Breath Stacking Research Articles

Post-insufflation diaphragm contractions in patients receiving various modes of mechanical ventilation

BackgroundDuring mechanical ventilation, post-insufflation diaphragm contractions (PIDCs) are non-physiologic and could be injurious. PIDCs could be frequent during reverse-triggering, where diaphragm contractions follow the ventilator rhythm. Whether PIDCs happens with different modes of assisted ventilation is unknown. In mechanically ventilated patients with hypoxemic respiratory failure, we aimed to examine whether PIDCs are associated with ventilator settings, patients’ characteristics or both.MethodsOne-hour recordings of diaphragm electromyography (EAdi), airway pressure and flow were collected once per day for up to five days from intubation until full recovery of diaphragm activity or death. Each breath was classified as mandatory (without-reverse-triggering), reverse-triggering, or patient triggered. Reverse triggering was further subclassified according to EAdi timing relative to ventilator cycle or reverse triggering leading to breath-stacking. EAdi timing (onset, offset), peak and neural inspiratory time (Tineuro) were measured breath-by-breath and compared to the ventilator expiratory time. A multivariable logistic regression model was used to investigate factors independently associated with PIDCs, including EAdi timing, amplitude, Tineuro, ventilator settings and APACHE II.ResultsForty-seven patients (median[25%-75%IQR] age: 63[52–77] years, BMI: 24.9[22.9–33.7] kg/m2, 49% male, APACHE II: 21[19–28]) contributed 2 ± 1 recordings each, totaling 183,962 breaths. PIDCs occurred in 74% of reverse-triggering, 27% of pressure support breaths, 21% of assist-control breaths, 5% of Neurally Adjusted Ventilatory Assist (NAVA) breaths. PIDCs were associated with higher EAdi peak (odds ratio [OR][95%CI] 1.01[1.01;1.01], longer Tineuro (OR 37.59[34.50;40.98]), shorter ventilator inspiratory time (OR 0.27[0.24;0.30]), high peak inspiratory flow (OR 0.22[0.20;0.26]), and small tidal volumes (OR 0.31[0.25;0.37]) (all P ≤ 0.008). NAVA was associated with absence of PIDCs (OR 0.03[0.02;0.03]; P < 0.001). Reverse triggering was characterized by lower EAdi peak than breaths triggered under pressure support and associated with small tidal volume and shorter set inspiratory time than breaths triggered under assist-control (all P < 0.05). Reverse triggering leading to breath stacking was characterized by higher peak EAdi and longer Tineuro and associated with small tidal volumes compared to all other reverse-triggering phenotypes (all P < 0.05).ConclusionsIn critically ill mechanically ventilated patients, PIDCs and reverse triggering phenotypes were associated with potentially modifiable factors, including ventilator settings. Proportional modes like NAVA represent a solution abolishing PIDCs.

Respiratory entrainment related reverse triggering in mechanically ventilated children

BackgroundThe underlying pathophysiological pathways how reverse triggering is being caused are not fully understood. Respiratory entrainment may be one of these mechanisms, but both terms are used interchangeably. We sought to characterize reverse triggering and the relationship with respiratory entrainment among mechanically ventilated children with and without acute lung injury.MethodsWe performed a secondary phyiology analysis of two previously published data sets of invasively mechanically ventilated children < 18 years with and without lung injury mechanically ventilated in a continuous or intermittent mandatory ventilation mode. Ventilator waveforms, electrical activity of the diaphragm measured with surface electromyography and oesophageal tracings were analyzed for entrained and non-entrained reverse triggered breaths.ResultsIn total 102 measurements (3110 min) from 67 patients (median age 4.9 [1.8 ; 19,1] months) were analyzed. Entrained RT was identified in 12 (12%) and non-entrained RT in 39 (38%) recordings. Breathing variability for entrained RT breaths was lower compared to non-entrained RT breaths. We did not observe breath stacking during entrained RT. Double triggering often occurred during non-entrained RT and led to an increased tidal volume. Patients with respiratory entrainment related RT had a shorter duration of MV and length of PICU stay.ConclusionsReverse triggering is not one entity but a clinical spectrum with different mechanisms and consequences.Trial registrationNot applicable.

