients are presented in the article. All patients were operated in the A.V. Vishnevskogo Institute of Surgery at the period from January 2009 to December 2010. During statistical analysis it was considered surgeries volume, presence of emphysema, respiratory function etc. Also it was defined the dependence of venting duration in patients with residual pleural cavity and long aerostasis failure.

Anatomy and pathophysiology of the pleura and pleural space.

Pleural effusions are most often secondary to an underlying condition and may be the first sign of the underlying pathologic condition. The balance between the hydrostatic and oncotic forces dictates pleural fluid homeostasis. The parietal pleura has a more significant role in pleural fluid homeostasis. Its vessels are closer to the pleural space compared with its visceral counterpart; it contains lymphatic stomata, absent on visceral pleura, which are responsible for a bulk clearance of fluid. The diagnosis and successful treatment of pleural effusions requires a mixture of imaging techniques and pleural fluid analysis.

The values of intrapleural pressure before the removal of chest tube in non-complicated pulmonary lobectomies.

OBJECTIVES: Digitalized chest drainage systems allow for quantification of air leak and measurement of intrapleural pressure. Little is known about the value of intrapleural pressure during the postoperative phase and its role in the recovering process after pulmonary resection. The objective of this investigation was to measure the values of pleural pressure immediately before the removal of chest tube after different types of pulmonary lobectomy. METHODS: Prospective observational analysis on 203 consecutive patients submitted to pulmonary lobectomy during a 12-month period at two centres. Multiple measurements were recorded in the last hour before the removal of chest tube and averaged for the analysis. All patients were seated in bed in a 45° up-right position or in a chair, had a single chest tube and were not connected to suction during the evaluation period. Analysis of variance (ANOVA) was used to assess the differences in pleural pressure between different types of lobectomies. RESULTS: The average maximum, minimum and differential pressures were -6.1, -19.5 and 13.3 cmH(2)O, respectively. The average pressures were similar in all types of lobectomies (ANOVA, P = 0.2) and ranged from -11 to -13 cmH(2)O, with the exception of right upper bilobectomy (-20 cmH(2)O, all P-values vs. other types of lobectomies <0.05). Similar values were also recorded for maximum pressures (range -4.4 to -8.4 cmH(2)O) and minimum pressures (-31.6 cmH(2)O vs. ranged from -15.4 to -20.5 cmH(2)O, all P-values <0.01). The average pleural pressure was not associated with FEV1 (P = 0.9), DLCO (P = 0.2) or FEV1/FVC ratio (P = 0.6), when tested with linear regression. Similarly, the average pleural pressure was similar in patients with and without COPD (-12.1 vs. -13.0 cmH(2)O, P = 0.4). The ANOVA test was used to assess differences in pressures between different lobectomies. CONCLUSIONS: The so-called water seal status may actually correspond to intrapleural pressures ranging from -13 to -20 cmH(2)O. Modern electronic chest drainage devices allow a stable control of the intrapleural pressure. Thus, the values found in this study may be used as target pressures for different types of lobectomies, in order to favour lung recovery after surgery.

[Causes and results of repeated videothoracoscopy].

For 7 years videothoracoscopies for diseases and traumas of the chest were fulfilled in 2075 patients, abscessoscopy in 27 patients. Repeated videothoracoscopies were fulfilled in 41 (2%) patients operated for spontaneous pneumothorax, pleural empyema, exudative pleurisy and injuries to the chest due to recurrent hydropneumothorasx, prolonged abundant release by drainage, bleedings by drainage or formation of clotted hemothorax, not effectiveness of sanation, of the empyema cavity, reabscessoscopy - in 2 patients. Revideothoracoscopies were divided into groups with the presence of drainages or removed drainages according to the terms - into emergent (on the first day, immediately after the development of complications), urgent (from 2 to5 days), postponed (from 6 to 15 days), and late (more than 15 days). In 4 cases the conversion to minithoracotomy had to be done due to continuing bleeding, the absence of lung hermetism. All patients with spontaneous pneumothorax, pleuritis and chest trauma recovered. Lethal outcome was in 1 (2.4%) case from lung artery thromboembolism. It was concluded that revideothoracoscopy was an alternative thoracotomy of full value in reinterventions.

