Unidirectional Valve Research Articles

Analysis of the positive expiratory pressure valves of coupled oronasal mask

Positive expiratory pressure (PEP) is a technique used in respiratory physiotherapy to treat diseases related to the respiratory system through spontaneous breathing. This equipment consists of an oronasal mask coupled to a T connector with a unidirectional valve. Studies that evaluate whether the pressure level in the one-way valve corresponds to the actual pressure level provided are scarce in the scientific literature. In order to investigate the failures, bench tests were carried out on the spring-loaded valves, using a U-tube manometer. This pressure was exerted on the valve using a syringe that generated air flow inside the U-tube, allowing analysis numerical value of the measured pressure and the specified values of the valve, thus verifying the disparity of these measured values in relation to the PEP values operated by valves (0 to 20 cmH2O) from the three manufacturers under study. PEPs generated by spring-loaded valves from all three manufacturers were higher than pressures in the range of 2.5 to 20 cmH2O, with significant differences between manufacturers. This bench study showed inaccurate operation of all spring-loaded PEP valves of the three manufactures. The results obtained and the performance of the valves require a reevaluation of manufacturing procedures to preserve product quality and efficacy in clinical application.

Janus graphene oxide membrane with rational allocation of functional regions as unidirectional ion valve system

Membrane-based ion sieving is critical to green desalination processes such as sustainable ionic resource extraction. Two-dimensional (2D) graphene oxide (GO) membranes exhibit unique ionic transport properties owning to the supernormal enhancement of channel effects induced by diverse functional regions under nanoconfinement. However, the discrete and random distribution of the hydrophilic/hydrophobic and positively/negatively charged regions restricts the GO membrane to give full play to its potential in selective ions separation. Herein, a novel strategy is proposed to engineer the asymmetric three-tier architecture of a Janus GO membrane with rational allocation of functional regions. The wise series connection of ① surface positively charged hydrophilic layer of PEI, ② intermediate negatively charged hydrophilic layer of GO and ③ bottom hydrophobic porous layer of rGO along the cross-membrane direction established internal gradients of structure, wetting and charge, resulting in reinforced exclusion of retained divalent ions and reduced stagnation of targeted monovalent ions. Based on the continuous anisotropic gradients, the Janus GO membrane was endowed with the unique capability to act as a unidirectional ion valve system, showcasing impressive permeation performance of monovalent ions permeation rate of 0.244 mol m−2 h−1 with monovalent/divalent ions selectivity of 66.1, and remarkable nanofiltration performance of divalent salt rejections of >96.5 % with monovalent/divalent ions separation factor up to 70.9. The implications of this work will revolutionize the regulation and functionalization of 2D nanofluidic channels for selective ions transport, which is highly desirable for a wide range of green desalination applications.

Comparison between use of a pleural drainage system with flutter valve and a conventional water-seal drainage system after lung resection: a randomized prospective study.

There is still a debate regarding the most appropriate pleural collector model to ensure a short hospital stay and minimum complications. To study aimed to compare the time of air leak, time to drain removal, and length of hospital stay between a standard water-seal drainage system and a pleural collector system with a unidirectional flutter valve and rigid chamber. A randomized prospective clinical trial was conducted at a high-complexity hospital in São Paulo, Brazil. Sixty-three patients who underwent open or video-assisted thoracoscopic lung wedge resection or lobectomy were randomized into two groups, according to the drainage system used: the control group (WS), which used a conventional water-seal pleural collector, and the study group (V), which used a flutter valve device (Sinapi® Model XL1000®). Variables related to the drainage system, time of air leak, time to drain removal, and time spent in hospital were compared between the groups. Most patients (63%) had lung cancer. No differences were observed between the groups in the time of air leak or time spent hospitalized. The time to drain removal was slightly shorter in the V group; however, the difference was not statistically significant. Seven patients presented with surgery-related complications: five and two in the WS and V groups, respectively. Air leak, time to drain removal, and time spent in the hospital were similar between the groups. The system used in the V group resulted in no adverse events and was safe. RBR-85qq6jc (https://ensaiosclinicos.gov.br/rg/RBR-85qq6jc).

