Development of a multivariable prediction model for prolonged air leak after lung resection.

OBJECTIVES: Prolonged air leak (PAL) is a common complication of lung resection. Research on predictors of PAL using a digital drainage system (DDS) remains insufficient. In this study, we investigated the predictive factors of PAL to establish a novel early postoperative prediction model for PAL. METHODS: A retrospective cohort study and validation study were conducted. We examined patients who underwent lung resection with DDS at our institute. The relationship between the clinical factors and measurements of the DDS, including the difference between the set and measured intrapleural pressure (named: additional negative pressure [ANP]) at postoperative hour (POH) 3, with PAL was analyzed. RESULTS: A total of 494 patients were enrolled, 29 of whom had PAL. Percent forced expiratory volume in 1 s <60%, ANP <1 cmH2O, air leak flow >20 mL/min and pleural adhesion findings at surgery were independent predictors of PAL according to a multivariable analysis. The PAL rate was clearly stratified according to our novel risk scoring system, which simply notes the presence of the above four factors, that is, the rate increases when the score increases. The area under the curve (AUC) of the receiver operating characteristic (ROC) analysis for this scoring system was 0.818. Analysis of the validation cohort (n = 133) revealed that this scoring system showed a sufficient ability to predict PAL. CONCLUSIONS: ANP at POH 3 is an independent predictor of PAL. Thus, the risk-scoring system proposed in this study is useful for predicting PAL in the early postoperative period.

Safety and efficacy of vacuum bottle plus catheter for drainage of iatrogenic pneumothorax.

BACKGROUND: Iatrogenic pneumothorax is common after thoracic procedures. For patients with pneumothorax larger than 15%, simple aspiration is suggested. Although vacuum bottle plus non-tunneled catheter drainage has been performed in many institutions, its safety and efficacy remain to be assessed. METHODS: Through this prospective cohort study (NCT03724721), we evaluated the safety and efficacy of vacuum bottle plus non-tunneled catheter drainage. Patients older than 20 years old who developed post-procedural pneumothorax were enrolled. A non-tunneled catheter was placed at the intersection of the midclavicular line and the second intercostal space. A 3-way stopcock, a drainage set, and a digital pressure gauge were connected. The stopcock was manipulated to connect the pleural space to the pressure gauge for measurement of end-expiration intrapleural pressure or to the vacuum bottle for air drainage. The rate of successful drainage, the end-expiration intrapleural pressure before, during, and after the procedure and the duration of hospitalization were recorded. RESULTS: From August 2018 to February 2020, 21 patients underwent vacuum bottle plus catheter drainage (intervention group) and 31 patients received conservative treatment (control group). The end-expiration intrapleural pressure of all patients remained less than - 20 cmH2O during drainage. No procedure related complication was observed. Large pneumothorax (≥ 15%) was associated with higher risk of persistent air leak (Odds ratio 12, 95% CI 1.2-569.7). Vacuum bottle assisted air drainage yielded shorter event-free duration than that of conservative treatment (2 days vs 5 days [interquartile range 1-4 days vs 3-7 days], p < .05). Vacuum bottle assisted air drainage also help identifying patients with persistent pneumothorax and necessitate the subsequent management. The event-free duration of persistent air leak in the intervention group was also comparable with that of conservative treatment (5 days vs 5 days [interquartile range 5-8 days vs 3-7 days], p = .45). CONCLUSIONS: Vacuum bottle plus catheter drainage of iatrogenic pneumothorax is a safe and efficient procedure. It may be considered as an alternative management of stable post-procedural pneumothorax with size larger than 15%. Trial registration The study protocol was approved by the Research Ethics Committee of National Taiwan University Hospital (No. 201805105DINA) on 6th August, 2018. The first participant was enrolled on 23rd August, 2018 after Research Ethics Committee approval. This clinical trial complete registration at U.S. National Library of Medicine clinicaltrials.gov with identifier NCT03724721 and URL: https://clinicaltrials.gov/ct2/show/NCT03724721 on 30th October, 2018.

Fritz Rohrer (1888-1926), a pioneer in pulmonary mechanics whose work was inexplicably ignored for about 30 years.