Efficacy and safety of tunneled pleural catheters in adults with malignant pleural effusions: a systematic review.

BACKGROUND: Malignant pleural effusions (MPE) are a frequent cause of dyspnea and discomfort at the end of cancer patients' lives. The tunneled indwelling pleural catheter (TIPC) was approved by the FDA in 1997 and has been investigated as a treatment for MPE. OBJECTIVE: To systematically review published data on the efficacy and safety of the TIPC for treatment of MPE. DESIGN: We searched the MEDLINE, EMBASE, and ISI Web of Science databases to identify studies published through October 2009 that reported outcomes in adult patients with MPE treated with a TIPC. Data were aggregated using summary statistics when outcomes were described in the same way among multiple primary studies. MAIN MEASURES: Symptomatic improvement and complications associated with use of the TIPC. KEY RESULTS: Nineteen studies with a total of 1,370 patients met criteria for inclusion in the review. Only one randomized study directly compared the TIPC with the current gold standard treatment, pleurodesis. All other studies were case series. Symptomatic improvement was reported in 628/657 patients (95.6%). Quality of life measurements were infrequently reported. Spontaneous pleurodesis occurred in 430/943 patients (45.6%). Serious complications were rare and included empyema in 33/1168 patients (2.8%), pneumothorax requiring a chest tube in 3/51 (5.9%), and unspecified pneumothorax in 17/439 (3.9%). Minor complications included cellulitis in 32/935 (3.4%), obstruction/clogging in 33/895 (3.7%) and unspecified malfunction of the catheter in 11/121 (9.1%). The use of the TIPC was without complication in 517/591 patients (87.5%). CONCLUSIONS: Based on low-quality evidence in the form of case series, the TIPC may improve symptoms for patients with MPE and does not appear to be associated with major complications. Prospective randomized studies comparing the TIPC to pleurodesis are needed before the TIPC can be definitively recommended as a first-line treatment of MPE.

A pleuro-peritoneal communication through the diaphragm affected with lymphangioleiomyomatosis.

A 30-year-old Japanese woman with lymphangioleiomyomatosis (LAM) developed a left chylothorax and chylous ascites. A pleuro-peritoneal communication was confirmed by a scintigram with (99)mTc-labeled macroaggregated-albumin injected into the peritoneal cavity. Video-assisted thoracic surgery revealed a protruding papillary lesion on the left diaphragm. Chyle was oozing into the pleural cavity through this lesion. Histopathological analyses demonstrated that the protrusion was a diaphragmatic LAM lesion and that LAM-associated lymphangiogenesis enabled communication between the pleural and peritoneal cavities through lymphatic vessels. This case demonstrated a new mechanism for chylous pleural effusion in LAM and illustrates the significance of LAM-associated lymphangiogenesis.

Subarachnoid-pleural fistula treated with noninvasive positive pressure ventilation: a two-case report and literature review.

STUDY DESIGN: A report on 2 cases of subarachnoid pleural fistula (SAPF) treated with noninvasive positive pressure ventilation (NPPV). OBJECTIVE: To highlight the efficacy of NPPV in patients with SAPF. SUMMARY OF BACKGROUND DATA: SAPF is a rare but distressing type of cerebrospinal fluid leakage. It is known to be a complication of anterior thoracic spine surgery. The pressure gradient between the subarachnoid space and the pleural cavity maintains the cerebrospinal fluid leakage and precludes the spontaneous closure of the dura. Surgical interventions such as primary repair, patch grafts, muscle flaps, and omental flaps have been advocated. Only limited reports were found with reference to NPPV applied to SAPF. METHODS: Two patients, a 45-year-old woman and a 39-year-old woman, underwent anterior thoracic spine surgery to treat thoracic myelopathy caused by ossification of the posterior longitudinal ligament. After surgery, they developed SAPF due to perforation of the dura during surgery. Placement of thoracostomy tubes and subarachnoid drains had no effect and an NPPV device was applied. RESULTS: During application of the NPPV device, 14 days in the first patient and 5 days in the second patient, the raised intrapleural pressure obstructed the fluid leakage and successfully treated the fistula. No recurrence of SAPF was observed after removal of the NPPV device and the patients avoided surgical interventions. CONCLUSION: SAPF is often resistant to conservative therapies and has been treated in an invasive manner. NPPV should be considered as an alternative before such interventions because it is effective, noninvasive, and safe.

