Wall Oscillation Research Articles

Chest physiotherapy can affect the lung clearance index in cystic fibrosis patients.

The lung clearance index (LCI) is determined by multiple-breath washout lung function (MBW). It is increasingly used as an endpoint in clinical trials. Chest physiotherapy (CP) is part of routine cystic fibrosis (CF) care. Whether the LCI is useful in detecting short-term treatment effects of CP has not been sufficiently investigated. We assessed the short-term influence of CP with highly standardized high-frequency chest wall oscillation (HFCWO) on the LCI in CF patients. In this randomized controlled study, the LCI was obtained in 20 CF patients (7-34 years) hospitalized for infective pulmonary exacerbation prior to and immediately after a single treatment of HFCWO. Twenty-one control group CF patients (7-51 years) received no treatment. We calculated the coefficient of repeatability (CR) to estimate the clinical relevance of possible treatment effects. HFCWO improved (ie, decreased) the LCI by a median of 0.9 (range -0.45; 3.47; P = 0.002); the LCI decreased in 15 of 20 intervention group patients. In five patients the decrease in LCI exceeded the CR (2.15), indicating a clinically relevant treatment effect; in five patients the LCI increased but did not exceed the CR. The LCI did not change significantly in the control group patients. HFCWO can have a short-term decreasing effect on the LCI, but the treatment response is heterogeneous. In future trials using LCI as an endpoint, the timing of CP in relation to MBW should be considered a possible bias.

Interaction dynamics of pulsating viscous liquid with the walls of the conduit on an elastic foundation

Bending oscillations of walls of conduit on Winkler foundation under the influence of pulsating flow of viscous liquid have been studied. The statement and solution of hyper-elasticity problem have allowed analytical expressions for channel wall bends and pressure in liquid to be defined, as well as the distribution functions for bend amplitudes and pressures along the channel to be plotted. The performed calculations showed the significant impact of taking into consideration the elastic compliance of the channel foundation on the bend amplitude of channel walls and pressure in the channel. The obtained results present the possibilities of studying the dynamic processes conditioned by the interactions of elastic structural elements with viscous liquid in hydraulic drives, assemblies, and devices.

Comparative Study of High Frequency Chest Wall Oscillation and Traditional Chest Physical Therapy in Intensive Care Unit Patients

Aims and objective: The aim of this study was to compare the efficacious treatment in intensive care unit patients: high frequency chest wall oscillation (HFCWO¸VEST) versus chest physiotherapy (CPT).Background: Patients with lung disease often have respiratory infections and hospitalization caused by sputum retention. Intensive care unit patients usually have intubated and ventilator and this make it difficult to clean the airway. Methods: A comparison study with random sampling was carried out 559 patients in the intensive care unit were recruited in the study. Patients either received HFCWO therapy using the vest system (n=208) or received CPT (n=351). The primary outcomes were length of stay in intensive care unit and the duration of mechanical ventilation, comfortable with therapy and lung condition were compared between the two groups. Result: The patients treated by the high frequency chest wall oscillation, their duration of mechanical ventilation (p=0.014), chest X-ray (p<0.0001) and their comfortability (p<0.0001) were significantly better than the chest physiotherapy patients. The sputum volume did not differ significantly between the two groups (p=0.085). Conclusion: HFCWO was associated with better comfort, produced an improvement in lung condition, and reduced the number of days to use the ventilator on patients who are in intensive care units, compared to manual percussion of CPT. HFCWO can be performed in acutely ill patients who may be unable to use handheld devices effectively. Those patients need airway clearance in intensive care units; this treatment could be included among the options in chest physiotherapy.