Fritz Rohrer (1888-1926) has a special place in the history of respiratory physiology for two reasons. The first is that he laid the foundations of modern pulmonary mechanics in the early 1900s. For example, his seminal paper on pulmonary dynamics, that is, the pressure-flow relationships in the airways, was published in 1915 in one of the top journals in the field. It included extensive measurements of airway dimensions in postmortem human lungs and a sophisticated analysis of the modes of airflow. This was closely followed by a very original analysis of lung statics, which included studies of airway pressures at normal, maximal, and minimal lung volumes in relaxed normal volunteers, and was published in 1916. Remarkably, both papers were essentially ignored at the time. Fortunately, in 1925 he was able to summarize his major findings in a chapter in an important handbook of physiology. However, he tragically died from pulmonary tuberculosis in the following year at the early age of 37. The second reason for his importance in the history of pulmonary mechanics is that inexplicably his very innovative research was essentially ignored for about 30 years. It was not until the 1940s that his work was rediscovered, although not in time to save investigators from duplicating his very original studies. Possible reasons why his work was ignored for so long are discussed. Even today it is not easy to recover some important features of his career, and some aspects of his very original research are still almost unknown.

Fluid Balance Is Associated with Clinical Outcomes and Extravascular Lung Water in Children with Acute Asthma Exacerbation.

RATIONALE: The effects of fluid administration during acute asthma exacerbation are likely unique in this patient population: highly negative inspiratory intrapleural pressure resulting from increased airway resistance may interact with excess fluid administration to favor the accumulation of extravascular lung water, leading to worse clinical outcomes. OBJECTIVES: Investigate how fluid balance influences clinical outcomes in children hospitalized for asthma exacerbation. METHODS: We analyzed the association between fluid overload and clinical outcomes in a retrospective cohort of children admitted to an urban children's hospital with acute asthma exacerbation. These findings were validated in two cohorts: a matched retrospective and a prospective observational cohort. Finally, ultrasound imaging was used to identify extravascular lung water and investigate the physiological basis for the inferential findings. MEASUREMENTS AND MAIN RESULTS: In the retrospective cohort, peak fluid overload [(fluid input - output)/weight] is associated with longer hospital length of stay, longer treatment duration, and increased risk of supplemental oxygen use (P values < 0.001). Similar results were obtained in the validation cohorts. There was a strong interaction between fluid balance and intrapleural pressure: the combination of positive fluid balance and highly negative inspiratory intrapleural pressures is associated with signs of increased extravascular lung water (P < 0.001), longer length of stay (P = 0.01), longer treatment duration (P = 0.03), and increased risk of supplemental oxygen use (P = 0.02). CONCLUSIONS: Excess volume administration leading to fluid overload in children with acute asthma exacerbation is associated with increased extravascular lung water and worse clinical outcomes.

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.

Assessment of Differential Pressures in Chest Drainage Systems: Is What You See What You Get?

BACKGROUND: Dry-suction chest drainage systems are used to achieve proper drainage of the pleural space after cardiothoracic operations. Data on the actual intrapleural pressure during the use of these systems is lacking. The present study was performed to evaluate pressure differences across the circuit using an ex vivo model. METHODS: An ex vivo apparatus coupled to a hospital-grade pleural drainage system was devised to provide calibrated levels of suction and air leak. Simultaneous pressure measurements were obtained at the system outlet and the simulated patient entry site. Trials were conducted with increasing levels of water between the patient and drainage modules at various levels of suction and leak pressures. Signals were recorded at 100 Hz and analyzed using two-way ANOVA. RESULTS: With no obstruction, the drainage system provided precise levels of negative pressure at the patient level (10-40 cm H2O). Addition of fluid in the drainage tubing caused significant differences in transmitted suction (P < 0.001). With increasing air leakage and fluid volume, the pressure differential between the system and patient increased significantly (1.14 to 36.69 cm H2O, P < 0.001). In the off-suction setting, increasing levels of obstruction to 22 cm of water led to development of positive intrapleural pressures (2.6 to 11.1 cm H2O, P < 0.001). CONCLUSIONS: While commercially available chest drainage systems are able to provide predictable levels of suction at the device, intrapleural pressures can be highly variable and depend on complete patency of connecting tubes. Systems capable of modulating the level of suction based on actual intrapleural pressures may enhance recovery after procedures requiring tube thoracotomy.