Respiratory restriction and elevated pleural and esophageal pressures in morbid obesity.

To explore mechanisms of restrictive respiratory physiology and high pleural pressure (P(Pl)) in severe obesity, we studied 51 obese subjects (body mass index = 38-80.7 kg/m(2)) and 10 nonobese subjects, both groups without lung disease, anesthetized, and paralyzed for surgery. We measured esophageal and gastric pressures (P(Es), P(Ga)) using a balloon-catheter, airway pressure (P(AO)), flow, and volume. We compared P(Es) to another estimate of P(Pl) based on P(AO) and flow. Reasoning that the lungs would not inflate until P(AO) exceeded alveolar and pleural pressures (P(AO) > P(Alv) > P(Pl)), we disconnected subjects from the ventilator for 10-15 s to allow them to reach relaxation volume (V(Rel)) and then slowly raised P(AO) until lung volume increased by 10 ml, indicating the "threshold P(AO)" (P(AO-Thr)) for inflation, which we took to be an estimate of the lowest P(Alv) or P(Pl) to be found in the chest at V(Rel). P(AO-Thr) ranged from 0.6 to 14.0 cmH2O in obese and 0.2 to 0.9 cmH2O in control subjects. P(Es) at V(Rel) was higher in obese than control subjects (12.5 +/- 3.9 vs. 6.9 +/- 3.1 cmH2O, means +/- SD; P = 0.0002) and correlated with P(AO-Thr) (R(2) = 0.16, P = 0.0015). Respiratory system compliance (C(RS)) was lower in obese than control (0.032 +/- 0.008 vs. 0.053 +/- 0.007 l/cmH2O) due principally to lower lung compliance (0.043 +/- 0.016 vs. 0.084 +/- 0.029 l/cmH2O) rather than chest wall compliance (obese 0.195 +/- 0.109, control 0.223 +/- 0.132 l/cmH2O). We conclude that many severely obese supine subjects at relaxation volume have positive P(pl) throughout the chest. High P(Es) suggests high P(Pl) in such individuals. Lung and respiratory system compliances are low because of breathing at abnormally low lung volumes.

Mesothelioma mortality in Brazil, 1980-2003.

Although asbestos causes asbestosis, lung cancer, and mesothelioma, it remains widely used in Brazil, mostly in cement-fiber products. We report the Brazilian mesothelioma mortality trend 1980-2003, using records of the national System of Mortality Information of DATASUS, including all deaths with IX International Disease Classification (ICD9) codes 163.n--pleura cancer during the period 1980-1995; and ICD10 codes c45.n--mesotheliomas and c38.4--pleura cancer for the years 1996-2003. Mesothelioma mortality rates increased over the period studied, from 0.56 to 1.01 deaths per 1,000,000 [corrected] habitants. The total number of mesothelioma deaths nationwide in the period studied was 2,414; the majority (1,415) were in the Southeast region. Mortality was highest among males and people over age 65. Given the history of asbestos exposure in Brazil, our findings support the need for policies that limit or ban the use of this product.

The effect of surgically created gastroesophageal reflux on intrapleural pressures in dogs.

