High-frequency Chest Wall Compression Research Articles

Airway Clearance Strategies and Secretion Management in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a rare, neurodegenerative motor neuron disease that affects voluntary muscle movement. Often, difficulty in coughing, breathing, and swallowing are sequela associated with the condition, and the presence of bulbar muscle predominant weakness results in deleterious effects on airway clearance and secretion management. This narrative review will provide practical guidance for clinicians treating this population. Cough insufficiency in this population typically manifests as a prolonged, slow, weak cough effort that impedes the clearability of secretions and airway protection. Dystussia and dysphagia frequently occur simultaneously in bulbar dysfunction, subsequently impacting respiratory health. Measures of respiratory strength should be obtained and monitored every 3-6 months, preferably in a multidisciplinary clinic setting. Cough augmentation, whether manual or mechanical techniques, should be sought as early in the disease progression as possible to adequately control secretions in the proximal airways. This airway clearance strategy can aid in the prevention and treatment of respiratory tract infections (RTIs), which can pose a significant clinical hurdle to those with ALS. The use of mechanical insufflation-exsufflation may be complicated by severe bulbar dysfunction rendering this technique ineffective. Though peripheral airway clearance strategies, such as high-frequency chest-wall compression, have the advantage of being less impacted by bulbar dysfunction, it is only recommended this modality be used in conjunction with, versus in lieu of, proximal strategies. Salivary secretion management includes the use of anticholinergics, botulinum toxin, and radiation therapy depending on severity and desire for relief.

The Impact of High-Frequency Chest-Wall Compression on Mechanical Ventilation Delivery and Flow Bias.

It is unclear if high-frequency chest-wall compression (HFCWC) has a role to assist with secretion clearance in patients on mechanical ventilation. The effect of HFCWC on the delivery of mechanical ventilation is unknown. This study describes the effect of HFCWC on mechanical ventilation delivery and flow bias in an orally intubated and mechanically ventilated bench model. An orally intubated mannequin was mechanically ventilated in 5 commonly used modes of ventilation at settings that reflect current practice. HFCWC was applied via a randomized combination of oscillation frequencies and pressure settings. Mechanical ventilator flow, flow bias, and breathing frequency were measured before and during the application of HFCWC. HFCWC led to 3- to 7-fold increases in ventilator-delivered breathing frequency during synchronized intermittent mandatory ventilation, bi-level (with pressure support), bi-level-assist, and pressure-regulated volume control modes of ventilation. Only in the bi-level mode without pressure support was the ventilator breathing frequency unaffected by HFCWC. During HFCWC, peak inspiratory flow to peak expiratory flow ratios toward an expiratory flow bias, particularly at higher HFCWC pressures, only in pressure-regulated volume control and synchronized intermittent mandatory ventilation modes were peak inspiratory flow to peak expiratory flow ratios of <0.9 generated that would facilitate secretion clearance. HFCWC led to 3- to 7-fold increases in ventilator breathing frequency delivered by mechanical ventilation except in the bi-level mode. The bi-level mode may be the optimal mode to use HFCWC to minimize disruption to the delivered ventilator breathing frequency. The peak inspiratory flow to peak expiratory flow ratios < 0.9, the optimal flow bias for secretion clearance, was only achieved in the pressure-regulated volume control and synchronized intermittent mandatory ventilation modes. However, the findings in this bench model with a fixed low compliance may not be generalizable to the patient in the ICU, and we recommend further investigation into the effects of HFCWC in the patient in the ICU.

A systematic review on the effects of high frequency chest wall compression and intrapulmonary percussive ventilation in patients with neuromuscular disease

Background: Respiratory insufficiency is the most common cause of mortality among patients with a neuromuscular disease. Methods: We followed the PRISMA statement for systematic reviews. We explored the effects of high frequency wall compression and intrapulmonary percussive ventilation, compared to a control intervention, on the lung volume and capacity, and quality of life in patients with neuromuscular disease. We further assessed the effects of these two interventions on clinical value, complications, and survival. The literature search was performed on 30/06/2020 in Embase, MEDLINE, CENTRAL, PEDro and CINAHL on 6/07/2020. Inclusion criteria: patients with neuromuscular disease; interventions of interest mentioned above; randomised controlled trials comparing these interventions with a control intervention. Results: Five studies were included, and results were presented narratively. High frequency wall compression was not shown to be superior to standard care in terms of lung volume and capacity, quality of life, complications, and survival rate. Compared with standard care, intrapulmonary percussive ventilation showed non-significant differences in terms of lung volume and capacity, and the risk of respiratory infection. Standard care was nevertheless associated with a significantly higher risk of days of hospitalisation (Incidence Rate Ratio 8.5 [1.1-67]) and of antibiotic use than intrapulmonary percussive ventilation (Incidence Rate Ratio 43 [6-333]). The assessment with the risk of bias tool 2.0 showed a high risk of bias for all outcomes. Moreover, the evidence is of very low-quality for all outcomes. Conclusions: Due to large variety of reported outcomes, missing data and limited number of studies, no meta-analysis could be conducted. The results should be interpreted with caution as the results have a very low certainty of evidence and reported outcomes have a high risk of bias. The evidence for high frequency wall compression and intrapulmonary percussive ventilation is still insufficient to draw final conclusions. Registration: PROSPERO ID: CRD42017064703.