Asymmetrical intrapleural pressure distribution: a cause for scoliosis? A computational analysis.

PURPOSE: The mechanical link between the pleural physiology and the development of scoliosis is still unresolved. The intrapleural pressure (IPP) which is distributed across the inner chest wall has yet been widely neglected in etiology debates. With this study, we attempted to investigate the mechanical influence of the IPP distribution on the shape of the spinal curvature. METHODS: A finite element model of pleura, chest and spine was created based on CT data of a patient with no visual deformities. Different IPP distributions at a static end of expiration condition were investigated, such as the influence of an asymmetry in the IPP distribution between the left and right hemithorax. The results were then compared to clinical data. RESULTS: The application of the IPP resulted in a compressive force of 22.3 N and a flexion moment of 2.8 N m at S1. An asymmetrical pressure between the left and right hemithorax resulted in lateral deviation of the spine towards the side of the reduced negative pressure. In particular, the pressure within the dorsal section of the rib cage had a strong influence on the vertebral rotation, while the pressure in medial and ventral region affected the lateral displacement. CONCLUSIONS: An asymmetrical IPP caused spinal deformation patterns which were comparable to deformation patterns seen in scoliotic spines. The calculated reaction forces suggest that the IPP contributes in counterbalancing the weight of the intrathoracic organs. The study confirms the potential relevance of the IPP for spinal biomechanics and pathologies, such as adolescent idiopathic scoliosis.

Chest tube removal at different gas flows in prolonged air leak: a randomized non-inferiority trial.

OBJECTIVES: To evaluate the safety and feasibility of removing drainage tubes at larger size of air leak in patients with prolonged air leak after pulmonary surgery. METHODS: Ninety-five patients who underwent pulmonary surgery with prolonged air leak in our centre were enrolled in this randomized controlled, single-centre, non-inferiority study. The drainage tube was clamped with a stable size of air leak observed over the last 6 h, which was quantified by gas flow rate using the digital drainage system. The control group (n = 48) and the study group (n = 46) had their drainage tube clamped at 0-20 ml/min and 60-80 ml/min, respectively. We continuously monitored clinical symptoms, conducted imaging and laboratory examinations, and decided whether to reopen the drainage tube. RESULTS: The reopening rate in the study group was not lower than that in the control group (2.08% vs 6.52%, P > 0.05). The absolute difference in reopening rate was 4.44% (95% confidence interval -0.038 to 0.126), with an upper limit of 12.6% below the non-inferiority margin (15%). There were significant differences in the length of stay [16.5 (13-24.75) vs 13.5 (12-19.25), P = 0.017] and the duration of drainage [12 (9.25-18.50) vs 10 (8-12.25), P = 0.007] between the control and study groups. No notable differences were observed in chest X-ray results 14 days after discharge or in the readmission rate. CONCLUSIONS: For patients with prolonged air leak, removing drainage tubes at larger size of air leak demonstrated similar safety compared to smaller size of air leak, and can shorten both length of stay and drainage duration. CLINICAL TRIAL REGISTRATION NUMBER: Name of registry: Gas flow threshold for safe removal of chest drainage in patients with alveolar-pleural fistula prolonged air leak after pulmonary surgery. Registration number: ChiCTR2200067120. URL: https://www.chictr.org.cn/.

-8 cm H2 O, the new paradigm in chest drain management following thoracoscopic lung resection?