Immediate Effect of Breath Stacking and Buteyko Breathing on Physiological Parameters in post Laparoscopic Cholecystectomy Patients: A Research Protocol of a Randomised Controlled Trial

Introduction: Laparoscopic cholecystectomy is frequently performed in acute, chronic, symptomatic, and asymptomatic cholelithiasis. It is simple, safer, and requires less recovery time than open cholecystectomy, which is why this procedure is increasingly utilised for various abdominal surgeries. Patients may experience postoperative pulmonary problems during the recovery phase and as per available literature there is a noticeable decline in the vital capacity of the patient. It was observed that Buteyko breathing and breath stacking breathing techniques has a good impact on the physiological parameters and vital capacity of patients with hypertension, asthma, Chronic Obstructive Pulmonary Disease (COPD), and other respiratory conditions. Need of the study: Buteyko breathing and breath stacking breathing techniques are effective in different conditions like hypertension, asthma, and cardiac surgery. The need of the study is to compare both techniques and find out which one is more effective and implement that with the standard exercises in the patients to help them improve their quality of life, reduce hospital stay, and improve lung capacity. Aim: To compare the effects of the Breath Stacking Technique (BST) and Buteyko Breathing Technique (BBT) on the physiological parameters of patients undergoing laparoscopic cholecystectomy. Materials and Methods: This will be a randomised controlled trial in which 140 patients will be included using purposive sampling via block randomisation. The study will be conducted in Surgery Intensive Care Unit (SICU) of Maharishi Markandeshwar Medical College and Hospital, Kumarhatti, Solan, from December 2023 to May 2024. Patients in Group-A will perform the BBT and Group-B will perform the BST. Each cycle of breathing consists of five repetitions with five sets and 30 seconds of rest in between. Outcome measures will be taken at baseline and after intervention on Postoperative Day 1 (POD). The normality of the data will be checked by KolmogorovSmirnov test. A paired t-test will be used if the data is normal, and the Wilcoxon Signed Rank test will be used if the data is non-normal. A p-value &lt; 0.05 will be considered significant.

Effect of Thoracic Mobility with Breath Stacking Exercise on Chest Expansion in Postsurgery Breast Cancer Patients: A Pilot Study

Context: Breast cancer is the most prevalent cancer among women accounting for nearly 14% of all types of cancer for which the therapeutic procedure modified radical mastectomy is frequently performed on patients. Postsurgery patients are prone to having incision or suture site pain that will interfere with chest expansion. Aim: The aim of this study was to determine the effectiveness of thoracic mobility exercises along with the breath stacking technique on chest expansion in breast cancer patients. Settings and Design: It was an experimental study carried out in an outpatient hospital setting. Subjects and Methods: A total of 46 participants eligible as per inclusion criteria were randomly assigned into 2 groups using a simple random sampling method. During the study period, Group A, the experimental group (n = 23), received thoracic mobility and breath stacking technique and the conventional group (n = 23) received thoracic mobility exercises alone. Pre- and postchest expansion was determined using a tape measure at the axillary and xiphisternum levels. Statistical analysis used: Data were analyzed using MS Excel on Windows 10 and usingStatistical Package for the Social Sciences (SPSS) version 21 (Armonk, NY: IBM Corp). Baseline data for participants in the experimental and comparison groups were summarized using descriptive statistics. Descriptive statistics included frequencies, percentages, mean, and standard deviation. Results: Chest circumference score at axillary and xiphisternum levels significantly improved in the intervention group after 4 weeks of the rehabilitation program (P &lt; 0.05). Conclusions: The present study concludes that thoracic mobility exercises along with the breath stacking technique are beneficial for improving chest expansion in postsurgery breast cancer patients.

Asynchrony Injures Lung and Diaphragm in Acute Respiratory Distress Syndrome.

