Pleural Pressure Targeted Positive Airway Pressure Improves Cardiopulmonary Function in Spontaneously Breathing Patients With Obesity.

BACKGROUND: Increased pleural pressure affects the mechanics of breathing of people with class III obesity (BMI > 40 kg/m2). RESEARCH QUESTION: What are the acute effects of CPAP titrated to match pleural pressure on cardiopulmonary function in spontaneously breathing patients with class III obesity? STUDY DESIGN AND METHODS: We enrolled six participants with BMI within normal range (control participants, group I) and 12 patients with class III obesity (group II) divided into subgroups: IIa, BMI of 40 to 50 kg/m2; and IIb, BMI of ≥ 50 kg/m2. The study was performed in two phases: in phase 1, participants were supine and breathing spontaneously at atmospheric pressure, and in phase 2, participants were supine and breathing with CPAP titrated to match their end-expiratory esophageal pressure in the absence of CPAP. Respiratory mechanics, esophageal pressure, and hemodynamic data were collected, and right heart function was evaluated by transthoracic echocardiography. RESULTS: The levels of CPAP titrated to match pleural pressure in group I, subgroup IIa, and subgroup IIb were 6 ± 2 cmH2O, 12 ± 3 cmH2O, and 18 ± 4 cmH2O, respectively. In both subgroups IIa and IIb, CPAP titrated to match pleural pressure decreased minute ventilation (IIa, P = .03; IIb, P = .03), improved peripheral oxygen saturation (IIa, P = .04; IIb, P = .02), improved homogeneity of tidal volume distribution between ventral and dorsal lung regions (IIa, P = .22; IIb, P = .03), and decreased work of breathing (IIa, P < .001; IIb, P = .003) with a reduction in both the work spent to initiate inspiratory flow as well as tidal ventilation. In five hypertensive participants with obesity, BP decreased to normal range, without impairment of right heart function. INTERPRETATION: In ambulatory patients with class III obesity, CPAP titrated to match pleural pressure decreased work of breathing and improved respiratory mechanics while maintaining hemodynamic stability, without impairing right heart function. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT02523352; URL: www.clinicaltrials.gov.

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.

Measurement of intrapleural pressure in patients with spontaneous pneumothorax: a pilot study.

BACKGROUND: The initial management of pneumothorax remains controversial, and we speculated that this might be because there is no method available for evaluation of air leak during initial management. We have developed a system for measurement of intrapleural pressure in pneumothorax to address air leak without the need for chest drainage. The aim of this clinical study was to confirm the ability of this measurement system and to determine the clinical impact of management of air leak. METHODS: Patients in whom need aspiration was indicated for spontaneous pneumothorax were enrolled in the study. The intrapleural pressure was measured during stable breathing and data recorded when patients were coughing were excluded. RESULTS: Eleven patients were enrolled in the study between December 2016 to July 2017. The patterns in change of intrapleural pressure varied widely depending on the state of the pneumothorax. The mean intrapleural pressure values on end-inspiration and end-expiration in patients with persistent air leak was significantly lower than those in patients without persistent air leak (p = 0.020). The number of negative mean pressure recordings in end-inspiration and end-expiration was significantly lower in patients with persistent air leak than in those without persistent air leak (p = 0.0060). CONCLUSIONS: In this study, we demonstrated that intrapleural pressure could be successfully measured and visualized in patients with pneumothorax. Whether or not the pressure value is a predictor of persistent air leak needs to be confirmed in the future.

The use of a virtual patient to follow pleural pressure changes associated with therapeutic thoracentesis.

PURPOSE: Influence of therapeutic thoracentesis on the pleural pressure (Pp) has been discussed in many clinical studies, however reasons of Pp changes are not precisely established. The aim of the study was to use a previously elaborated virtual cardiopulmonary patient (VP) in analysis of impact of physiological factors on Pp during the procedure. METHODS: Simulations were performed on VP with default values of parameters for which VP simulated the respiratory system of the average 50-year-old healthy Polish woman according to spirometric examination. Alterations of Pp and the amplitude of Pp changes related to breathing (AP) were analyzed. Model parameters related to chosen factors were deviated from their default values to analyze the degree of their impact on Pp and AP. The analysis was based on and supported by our own clinical data. RESULTS: The Pp and AP alteration intensity appeared to be most sensitive to the compliances of the rib cage and mediastinum, and the nonlinearity of the dependence between the recoil pressure and the lung volume: the lower the compliances and the higher the nonlinearity were, the deeper the Pp fall during the procedure and the bigger the AP increase were observed. CONCLUSIONS: Experiments in silico are very useful in analyzing sophisticated physiological and medical problems. They made it possible to show which factors are particularly responsible for changes in Pp during thoracentesis. In the future, they may be useful in establishing objective conditions under which thoracentesis needs to be stopped.