BACKGROUND: Chest drain suction of -20 cm H2 O has been used universally after lung resection. After introducing new guidelines,-8 cm H2 O was used routinely for all non-pneumonectomy, thoracoscopic lung resections. We conducted a review to determine outcomes and safety. METHODS: After introduction of the guidelines data were collected in the study institutions' thoracic surgical database and subsequently analysed. RESULTS: A total of 155 patients underwent thoracoscopic lung resection. Mean patient age was 61.5 ± 13.6 years. Video-assisted thoracoscopic surgery was performed in 92.2% (144/155) of patients and robotically-assisted thoracoscopic surgery was performed in 7.8% (12/155) of patients. Lobectomy was performed in 56.8% (88/155) of patients, segmentectomy was performed in 11.6% (18/155) of patients and wedge resection was performed in 31.6% (49/155) of patients. Median ICC duration time was 1 day (IQR 1-3). Median length of stay was 3 days (IQR 2-6). For patients undergoing lobectomy median ICC time was 2 days (IQR 1-4.5) and median length of stay was 3.5 days (IQR 2-7), for segmentectomy median ICC time was 1 day (IQR 1-5) and median length of stay was 2 days (IQR 1-5) and for wedge resection median ICC time was 1 day (IQR 1-1) and median admission time was 2 days (IQR 1-4). CONCLUSION: A suction level -8 cm H2 O is safe to use for thoracoscopic lung resections from day 0 post-operatively. A dedicated, prospective study comparing levels of suction should be performed.

Positive Intrapleural Pressure with Carbon Dioxide May Limit Intraoperative Pulmonary Arterial Bleeding: Verification by Animal Model.

PURPOSE: Intraoperative complications, especially unexpected bleeding, are of great concern in the safety of thoracoscopic surgery. We investigated the hemostatic efficacy and safety of positive intrapleural pressure (PIP) with carbon dioxide insufflation by assessing the amount of blood loss in a pulmonary arterial hemorrhage model. METHODS: An ex vivo experimental model of saline flow into a swine vessel was created in a container simulating a chest cavity. From the results, in vivo experiments (swine model) were conducted to compare the pulmonary arterial bleeding volume while applying PIP. RESULTS: In the ex vivo experiment, regardless of the incision type, the outflow volumes did not significantly differ at flow pressures of 20, 30, and 40 mmHg. At each flow pressure, the outflow volumes at 10, 15, and 20 mmHg of positive pressure in the container were significantly smaller than those of the control (p = 0.027, p = 0.002, and p = 0.005, respectively). Similarly, the in vivo experiments showed that bleeding decreased as intrapleural pressure increased (slope = -0.22, F = 55.13, p <0.0001). CONCLUSION: It may be possible to temporarily suppress pulmonary arterial bleeding by increasing the intrapleural pressure to 10 to 20 mmHg using carbon dioxide insufflation. This method may be an adjunctive hemostatic maneuver for intraoperative bleeding.

Chest Drainage Therapy: What Comes out of Pandora's Box Can Affect Patient Outcomes.

Background: Over the last 100 years, the original three-bottle chest drainage system has been variously engineered into compact disposables and electronic units. Clinicians are now surrounded by a plethora of different types of systems, but little is known about the way that they work and perform. Thus, we sought to test the performance of the most commonly used chest drainage units under conditions that are relevant to clinical practice. Methods: A pleural space environment simulator was built. Thirty-two units were tested under four clinical scenarios: air leak interpretation during quiet breathing and after obstructed inspiration (−5 to −150 cmH2O), a buildup of negative pressure (−100 cmH2O), a bronchopleural fistula (10 L/min) and the need for effective external suction in the presence of air leakage. Twenty-five units were "traditional" thoracic drainages, five were "digital" low-flow/low-vacuum pumps and two were hybrids (a combination of the two). According to the design of the seal and of the suction control, the units were classified as wet-wet, wet-dry and dry-dry. Results: All wet units showed reverse air flow, with the potential to mimic an air leak when there was none. Ten wet units showed no automatic negative pressure relief features, while five dry-dry did but were slow to react. Ten wet and five dry-dry units showed no capability to handle a 10 L/min leak, as they were restrictive to flow (peak pressure up to 55 cmH2O). Only seven dry-suction units were able to maintain the set suction at high airflow rates (>20 L/min). Conclusions: Different chest drainage unit designs lead to different performances, some of which may negatively impact patient outcomes. This sounds the call to tailor our clinical practice for the individual patient. A paradigm shift to better understand all components of pleural physiology post-surgical intervention on this relatively neglected topic is needed to improve our daily practice.

Usefulness of monitoring intrapleural pressure with digital chest drainage system for the management of air leakage after lung resection.

