A novel reflex cough testing device

Auditory-Perceptual Assessments of Cough: Characterizing Rater Reliability and the Effects of a Standardized Training Protocol

INTRODUCTION

Auditory-perceptual assessments of cough are commonly used by speech-language pathologists working with people with swallowing disorders with emerging evidence beginning to demonstrate their validity; however, their reliability among novice clinicians is unknown. Therefore, the primary aim of this study was to characterize the reliability of auditory-perceptual assessments of cough among a group of novice clinicians. As a secondary aim, we assessed the effects of a standardized training protocol on the reliability of auditory-perceptual assessments of cough.

METHODS

Twelve novice clinicians blindly rated ten auditory-perceptual cough descriptors for 120 cough audio clips. Standardized training was then completed by the group of clinicians. The same cough audio clips were then re-randomized and blindly rated. Reliability was analyzed pre- and post-training within each clinician (intra-rater), between each unique pair of raters (dyad-level inter-rater), and for the entire group of raters (group-level inter-rater) using intraclass correlation coefficients and Cohen's Kappa.

RESULTS

Pre-training reliability was greatest for measures of strength, effectiveness, and normality and lowest when judging the type of expiratory maneuver (cough, throat clear, huff, other). The measures that improved the most with training were ratings of perceived crispness, amount of voicing, and type of expiratory maneuver. Intra-rater reliability coefficients ranged from 0.580 to 0.903 pre-training and 0.756-0.904 post-training. Dyad-level inter-rater reliability coefficients ranged from 0.295 to 0.745 pre-training and 0.450-0.804 post-training. Group-level inter-rater reliability coefficients ranged from 0.454 to 0.919 pre-training and 0.558-0.948 post-training.

CONCLUSION

Reliability of auditory-perceptual assessments varied across perceptual cough descriptors, but all appeared within the range of what has been historically reported for auditory-perceptual assessments of voice and visual-perceptual assessments of swallowing and cough airflow. Reliability improved for most cough descriptors following 30-60 min of standardized training. Future research is needed to examine the validity of auditory-perceptual assessments of cough by assessing the relationship between perceptual cough descriptors and instrumental measures of cough effectiveness to better understand the role of perceptual assessments in clinical practice.

Cough as a neurological sign: What a clinician should know

Cough is a common respiratory complaint driving patients to seek medical advice. Besides being a fundamental respiratory sign, it is also a crucial neurological sign. There are three main types of coughs: Reflex cough (type I), voluntary cough (type II), and evoked cough (type III). Cough is a reflex predominantly mediated by control centers in the respiratory areas of the brainstem, modulated by the cerebral cortex. Cough reflex sensitivity could be increased in many neurological disorders such as brainstem space-occupying lesions, medullary lesions secondary to Chiari type I malformations, tics disorders such as Tourette's syndrome, somatic cough, cerebellar neurodegenerative diseases, and chronic vagal neuropathy due to allergic and non-allergic conditions. Meanwhile, cough sensitivity decreases in multiple sclerosis, brain hypoxia, cerebral hemispheric stroke with a brainstem shock, Parkinson's disease, dementia due to Lewy body disease, amyotrophic lateral sclerosis, and peripheral neuropathy as diabetic neuropathy, hereditary sensory and autonomic neuropathy type IV, vitamin B12, and folate deficiency. Arnold's nerve ear-cough reflex, syncopal cough, cough headache, opioids-associated cough, and cough-anal reflex are signs that could help diagnose underlying neurological conditions. Cough reflex testing is a quick, easy, and cheap test performed during the cranial nerve examination. In this article, we reviewed the role of cough in various neurological disorders that increase or decrease cough sensitivity.

Evaluation methods and influencing factors of cough sensitivity

Increased cough sensitivity is an important mechanism of chronic cough, and the evaluation of cough sensitivity helps understand the mechanism of cough and explore better methods to reduce cough. Evaluation methods may be direct or indirect. Direct methods include mechanical stimulation and chemical stimulation, and indirect methods include laryngeal reflex test, questionnaires, and brain functional magnetic resonance imaging (fMRI). Chemical stimulation is the most common method, while the capsaicin cough challenge test is proven and widely used. In this article, we will compare evaluation methods and explore influencing factors of cough sensitivity.

A New Therapeutic Approach for Dystussia and Atussia in Neurogenic Dysphagia: Effect of Aerosolized Capsaicin on Peak Cough Flow