A systematic review on the effects of high frequency chest wall compression and intrapulmonary percussive ventilation in patients with neuromuscular disease

Background: Respiratory insufficiency is the most common cause of mortality among patients with a neuromuscular disease. Methods: We explored the effects of high frequency wall compression and intrapulmonary percussive ventilation, compared with standard care or no treatment, on the lung volume and capacity, and quality of life in patients with neuromuscular disease during respiratory infections or in stable periods. We further assessed the effects of these two interventions on clinical value, complications, and survival. The literature search was performed on Embase, MEDLINE, CINAHL, CENTRAL and PEDro. Randomised controlled trials and cross-over studies were eligible. Results: Five studies were included, and results were presented narratively. High frequency wall compression was not shown to be superior to standard care in terms of lung volume and capacity, quality of life, complications, and survival rate. Compared with standard care, intrapulmonary percussive ventilation showed non-significant differences in terms of lung volume and capacity, and the risk of respiratory infection. Standard care was nevertheless associated with a significantly higher risk of days of hospitalisation (Incidence Rate Ratio 8.5 [1.1-67]) and of antibiotic use than intrapulmonary percussive ventilation (Incidence Rate Ratio 43 [6-333]). Conclusions: Due to large variety of reported outcomes, missing data and limited number of studies, no meta-analysis could be conducted. The results should be interpreted with caution as the results have a very low certainty of evidence and reported outcomes have a high risk of bias. The evidence for high frequency wall compression and intrapulmonary percussive ventilation is still insufficient to draw final conclusions. Protocol registration: PROSPERO ID: CRD42017064703.

Immediate Effects and Safety of High-Frequency Chest Wall Compression Compared to Airway Clearance Techniques in Non-Hospitalized Infants With Acute Viral Bronchiolitis.

No studies have investigated the use and safety of high-frequency chest wall compression (HFCWC) for non-hospitalized infants with acute viral bronchiolitis (AVB). The aim of the present study was to evaluate the immediate effects and safety of HFCWC as compared to airway clearance techniques in children with AVB. In this randomized clinical trial in non-hospitalized infants (0-12 months old) with mild to moderate AVB, children were randomized into 2 groups: airway clearance techniques (20 min of prolonged slow expiration and provoked cough) or HFCWC (15 min). A single session was performed and children were evaluated at baseline and at 10 min and 20 min after treatments. Outcomes measures were the Wang severity score, [Formula: see text], sputum wet-weight, and the presence of adverse events. A total of 91 infant subjects, mean age 7.9 ± 2.6 months, were included. Significant (P = .004) between-group differences were found in the Wang score, which was 0.28 points lower in the airway clearance techniques group. There was a greater increase of infants classified as normal and a greater decrease of those classified as mild according to the Wang score when airway clearance techniques were used compared to the use of HFCWC (P = .009). The sputum wet-weight was lower in subjects treated with the airway clearance techniques (P < .001). Although [Formula: see text]improved in both groups, no differences were found between them. There was also no difference for adverse events, and the majority of children did not present any adverse events after 20 min. The use of HFCWC induced similar clinical effects as airway clearance techniques and was safe for non-hospitalized infants with AVB. Both techniques reduced respiratory symptoms and acutely improved [Formula: see text]. (ClinicalTrials.gov: NCT03835936.).

Objective Measurement of Adherence to Out-Patient Airway Clearance Therapy by High-Frequency Chest Wall Compression in Cystic Fibrosis.

