Spontaneous pneumomediastinum, pneumothorax and subcutaneous emphysema in critically ill COVID-19 patients: A systematic review

Objectives: COVID-19 patients develop Life-threatening complications like pneumomediastinum/pneumothorax and emphysema which might experience prolonged hospital stays and additional costs might be imposed on the patient and the health system. The clinical features and outcomes of mechanically ventilated patients with COVID-19 infection who develop a pneumothorax, pneumomediastinum and subcutaneous emphysema has not been rigorously described or compared to those who do not develop these complications. So a systematic review of studies conducted on this subject was carried out to better manage these complications by investigating the underlying factors in COVID-19 patients. Methods: The search was conducted between early January and late December 2020 in databases including PubMed, Scopus, ProQuest, Embase, Cochrane Library, and Web of Science, using the following keywords and their combinations: COVID-19 Complication, Pneumothorax, Pneumomediastinum, Pneumopericardium, and Subcutaneous Emphysema. The extracted studies were screened separately by two researchers based on the PRISMA statement. After eliminating the duplicate studies, the title, abstract, and full text of the remaining studies were reviewed. Disagreements in the screening and selection of the studies were resolved by consensus or through a third-party opinion. Results: A total of 793 articles were retrieved through the literature search, and 99 studies conducted on a total of 139 patients were finally included The patient mortality was found to have a significant relationship with positive pressure ventilation (P=0.0001). There was no significant relationship between the patients’ death and chest tube insertion (P=0.2) or between the interval of time from the onset of symptoms to the diagnosis of pneumothorax (P=0.7). The mean age was higher in the deceased cases, and the mean difference observed was statistically significant (P=0.001). Conclusion: With the expansion of our clinical understanding of COVID-19, recognition of the uncommon complications of COVID-19 especially pneumothorax is crucial. Although in our review we couldn’t find a causal relationship between COVID-19 and pneumothorax or association between pneumothorax and death, as it is limited by many variables such as included studies’ design, or incomplete outcome data especially more information about the associated risk factors, we recommend performing more well-designed studies to describe the pneumothoraxes› incidence, risk factors, and outcomes in COVID-19 patients. doi: https://doi.org/10.12669/pjms.38.3.5529 How to cite this:Shahsavarinia K, Rahvar G, Soleimanpour H, Saadati M, Vahedi L, Mahmoodpoor A. Spontaneous pneumomediastinum, pneumothorax and subcutaneous emphysema in critically ill COVID-19 patients: A systematic review. Pak J Med Sci. 2022;38(3):---------. doi: https://doi.org/10.12669/pjms.38.3.5529 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Positive Airway Pressure at Extubation Minimizes Subglottic Secretion Leak In Vitro

Accumulated secretion above the endotracheal tube cuff can be aspirated during extubation after deflation. The possible techniques for minimizing pulmonary aspiration from subglottic secretion during extubation have not been well explored. This study aimed to determine the effect of different extubation techniques on secretion leakage. An endotracheal tube was placed in a tube mimicking an airway. We measured the leak volume of water or artificial sputum of different viscosities with three extubation techniques—negative pressure with suctioning; positive pressure with a resuscitator; and continuous positive airway pressure set at 5, 10, and 20 cm H2O. Extubation with continuous positive airway pressure resulted in lower secretion leakage than that with negative pressure with suctioning and positive pressure with a resuscitator. Increasing the continuous positive airway pressure level decreased secretion leakage volume during extubation. We further determined a correlation of leak volume with sputum viscosity. Continuous positive airway pressure at 5 cm H2O produced lower volume secretion leakage than the other two techniques, even with higher secretion viscosity. Based on these results, using continuous positive airway pressure with a previous ventilator continuous positive airway pressure/positive end-expiratory pressure setting for extubation is recommended.

A 3D Printed Modular Soft Gripper Integrated With Metamaterials for Conformal Grasping

A single universal robotic gripper with the capacity to fulfill a wide variety of gripping and grasping tasks has always been desirable. A three-dimensional (3D) printed modular soft gripper with highly conformal soft fingers that are composed of positive pressure soft pneumatic actuators along with a mechanical metamaterial was developed. The fingers of the soft gripper along with the mechanical metamaterial, which integrates a soft auxetic structure and compliant ribs, was 3D printed in a single step, without requiring support material and postprocessing, using a low-cost and open-source fused deposition modeling (FDM) 3D printer that employs a commercially available thermoplastic poly (urethane) (TPU). The soft fingers of the gripper were optimized using finite element modeling (FEM). The FE simulations accurately predicted the behavior and performance of the fingers in terms of deformation and tip force. Also, FEM was used to predict the contact behavior of the mechanical metamaterial to prove that it highly decreases the contact pressure by increasing the contact area between the soft fingers and the grasped objects and thus proving its effectiveness in enhancing the grasping performance of the gripper. The contact pressure can be decreased by up to 8.5 times with the implementation of the mechanical metamaterial. The configuration of the highly conformal gripper can be easily modulated by changing the number of fingers attached to its base to tailor it for specific manipulation tasks. Two-dimensional (2D) and 3D grasping experiments were conducted to assess the grasping performance of the soft modular gripper and to prove that the inclusion of the metamaterial increases its conformability and reduces the out-of-plane deformations of the soft monolithic fingers upon grasping different objects and consequently, resulting in the gripper in three different configurations including two, three and four-finger configurations successfully grasping a wide variety of objects.

Study on dry friction vibration model based on energy method

Purpose This study aims to establish the friction vibration model. Design/methodology/approach The friction vibration experiment was carried out on a pin disk friction tester. The causes of friction vibration are discussed, and the friction vibration model is established based on the energy method. Findings The experimental and simulation results show that the main cause of friction vibration is the nonlinear change of friction coefficient; degree of the friction vibration has a positive relationship with the friction relative velocity and normal contact positive pressure; the proposed friction vibration model is highly consistent in chaotic attractor and time-frequency distribution map and can well predict friction vibration. Originality/value The proposed friction vibration model is highly consistent in chaotic attractor and time-frequency distribution map and can well predict friction vibration.

Non-invasive Respiratory Support in COVID-19: A Narrative Review

Acute respiratory failure secondary to COVID-19 pneumonia may require a variety of non-pharmacological strategies in addition to oxygen therapy to avoid endotracheal intubation. The response to all these strategies, which include high nasal flow, continuous positive pressure, non-invasive ventilation, or even prone positioning in awake patients, can be highly variable depending on the predominant phenotypic involvement. Deciding when to replace conventional oxygen therapy with non-invasive respiratory support, which to choose, the role of combined methods, definitions, and attitudes toward treatment failure, and improved case improvement procedures are directly relevant clinical questions for the daily care of critically ill COVID-19 patients. The experience accumulated after more than a year of the pandemic should lead to developing recommendations that give answers to all these questions.