Control of intracellular pH and bicarbonate by CO2 diffusion into human sperm

The reaction of CO2 with H2O to form bicarbonate (HCO3−) and H+ controls sperm motility and fertilization via HCO3−-stimulated cAMP synthesis. A complex network of signaling proteins participates in this reaction. Here, we identify key players that regulate intracellular pH (pHi) and HCO3− in human sperm by quantitative mass spectrometry (MS) and kinetic patch-clamp fluorometry. The resting pHi is set by amiloride-sensitive Na+/H+ exchange. The sperm-specific putative Na+/H+ exchanger SLC9C1, unlike its sea urchin homologue, is not gated by voltage or cAMP. Transporters and channels implied in HCO3− transport are not detected, and may be present at copy numbers < 10 molecules/sperm cell. Instead, HCO3− is produced by diffusion of CO2 into cells and readjustment of the CO2/HCO3−/H+ equilibrium. The proton channel Hv1 may serve as a unidirectional valve that blunts the acidification ensuing from HCO3− synthesis. This work provides a new framework for the study of male infertility.

Development of gradient-wetting Janus wood membrane with high-efficiency fog collection and oil-water separation

Conventional preparation of Janus membranes with asymmetric wettability focuses on the preparation of extreme hydrophilic side and hydrophobic side, but suffers from pore clogging, low liquid transfer and collection efficiency and short service life. In this study, Janus wood (JW) with a continuous wettability gradient was created throughunidirectional vacuum impregnation of a hydrophobic solvent after the delignification of wood. Digital image correlation (DIC) and layer-by-layer contact angle assessment were utilized to examine the thickness-dependent wettability gradient of the JW membrane. The JW membrane completed the modification of the cell walls without blocking the cell lumens. The presence of wettability gradient in the JW membrane effectively reduced the capillary force of liquid penetration, resulting in decreased adhesion and stagnation of liquid on the membrane surface, and increased flow rate and transport efficiency. Based on the continuous wettability change of the JW membrane, the JW membrane was endowed with the ability to act as a “unidirectional valve” to enable continuous and rapid directional transport of liquids. The mechanical properties of the JW membrane prepared by the unidirectional introduction method were significantly improved, rendering them highly stable and environmentally durable. The fog collection efficiency of the JW membrane was maintained at 97.7% over 10 repeated use cycles. For light oil/water and heavy oil/water mixtures, JW membrane maintained an efficiency of 99.6% or higher. Unlike conventional surface modification methods, the unidirectional introduction method proved practical and effective for modifying the JW membrane in the thickness direction. Furthermore, the prepared JW membrane was sustainable, inexpensive, durable, and environmentally friendly. This study provides a wide range of potential applications in fields such as droplet manipulation, multi-liquid separation, industrial wastewater purification, and microfluidics.

Design Approach For Ambu Bag Automation

The main objective of this paper is improve the system and the working of the ambu bag by automation with reliable cost. Existing ambu bag system is very efficient but it has certain drawbacks which made it not much helpful the emergency conditions like pandemic Covid-19. The existing ambu bag system which can provide medical assistance to patients. It creates difficulty when there is extreme need to provide the oxygen and the patients required to move from remote area for the better medical help. Where at the earlier system was made to prevent from failure in supply of the oxygen, low level of the oxygen reservoir, the pressure of the air, here the new system is based on salving the new problems arrived the maximum time it can take to move the patients, consistency in inflating the bag and widening if making advancement. Future work is needed to achieve the potential of this approach by developing policies, updating regulations, and securing funding mechanism for the development and testing for open source Ambu Bag Automation for both the current Covid- 19 pandemic as well as for the future pandemic, for all the emergency conditions &amp; for everyday use in low- resource settings. A bag used to give rescue breaths for victims of cardiac arrest, used along with a face mask (bag and mask ventilation). It is an integral part of any emergency kit. Holger Hesse and Henning Ruben introduced the concept of bag-valve-mask (BVM) 1953. There is a unidirectional valve at the patient end of the BVM. When the rescuer initially attaches the bag with the mask over the face and nostril of the victim who has stopped breathing. The rescuer then squeezes the bag and air enters the lungs of the victim. The self-inflating bag fills up on releasing the squeezing effort. The unidirectional valve prevents sucking in of expired air when the bag inflates. An Ambu Bag is a device that is needed when a person can't breathe properly or they can't breathe on their own. Ambu Bags are very important for sufferers of COVID-19 &amp; other breathing problems and existing ventilators in hospitals are very complex &amp; are very expensive. The availability of existing ventilators is not sufficient to meet the demand when the patients in hospitals are more due to pandemic like situations and many countries will struggle to afford expensive conventional ventilators, and so many critically ill patients are dying because of lack of ventilator facility, so we need an alternative to meet the demand. In this paper we are going review methods to make an automatic ambu bag operating device with a simple mechanism and cost- effective.

