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

Abstract

BackgroundMost 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.MethodsWe 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.ResultsAt 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.ConclusionsLaryngoscopy 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.

Laryngoscopy Can Be a Valuable Tool for Unexpected Therapeutic Response in Noninvasive Respiratory Interventions

“…We thank Antonio M. Esquinas and Giuseppe Fiorentino for their acknowledgments and for their summary of some of the findings from our investigation 1 on this under-studied topic of laryngeal response patterns to mechanical insufflation-exsufflation. [2][3][4] We certainly agree that the larynx must not be seen merely as an opening at the top of the airway tree. As we have described in our work, the larynx is a highly complex valve that needs to adjust, adapt, and actively respond to a wide range of physiological situations and stressors.…”

“…They surmise that upper airway reflexes may be hyper-regulated to prevent aspiration of foreign material into the airways, which will stimulate glottis closure, with the collapse of more floppy supraglottic structures. 3 Second, mechanical insufflationexsufflation has been increasingly used in individuals with neuromuscular weakness, despite the lack of large randomized trials, although there is cumulative evidence that mechanical insufflation-exsufflation increases cough peak flow and, in combination with noninvasive ventilation, can prolong survival. The literature varies regarding appropriate settings of inspiratory and expiratory pressures, which range from 20 to 60 cm H 2 O in positive and negative pressures.…”

Optimizing expiratory flows during mechanical cough in a pediatric neuromuscular lung model

“…This may reduce comfort for the child and occlude upper airways due to retrognathia. The use of asymmetric MI‐E treatment pressures is also recommended in adult patients with dysfunction in bulbar innervated muscles because high P i results in laryngeal closure . This might be highly relevant in children with severe Spinal Muscular Atrophy type 1, who may also have a bulbar innervated muscle dysfunction and which may be a possible challenge to treatment efficacy .…”

“…Green cells, fulfill both criteria for optimal settings; light blue, low values for airflow and volume thus fulfill neither criteria; red cells, insufflated volume too high; yellow cells, fulfill only volume criteria [Color figure can be viewed at wileyonlinelibrary.com] recommended in adult patients with dysfunction in bulbar innervated muscles because high P i results in laryngeal closure. 22 This might be highly relevant in children with severe Spinal Muscular Atrophy type 1, who may also have a bulbar innervated muscle dysfunction and which may be a possible challenge to treatment efficacy. 6,23 However, the laryngeal collapsibility during MI-E is not systematically examined in pediatric NMD diagnoses but underlines the importance to take upper airway collapsibility into consideration when using the MI-E in small children.…”

Mechanical Insufflation-Exsufflation: Room for Improvement

“…DOI: 10.4187/respcare.06542 ryngeal visualization disclosed that higher insufflation pressure and flow promoted adduction of the vocal folds. 7,8 Evidence-based medicine does not provide sufficient evidence to recommend the systematic use of mechanical insufflation-exsufflation in patients with chronic neuromuscular weakness. 9 Perhaps the negative results of some trials come from suboptimal use of the device.…”