The causal relationship between gastroesophageal reflux (GER) and respiratory disorders is not well understood. Previous experimental studies that investigated this relationship were performed in anesthetized animals and used artificial acidification of esophagus for simulation of GER. In this study, we investigated the impact of GER on intrapleural pressures (IPP) in conscious, unanesthetized dogs. After the induction of appropriate anesthesia, 5 purpose-bred mongrel dogs underwent reflux-creating surgery (partial cardiomyectomy). The presence of GER was confirmed by determining the reflux index (RI) and the duration of longest reflux episode (DLRE) after 24-h intraesophageal pH-metry. IP was monitored before and after cardiomyectomy using a subcutaneously placed telemetric implant with its pressure-sensor catheter tip inserted into the pleural space. Partial cardiomyectomy resulted in a significant increase in RI from a preoperative mean value of 0.38 +/- 0.21 to 7.52 +/- 2.56%, and DLRE from 1.22 +/- 1.12 to 36.80 +/- 12.71 min, as recorded by the proximal sensor of the pH probe. A similar trend was observed at the distal sensor. After cardiomyectomy, the negative inspiratory IPP significantly increased from 17.2 +/- 7.9 to 28.4 +/- 9.7 mm Hg. A similar effect was observed in the negative expiratory IPP. The negative inspiratory IPP had a significant correlation with both RI (R = 0.932) and DLRE (R = 0.899). Cardiomyectomy causes GER, the severity of which correlates with negative inspiratory IPP in a dog model. The suggested model allows for the investigation of the pathologic association of GER with respiratory disorders in conscious animals.

Pleural cellular reaction to the filarial infection Litomosoides sigmodontis is determined by the moulting process, the worm alteration, and the host strain.

The filarial nematode Litomosoides sigmodontis model was used to decipher the complex in vivo relationships between filariae, granulomas and leukocytes in the host's pleural cavity. The study was performed from D5 p.i.: to D47 p.i. in resistant C57BL/6 mice, to D74 p.i. in susceptible BALB/c mice, and to D420 p.i. in permissive jirds. We showed that, during the first month, leukocytes only clustered as granulomas around shed cuticles (exuviae) and with eosinophils as the major constituents. In addition, carbohydrates residues became abundant on exuviae only, suggesting a glycan-dependent mechanism of eosinophil attachment. Neutrophils were absent from the pleural cavity of all rodents and from the murine granulomas, but they made up 25% of the granuloma cell population in jirds. After the first month of infection granulomas formed around developed adult worms and morphological evidence suggested that leukocytes preferentially clustered around altered, but still motile, worms. No carbohydrates were detected on these worms and neutrophils were abundant in those granulomas. Finally, a rare third type of granuloma was observed in the resistant mice only; they contained young newly moulted adult worms; typically these granulomas were attached to the lateral lines of the worm via eosinophils; this feature correlated with the persistence of carbohydrate residues on the worms' lateral lines. Neutrophils were always in low proportion in all granulomas from resistant mice, suggesting difference in their adhesive properties in these mice. In vitro neutrophil recruitment in resistant mice was similar to that observed in susceptible mice although they expressed less cell surface CD11b.

Large-volume thoracentesis and the risk of reexpansion pulmonary edema.

BACKGROUND: To avoid reexpansion pulmonary edema (RPE), thoracenteses are often limited to draining no more than 1 L. There are, however, significant clinical benefits to removing more than 1 L of fluid. The purpose of this study was to define the incidence of RPE among patients undergoing large-volume (> or = 1 L) thoracentesis. METHODS: One hundred eighty-five patients undergoing large-volume thoracentesis were included in this study. The volume of fluid removed, absolute pleural pressure, pleural elastance, and symptoms during thoracentesis were compared in patients who did and did not experience RPE. RESULTS: Of the 185 patients, 98 (53%) had between 1 L and 1.5 L withdrawn, 40 (22%) had between 1.5 L and 2 L withdrawn, 38 (20%) had between 2 L and 3 L withdrawn, and 9 (5%) had more than 3 L withdrawn. Only 1 patient (0.5%, 95% confidence interval: 0.01% to 3%) experienced clinical RPE. Four patients (2.2%, 95% confidence interval: 0.06% to 5.4%) had radiographic RPE (diagnosed only on postprocedure imaging without clinical symptoms). The incidence of RPE was not associated with the absolute change in pleural pressure, pleural elastance, or symptoms during thoracentesis. CONCLUSIONS: Clinical and radiographic RPE after large-volume thoracentesis is rare and independent of the volume of fluid removed, pleural pressures, and pleural elastance. The recommendation to terminate thoracentesis after removing 1 L of fluid needs to be reconsidered: large effusions can, and should, be drained completely as long as chest discomfort or end-expiratory pleural pressure less than -20 cm H2O does not develop.