Maximal expiratory pressure compared with maximal expiratory pressure during induced cough as a predictor of extubation failure.

To compare the diagnostic performance of maximal expiratory pressure with maximal expiratory pressure during induced cough for predicting extubation failure within 72 hours in patients who completed a spontaneous breathing trial (SBT). The study was conducted between October 2018 and September 2019. All patients aged over 18 years admitted to the intensive care unit who required invasive mechanical ventilation for over 48 hours and successfully completed a spontaneous breathing trial were included. The maximal expiratory pressure was assessed with a unidirectional valve for 40 seconds, and verbal encouragement was given. The maximal expiratory pressure during induced cough was measured with slow instillation of 2mL of a 0.9% saline solution. The primary outcome variable was extubation failure. Eighty patients were included, of which 43 (54%) were male. Twenty-two patients [27.5% (95%CI 18.9 - 38.1)] failed extubation within 72 hours. Differences were observed in the maximal expiratory pressure during induced cough between the group who failed extubation, with a median of 0cmH2O (P25-75: 0 - 90), and the group without extubation failure, with a median of 120cmH2O (P25-75: 73 - 120); p < 0.001. In patients who completed a spontaneous breathing trial, the maximal expiratory pressure during induced cough had a higher diagnostic performance for predicting extubation failure within 72 hours.Clinicaltrials.gov Registry: NCT04356625.

Comparação da pressão expiratória máxima e da pressão expiratória máxima durante a tosse induzida como preditor de falha na extubação

OBJECTIVE: To compare the diagnostic performance of maximal expiratory pressure with maximal expiratory pressure during induced cough for predicting extubation failure within 72 hours in patients who completed a spontaneous breathing trial (SBT). METHODS: The study was conducted between October 2018 and September 2019. All patients aged over 18 years admitted to the intensive care unit who required invasive mechanical ventilation for over 48 hours and successfully completed a spontaneous breathing trial were included. The maximal expiratory pressure was assessed with a unidirectional valve for 40 seconds, and verbal encouragement was given. The maximal expiratory pressure during induced cough was measured with slow instillation of 2mL of a 0.9% saline solution. The primary outcome variable was extubation failure. RESULTS: Eighty patients were included, of which 43 (54%) were male. Twenty-two patients [27.5% (95%CI 18.9 - 38.1)] failed extubation within 72 hours. Differences were observed in the maximal expiratory pressure during induced cough between the group who failed extubation, with a median of 0cmH2O (P25-75: 0 - 90), and the group without extubation failure, with a median of 120cmH2O (P25-75: 73 - 120); p < 0.001. CONCLUSION: In patients who completed a spontaneous breathing trial, the maximal expiratory pressure during induced cough had a higher diagnostic performance for predicting extubation failure within 72 hours. Clinicaltrials.gov Registry: NCT04356625

Efficacy of selective bronchial occlusion in the treatment of biliary bronchial fistula

Objective: To analyze the effect of selective bronchial occlusion (SBO) in the treatment of biliary bronchial fistula (BBF). Methods: Eight patients with BBF that without biliary obstruction admitted to the Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Naval Medical University from January 1, 2015 to December 31, 2021 were included in this study. Bronchial silicone plug (6 cases) and autologous blood+thrombin (2 cases) were used as sealing materials for SBO treatment for the first time. Among the 7 patients who underwent subsequent closure treatment, 5 cases were blocked by bronchial silicone plug, 1 case was blocked by "bronchial silicone plug+bullet-covered stent" and 1 case was blocked by "bronchial silicone plug+bronchial one-way valve". The clinical data related to SBO treatment were collected and patients were followed up, and the therapeutic effect of SBO on BBF was analyzed. Results: The age of BBF onset was (58±9) years old, including 6 males. Among the 6 patients who used bronchial silicone plug as plugging material in the first SBO treatment, 1 case was successfully plugged, 2 cases did not achieve symptoms relief after plugging, 2 cases coughed up the plugging device immediately after surgery, and 1 case developed a new fistula. Autologous blood and thrombin were used as sealing materials in 2 patients, and both failed. Among the 7 patients who received subsequent closure treatment, bronchial silicone plug+bullet-covered stent (1 case) and bronchial silicone plug+bronchial unidirectional valve (1 case) were successful. After 2-6 times of bronchial silicone plug (5 cases), fistula were successfully blocked in 3 cases, and the frequency and volume of bile-like sputum decreased by 50% or more in 2 cases. The main postoperative complications were fever and cough (expectoration) in 7 and 6 cases, respectively. During the follow-up period, 2 patients were lost to follow-up, and the remaining 6 patients were followed up for 2-31 months. During the follow-up period, the effect of closure treatment was basically stable, and there was no death case. Conclusion: SBO therapy provides a safe and feasible palliative treatment for BBF.