A comparison of high frequency chest wall oscillation and intrapulmonary percussive ventilation for airway clearance in pediatric patients with tracheostomy

ABSTRACTObjectives: The aim of this study was to compare two modes of airway clearance, the intrapulmonary percussive ventilation system (IPV) to high frequency chest wall oscillation system (HFCWO) in medically complex pediatric patients with tracheostomy requiring long term care.Methods: This was a single center, retrospective study comparing the number of respiratory illnesses, lower respiratory tract infections (LRTI), utilization of bronchodilator and systemic steroids, and respiratory illnesses requiring acute care hospitalizations. A total of 8 tracheostomy dependent patients between the ages of 1–22 years were included for a 2-year study period. Each patient was used as their own control. During the period studied, the only variable in the medical regimen was the modality used for airway clearance. A Poisson regression model and generalized estimating equations were used to compare pre and post rates and to account for the correlation of count data from the same individual. Additionally, the paired differences (post—pre) for each event count were computed to provide the median and range of reductions in event rates while using intrapulmonary percussive ventilation system device. The non-parametric wilcoxon signed-rank test employed to determine whether the results from the Poisson model were consistently observed regardless of method of analysis.Results: The total number of respiratory illnesses were reduced from 32 per year on HFCWO therapy to 15 per year on IPV system therapy (p < 0.001). The total number of LRTI requiring antibiotic use were decreased from 15 per year to 6 per year (p = 0.01), use of bronchodilator treatments were reduced from 53 to 21 (p < 0.001) and utilization of systemic steroids were reduced from 12 to 4 on IPV (p = 0.003). Numbers of hospitalizations to acute care facilities were reduced from 8 to 3 hospitalizations during the period of IPV use for airway clearance (p = 0.003).Conclusion: This study suggests that airway clearance by IPV therapy could be more effective and beneficial in providing airway clearance in specific subsets of the medically complex pediatric population.

Intrapulmonary Percussive Ventilation as a Lung Recruitment Strategy in Brain-Dead Organ Donors.

To determine the strength of the evidence evaluating the effectiveness of intrapulmonary percussive ventilation (IPV) as a safe alternative or adjunctive therapy to traditional chest physiotherapy (CPT) among potential organ donors. Literature search conducted from February 2015 to November 2015 using PubMed, Cumulative Index of Nursing and Allied Health Literature, Scopus, and bibliographies of pertinent articles. Search Terms: Intrapulmonary percussive ventilation, chest physiotherapy, chest wall oscillation, organ donors, and ventilation. Articles in English from 1994 to present directly compared IPV to CPT or conventional (no) therapy. Association of Critical-Care Nurses Levels of Evidence was used to determine the strength of evidence. Level B and level C articles were reviewed. No studies were found using IPV in the donor population. Results from studies using IPV in other populations indicated IPV had no adverse effects, improved sputum clearance and oxygenation, and reduced atelectasis and pneumonia in patients with artificial airways. Intrapulmonary percussive ventilation may be a safe and effective alternative or adjunctive to CPT therapy and improve the number of lungs available for transplantation. Clinical research is essential to determine the effectiveness of this therapy for lung recruitment in the donor population.

Ferromagnetic resonance in interacting magnetic microstrips

The results of the micromagnetic simulation of forced oscillations of the magnetization in a system of two interacting microstrips located at an angle to each other have been presented. The ferromagnetic resonance spectra and the mode composition of resonant oscillations of the system have been investigated under the conditions of magnetostatic and exchange interactions between the microstrips. It has been shown that the magnetostatic interaction leads to the possibility of the excitation of in-phase and out-of-phase coupled oscillations of the magnetization of the microstrips. In the systems of exchange-coupled microstrips, there are intense resonances due to oscillations of the domain walls. The transformation of the ferromagnetic resonance spectrum and the change in the mode composition of resonant oscillations in different equilibrium configurations of the magnetization of the system have been discussed, as well as the conditions for the excitation of oscillations of different types depending on the direction of the microwave magnetic field.

