Clinical review: Endobronchial valve treatment for emphysema

Effect of cartilaginous rings in tracheal flow with stenosis

BACKGROUND

In respiratory fluid dynamics research, it is typically assumed that the wall of the trachea is smooth. However, the trachea is structurally supported by a series of cartilaginous rings that create undulations on the wall surface, which introduce perturbations into the flow. Even though many studies use realistic Computer Tomography (CT) scan data to capture the complex geometry of the respiratory system, its limited spatial resolution does not resolve small features, including those introduced by the cartilaginous rings.

RESULTS

Here we present an experimental comparison of two simplified trachea models with Grade II stenosis (70% blockage), one with smooth walls and second with cartilaginous rings. The use a unique refractive index-matching method provides unprecedented optical access and allowed us to perform non-intrusive velocity field measurements close to the wall (e.g., Particle Image Velocimetry (PIV)). Measurements were performed in a flow regime comparable to a resting breathing state (Reynolds number Re_D = 3350). The cartilaginous rings induce velocity fluctuations in the downstream flow, enhancing the near-wall transport of momentum flux and thus reducing flow separation in the downstream flow. The maximum upstream velocity in the recirculation region is reduced by 38%, resulting in a much weaker recirculation zone- a direct consequence of the cartilaginous rings.

CONCLUSIONS

These results highlight the importance of the cartilaginous rings in respiratory flow studies and the mechanism to reduce flow separation in trachea stenosis.

The Potential Role of Regulated Cell Death in Dry Eye Diseases and Ocular Surface Dysfunction

The research on new treatments for dry eye diseases (DED) has exponentially grown over the past decades. The increased prevalence of dry eye conditions, particularly in the younger population, has received much attention. Therefore, it is of utmost importance to identify novel therapeutical targets. Regulated cell death (RCD) is an essential process to control the biological homeostasis of tissues and organisms. The identification of different mechanisms of RCD stimulated the research on their involvement in different human pathologies. Whereas apoptosis has been widely studied in DED and included in the DED vicious cycle, the role of RCD still needs to be completely elucidated. In this review, we will explore the potential roles of different types of RCD in DED and ocular surface dysfunction. Starting from the evidence of oxidative stress and inflammation in dry eye pathology, we will analyse the potential therapeutic applications of the following principal RCD mechanisms: ferroptosis, necroptosis, and pyroptosis.

When Treatment of Pulmonary Emphysema with Endobronchial Valves Did Not Work: Evaluation of Quantitative CT Analysis and Pulmonary Function Tests Before and After Valve Explantation

Purpose

To investigate changes in quantitative CT analysis (QCT) and pulmonary function tests (PFT) in pulmonary emphysema patients who required premature removal of endobronchial valves (EBV).

Patients and Methods

Our hospital’s medical records listed 274 patients with high-grade COPD (GOLD stages 3 and 4) and pulmonary emphysema who were treated with EBV to reduce lung volume. Prior to intervention, a complete evaluation was performed that included quantitative computed tomography analysis (QCT) of scans acquired at full inspiration and full expiration, pulmonary function tests (PFT), and paraclinical findings (6-minute walking distance test (6MWDT) and quality of life questionnaires). In 41 of these 274 patients, EBV treatment was unsuccessful and the valves had to be removed for various reasons. A total of 10 of these 41 patients ventured a second attempt at EBV therapy and underwent complete reevaluation. In our retrospective study, results from three time points were compared: Before EBV implantation (BL), after EBV implantation (TP2), and after EBV explantation (TP3). QCT parameters included lung volume, total emphysema score (TES, ie, the emphysema index) and the 15th percentile of lung attenuation (P15) for the whole lung and each lobe separately. Differences in these parameters between inspiration and expiration were calculated (Vol. Diff (%), TES Diff (%), P15 Diff (%)). The results of PFT and further clinical tests were taken from the patient’s records.

Results

We found persistent therapy effect in the target lobe even after valve explantation together with a compensatory hyperinflation of the rest of the lung. As a result of these two divergent effects, the volume of the total lung remained rather constant. Furthermore, there was a slight deterioration of the emphysema score for the whole lung, whereas the TES of the target lobe persistently improved.

Conclusion

Interestingly, we found evidence that, contrary to our expectations, unsuccessful EBV therapy can have a persistent positive effect on target lobe QCT scores.

Anaesthetic management for endobronchial valve insertion: lessons learned from a single centre retrospective series and a literature review

Background

Endoscopic lung volume reduction using one or more endobronchial valves is a treatment option for a select group of patients with severe emphysema. Patients presenting for this procedure pose various challenges to the anaesthetist; in addition to their lung condition, they are often elderly with multiple comorbidities. The procedure is usually performed outside the operating room. Monitored anaesthesia care with intravenous sedation, and general anaesthesia with an endotracheal tube have both been described for these procedures, aiming for adequate ventilation and haemodynamic stability.

Methods

We present our experience on 20 of these procedures in relation to the anaesthetic techniques employed and discuss the perioperative challenges involved in managing these cases.

Results

Twenty one planned endobronchial valve insertion procedures were identified on 18 patients. There were ten cases of monitored anaesthesia care with sedation and 10 cases which used general anaesthesia with an endotracheal tube. Two have been excluded; one had features of anaphylaxis and the procedure was abandoned, and the other required conversion from monitored anaesthesia care to general anaesthesia with endotracheal tube.

Conclusions

Both monitored anaesthesia care with sedation and general anaesthesia with endotracheal tube were well tolerated during endobronchial valve insertion procedures. General anaesthesia with endotracheal tube may offer better interventional conditions, patient comfort and reduced anaesthetic time.

Bronchoscopic Lung Volume Reduction: A 2018 Review and Update

Bronchoscopic lung volume reduction (BLVR) procedure has expanded the treatment spectrum of patients with end-stage emphysema. These treatments include valve, coil, thermal vapor ablation, bio-lung volume reduction, targeted lung denervation, and airway bypass stent. This short review provides an up-to-date information on BLVR treatments, their clinical benefits, and an overview of complications. BLVR treatments generally affect dyspnea by reducing hyperinflation and residual volume (RV). Benefits of treatment are associated with improvement in lung function parameters (forced expiration volume in the first second, total lung capacity, RV, and 6-minute walking test) and quality of life. Serious potential pulmonary complications, such as pneumothorax, pneumonia, respiratory failure, and chronic obstructive pulmonary disease exacerbation, may also occur after BLVR treatment. In addition to these, low-cost BLVR methods, such as autologous blood and fibrin glue, are in the developmental stage. Bronchoscopic lung volume reduction treatments are a promising method with positive results for patients with severe emphysema. The widespread use of these techniques, inadequate selection of patients, and non-critical and, therefore, unsuccessful use of BLVR in non-specialist centers lead to a false negative impression of the effectiveness of these techniques. In addition to these considerations, it is obvious that these treatments, which are quite expensive, are burdening social health systems. The reduction of costs or the development of lower-cost treatment methods is important for the future and for the availability of treatments.