Alternative therapy for respiratory muscle training using breath stacking

Objective: To evaluate the effectiveness of the breath-stacking technique as a method of ventilatory muscle training. Methods: Thirty-eight healthy youngsters were included in the study. The maximum respiratory pressures were evaluated in cmH2O by a digital manovacuometer. The breath-stacking system (face mask attached to a T-tube with a unidirectional inspiratory valve) was used as an overload method in a 4-week 12-session ventilatory muscle training program. Results: Both maximal inspiratory and expiratory pressures increased significantly after ventilatory muscle training for all. Positive peak pressure also increased significantly at the end of the program. Conclusion: Breath-stacking generates sufficient overload to ventilatory muscles to consistently increase maximal respiratory pressures when used in a ventilatory muscle training protocol. The technique was well tolerated, although it needs to be tested in clinical situations involving muscle weakness and other organic dysfunctions.

WHERE IS THE AIR? THE CASE OF A NON-ISOLATING AIR LEAK IN A 19-YEAR-OLD THORACIC STAB WOUND PATIENT

TOPIC: Procedures TYPE: Fellow Case Reports INTRODUCTION: Unidirectional bronchoscopically deployed endobronchial valves have been are indicated for emphysematous disease as an alternative to lung volume reduction surgery. These valves have found a second indication in the treatment of bronchopleural fistulas. CASE PRESENTATION: A 19 year-old male presented with multiple stab wounds after a homicide attempt. The patient had a series of intra-thoracic surgeries including partial wedge resection of the left upper lobe, removal of impaled knife from thoracic vertebra, several orthopedic procedures, and an esophageal repair. The two left sided large bore chest tubes placed intraoperatively had persistent air leaks on post-operative day 6 (image 1). We attempted a bronchoscopic balloon occlusion of the airway to isolate a suspected bronchopleural fistula with the intent to place a unidirectional endobronchial valve. However, balloon occlusion of the left upper lobe and then the left lower lobe did not result in an appreciable decrease in air leak. The entire left mainstem bronchus was then occluded without a decrease air leak (image 2). As such no valve could be deployed and the procedure was aborted. Careful consideration was given to the alternative sources of intra-thoracic air including fistulation from the esophagus or mediastinum. We considered abdominal free air crossing the diaphragm and even free air crossing the contralateral hemithorax. After these had been carefully ruled out with contrast studies and imaging, the patient was scheduled for video-assisted thoracic surgery (VATS) with wedge resection. On the morning of surgery, we noted that the patient's chest tubes were leaking around the insertion site. Furthermore there was fluid bubbling around the insertion site suggesting that the site itself was the origin of the patient's intrathoracic air. Both chest tubes were then removed and replaced with a small-bore pigtail chest tube resulting in complete resolution of air leak (image 3). DISCUSSION: The technique for placing unidirectional endobronchial valves for a bronchopleural fistula first involves isolating the source of the air leak. Segments of the affected lung are occluded using a sizing balloon starting proximally. When the segment where the bronchopleural fistula originates is occluded, the air leak will diminish indicating a decrease in airflow distally. A unidirectional endobronchial valve can then be deployed resulting in occlusion of the diseased airway, distal atelectasis, and a resolution of the bronchopleural fistula. This algorithmic approach will identify the diseased segment unless there is significant collateralization of airways, in which case a VATS is indicated. Our case highlights how alternative sources of air leak should be entertained prior to more aggressive surgical intervention. CONCLUSIONS: The patient's VATS was canceled and he has made a full recovery. REFERENCE #1: Mahajan AK, Khandhar SJ. Bronchoscopic valves for prolonged air leak: current status and technique. J Thorac Dis. 2017;9(Suppl 2):S110-S115. doi:10.21037/jtd.2016.12.63 REFERENCE #2: Travaline JM, McKenna RJ, Jr, De Giacomo T, et al. Treatment of persistent pulmonary air leaks using endobronchial valves. Chest 2009;136:355-60. 10.1378/chest.08-2389 REFERENCE #3: Reed MF, Gilbert CR, Taylor MD, et al. Endobronchial Valves for Challenging Air Leaks. Ann Thorac Surg 2015;100:1181-6. 10.1016/j.athoracsur.2015.04.104 DISCLOSURES: No relevant relationships by Jonathan Xian, source=Web Response