Simultaneous pulsatile flow and oscillating wall of a non-Newtonian liquid

In this work, analytical predictions of the rectilinear flow of a non-Newtonian liquid are given. The fluid is subjected to a combined flow: A pulsatile time-dependent pressure gradient and a random longitudinal vibration at the wall acting simultaneously. The fluctuating component of the combined pressure gradient and oscillating flow is assumed to be of small amplitude and can be adequately represented by a weakly stochastic process, for which a quasi-static perturbation solution scheme is suggested, in terms of a small parameter. This flow is analyzed with the Tanner constitutive equation model with the viscosity function represented by the Ellis model. According to the coupled Tanner-Ellis model, the flow enhancement can be separated in two contributions (pulsatile and oscillating mechanisms) and the power requirement is always positive and can be interpreted as the sum of a pulsatile, oscillating, and the coupled systems respectively. Both expressions depend on the amplitude of the oscillations, the perturbation parameter, the exponent of the Ellis model (associated to the shear thinning or thickening mechanisms), and the Reynolds and Deborah numbers. At small wall stress values, the flow enhancement is dominated by the axial wall oscillations whereas at high wall stress values, the system is governed by the pulsating noise perturbation. The flow transition is obtained for a critical shear stress which is a function of the Reynolds number, dimensionless frequency and the ratio of the two amplitudes associated with the pulsating and oscillating perturbations. In addition, the flow enhancement is compared with analytical and numerical predictions of the Reiner-Phillipoff and Carreau models. Finally, the flow enhancement and power requirement are predicted using biological rheometric data of blood with low cholesterol content.

Application value of high frequency chest wall oscillation after operation of abdominal incisional hernia

Objective To investigate the application value of high frequency chest wall oscillation (HFCWO) after operation of abdominal incisional hernia. Methods A prospectively randomized double-blind study was adopted. Fifty patients who underwent operation of abdominal incisional hernia at the Huadong Hospital Affiliated to Fudan University between January 2014 and September 2015 were allocated into the HFCWO group (undergoing postoperative HFCWO) and control group [undergoing postoperative conventional chest physiotherapy (CPT )] using random number table. Observation indicators included: (1) adverse events, (2) pain perception index: postoperative pain intensity from 1 day to 5 days was assessed by visual analogue scale (VAS), (3) respiratory function: arterial oxygen saturation (SaO2), oxygenation index (OI), arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2) at postoperative day 1, 3 and 5, (4) follow-up. The follow-up using outpatient examination and telephone interview was performed to detect the recovery of patients up to March 2016. Measurement data with normal distribution were represented as ±s. The comparisons between groups were evaluated with the t test. The repeated measurement data were done using the repeated measures ANOVA and the count data were analyzed using the chi-square test. Results Fifty patients were screened for eligibility and were allocated into the 2 groups, 25 in each group. (1) Adverse events: all the patients in the 2 groups underwent successfully treatment, without the occurrence of hypoxemia, hemodynamic instability, arrhythmia, bronchospasm, vomiting, wound dehiscence, shedding catheter and so on. (2) Pain perception index: VAS from before chest treatment to postoperative day 5 was from 1.7±1.0 to 1.5±1.1 in the HFCWO group and from 1.4±0.8 to 1.8±0.6 in the control group, with a statistically significant difference in the change trend of pain intensity between the 2 groups (F=0.02, P 0. 05). (4) Follow-up: 43 patients were followed up after discharge from hospital for 1-6 months, with a median time of 5 months. During the follow-up, patients were not complicated with chest tightness and shortness of breath, with good wound healing. Conclusion Compared with conventional chest physiotherapy, HFCWO could improve tolerability of patients and reduce the pain after operation of abdominal incisional hernia. Key words: Abdominal incisional hernia; Surgical procedures, operative; High frequency chest wall oscillation

Efficacy of high frequency chest wall oscillation method in acute exacerbation of chronic obstructive pulmonary disease

This study was aimed at investigation of clinical efficacy and safety of high frequency chest wall oscillation (HFCWO) method in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods . This was a prospective randomized controlled comparative study. Patients hospitalized for AECOPD (GOLD III or IV stage; mean FEV 1, 37% pred.) were included. In first two days of admission, all patients were randomized to HFCWO treatment (Vest Ò Airway Clearance System; 15–25 min b.i.d.; oscillation frequency, 10–15 Hz; pressure, 4–6 cm H2O) or standard therapy (the control group). Results . Fifty patients completed the study: 25 patients in HFCWO group and 25 patients in the standard therapy group. Therapy with HFCWO was associated with increasing sputum volume to the 3 rd and the 7 th days of the study (р &lt; 0.001) and more significant reduction in symptom intensity compared to the controls (р = 0.006). Symptom severity measured with the BCSS score decreased by 3.4 and 1.5, respectively (р = 0,006). Therapy with HFCWO was also associated with more significant improvement in oxygenation parameters and reduction in C-reactive protein (CRP) level (р = 0,001 for both). Conclusion. Therefore, treatment with HFCWO was associated to improved sputum clearance, significant improvement in clinical symptoms, earlier oxygenation improvement and CRP reduction.

