Cough augmentation techniques for people with chronic neuromuscular disorders

BACKGROUND

People with neuromuscular disorders may have a weak, ineffective cough predisposing them to respiratory complications. Cough augmentation techniques aim to improve cough effectiveness and mucous clearance, reduce the frequency and duration of respiratory infections requiring hospital admission, and improve quality of life.

OBJECTIVES

To determine the efficacy and safety of cough augmentation techniques in adults and children with chronic neuromuscular disorders.

SEARCH METHODS

On 13 April 2020, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, and ClinicalTrials.gov for randomised controlled trials (RCTs), quasi-RCTs, and randomised cross-over trials.

SELECTION CRITERIA

We included trials of cough augmentation techniques compared to no treatment, alternative techniques, or combinations thereof, in adults and children with chronic neuromuscular disorders.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, extracted data, and assessed risk of bias. The primary outcomes were the number and duration of unscheduled hospitalisations for acute respiratory exacerbations. We assessed the certainty of evidence using GRADE.

MAIN RESULTS

The review included 11 studies involving 287 adults and children, aged three to 73 years. Inadequately reported cross-over studies and the limited additional information provided by authors severely restricted the number of analyses that could be performed. Studies compared manually assisted cough, mechanical insufflation, manual and mechanical breathstacking, mechanical insufflation-exsufflation, glossopharyngeal breathing, and combination techniques to unassisted cough and alternative or sham interventions. None of the included studies reported on the primary outcomes of this review (number and duration of unscheduled hospital admissions) or listed 'adverse events' as primary or secondary outcome measures. The evidence suggests that a range of cough augmentation techniques may increase peak cough flow compared to unassisted cough (199 participants, 8 RCTs), but the evidence is very uncertain. There may be little to no difference in peak cough flow outcomes between alternative cough augmentation techniques (216 participants, 9 RCTs). There was insufficient evidence to determine the effect of interventions on measures of gaseous exchange, pulmonary function, quality of life, general function, or participant preference and satisfaction.

AUTHORS' CONCLUSIONS

We are very uncertain about the safety and efficacy of cough augmentation techniques in adults and children with chronic neuromuscular disorders and further studies are needed.

Cough peak flow with different mechanically assisted coughing approaches under different conditions in patients with neuromuscular disorders

PURPOSE

Mechanically assisted coughing (MAC) is an airway clearance method in which the thorax/abdomen is compressed in synchronization with mechanical insufflation-exsufflation (MI-E). MAC can be performed with manual assistance at the upper thorax (MAC-UT), lower thorax (MAC-LT), and upper thorax + abdomen (MAC-UT/A). This study aimed to determine the most effective approach under different conditions (air stacking or tracheostomy) in patients with neuromuscular disorders (NMDs).

METHODS

The study included 34 patients with NMDs. The patients were categorized into air stacking group (n=15), no air stacking group (n=9), and tracheostomy/tracheostomy positive-pressure ventilation (TPPV) group (n=10).

RESULTS

In each group, the cough peak flow (CPF) at 75% of the forced vital capacity (V̇75), V̇50, V̇25, and V̇10 were investigated during the approaches. In the air stacking group, the CPF was higher with MAC-UT, MAC-LT, and MAC-UT/A than with MI-E (p < 0.05). Additionally, V̇75 was higher with MAC-LT and MAC-UT/A than with MI-E (p < 0.05 and p < 0.01, respectively). In the no air stacking group, V̇75 was higher with MAC-UT/A than with MI-E (p < 0.05). In the tracheotomy/TPPV group, there were no significant differences.

CONCLUSIONS

MAC approaches, especially MAC-LT and MAC-UT/A, are preferred in air stacking patients. However, in tracheostomy/TPPV patients, the CPF might not increase with MAC.

Titration of Mechanical Insufflation-Exsufflation Optimal Pressure Combinations in Neuromuscular Diseases by Flow/Pressure Waveform Analysis

INTRODUCTION

The aim of this study was to assess several air-pressure settings for MI-E to determine their effect on peak cough flow (PCF), and to compare the best pressures with those are more common used in the literature (±40cmH₂O) in patients with neuromuscular disorders (NMD).

METHODS

Adults with NMD in whom MI-E was indicated were recruited. Assisted PCF was measured by an external pneumotachograph. The protocol included 9 PCF measures per patient: 1 baseline (non-assisted), 4 with increasing inspiratory pressures without negative pressure (10, 20, 30 and 40cmH₂O or maximum tolerated), and then 4 adding expiratory pressures (-10, -20, -30 and -40cmH₂O or maximum tolerated) with maximum inspiratory pressure previously achieved.