Objective measures of adherence to high-frequency chest wall compression (HFCWC), a form of airway clearance therapy for patients with cystic fibrosis, are lacking. We used a novel electronic monitoring device integrated into an HFCWC vest to measure adherence compared with self-reported adherence. We determined factors that influenced adherence and how adherence correlated with baseline pulmonary function and pulmonary exacerbations. Data were collected by direct measurement of date, time of day, and duration of HFCWC use to determine the number of daily treatments and daily duration of treatments. Chart review provided prescribed airway clearance therapy treatment and demographic and clinical information. Subject and caregiver report of the daily number of airway clearance therapy treatments was obtained by telephone interviews. Analysis used 2-sample and paired t test, analysis of variance, and linear regression. Average adherence was 69%. Adherence was highest in children (82%, P = .02) and those receiving assistance with treatment (82%, P < .001). Subjects overestimated therapy duration from a mean ± SD of 127 ± 169% by adults to 19.2 ± 26.3% by parents or guardians of children. Average adherence decreased with increasing prescribed therapy time (P = .02). Average daily therapy time and adherence had significant positive associations with baseline FEV1 percent of predicted (P = .02 and P = .02, respectively) and negative associations with pulmonary exacerbations during the pre-study period and at baseline (P = .044 and P = .02, respectively). Greater adherence to HFCWC measured directly by a novel recorder was associated with better baseline pulmonary function and fewer exacerbations in the pre-study and baseline period. Adherence decreased with age and prescribed therapy time and increased with therapy assistance. Self-report overestimation is large and thus not an accurate measure of adherence.

AARC Clinical Practice Guideline: Effectiveness of Nonpharmacologic Airway Clearance Therapies in Hospitalized Patients

Airway clearance therapy (ACT) is used in a variety of settings for a variety of ailments. These guidelines were developed from a systematic review with the purpose of determining whether the use of nonpharmacologic ACT improves oxygenation, reduces length of time on the ventilator, reduces stay in the ICU, resolves atelectasis/consolidation, and/or improves respiratory mechanics, versus usual care in 3 populations. For hospitalized, adult and pediatric patients without cystic fibrosis, 1) chest physiotherapy (CPT) is not recommended for the routine treatment of uncomplicated pneumonia; 2) ACT is not recommended for routine use in patients with COPD; 3) ACT may be considered in patients with COPD with symptomatic secretion retention, guided by patient preference, toleration, and effectiveness of therapy; 4) ACT is not recommended if the patient is able to mobilize secretions with cough, but instruction in effective cough technique may be useful. For adult and pediatric patients with neuromuscular disease, respiratory muscle weakness, or impaired cough, 1) cough assist techniques should be used in patients with neuromuscular disease, particularly when peak cough flow is < 270 L/min; CPT, positive expiratory pressure, intrapulmonary percussive ventilation, and high-frequency chest wall compression cannot be recommended, due to insufficient evidence. For postoperative adult and pediatric patients, 1) incentive spirometry is not recommended for routine, prophylactic use in postoperative patients, 2) early mobility and ambulation is recommended to reduce postoperative complications and promote airway clearance, 3) ACT is not recommended for routine postoperative care. The lack of available high-level evidence related to ACT should prompt the design and completion of properly designed studies to determine the appropriate role for these therapies.

High-Frequency Chest Wall Compression Therapy in Neurologically Impaired Children

Children with neurological impairment often suffer from insufficient airway secretion clearance, which substantially increases their respiratory morbidity. The goal of the study was to assess the clinical feasibility of high-frequency chest wall compression (HFCWC) therapy in neurologically impaired children with respiratory symptoms. This was a single-center, investigator initiated, prospective study. Twenty-two subjects were studied for 12 months before and 12 months after initiation of HFCWC therapy, and 15 subjects were followed for an additional 12 months. The threshold of adherence to HFCWC therapy was 70%. The number of pulmonary exacerbations that required hospitalization was recorded. Forty-five percent of the subjects required hospital admission before initiation of HFCWC therapy. This rate decreased to 36% after the first year with HFCWC, and to 13% after the second year with HFCWC. There was a statistically significant reduction of the number of hospital days at follow-up, relative to before treatment. Use of an assisted-cough device or the presence of tracheostomy did not significantly affect hospitalization days. Regular HFCWC therapy may reduce the number of hospitalizations in neurologically impaired children.

The Evidence for Secretion Clearance Techniques

Many acute and chronic respiratory diseases are associated with increased respiratory secretions in the airways. Narrative reviews and a few systematic reviews of secretion clearance techniques have been published. These reviews raise concerns regarding the lack of evidence to support the various secretion clearance techniques. I conducted a comprehensive MEDLINE search of the following subjects: chest physical therapy, chest physiotherapy, postural drainage, forced expiratory technique, autogenic drainage, high-frequency chest wall compression, flutter device and secretions, positive expiratory pressure and secretions, intrapulmonary percussion, mechanical in-exsufflation and secretions. This was followed by a comprehensive search of cross-references to identify additional studies. The results of this review are reported herein. There are a number of methodological limitations of the literature reporting studies of the use of secretion clearance techniques. Most of the studies were small, most used crossover designs, and few used sham therapy. Many studies were limited to short-term outcomes such as sputum clearance with a single treatment session. Despite the clinical observation that retained secretions are detrimental to respiratory function and despite anecdotal associations between secretion clearance and improvements in respiratory function, there is a dearth of high-level evidence to support any secretion clearance technique.