Swallowing and cough are crucial components of airway protection. In patients with neurogenic dysphagia (ND), there is a high prevalence of dystussia (impaired cough) and atussia (absence of cough). As a result, the ability to detect and remove aspirated material from the airway decreases, exacerbating the sequelae associated with ND, including aspiration pneumonia, a leading cause of mortality in ND. This controlled intervention study aimed to quantify the cough response to aerosolized capsaicin (AC) in patients with ND and assess the potential of AC as a therapeutic tool in treating ND-related dystussia and atussia. Furthermore, we propose a novel application method that enables AC treatment to be performed at home. Spirometry was used to measure peak cough flow (PCF) of voluntary cough (cough on command) and reflexive cough (cough secondary to pharyngeal exposure to AC) in 30 subjects with and 30 without ND. The capsaicin aerosol was generated by adding 1-10 drops of liquid cayenne extract (1.5-2% capsaicin) to 100 mL carbonated water (0.00075-0.001% to 0.0075-0.01% capsaicin). Voluntary PCF in the ND group was significantly lower than in the control group (p < 0.001), while there was no significant difference in reflexive PCF (p = 0.225). Within the ND group, reflexive PCF was significantly higher than voluntary PCF (p = 0.001), while in healthy controls, reflexive PCF was significantly lower (p < 0.001). The data show that AC increased the tracheobronchial clearance efficacy in ND patients with dystussia and atussia, as it enabled subjects to access their individual cough potential, which is present, but inaccessible, due to neurological disorder.

Objective measurement of acoustic intensity of coughing for clearance of penetration and aspiration on video-fluoroscopy

PURPOSE

This preliminary, exploratory study evaluated the acoustic intensity of effective and ineffective clearance of penetrated and aspirated material from the laryngeal vestibule in patients with dysphagia.

METHOD

A lapel microphone was attached anterior to participants' tragus and recorded coughing in decibels during their videofluoroscopic swallowing studies (VFSS).

RESULT

Eighty-eight patients were recruited. Thirteen patients, with visible airway invasion and coughing were included in the final analysis. No coughs were effective at expelling aspirated material from the airway (n = 10). Both effective (4/7) and ineffective (3/7) coughing to penetration were recorded. The mean acoustic intensity of effective coughing to penetration was -44.0 dBFS (decibel level relative to full scale) [SD = 7.3, 95% CI = -51.14, -36.86], and ineffective coughing to penetration was only marginally lower at -42.9 dBFS [SD = 2.0, 95% CI = -45.21, -40.59].

CONCLUSION

No coughs were effective at expelling aspirated material from the airway. Some coughs effectively expelled penetrated material from the airway. However, the relationship between acoustic intensity and cough effectiveness is unclear due to the limited number of observations. Given that perceptual evaluation of coughing is widely used in dysphagia clinical practice to determine cough effectiveness, this is an important area for future research.

Methods for assessing cough sensitivity

Cough sensitivity can be described as the reaction intensity of the cough reflex to different stimuli which activate chemically and mechanically sensitive vagal afferent nerves innervating airways and lungs. Measurement of cough reflex sensitivity plays an important role in revealing the underlying mechanisms of cough and evaluating the effects of pharmacological interventions. Besides, different responses to cough suppression therapies indicate the existence of cough hypersensitivity. In consideration of these factors stated above, cough sensitivity should therefore be assessed with a variety of cough challenge tests. Based on the neuroanatomical characteristics of the cough reflex, chemical challenge tests have been developed to objectively assess cough sensitivity. In cough inhalation challenges, capsaicin and citric acid are commonly used as the tussive agents to induce cough, which are validated for describing a profile of cough sensitivity to chemical irritants. Recently, mechanical methodologies have also been tried to measure the mechanical sensitivity of the cough reflex. Methodological consideration and selection are necessary for the reasonable assessment of cough sensitivity while employing cough challenges in clinical trials. Thus, in this review, we will focus on describing various methodologies of cough sensitivity measurement and, detailing some factors influencing on the accuracy of outcomes in the experimentally induced cough.

The assessment of the peak of reflex cough in subjects with acquired brain injury and tracheostomy and healthy controls

INTRODUCTION

There is no standard procedure to evaluated the peak of reflex cough flow (PCF-reflex) in the literature, which is important assessment in subjects with acquired brain injury and tracheostomy cannula. The present study aims to investigate the PCF of the reflex cough in a broad sample of healthy controls and, furthermore, the presence and the strength of voluntary and reflex cough in subjects with ABI with tracheostomy cannula.

MATERIALS AND METHODS

We recruited 147 participants including the healthy subjects (n = 105) and acquired brain injury subjects (n = 43), who underwent respiratory assessment: the Tidal Volume, Forced Vital Capacity, PCF of voluntary cough (PCF-voluntary) and PCF-reflex (using a spirometer connected with a nebulizer by a bidirectional).

RESULTS

The PCF-reflex of controls and subjects was significant lower than the PCF-voluntary (P < 0.01). The PCF-voluntary was not assessed in 26 (60.5 %) subjects due to severe cognitive deficit. In subjects without cognitive deficits (n = 17; 39.5 %), it was significantly lower than in healthy controls (p < 0.01). In contrast, the PCF-reflex was completed in all subjects and it was not significantly different from healthy controls. Furthermore, the strength of the PCF-reflex decreased with increasing inhalation numbers of nebulised air.

CONCLUSION

Reflex cough behaviour differs largely from voluntary cough and the PCF results reflect this great discrepancy. PCF-reflex could be useful parameter for assessing the airway protection whereas PCF-voluntary for measuring airway clearance.