Effect of High-Frequency Chest Wall Oscillation on Sputum Discharge in the Patiens With Bronchiectasis: Preliminary Results

Effect of High-Frequency Chest Wall Oscillation on Sputum Discharge in the Patiens With Bronchiectasis: Preliminary Results

A SOLAR FLARE DISTURBING A LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

ABSTRACT With the high-resolution data from the Interface Region Imaging Spectrograph, we detect a light wall above a sunspot light bridge in the NOAA active region (AR) 12403. In the 1330 Å slit-jaw images, the light wall is brighter than the ambient areas while the wall top and base are much brighter than the wall body, and it keeps oscillating above the light bridge. A C8.0 flare caused by a filament activation occurred in this AR with the peak at 02:52 UT on 2015 August 28, and the flare’s one ribbon overlapped the light bridge, which was the observational base of the light wall. Consequently, the oscillation of the light wall was evidently disturbed. The mean projective oscillation amplitude of the light wall increased from 0.5 to 1.6 Mm before the flare and decreased to 0.6 Mm after the flare. We suggest that the light wall shares a group of magnetic field lines with the flare loops, which undergo a magnetic reconnection process, and they constitute a coupled system. When the magnetic field lines are pushed upward at the pre-flare stage, the light wall turns to the vertical direction, resulting in the increase of the light wall’s projective oscillation amplitude. After the magnetic reconnection takes place, a group of new field lines with smaller scales are formed underneath the reconnection site, and the light wall inclines. Thus, the projective amplitude notably decrease at the post-flare stage.

Molecular dynamics simulation of fluid properties by the streamwise oscillation of the solid wall

In this paper, the hydrodynamics of streamwise wall oscillations on a Couette flow are studied using the molecular dynamics method. Firstly, based on the two-dimensional Couette flow model which is made up of copper wall and argon fluid, the characters of the fluid near the streamwise oscillation wall are simulated under the condition of varied oscillating parameters. By scrupulous data processing, some significative results such as the velocity distribution, the density distribution, the potential energy curves of the flow field and the frictional force of the wall are obtained. Secondly, the mechanism how the wall oscillation brings about change to the frictional drag at liquid–solid interface is investigated. And the results indicate that the frictional drag can be reduced significantly by applying appropriate streamwise oscillation to the solid wall. The drag reduction rate mainly depends on the oscillation parameters. In addition, the decrease in the fluid’s density near the wall is another important reason behind the frictional drag reduction.

Rebound suppression of a droplet impacting on an oscillating horizontal surface.

The behavior of a droplet impinging onto a solid substrate can be influenced significantly by the horizontal motion of the substrate. The coupled interactions between the moving wall and the impacting droplet may result in various outcomes, which may be different from the usual normal droplet impact on a stationary wall. In this paper, we present a method to suppress drop rebound on hydrophobic surfaces via transverse wall oscillations, normal to the impact direction. The numerical investigation shows that the suppression of droplet rebound has a direct relationship with the oscillation phase, amplitude, and frequency. For a particular range of oscillation frequencies and amplitudes, a lateral shifting of the droplet position is observed along the oscillating direction. While large oscillation amplitude favors the process of droplet deposition, a high frequency promotes droplet rebound from the oscillating wall. A linear trend in the transition region between deposition and rebound is observed from a scaled phase diagram of the oscillation amplitude versus frequency. We provide a systematic investigation of drop deposition and elucidate the mechanism of rebound suppression through the temporal evolution of the nonaxial kinetic energy and the velocity flow field.

Benefits of interventions for respiratory secretion management in adult palliative care patients-a systematic review.