Therapeutic thoracentesis: the role of ultrasound and pleural manometry.

PURPOSE OF REVIEW: Therapeutic thoracentesis is one of the most commonly performed medical procedures. The availability of handheld ultrasound machines has greatly enhanced the evaluation and management of patients with pleural effusions, with advantages including the absence of radiation, ease of use, portability and real-time/dynamic imaging. Pleural manometry refers to the measurement of pleural pressure during thoracentesis. Though described more than 122 years ago, most physicians do not measure pleural pressure, or even consider the role pleural pressures plays in the development of pleural effusions. This review summarizes the relevant data behind the use of ultrasound and manometry and explores their use during therapeutic thoracentesis RECENT FINDINGS: The use of ultrasound has been associated with a higher sensitivity for identifying pleural effusions, avoiding 'near misses' and a lower pneumothorax rate for thoracentesis. Pleural manometry can be used to distinguish patients with lung entrapment from those with trapped lung. Manometry is also able to predict the ability to pleurodesis patients with malignant effusions, and possibly minimize the risk of reexpansion pulmonary edema when large volumes of pleural fluid are removed. SUMMARY: The use of ultrasound and pleural manometry enhances the understanding of pleural disease and is associated with clinical benefit that will lead to improved patient care.

Postoperative residual pleural spaces: characteristics and natural history.

This study was conducted in order to re-define the incidence and natural history of postresectional residual pleural spaces (PRS). From 1997 to 2005, 966 patients who were subjected to less than entire lung resections, were followed and any cases of PRS were recorded. The records of these patients were retrospectively analyzed for age, gender, type of resection, side, apical or basal location, size, PRS wall thickness, empyema as well as for bronchopleural fistula occurence, management, and outcome. Postresectional residual pleural spaces outcome was correlated with space characteristics. A total of 92 cases (9.5%) of PRS were documented which developed frequently ( p < 0.001) after upper lobectomies, malignant disease, at an apical location, and on the right side. Unfavorable outcome was strongly correlated with age > 70 years ( p < 0.001), air leak ( p < 0.001), empyema ( p < 0.001), and thickened pleura ( p < 0.001). Good prognosis of PRS was strongly correlated with male gender, apical location, right side, normal pleura thickness, and small size. Postresectional residual pleural spaces of small size without any associated complications should not prolong hospitalization time.

Time course of physiologic variables in response to ventilator-induced lung injury.

BACKGROUND: The time course of the physiological derangements that result from ventilator-induced lung injury has not been adequately described. Similarly, the regional topographies of pleural pressure and tissue edema have not been carefully mapped for this injury process. METHODS: Lung injury was induced in 9 normal pigs by ventilating for 6 hours at a transpulmonary pressure of 35 cm H(2)O, with the animals in the supine position. Eight additional normal pigs received right thoracotomy to place pleural-surface-pressure sensors prior to an identical period and intensity of injurious ventilation. Gas exchange and lung mechanics were tracked in all the animals. Cytokines (tumor necrosis factor alpha, interleukin 6, and interleukin 8) in peripheral blood were assayed at 2 hour intervals, beginning at the onset of mechanical ventilation, from all the animals. RESULTS: After a brief "induction" period, P(aO(2)) and tidal volume declined steadily in the animals that were ventilated to induce lung injury. The rate of decline was greater in the animals that received thoracotomy. The pleural pressure gradient steadily increased from ventral to dorsal. The serum cytokine levels did not evolve with developing injury, but cytokines were elevated at the onset of ventilation. Tissue edema, as assessed by the ratio of wet weight to dry weight, was greater in the thoracotomized animals than in the nonthoracotomized animals, and tissue edema tended to be greater in the caudal lung regions than in the cephalad lung regions. CONCLUSIONS: Following the induction period, the development of ventilator-induced lung injury progressed steadily and then plateaued, as assessed by quantitative physiology variables during 6 hours of ventilation at a transpulmonary pressure of 35 cm H(2)O. Greater injury developed in animals that had a coexisting potential insult (thoracotomy). Injury development was not paralleled by bloodborne inflammatory cytokines.

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.