A Slip-Force Device for Maintaining Constant Lateral Pressure on Retaining Structures in Expansive Soils

Expansive soils can pose tough issues to civil engineering applications. In a typical year, expansive soils can cause a greater financial loss than earthquakes, floods, hurricanes and tornadoes combined. Various means have been studied to tackle problems associated with expansive soils. The majority of the methods are based on treatment of the soils. While the methods may be effective in some cases, their limitations are also obvious: The treatment normally involves complex processes and may not be eco-friendly in the long run. In many cases, the effectiveness of the treatment is uncertain. A retaining system that maintains a constant lateral pressure is proposed, which consists of three components: the retaining sheet, the slip-force device and the bracing column. The retaining sheet bears the pressure exerted by expansive backfills and is not embedded into the soils. Placed between the retaining sheet and bracing column, the slip-force device permits displacement of the retaining sheet but keeps the force on the sheet and the bracing column constant. The governing equation of the motion of the piston in the slip-force device is derived and a numerical simulation of a practical case is conducted based on the derived governing equation. Numerical results show that as the expansive soil swell, the spring force will increase and the piston will move accordingly. When the pressure of the oil in chamber reaches the open threshold of the unidirectional relief valve, the valve will open and the spring force and the oil pressure in the chamber will keep constant. The results also show that some parameters, such as damping ratio, have very slight influences on the device behavior, say 2 × 10-6 or even 4.8 × 10-9. Theoretical and numerical studies prove the effectiveness of the proposed retaining system.

Abstract 15801: Early and Late Risk of Mortality or Development of Severe Pulmonary Hypertension Following Closure of Ventricular Septal Defects in Children With Severe Pulmonary Hypertension and Elevated Pulmonary Vascular Resistance Using Traditional or Uni-directional Flap Valve Patch Closure

Introduction: Children with large ventricular septal defects, severe pulmonary hypertension (PHT), and elevated pulmonary vascular resistance (PVR) are frequently denied operation in low and middle-income countries secondary to concerns of high mortality and development of severe pulmonary hypertension following operation, early and late. Hypothesis: We hypothesized that closure with a uni-directional flap valve patch (DP) would provide lower mortality and better survival without severe PHT. Methods: From 5/96 - 12/2016 all patients undergoing VSD closure with severe PHT and elevated PVR by either traditional (TP) or DP closure were followed annually. Baseline and O 2 provocation catheterization were performed before operation. Echocardiograms were performed at discharge and follow-up. The decision on TP or DP closure was based upon age and surgeon preference. Beginning in 2005 all patients regardless of technique received sildenafil 3 mgs/kg/day for 3 months before operation. Results: The number of patients receiving operation was 129, of which 40 received the DP. Males were 66/129, age and weight differed significantly for DP group compared to the TP group (7.5 vs 2.6 years, p&lt;0.001 and 20 vs 11.5 kgs, p&lt;0.001).Catheterization baseline data, PVR 9.0 vs 7.4 for DP and TP respectively (p&lt;0.001), negative vasoactive test 32.5% vs 13.5% for DP and TP respectively (p=0.016). Mortality was 1/40 for DP and 9/89 for TP. Pulmonary to Systemic systolic pressure ratio was lower at discharge vs baseline cath (0.38 vs 0.99, p&lt;0.001). Predictors of late severe pulmonary hypertension were PVR/SVR &gt;0.5, p&lt;0.024; and a negative vasoactive test of &lt;10% decrease, p&lt;0.001. PHT at last follow-up, none or mild 86/115 (74.8%), moderate 16/115 (13.9%) or severe 13/115 (11.3%). Conclusions: DP patients had less risk of death and both groups had few patients with severe PHT at late follow-up..