RESULTS

Twenty one patients were included, 61% with amyotrophic lateral sclerosis (ALS). Mean PCFs with recommended pressures (±40cmH₂O) were lower than the scored in the individualized steps of the titration protocol (197.7±67l/min vs 214.2±60l/min, p<0.05). Regarding subgroups, mean PCF_max values in ALS patients with bulbar symptoms were significantly higher than those achieved with recommended pressures (163.6±80 vs 189±66l/min, p<0.05).

CONCLUSION

The PCF_max obtained with the protocol did not always match the recommended settings. It may be advisable to perform MI-E titration assessed by non-invasive PCF monitoring in patients with NMD, especially in ALS with bulbar involvement to improve the therapy detecting airway collapse induced by high pressures.

Changing respiratory expectations with the new disease trajectory of nusinersen treated spinal muscular atrophy [SMA] type 1

Spinal muscular atrophy [SMA] is the most common genetic cause of childhood mortality, primarily from the most severe form SMA type 1. It is a severe, progressive motor neurone disease, affecting the lower brainstem nuclei and the spinal cord. There is a graded level of severity with SMA children from a practical viewpoint described as "Non-sitters", "Sitters" and less commonly, "Ambulant" correlating with SMA Type 0/Type 1, Type 2 and Type 3 respectively. Children with SMA Type 0 have a severe neonatal form whilst those with SMA Type 1 develop hypoventilation, pulmonary aspiration, recurrent lower respiratory tract infections, dysphagia and failure to thrive before usually succumbing to respiratory failure and death before the age of 2 years. The recent introduction of the antisense oligonucleotide nusinersen into clinical practice in certain countries, following limited trials of less than two years duration, has altered the treatment landscape and improved the outlook considerably for SMN1 related SMA. Approximately 70% of infants appear to have a clinically significant response to nusinersen with improved motor function. It appears the earlier the treatment is initiated the better the response. There are other rarer genetic forms of SMA that are not treated with nusinersen. Clinical expectations will change although it is unclear as yet what the extent of response will mean in terms of screening initiatives [e.g., newborn screening], "preventative strategies" to maintain respiratory wellbeing, timing of introduction of respiratory supports, and prolonged life expectancy for the subcategory of children with treated SMA type 1. This article provides a review of the strategies available for supporting children with respiratory complications of SMA, with a particular emphasis on SMA Type 1.

Physiotherapists' experiences of respiratory compromise in patients with Parkinson's disease: A qualitative study

Background/Aims:

To explore the experiences and perceptions of physiotherapists involved in the care of people with Parkinson's disease and respiratory compromise.

Methods:

This exploratory qualitative study recruited four physiotherapists who participated in a focus group and completed reflective diaries over a 3-month period. Experiences were explored using Interpretative Phenomenological Analysis.

Findings:

The study highlights three key themes: application of professional knowledge, application of clinical decision making and challenges to application of care.

Conclusions:

The results demonstrate sensitive awareness in caring for a dependent and vulnerable population whose key motor signs, compounded by ageing are perceived as influencing the presentation of respiratory compromise. There are descriptions of a reactive response to illness, alongside reflections on the challenges faced when asserting autonomy and recognising where the role of physiotherapy fits within the multidisciplinary team. Sputum clearance is perceived as being a key aspect of this role, although there is uncertainty with regard to the effectiveness and appropriateness of treatment options. Multiple perceived challenges to care provision are highlighted, with key concerns surrounding clinician and patient knowledge levels, maintenance of patient mobility, person-centred care and clarity in the direction of care.

Laryngeal response patterns influence the efficacy of mechanical assisted cough in amyotrophic lateral sclerosis

BACKGROUND

Most patients with amyotrophic lateral sclerosis (ALS) are treated with mechanical insufflation-exsufflation (MI-E) in order to improve cough. This method often fails in ALS with bulbar involvement, allegedly due to upper-airway malfunction. We have studied this phenomenon in detail with laryngoscopy to unravel information that could lead to better treatment.

METHODS

We conducted a cross-sectional study of 20 patients with ALS and 20 healthy age-matched and sex-matched volunteers. We used video-recorded flexible transnasal fibre-optic laryngoscopy during MI-E undertaken according to a standardised protocol, applying pressures of ±20 to ±50 cm H₂O. Laryngeal movements were assessed from video files. ALS type and characteristics of upper and lower motor neuron symptoms were determined.

RESULTS

At the supraglottic level, all patients with ALS and bulbar symptoms (n=14) adducted their laryngeal structures during insufflation. At the glottic level, initial abduction followed by subsequent adduction was observed in all patients with ALS during insufflation and exsufflation. Hypopharyngeal constriction during exsufflation was observed in all subjects, most prominently in patients with ALS and bulbar symptoms. Healthy subjects and patients with ALS and no bulbar symptoms (n=6) coordinated their cough well during MI-E.