Patient-ventilator asynchrony is often observed during mechanical ventilation and is associated with higher mortality. We hypothesized that patient-ventilator asynchrony causes lung and diaphragm injury and dysfunction. Prospective randomized animal study. University research laboratory. Eighteen New Zealand White rabbits. Acute respiratory distress syndrome (ARDS) model was established by depleting surfactants. Each group (assist control, breath stacking, and reverse triggering) was simulated by phrenic nerve stimulation. The effects of each group on lung function, lung injury (wet-to-dry lung weight ratio, total protein, and interleukin-6 in bronchoalveolar lavage), diaphragm function (diaphragm force generation curve), and diaphragm injury (cross-sectional area of diaphragm muscle fibers, histology) were measured. Diaphragm RNA sequencing was performed using breath stacking and assist control (n = 2 each). Inspiratory effort generated by phrenic nerve stimulation was small and similar among groups (esophageal pressure swing ≈ -2.5 cm H2O). Breath stacking resulted in the largest tidal volume (>10 mL/kg) and highest inspiratory transpulmonary pressure, leading to worse oxygenation, worse lung compliance, and lung injury. Reverse triggering did not cause lung injury. No asynchrony events were observed in assist control, whereas eccentric contractions occurred in breath stacking and reverse triggering, but more frequently in breath stacking. Breath stacking and reverse triggering significantly reduced diaphragm force generation. Diaphragmatic histology revealed that the area fraction of abnormal muscle was ×2.5 higher in breath stacking (vs assist control) and ×2.1 higher in reverse triggering (vs assist control). Diaphragm RNA sequencing analysis revealed that genes associated with muscle differentiation and contraction were suppressed, whereas cytokine- and chemokine-mediated proinflammatory responses were activated in breath stacking versus assist control. Breath stacking caused lung and diaphragm injury, whereas reverse triggering caused diaphragm injury. Thus, careful monitoring and management of patient-ventilator asynchrony may be important to minimize lung and diaphragm injury from spontaneous breathing in ARDS.

Reverse triggering neural network and rules-based automated detection in acute respiratory distress syndrome.

PurposeDyssynchrony may cause lung injury and is associated with worse outcomes in mechanically ventilated patients. Reverse triggering (RT) is a common type of dyssynchrony presenting with several phenotypes which may directly cause lung injury and be difficult to identify. Due to these challenges, automated software to assist in identification is needed. Materials and methodsThis was a prospective observational study using a training set of 15 patients and a validation dataset of 13 patients. RT events were manually identified and compared with “rules-based” programs (with and without esophageal manometry and reverse triggering with breath stacking), and were used to train a neural network artificial intelligence (AI) program. RT phenotypes were identified using previously defined rules. Performance of the programs was compared via sensitivity, specificity, positive predictive value (PPV) and F1 score. Results33,244 breaths were manually analyzed, with 8718 manually identified as reverse-triggers. The rules-based and AI programs yielded excellent specificity (>95% in all programs) and F1 score (>75% in all programs). RT with breath stacking (24.4%) and mid-cycle RT (37.8%) were the most common phenotypes. ConclusionsAutomated detection of RT demonstrated good performance, with the potential application of these programs for research and clinical care.

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.

Effects of the breath stacking technique after upper abdominal surgery: a randomized clinical trial.

ABSTRACTObjective:To evaluate the effect of the association of the breath stacking (BS) technique associated with routine physiotherapy on pulmonary function, lung volumes, maximum respiratory pressures, vital signs, peripheral oxygenation, thoracoabdominal mobility, and pain in the surgical incision in patients submitted to upper abdominal surgery during the postoperative period, as well as to analyze BS safety. Methods:This was a randomized clinical trial involving 34 patients divided into a control group (CG; n = 16), who underwent conventional physiotherapy only, and the BS group (BSG; n = 18), who underwent conventional physiotherapy and BS. Both groups performed two daily sessions from postoperative day 2 until hospital discharge. The primary outcomes were FVC and Vt. The safety of BS was assessed by the incidence of gastrointestinal, hemodynamic, and respiratory repercussions. Results:Although FVC significantly increased at hospital discharge in both groups, the effect was greater on the BSG. Significant increases in FEV1, FEV1/FVC ratio, PEF, and FEF25-75% occurred only in the BSG. There were also significant increases in Ve and Vt in the BSG, but not when compared with the CG values at discharge. MIP and MEP significantly increased in both groups, with a greater effect on the BSG. There was a significant decrease in RR, as well as a significant increase in SpO2 only in the BSG. SpO2 acutely increased after BS; however, no changes were observed in the degree of dyspnea, vital signs, or signs of respiratory distress, and no gastrointestinal and hemodynamic repercussions were observed. Conclusions:BS has proven to be safe and effective for recovering pulmonary function; improving lung volumes, maximum respiratory pressures, and peripheral oxygenation; and reducing respiratory work during the postoperative period after upper abdominal surgery.