Improvement in Lung Insufflation in Spontaneously Breathing Tracheostomized Patients by Using a New Pulmonary Expansion Device: A Pilot Study

Abstract Lung expansion techniques (LETs) are a key component of pulmonary rehabilitation. Nevertheless, these can be limited in tracheostomized patients because of the infraglottic position of tracheostomy cannulas. We propose a novel pulmonary expansion device (PED) that allows deep inspiration with a postinspiratory pause for a few seconds by means of a unidirectional valve and an occlusion/flow release cap. It is equipped with a relief valve that opens at 60 cm H2O in cases in which this threshold is attained. We aimed to evaluate the impact on lung volume and pressure in spontaneously breathing tracheostomized patients subjected to LETs. A single-arm pilot interventional study was conducted in an adult intensive care unit (ICU), including spontaneously breathing tracheostomized patients. 80 treatments were performed on 10 patients with tracheostomies with PED over a period of 3 months. The maximal inspiratory volume (MIV) was significantly increased by using PED (MIV-PED) at both day 1 (725 (600–820) mL versus 1550 (1250–1700) mL, P &amp;lt; 0.001) and day 3 (870 (750–950) mL versus 1662 (1550–1900) mL, P &amp;lt; 0.001). Inspiratory pause pressure (PIP-PED) did not significantly change from day 1 to day 3 (18 (14–20) cm H2O versus 14 (12–22) cm H2O, P = 0.36). The use of the PED in tracheostomy patients acted as an artificial glottis by performing a novel pulmonary re-expansion maneuver, and increased volumes and intrapulmonary pressure with prolongation of maximum inspiration were achieved.

Valve patch technique for repair of ventricular septal defect: long-term results

This study aimed to show the long-term results in patients who underwent unidirectional valve patch repair of ventricular septal defect with pulmonary artery hypertension. Thirty-five acyanotic patients aged 2 to 26 years (mean 9.3 years) with a large ventricular septal defect and elevated pulmonary vascular resistance (mean 9.5 Wood units) underwent surgery in Madani Heart Hospital. The medical records and clinical outcomes were reviewed from March 1998 to March 2017. Five patients died in the first postoperative week. In the long-term follow-up (mean 11 years), two patients were lost to follow-up. Pulmonary artery hypertension gradually decreased in 17 patients within 6-12 months with significant improvement in right ventricular end-diastolic diameter, New York Heart Association functional class, and tricuspid regurgitation. Eleven patients with persistent pulmonary artery hypertension were divided into tolerable and non-tolerable groups. Six patients in the tolerable group had satisfactory conditions compared to before the operation, and gained weight with improved functional class despite echocardiographic findings of persistent elevated pulmonary artery pressure. One had a full-term delivery by caesarean section in the fifth postoperative year. Five patients in the non-tolerable group gradually developed right heart failure and complications such as extremity edema, ascites, pleural effusions, and died after 10-30 months. Although relatively high mortality occurred during long-term follow-up, surviving patients were in a better condition and functional class despite persistent pulmonary artery hypertension. Therefore, fear of persistent pulmonary artery hypertension should not prohibit surgery in this group of patients.

Percutaneous Treatment of Meckel Cave Arachnoid Cyst: Case Report, Surgical Strategy and Literature Review

AbstractArachnoid cysts are benign intracranial lesions. They are usually located in the middle fossa, but can be found in other locations. We present a case of symptomatic Meckel cave (MC) arachnoid cyst - a very rare location - and a treatment strategy not elsewhere described before for this condition. A 54-year-old female with trigeminal neuralgia with previous history of radiofrequency rhizotomy treatment 6 years before admission had been experiencing pain recurrence with progression, which required successive increases in carbamazepine dosage. Magnetic Resonance Imaging (MRI) showed dilatation of the right MC with extension to the petrous apex. The lesion was compatible with arachnoid cyst, and due to the worsening of the clinical condition, surgical treatment was chosen. Percutaneous puncture of the cyst through the foramen ovale with injection of intracystic fibrin sealant was performed. The patient woke up from anesthesia with pain improvement and was discharged asymptomatic the next day. After 12 months of follow-up, she remained pain-free. In the literature review, we found only eight cases reported as MC arachnoid cyst. These are likely to progress and become symptomatic owing to their communication with the subarachnoid space and a unidirectional valve mechanism. Pain improvement with this technique is probably secondary to the interruption of these mechanisms.