BackgroundRespiratory secretions impact negatively on palliative patients. Unfortunately, a gold standard therapy is not yet available. The purpose of this study was to identify which interventions are in use to control respiratory secretions in patients with chronic disease with a poor prognosis and verify their effects on outcomes relevant for palliative care patients.MethodsA systematic review of the literature with narrative summary was conducted. We searched eight electronic databases in April 6th, 2016. Citation-tracking and reference list searches were conducted. We included randomized controlled trials, crossover trials, observational and qualitative studies regarding interventions for respiratory secretion management in adult patients with chronic diseases that met inclusion criteria indicating short prognosis.ResultsSix randomized controlled trials, 11 observational studies, ten crossover trials and one qualitative study were found. Interventions included mechanical insufflation-exsufflation (MIE), expiratory muscle training, manually-assisted cough, tracheotomy, chest physiotherapy, suctioning, air stacking, electrical stimulation of abdominal muscles, nebulized saline, positive expiratory pressure masks, percussive ventilation, high frequency chest wall oscillations. The interventions with most promising benefits to patients in palliative care were manually-assisted cough and mechanical insufflation-exsufflation to promote expectoration and percussive ventilation to improve mucous clearance.ConclusionTherapies, such as manually assisted cough, mechanical insufflation-exsufflation and percussive ventilation, which aim to deal with respiratory secretion, were the most promising treatment for use in palliative care for specific diseases. Nevertheless, the evidence still needs to improve in order to identify which treatment is the best.Electronic supplementary materialThe online version of this article (doi:10.1186/s12904-016-0147-y) contains supplementary material, which is available to authorized users.

Modeling peristaltic flow in vessels equipped with valves: Implications for vasomotion in bat wing venules

We study the flow of a Newtonian fluid through a vessel provided with valves ensuring a unidirectional motion and whose walls are animated by periodic peristaltic waves. The ultimate target is to describe the phenomenon of vasomotion, consisting in periodic oscillations of blood vessels walls which is particularly important for the blood flow in veins. Here we formulate a mathematical model based on approximations of the flow equations due to the smallness of the radius-to-length ratio. In particular we examine venules equipped with just two valves, showing that the model reproduces the periodic pressure pulses that have been experimentally detected in venules of the bat wing. The flow generated by the synchronous vessel oscillations is recovered in the limit of large peristaltic wavelength.

The Impact of High-Frequency Chest Wall Oscillation on Healthcare Use in Patients with Neuromuscular Diseases.

People with neuromuscular disease frequently have difficulty clearing pulmonary secretions, which leads to pneumonia and respiratory failure. High-frequency chest wall oscillation (HFCWO) is one intervention used to facilitate secretion clearance. The objective of this study was to determine if HFCWO therapy leads to improved outcomes as measured by lower healthcare use for patients who have a chronic neuromuscular disease. We performed a cohort study comparing healthcare claims before and after initiation of HFCWO. Data were obtained from two large databases of commercial insurance claims. Study subjects were commercial insurance members with an International Classification of Diseases, Ninth Revision, code for a neuromuscular disease and a claim for HFCWO between 2007 and 2011. The study included both children and adults. There were 426 patients in this study. Their mean age was 29.9 ± 22 years. Total medical costs per member per month decreased by $1,949 (18.6%) after initiation of HFCWO (P = 0.002). Inpatient admission costs decreased by $2,392 (41.7%) (P = 0.001), and pneumonia costs decreased by $514 (18.1%) (P = 0.015). To account for the possibilities of misclassification based on diagnosis and bias due to loss to follow-up, we compared outcomes between those lost to follow-up and those not, and we found similar results. Total medical costs, hospitalizations, and pneumonia claims were less after than before initiation of HFCWO in a broad group of patients with neuromuscular disease. Subject to the limitations that administrative data did not capture how HFCWO was used and that HFCWO may be a marker of generally better care, our findings lend support to the routine use of this intervention in the care of patients with neuromuscular diseases.

Investigation of oscillations of a soliton of a bose condensate of atoms in a trap in the limit of small oscillations of its walls

The motion of the center of a soliton in a trap with oscillating walls is studied analytically and numerically for the case in which the intrinsic frequency of small soliton oscillations in the equilibrium state considerably exceeds the frequency of wall oscillations. this problem can be solved either by applying the gross–pitaevskii equation, which most exactly describes the behavior of the soliton in the trap, or by using the approximate, “mechanical,” equation of motion of the newtonian type for the center of the soliton. an approximate analytical solution of the mechanical equation is obtained and is compared with the numerical solution of the newton equation, while the latter solution is compared with the numerical solution of the gross–pitaevskii equation. good agreement between the first two solutions is revealed. it is also shown that there is a range of parameters in which the numerical solutions of the newton and gross–pitaevskii equations are closest to each other. the frequency-sweeping effect of soliton center oscillations is revealed. an approximate analytical formula for the limiting frequency of these oscillations is obtained and the numerical analysis of this phenomenon is performed.