Reverse Trigger in Ventilated Non-ARDS Patients: A Phenomenon Can Not Be Ignored!

IntroductionThe role of reverse trigger (RT) was unknown in ventilated non-acute respiratory distress syndrome (ARDS) patients. So we conducted a retrospective study to evaluate the incidence, characteristics and physiologic consequence of RT in such population.MethodSix ventilated non-ARDS patients were included, the esophageal balloon catheter were placed for measurements of respiratory mechanics in all patients. And the data were analyzed to identified the occurrence of RT, duration of the entrainment, the entrainment pattern or ratio, the phase difference (dP) and the phase angle (θ), phenotypes, Effects and clinical correlations of RT.ResultRT was detected in four patients of our series (66.7%), and the occurrence of RT varying from 19 to 88.6% of their recording time in these 4 patients. One patient (No.2) showed a stable 1:1 ratio and Mid-cycle RT was the most common phenotype. However, the remained patients showed a mixed ratios, and Late RT was the most common phenotype, followed by RT with breath stacking. The average values of mean phase delay and phase angles were 0.39s (0.32, 0.98) and 60.52° (49.66, 102.24). Mean phase delay and phase angles were shorter in early reverse triggering with early and delayed relaxation, and longer in mid, late RT and RT with breath stacking. Pmus was variable between patients and phenotypes, and larger Pmus was generated in Early RT, Delayed Relaxation and mid cycle RT. When the RT occurred, the Peso increased 17.27 (4.91, 19.71) cmH2O compared to the controlled breathing, and the average value of incremental ΔPeso varied widely inter and intra patients (Table 3B and Figure 1). Larger ΔPeso was always generated in Early RT, Delayed Relaxation and mid cycle RT, accompanied by an significant increase of PL with 19.12 (0.75) cmH2O and 16.10 (6.23) cmH2O.ConclusionRT could also be observed in ventilated non-ARDS patients. The characteristics of pattern and phenotype was similar to RT in ARDS patients to a large extent. And RT appeared to alter lung stress and delivered volumes.

A pilot study of the breath stacking technique associated with respiratory muscle endurance training in patients with amyotrophic lateral sclerosis: videofluoroscopic findings in the upper airway.

Bulbar impairment represents a hallmark feature of amyotrophic lateral sclerosis (ALS) that significantly impacts survival and quality of life. Respiratory complications arise because of the weakness of the upper airway and respiratory muscles leading to respiratory failure, impaired swallowing, and reduced airway safety. Breath stacking and respiratory muscle endurance training are techniques that have been described to improve respiratory and bulbar function in patients with ALS. Considering the above, a respiratory technique named TR3 was developed. This study aimed to measure the acute effects of this technique on the upper airway through videofluoroscopy and to assess its clinical trial feasibility in patients with ALS. In this cross-sectional study, we enrolled participants diagnosed with ALS to perform a single session of TR3. Epidemiological data and baseline assessments were collected. The assessments included kinematics from videofluoroscopy measuring the retropalatal airspace size, the size of the narrowest airway, and the pharyngeal area during rest and TR3. Eight participants were included. During TR3, an acute increase of 15% was observed in the retropalatal airspace size (t = 5.14, p < 0.01), a 123% increase was observed in the size of the narrowest airway (t = -4.18, p < 0.001), and a 277% increase was observed in the pharyngeal area (t = -5.34, p < 0.001). During the intervention, TR3 showed acute effects in increasing pharyngeal constriction, pharyngeal expansion, retropalatal airspace size, and post-lingual narrowest airway size and is feasible for a larger research program. A clinical trial (NCT04226144) is already being conducted to assess the chronic therapeutic effects of this technique and its impact on the clinical evolution of ALS.