CONCLUSIONS

Laryngoscopy during ongoing MI-E in patients with ALS and bulbar symptoms revealed laryngeal adduction especially during insufflation but also during exsufflation, thereby severely compromising the size of the laryngeal inlet in some patients. Individually customised settings can prevent this and thereby improve and extend the use of non-invasive MI-E.

Mechanical insufflation-exsufflation for people with neuromuscular disorders

BACKGROUND

People with neuromuscular disorders (NMDs) may have weak respiratory (breathing) muscles which makes it difficult for them to effectively cough and clear mucus from the lungs. This places them at risk of recurrent chest infections and chronic lung disease. Mechanical insufflation-exsufflation (MI-E) is one of a number of techniques available to improve cough efficacy and mucus clearance.

OBJECTIVES

To determine the efficacy and safety of MI-E in people with NMDs.

SEARCH METHODS

On 7 October 2013, we searched the following databases from inception: the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL (The Cochrane Library), MEDLINE, and EMBASE. We also searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform for ongoing trials. We conducted handsearches of reference lists and conference proceedings.

SELECTION CRITERIA

We considered randomised or quasi-randomised clinical trials, and randomised cross-over trials of MI-E used to assist airway clearance in people with a NMD and respiratory insufficiency. We considered comparisons of MI-E with no treatment, or alternative cough augmentation techniques.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial eligibility, extracted data, and assessed risk of bias in included studies according to standard Cochrane methodology. The primary outcome was mortality throughout follow-up or at six months follow-up.

MAIN RESULTS

Five studies with a total of 105 participants were found to be eligible for inclusion in this review. All included trials were short-term studies (two days or less), measuring immediate effects of the interventions. There was insufficient detail in the reports to assess methods of randomisation and allocation concealment. All five studies were at a high risk of bias from lack of blinding. The studies did not report on mortality, morbidity, quality of life, serious adverse events or any of the other prespecified outcomes. One study was a randomised cross-over trial conducted over two days, in which investigators applied two interventions twice daily in randomly assigned order, with a reverse cross-over the following day. Four studies applied multiple interventions for cough augmentation to each participant, in random order. One study reported fatigue as an adverse effect of MI-E, using a visual analogue scale. Peak cough expiratory flow (PCEF) was the most common outcome measure and was reported in four studies. Based on three studies, MI-E may improve PCEF compared to an unassisted cough. All interventions increased PCEF to the critical level necessary for mucus clearance. The included studies did not clearly show that MI-E improves cough expiratory flow more than other cough augmentation techniques. Based on one study, which was at risk of assessor bias, the addition of MI-E may reduce treatment time when added to a standard airway clearance regimen with manually assisted cough. MI-E appeared to be as well tolerated as other cough augmentation techniques, based on three studies which reported comfort visual analogue scores.

AUTHORS' CONCLUSIONS

The results of this review do not provide sufficient evidence on which to base clinical practice as we were unable to address important short- and long-term outcomes, including adverse effects of MI-E. There is currently insufficient evidence for or against the use of MI-E in people with NMDs. Further randomised controlled clinical trials are needed to test the safety and efficacy of MI-E.

Laryngeal response patterns to mechanical insufflation-exsufflation in healthy subjects

OBJECTIVE

Mechanical insufflation-exsufflation (MI-E) is used to assist cough in patients with neuromuscular diseases. Clinically, application may be challenging in some patient groups, possibly related to laryngeal dysfunction. Before launching a study in patients, the authors investigated laryngeal responses to MI-E in healthy individuals.

DESIGN

Twenty healthy volunteers, aged 21-29 yrs, were studied with video-recorded flexible transnasal fiber-optic laryngoscopy while performing MI-E using the Cough Assist (Respironics, United States) according to a standardized protocol applying pressures of ±20 to ±50 cm H2O.

RESULTS

An initial abduction of the vocal folds was observed in all subjects, both during the insufflation and exsufflation phases. Nineteen of the 20 subjects adequately coordinated glottic closure when instructed to cough. When instructed simply to exhale during exsufflation, the glottis stayed open in a majority. Subsequent to an initial abduction during exsufflation and cough, various obstructive laryngeal movements were observed in some subjects, such as narrowing of the vocal folds, retroflexion of the epiglottis, hypopharyngeal constriction, and backward movement of the base of the tongue.

CONCLUSIONS

The larynx can be studied with transnasal laryngoscopy during MI-E in healthy individuals. Laryngeal responses to MI-E vary, and laryngoscopy may offer valuable clinical information when applying MI-E in patients with bulbar muscle weakness.