Dynamic response for Dzyaloshinskii–Moriya interaction on bubble-like magnetic solitons driven by spin-polarized current

By using micromagnetic simulations, we studied the dynamic response for different bubble-like magnetic solitons in the [CoPt-CoNi]/Cu/CoNi magnetic multilayer with perpendicular magnetic anisotropy. It is found that a localized spin-polarized current can not only nucleate a dissipative magnetic droplet but also excite the in-plane domain wall (DW) oscillation at the edge of bubble-like magnetic solitons. The dependence of oscillation frequency on current for the dissipative magnetic droplet is hysteretic in the absence of the Dzyaloshinskii–Moriya interactions (DMI). In the presence of DMI, three different bubble-like magnetic solitons are excited: (1) singular magnetic droplet, (2) pseudonormal magnetic droplet, (3) dynamical skyrmion. Meanwhile, the oscillation frequencies of these magnetic solitons have different response as current density varies. These results open up new possibilities for the applications of magnetic soliton-based spin transfer nano-oscillators.

Diversity in Fish Auditory Systems: One of the Riddles of Sensory Biology

An astonishing diversity of inner ears and accessory hearing structures (AHS) that can enhance hearing has evolved in fishes. Inner ears mainly differ in the size of the otolith end organs, the shape and orientation of the sensory epithelia, and the orientation patterns of ciliary bundles of sensory hair cells. Despite our profound morphological knowledge of inner ear variation, two main questions remain widely unanswered. (i) What selective forces and/or constraints led to the evolution of this inner ear diversity? (ii) How is the morphological variability linked to hearing abilities? Improved hearing is mainly based on the ability of many fish species to transmit oscillations of swim bladder walls or other gas-filled bladders to the inner ears. Swim bladders may be linked to the inner ears via a chain of ossicles (in otophysans), anterior extensions (e.g. some cichlids, squirrelfishes), or the gas bladders may touch the inner ears directly (labyrinth fishes). Studies on catfishes and cichlids demonstrate that larger swim bladders and more pronounced linkages to the inner ears positively affect both auditory sensitivities and the detectable frequency range, but lack of a connection does not exclude hearing enhancement. This diversity of auditory structures and hearing abilities is one of the main riddles in fish bioacoustics research. Hearing enhancement might have evolved to facilitate intraspecific acoustic communication. A comparison of sound-producing species, however, indicates that acoustic communication is widespread in taxa lacking AHS. Eco-acoustical constraints are a more likely explanation for the diversity in fish hearing sensitivities. Low ambient noise levels may have facilitated the evolution of AHS, enabling fish to detect low-level abiotic noise and sounds from con- and heterospecifics, including predators and prey. Aquatic habitats differ in ambient noise regimes, and preliminary data indicate that hearing sensitivities of fishes vary accordingly.

Direct Numerical Simulation of Supersonic Turbulent Boundary Layer with Spanwise Wall Oscillation

Direct numerical simulations (DNS) of Mach = 2.9 supersonic turbulent boundary layers with spanwise wall oscillation (SWO) are conducted to investigate the turbulent heat transport mechanism and its relation with the turbulent momentum transport. The turbulent coherent structures are suppressed by SWO and the drag is reduced. Although the velocity and temperature statistics are disturbed by SWO differently, the turbulence transports of momentum and heat are simultaneously suppressed. The Reynolds analogy and the strong Reynolds analogy are also preserved in all the controlled flows, proving the consistent mechanisms of momentum transport and heat transport in the turbulent boundary layer with SWO. Despite the extra dissipation and heat induced by SWO, a net wall heat flux reduction can be achieved with the proper selected SWO parameters. The consistent mechanism of momentum and heat transports supports the application of turbulent drag reduction technologies to wall heat flux controls in high-speed vehicles.