Automated detection and quantification of reverse triggering effort under mechanical ventilation

BackgroundReverse triggering (RT) is a dyssynchrony defined by a respiratory muscle contraction following a passive mechanical insufflation. It is potentially harmful for the lung and the diaphragm, but its detection is challenging. Magnitude of effort generated by RT is currently unknown. Our objective was to validate supervised methods for automatic detection of RT using only airway pressure (Paw) and flow. A secondary objective was to describe the magnitude of the efforts generated during RT.MethodsWe developed algorithms for detection of RT using Paw and flow waveforms. Experts having Paw, flow and esophageal pressure (Pes) assessed automatic detection accuracy by comparison against visual assessment. Muscular pressure (Pmus) was measured from Pes during RT, triggered breaths and ineffective efforts.ResultsTracings from 20 hypoxemic patients were used (mean age 65 ± 12 years, 65% male, ICU survival 75%). RT was present in 24% of the breaths ranging from 0 (patients paralyzed or in pressure support ventilation) to 93.3%. Automatic detection accuracy was 95.5%: sensitivity 83.1%, specificity 99.4%, positive predictive value 97.6%, negative predictive value 95.0% and kappa index of 0.87. Pmus of RT ranged from 1.3 to 36.8 cmH20, with a median of 8.7 cmH20. RT with breath stacking had the highest levels of Pmus, and RTs with no breath stacking were of similar magnitude than pressure support breaths.ConclusionAn automated detection tool using airway pressure and flow can diagnose reverse triggering with excellent accuracy. RT generates a median Pmus of 9 cmH2O with important variability between and within patients.Trial registrationBEARDS, NCT03447288.

Frequency and Risk Factors for Reverse Triggering in Pediatric Acute Respiratory Distress Syndrome during Synchronized Intermittent Mandatory Ventilation

Rationale: Reverse triggering (RT) occurs when respiratory effort begins after a mandatory breath is initiated by the ventilator. RT may exacerbate ventilator-induced lung injury and lead to breath stacking.Objectives: We sought to describe the frequency and risk factors for RT among patients with acute respiratory distress syndrome (ARDS) and identify risk factors for breath stacking.Methods: We performed a secondary analysis of physiologic data from children on synchronized intermittent mandatory pressure-controlled ventilation enrolled in a single-center randomized controlled trial for ARDS. When children had a spontaneous effort on esophageal manometry, waveforms were recorded and independently analyzed by two investigators to identify RT.Results: We included 81,990 breaths from 100 patient-days and 36 patients. Overall, 2.46% of breaths were RTs, occurring in 15/36 patients (41.6%). A higher tidal volume and a minimal difference between neural respiratory rate and set ventilator rate were independently associated with RT (P = 0.001) in multivariable modeling. Breath stacking occurred in 534 (26.5%) of 2,017 RT breaths and in 14 (93.3%) of 15 patients with RT. In multivariable modeling, breath stacking was more likely to occur when total airway Δpressure (peak inspiratory pressure - positive end-expiratory pressure [PEEP]) at the time patient effort began, peak inspiratory pressure, PEEP, and Δpressure were lower and when patient effort started well after the ventilator-initiated breath (higher phase angle) (all P < 0.05). Together, these parameters were highly predictive of breath stacking (area under the curve, 0.979).Conclusions: Patients with higher tidal volume who have a set ventilator rate close to their spontaneous respiratory rate are more likely to have RT, which results in breath stacking >25% of the time.Clinical trial registered with ClinicalTrials.gov (NCT03266016).

Nonpharmacological interventions for respiratory health in Parkinson's disease: A systematic review and meta-analysis.