Accidental hypothermic cardiac arrest and rapid mediastinal warming with pleural lavage: a survivor after 3.5 hours of manual CPR.

A 30-year-old man suffered post-traumatic hypothermic cardiac arrest. On arrival in the emergency department, rectal core temperature was 23°C. Manual cardiopulmonary resuscitation (CPR) was continued as no mechanical chest compression device was available, and active and passive rewarming was undertaken. Bilateral thoracostomies confirmed good lung inflation. Defibrillation and intravenous epinephrine were discontinued until core temperature was elevated above 30°C. Extracorporeal rewarming was unavailable. When no increase in rectal temperature was achieved after 90 min, an alternative oesophageal probe confirmed mediastinal temperature as 23°C. Bilateral chest drain insertion, followed by microwave-heated saline pleural lavage, rapidly raised the oesophageal temperature above 30°C with subsequent successful defibrillation, initially to pulseless electrical activity and finally return of spontaneous circulation 3.5 hours after the commencement of CPR. The patient recovered fully and was discharged without neurological deficit. Rapid mediastinal warming with pleural lavage should be considered in units with no access to extracorporeal rewarming service.

Cough during therapeutic thoracentesis: friend or foe?

We report intriguing preliminary observations on the effect of cough on pleural pressure changes during therapeutic thoracentesis. We found that cough-related elevation of pleural pressure persisted even when the cough had stopped. Thus, we hypothesize that cough during therapeutic thoracentesis may have a beneficial effect preventing the excessive drop in pleural pressure. The true role of cough-related elevation of pleural pressure is unknown, but it seems to be an interesting subject for further research.

[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.

Real-time noninvasive estimation of intrapleural pressure in mechanically ventilated patients: a feasibility study.

A method for real-time noninvasive estimation of intrapleural pressure in mechanically ventilated patients is proposed. The method employs a simple first-order lung mechanics model that is fitted in real-time to flow and pressure signals acquired non-invasively at the opening of the patient airways, in order to estimate lung resistance (RL), lung compliance (CL) and intrapleural pressure (Ppl) continuously in time. Estimation is achieved by minimizing the sum of squared residuals between measured and model predicted airway pressure using a modified Recursive Least Squares (RLS) approach. Particularly, two different RLS algorithms, namely the conventional RLS with Exponential Forgetting (EF-RLS) and the RLS with Vector-type Forgetting Factor (VFF-RLS), are considered in this study and their performances are first evaluated using simulated data. Simulations suggest that the conventional EF-RLS algorithm is not suitable for our purposes, whereas the VFF-RLS method provides satisfactory results. The potential of the VFF-RLS based method is then proved on experimental data collected from a mechanically ventilated pig. Results show that the method provides continuous estimated lung resistance and compliance in normal physiological ranges and pleural pressure in good agreement with invasive esophageal pressure measurements.

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.

Pleural space elastance and changes in oxygenation after therapeutic thoracentesis in ventilated patients with heart failure and transudative pleural effusions.

BACKGROUND AND OBJECTIVE: Therapeutic thoracentesis (TT) is required in patients with refractory pleural effusions and impaired oxygenation. In this study, the relationship between pleural space elastance (PE) and changes in oxygenation after TT was investigated in ventilated patients with heart failure and transudative pleural effusions. METHODS: Twenty-six mechanically ventilated patients with heart failure and significant transudative effusions, who were undergoing TT, were studied. The effusion was drained as completely as possible, with monitoring of pleural liquid pressure (Pliq) and chest symptoms. The volume of effusion removed, the changes in Pliq during TT, PE and arterial blood gases before and after TT were recorded. RESULTS: The mean volume of effusion removed was 1011.9 +/- 58.2 mL. The mean Pliq decreased from 14.5 +/- 1.0 to 0.1 +/- 1.5 cm H(2)O after TT, and the mean PE was 15.3 +/- 1.8 cm H(2)O/L. TT significantly increased the mean ratio of PaO(2)/fraction of inspired oxygen (FiO(2)) from 243.2 +/- 19.9 to 336.0 +/- 17.8 mm Hg (P < 0.0001). The changes in PaO(2)/FiO(2) ratio after TT were inversely correlated with PE (r = -0.803, P < 0.0001). The 14 patients (54%) with normal PE (14.5 cm H(2)O/L). CONCLUSIONS: Measurement of PE during TT may be valuable for predicting improvement in oxygenation in ventilated patients with heart failure and pleural effusions. Patients with lower PE showed greater improvement in oxygenation after TT.