High frequency chest wall compression in cats with normal lungs.

Ten anesthetized, paralyzed adult cats were ventilated by high frequency chest wall compression (HFCWC) at 3, 5, 7, and 9 Hz by means of a single chamber cuff enclosing the thorax from the axillae to the xyphisternum. The effects of HFCWC in terms of gas exchange, end-expiratory lung volume, and respiratory system compliance were compared to conventional intermittent positive pressure ventilation (IPPV) (30 breaths/mn). HFCWC and IPPV were compared at three levels of matched end-expiratory airway pressure [continuous positive airway pressure (CPAP)/positive end-expiratory pressure/(PEEP) of 0, 2, and 5 cm H2O]. In the absence of CPAP, HFCWC resulted in a marked decrease (up to 50%) in end-expiratory lung volume with significantly lower PaO2, lower compliance, and higher alveolar-arterial oxygen gradient than during IPPV. No differences in PaO2 and a-ADO2 were observed when HFCWC was combined to CPAP greater than or equal to 2 cm H2O. At frequencies below 9 Hz, PaCO2 became significantly lower during HFCWC + CPAP than during IPPV. During HFCWC + 2 cm H2O CPAP, lung volume was lower than during IPPV + 2 cm H2O and similar to the volumes observed during IPPV + 0 positive end-expiratory pressure. Additional studies in six cats at HFCWC + 3 cm H2O confirmed that CPAP greater than 2 cm H2O more than adequately compensated the decrease in lung volume associated with HFCWC alone. Peak cuff pressures between 14 and 17 cm H2O generated oscillary tidal volumes between 4.5 and 2.1 ml/kg. The size of the oscillatory volume was significantly affected by increasing frequencies (decrease in tidal volume) and increasing levels of positive airway pressure (increase in tidal volume). We conclude that in cats with normal lungs, HFCWC can provide for normal gas exchange, provided that it is combined with low level CPAP in order to prevent the occurrence of airway closure associated with HFCWC alone.

Peripheral mucociliary clearance with high-frequency chest wall compression

We investigated the effects of high-frequency chest wall compression (HFCWC) on peripheral and tracheal mucus clearance in anesthetized spontaneously breathing dogs. HFCWC was achieved by oscillating the pressure in a thoracic cuff with a piston pump. Regional lung retention of a technetium-99m sulfur colloid aerosol was monitored with a gamma camera. A peripheral mucus clearance index (PMCI) was defined for each region of interest. The tracheal mucus clearance rate (TMCR) was determined by bronchoscopic visualization of marker particle transport. Phase I: In seven dogs, 30 min of HFCWC at 13 Hz with peak cuff pressure (Pcuff) 100-120 cmH2O was found to significantly enhance PMCI in regions immediately under the cuff. (delta PMCI = 24.4 +/- 4.6 in the basal peripheral region.) Phase II: Because of subpleural hemorrhage in phase I, the effect of HFCWC on TMCR at various Pcuff levels was studied in five dogs. The enhancement of TMCR by HFCWC reached a plateau level at Pcuff = 50 cmH2O. Phase III: HFCWC at 13 Hz with Pcuff = 50-60 cmH2O was found to significantly enhance PMCI in five dogs without the consequence of hemorrhage. Correlations were found between the enhancement of PMCI and TMCR by HFCWC. These results demonstrate that HFCWC is effective in enhancing both peripheral and central mucus clearance in dogs and safe when moderate pressures are applied.

Enhanced tracheal mucus clearance with high frequency chest wall compression.

The clearance of mucus in the trachea during high frequency chest wall compression (HFCWC) was studied in nine anesthetized dogs. High frequency chest wall compression was applied by oscillating the pressure in a thoracic cuff such that it produced oscillatory tidal volumes of 25 to 100 cc at frequencies of 3 to 17 Hz. The tracheal mucus clearance rate (TMCR) was determined by direct observation of the rate of displacement of a charcoal particle spot by means of a fiberoptic bronchoscope. Baseline TMCR during spontaneous breathing averaged 8.2 +/- 5.6 mm/min in the 9 dogs. The TMCR during 2 min of HFCWC was increased at 5, 8, 11, 13, 15, and 17 Hz but not at 3 Hz. The enhancement of clearance was most pronounced in the range of 11 to 15 Hz, reaching a peak value of 340% of control at 13 Hz. These studies suggest that HFCWC might be of considerable potential benefit as a mode of chest physiotherapy.