Respiratory dysfunction in Parkinson's disease (PD) is often an underdiagnosed and untreated impairment associated with the disease. Clinically, a reactive approach to respiratory morbidity is taken, rather than preventative approaches that address underlying impairment/s. This systematic review identifies the current evidence to support nonpharmacological interventions to improve respiratory impairments in individuals with PD. The relevant literature was searched using a customised and systematic strategy. Randomised and nonrandomised control trials of nonpharmacological interventions targeting respiratory outcome measures in PD were included. Outcomes of interest were respiratory morbidity and mortality, respiratory muscle strength, spirometry measures, lung volumes, peak cough flow, and perception of dyspnoea. Nonpharmacological interventions included: functional training, generalised strength training, respiratory muscle strength training, aerobic exercise, qigong, yoga, breath stacking, incentive spirometry and singing. Methodological quality of included studies varied. Meta-analyses of nonpharmacological interventions demonstrated significant effects for inspiratory muscle strength (mean difference [MD] 19.68; confidence interval [CI] 8.49, 30.87; z=3.45; p=0.0006; I2 =2%), expiratory muscle strength (MD 18.97; CI 7.79, 30.14; z=3.33; p=0.0009; I2 =23%) and peak expiratory flow (MD 72.21; CI 31.19, 113.24; z=3.45; p=0.0006; I2 =0%). Best-evidence synthesis identified level 1 evidence supporting nonpharmacological interventions for improving peak cough flow and perceived dyspnoea. No studies were identified reporting outcomes of respiratory rate, inspiration:expiration ratio or respiratory morbidity or mortality in PD. Nonpharmacological interventions improved respiratory muscle strength and peak expiratory flow in PD. Additional trials targeting respiratory dysfunction and longitudinal studies examining the relationship between respiratory dysfunction and morbidity and mortality rates in PD are required.

Comparison between breath stacking technique associated with expiratory muscle training and breath stacking technique in amyotrophic lateral sclerosis patients: Protocol for randomized single blind trial

IntroductionAmyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting both upper and lower motor neurons, and lead to respiratory failure. Strategies are suggested to respiratory management in ALS patients, as the breath stacking and Expiratory muscle training (EMT), which have been used as aid to assist cough in neuromuscular disorders. However, the randomized controlled trials performed in ALS patients have not investigated the addiction of EMT together breath stacking in this population. This trial aims to determine if breath stacking plus EMT is more effective than breath stacking alone to decrease the decline rate on the inspiratory/expiratory muscle strength, FVC and voluntary PCF in ALS patients. MethodsThis parallel-group, assessor-blinded randomized controlled trial, powered for superiority, aims to assess pulmonary function, respiratory muscle strength, peak cough flow as primary outcomes. Forty-two participants are being recruited referral neuromuscular disease center at Brasilia, Brazil. Following baseline testing, participants are randomized using concealed allocation, to receive either: a) breath stacking technique alone or b) breath stacking technique plus EMT. ConclusionThere is a lack of evidence regarding the benefit of EMT plus breath stacking in ALS patients. This trial will contribute to evidence currently being generated in national and international trials by implementing and evaluating a respiratory therapy program including two components not yet combined in previous research, for people with ALS involving longer-term follow-up of outcomes. This trial is ongoing and currently recruiting. Trial registrationThis trial was prospectively registered on the Clinical Trials Registry NCT04226144.

Reverse Trigger Phenotypes in Acute Respiratory Distress Syndrome.

Rationale: Reverse triggering is an underexplored form of dyssynchrony with important clinical implications in patients with acute respiratory distress syndrome.Objectives: This retrospective study identified reverse trigger phenotypes and characterized their impacts on Vt and transpulmonary pressure.Methods: Fifty-five patients with acute respiratory distress syndrome on pressure-regulated ventilator modes were included. Four phenotypes of reverse triggering with and without breath stacking and their impact on lung inflation and deflation were investigated.Measurements and Main Results: Inflation volumes, respiratory muscle pressure generation, and transpulmonary pressures were determined and phenotypes differentiated using Campbell diagrams of respiratory activity. Reverse triggering was detected in 25 patients, 15 with associated breath stacking, and 13 with stable reverse triggering consistent with respiratory entrainment. Phenotypes were associated with variable levels of inspiratory effort (mean 4-10 cm H2O per phenotype). Early reverse triggering with early expiratory relaxation increased Vts (88 [64-113] ml) and inspiratory transpulmonary pressures (3 [2-3] cm H2O) compared with passive breaths. Early reverse triggering with delayed expiratory relaxation increased Vts (128 [86-170] ml) and increased inspiratory and mean-expiratory transpulmonary pressure (7 [5-9] cm H2O and 5 [4-6] cm H2O). Mid-cycle reverse triggering (initiation during inflation and maximal effort during deflation) increased Vt (51 [38-64] ml), increased inspiratory and mean-expiratory transpulmonary pressure (3 [2-4] cm H2O and 3 [2-3] cm H2O), and caused incomplete exhalation. Late reverse triggering (occurring exclusively during exhalation) increased mean expiratory transpulmonary pressure (2 [1-2] cm H2O) and caused incomplete exhalation. Breath stacking resulted in large delivered volumes (176 [155-197] ml).Conclusions: Reverse triggering causes variable physiological effects, depending on the phenotype. Differentiation of phenotype effects may be important to understand the clinical impacts of these events.