Design of a unidirectional water valve in Tillandsia

The bromeliad Tillandsia landbeckii thrives in the Atacama desert of Chile using the fog captured by specialized leaf trichomes to satisfy its water needs. However, it is still unclear how the trichome of T. landbeckii and other Tillandsia species is able to absorb fine water droplets during intermittent fog events while also preventing evaporation when the plant is exposed to the desert’s hyperarid conditions. Here, we explain how a 5800-fold asymmetry in water conductance arises from a clever juxtaposition of a thick hygroscopic wall and a semipermeable membrane. While absorption is achieved by osmosis of liquid water, evaporation under dry external conditions shifts the liquid-gas interface forcing water to diffuse through the thick trichome wall in the vapor phase. We confirm this mechanism by fabricating artificial composite membranes mimicking the trichome structure. The reliance on intrinsic material properties instead of moving parts makes the trichome a promising basis for the development of microfluidics valves.

Robust Repetitive Learning-Based Trajectory Tracking Control for a Leg Exoskeleton Driven by Hybrid Hydraulic System

For the purpose of reducing power consumption of a leg exoskeleton for augmenting human performance, a novel hybrid hydraulic system (HHS) which includes a unidirectional servo valve and a solenoid on-off valve is excogitated, and its energy saving control is studied in this paper. Inspired by the varieties of contact force between human leg and ground during walking, the unidirectional servo valve and the solenoid on-off valve are only activated in the stance phase and the swing phase, respectively. In the stance phase, a robust repetitive learning scheme is presented by using the backstepping technique for the unidirectional servo valve, aiming to track the periodic human leg movement, and in the swing phase, an on-off control is proposed for the solenoid valve to release the pressure in the hydraulic cylinder so that the exoskeleton leg is bent by the human leg passively. The proposed control strategy is implemented in an ARM-based embedded microprocessor and the control performance is verified via experiment on the developed exoskeleton robot. The experimental results show that the power consumption of the proposed system is almost 30% less than that of systems with bidirectional hydraulic system.

Efficacy of Ultrasound-Guided Unidirectional Valve Enlargement in Treatment of Popliteal Cysts

Purpose: To investigate the effect of ultrasound-guided unidirectional valve cleft enlargement in the treatment of popliteal cysts. Methods: Forty-eight patients with popliteal cysts who met the inclusion criteria and were admitted to our hospital from December 2018 to June 2020 were randomly divided into group A (24 cases) and group B (24 cases). Group A was treated with a central venous catheter dilator, and group B was treated with traditional open surgery to remove the popliteal cyst. Visual analogue scale (VAS) was used to evaluate discomfort. The VAS, Lysholm score of knee joint and Rauschning-Lindgren grade 0~I improvement rate were compared at 6 months after operation. Results: The postoperative VAS in group A was significantly better than that in group B (P < 0.05), and the postoperative Lysholm score and Rauschning-Lindgren grade 0~I in group A were higher than those in group B (P < 0.05). There was no recurrence or other complications in either group. Conclusions: Ultrasound-guided central venous catheter dilator is more effective than traditional surgical resection of popliteal cysts.

Bronchoscopic lung volume reduction using an endobronchial valve to treat a huge emphysematous bullae: a case report

BackgroundIn patients with chronic obstructive pulmonary disease (COPD), bronchoscopic lung volume reduction (BLVR) techniques using unidirectional endobronchial valves improve lung function and increase exercise tolerance. BLVR treatment is included in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) treatment guidelines for COPD patients without interlobar collateral ventilation. However, BLVR using an endobronchial valve has not been attempted in patients with giant bullae.Case presentationWe report successful and safe BLVR using an endobronchial valve in a patient with a huge bullous emphysema in the right middle lobe. A 65-year-old male was diagnosed with COPD 5 years prior and had a large bullae in the right middle lobe at that time. During regular follow-up, the symptoms of respiratory distress gradually worsened, and the size of the bullae gradually increased on computed tomography (CT). Therefore, we decided to treat the patient via BLVR using an unidirectional endobronchial valve. The Chartis system (Pulmonx, Inc., Palo Alto, CA) confirmed the absence of collateral ventilation of the right middle lobe. We successfully inserted an endobronchial valve into the right middle bronchus. After insertion, the bullae decreased dramatically in size, and the patient’s symptoms and quality of life improved markedly.ConclusionThis case supports recent suggestions that BLVR can serve as a good alternative treatment for appropriately selected patients.