OBJECTIVES: The objective of this study was to determine the variation in intrapleural pressure (IPP) with and without air leakage using a digital chest drainage system (DCS) for each pressure setting. METHODS: In this retrospective single-centre study, we analysed 49,553 h of air leakage after anatomical lung resection in 714 patients between 2018 and 2020. The transition of mean IPP and mean air leak flow was monitored using DCS, and the association between mean IPP and mean air leak flow was examined. The relationship between the transition of mean IPP and air leakage according to the varying suction pressures on DCS was also investigated. RESULTS: Overall, 272 patients (38.1%) showed air leakage after surgery. The mean IPP in patients without air leakage was -12.0 ± 2.9 cmH2O and maintained at about -12 cmH2O constantly, while the mean IPP in patients with air leakage was -8.3 ± 1.9 cmH2O, which changed to -12 cmH2O instantly if air leakage disappeared (P < 0.001). Among patients with air leakage, the mean IPP changed more distinctly in patients with mild suction management than in those with conventional suction management (-5.0 ± 2.6 to -11.5 ± 4.2 and -8.8 ± 1.3 to -12.1 ± 2.5 cmH2O, respectively; P < 0.001). CONCLUSIONS: The change in IPP on a DCS is useful for detecting air leakage. Furthermore, management with a mild suction setting on DCS makes it easy to recognize the disappearance of postoperative air leakage.

Work in progress report of a multicentre retrospective observational study to evaluate the association between the airflows and the intrapleural pressures digitally recorded after video-assisted lobectomy.

OBJECTIVES: Digital chest drainage systems allow real-time and continuous monitoring and recording of air leak flow rate and intrapleural pressure (IPP) from the immediate postoperative period to the chest drainage removal. A multicentre retrospective observational analysis of consecutive patients undergoing pulmonary lobectomy for lung cancer was performed to evaluate the association between the airflow and IPP digitally recorded during the immediate postoperative period after video-assisted thoracic surgery (VATS) lobectomy for lung cancer. Here, we present a work in progress report. METHODS: All patients treated with VATS lobectomies for lung cancer were included. Multiple airflow measurements and minimum and maximum IPP through the chest tubes were digitally monitored and recorded using microelectronic mechanical sensor technology. The PALs were defined as an air leak lasting >5 days from the conclusion of the surgical procedure. The cessation of air leaks was defined as an airflow <10 ml/min during 6 consecutive hours. RESULTS: This analysis comprised 76 patients who underwent VATS lobectomy for lung cancer. Nineteen patients (25%) showed prolonged air leaks (PAL) (≥5 days). The operative time was higher in the PAL group (mean difference = 44 min) without a statistically significant difference. Before the 7th postoperative hours, there were no statistically significant differences in IPPs. CONCLUSIONS: Patients with PAL showed less negative IPP in the first 24 postoperative hours. Therefore, the 7th-24th postoperative hours were critical in PAL prediction since the mechanism for PAL seems to develop after the 7th postoperative hour.

Systemic air embolism during pleural lavage for empyema.

Pleural lavage has been considered a convenient and safe method that is often performed for empyema. We report a case of systemic air embolism that developed during pleural lavage. A 53-year-old man with empyema in the organizing phase suddenly developed paralysis of the left side of the body and altered level of consciousness during pleural lavage, which was performed in a sitting position without negative pressure suction. Systemic air embolism was diagnosed based on computed tomography. In this case, use of fibrinolytic agents, positioning during pleural lavage, and pressure in an empyema cavity may have predisposed to development of systemic air embolism. Conversion from thoracoscopic therapy to open decortication or fenestration should be considered to prevent this type of complication.

A case of negative pressure pulmonary edema in an asthmatic patient after laparoscopic cholecystectomy.

Negative pressure pulmonary edema is often misdiagnosed or can go clinically unrecognized by anesthesiologists. It is characterized by a markedly low intrapleural pressure which leads to exudation of fluid and red blood cells in the interstitium. Recognition of patients with predisposing factors for upper airway obstruction is important in the diagnosis which is often confused with pulmonary aspiration of gastric contents. Signs and symptoms are subtle and edema is usually self-limited. Our patient was management conservatively with maintenance of a patent airway and administration of supplemental oxygen and had a successful outcome.