Prevalence of Reverse Triggering in Early ARDS: Results From a Multicenter Observational Study

The prevalence of reverse triggering (RT) in the early phase of ARDS is unknown. During early ARDS, what is the proportion of patients affected by RT, what are its potential predictors, and what is its association with clinical outcomes? This was prospective, multicenter, and observational study. Patients who met the Berlin definition of ARDS with less than 72h of mechanical ventilation and had not been paralyzed with neuromuscular blockers were screened. A 30-min recording of respiratory signals was obtained from the patients as soon as they were enrolled, and the number of breaths with RT were counted. One hundred patients were included. ARDS was mild to moderate in 92%of them. The recordings were obtained after a median of 1day (interquartile range, 1-2days) of ventilation. Fifty patients had RT, and most of these events (97%) were not associated with breath stacking. Detecting RT was associated with lower tidal volume (Vt) and less opiate infusion. The presence of RT was not associated with time to discontinuation of mechanical ventilation (subdistribution hazard ratio, 1.03; 95%CI, 0.6-1.77), but it possibly was associated with a reduced hospital mortality (hazard ratio, 0.65; 95%CI, 0.57-0.73). Fifty percent of patients receiving assist-control ventilation for mild or moderate ARDS, sedated and nonparalyzed, demonstrate RT without breath stacking on the first day of mechanical ventilation. RT may be associated with low VTS and opiate doses. ClinicalTrials.gov; No.: NCT02732041; URL: www.clinicaltrials.gov.

The French national protocol for Kennedy\u2019s disease (SBMA): consensus diagnostic and management recommendations

BackgroundKennedy’s disease (KD), also known as spinal and bulbar muscular atrophy (SBMA), is a rare, adult-onset, X-linked recessive neuromuscular disease caused by CAG expansions in exon 1 of the androgen receptor gene (AR). The objective of the French national diagnostic and management protocol is to provide evidence-based best practice recommendations and outline an optimised care pathway for patients with KD, based on a systematic literature review and consensus multidisciplinary observations.ResultsThe initial evaluation, confirmation of the diagnosis, and management should ideally take place in a tertiary referral centre for motor neuron diseases, and involve an experienced multidisciplinary team of neurologists, endocrinologists, cardiologists and allied healthcare professionals. The diagnosis should be suspected in an adult male presenting with slowly progressive lower motor neuron symptoms, typically affecting the lower limbs at onset. Bulbar involvement (dysarthria and dysphagia) is often a later manifestation of the disease. Gynecomastia is not a constant feature, but is suggestive of a suspected diagnosis, which is further supported by electromyography showing diffuse motor neuron involvement often with asymptomatic sensory changes. A suspected diagnosis is confirmed by genetic testing. The multidisciplinary assessment should ascertain extra-neurological involvement such as cardiac repolarisation abnormalities (Brugada syndrome), signs of androgen resistance, genitourinary abnormalities, endocrine and metabolic changes (glucose intolerance, hyperlipidemia). In the absence of effective disease modifying therapies, the mainstay of management is symptomatic support using rehabilitation strategies (physiotherapy and speech therapy). Nutritional evaluation by an expert dietician is essential, and enteral nutrition (gastrostomy) may be required. Respiratory management centres on the detection and treatment of bronchial obstructions, as well as screening for aspiration pneumonia (chest physiotherapy, drainage, positioning, breath stacking, mechanical insufflation-exsufflation, cough assist machnie, antibiotics). Non-invasive mechanical ventilation is seldom needed. Symptomatic pharmaceutical therapy includes pain management, endocrine and metabolic interventions. There is no evidence for androgen substitution therapy.ConclusionThe French national Kennedy’s disease protocol provides management recommendations for patients with KD. In a low-incidence condition, sharing and integrating regional expertise, multidisciplinary experience and defining consensus best-practice recommendations is particularly important. Well-coordinated collaborative efforts will ultimately pave the way to the development of evidence-based international guidelines.

Breath Stacking Technique Associated With Expiratory Muscle Training in Amyotrophic Lateral Sclerosis Patients

Breath Stacking Technique Associated With Expiratory Muscle Training in Amyotrophic Lateral Sclerosis Patients

Comparison of the effects of voluntary and involuntary breath stacking techniques on respiratory mechanics and lung function patterns in tracheostomized patients: a randomized crossover clinical trial.

ABSTRACTObjective:To compare the effects of voluntary breath stacking (VBS) and involuntary breath stacking (IBS) techniques on respiratory mechanics, lung function patterns, and inspiratory capacity in tracheostomized patients. Methods:This was a randomized crossover clinical trial involving 20 tracheostomized patients admitted to the ICU and submitted to the VBS and IBS techniques, in random order, with an interval of 5 h between each. Ten cycles of each technique were performed with an interval of 30 s between each cycle. In VBS, patients performed successive inspirations for up to 30 s through a one-way valve, whereas in IBS, successive slow insufflations were performed with a resuscitator bag until the pressure reached 40 cmH2O. Respiratory mechanics, inspiratory capacity, and the lung function pattern were evaluated before and after the interventions. Results:After IBS, there was an increase in static compliance (p = 0.007), which was also higher after IBS than after VBS (p = 0.03). There was no significant difference between the pre-VBS and post-VBS evaluations in terms of static compliance (p = 0.42). Inspiratory capacity was also greater after IBS than after VBS (2,420.7 ± 480.9 mL vs. 1,211.3 ± 562.8 mL; p < 0.001), as was airway pressure (38.3 ± 2.6 cmH2O vs. 25.8 ± 5.5 cmH2O; p < 0.001). There were no changes in resistance or lung function pattern after the application of either technique. Conclusions:In comparison with VBS, IBS promoted greater inspiratory capacity and higher airway pressure, resulting in an increase in static compliance.

Automatic detection of reverse-triggering related asynchronies during mechanical ventilation in ARDS patients using flow and pressure signals.

Asynchrony due to reverse-triggering (RT) may appear in ARDS patients. The objective of this study is to validate an algorithm developed to detect these alterations in patient-ventilator interaction. We developed an algorithm that uses flow and airway pressure signals to classify breaths as normal, RT with or without breath stacking (BS) and patient initiated double-triggering (DT). The diagnostic performance of the algorithm was validated using two datasets of breaths, that are classified as stated above. The first dataset classification was based on visual inspection of esophageal pressure (Pes) signal from 699 breaths recorded from 11 ARDS patients. The other classification was obtained by vote of a group of 7 experts (2 physicians and 5 respiratory therapists, who were trained in ICU), who evaluated 1881 breaths gathered from recordings from 99 subjects. Experts used airway pressure and flow signals for breaths classification. The RT with or without BS represented 19% and 37% of breaths in Pes dataset while their frequency in the expert's dataset were 3% and 12%, respectively. The DT was very infrequent in both datasets. Algorithm classification accuracy was 0.92 (95% CI 0.89-0.94, P < 0.001) and 0.96 (95% CI 0.95-0.97, P < 0.001), in comparison with Pes and experts' opinion. Kappa statistics were 0.86 and 0.84, respectively. The algorithm precision, sensitivity and specificity for individual asynchronies were excellent. The algorithm yields an excellent accuracy for detecting clinically relevant asynchronies related to RT.