Primary site of constriction during the compression phase of cough in healthy young adults.

Glottal closure has been considered as the primary constriction point during the compression phase (CP); however, vocal fold adduction alone cannot resist the high pressures, providing motivation to explore other mechanisms contributing to that resistance. The goal of this study was to identify site(s) and degree of constriction during the CP of cough of varying types in healthy young adults. Twenty-five healthy young participants participated in this study. The experimental protocol was comprised of: 1) baseline pulmonary function measures; 2) cough practice to establish weak, moderate and strong coughs; 3) voluntary and reflex cough assessments with fluoroscopy and airflow measures. We used a repeated measures ANOVA to identify whether there are differences in constriction ratio between cough types. There was a significant difference in constriction of varying cough types. Degree of constriction in all cough strengths showed that the glottis was the most constricted area, followed by the laryngeal vestibule, nasopharynx, hypopharynx, oropharynx, and cervical trachea, in order, but stronger cough resulted in more constriction in all areas compared to weaker cough. Degree of constriction in reflex cough showed a similar pattern though there was greater constriction in the oropharynx than the hypopharynx. Airflow measures in voluntary cough were consistent with previous findings. Differences in upper airway constriction during the compression phase of cough may be attributed to differences in motor control between reflex and voluntary cough, and the increased constriction seen during strong cough may reflect increased muscle recruitment during that task. In the future, we can use this knowledge to develop novel methods for cough rehabilitation.

Association Between Subglottic Pressure and Pulmonary Function in Individuals With Parkinson's Disease.

INTRODUCTION: In individuals with Parkinson's disease (PD), pulmonary complication such as weakness and rigidity of respiratory muscles and reduced cough airflow may be associated with reduced voice production due to limited pulmonary capacity and reduced airflow needed to vibrate the vocal folds. It is not clear, however, which pulmonary function parameter is determinant in the association with peak subglottic pressure (SGP). Therefore, the purpose of this study was to determine the association between peak SGP and pulmonary function parameters in individuals with PD. METHODS: Forty-two individuals with diagnosis of idiopathic PD of both genders were recruited in the study. Mean and peak SGP, spirometric indices, maximum inspiratory pressure, maximum expiratory pressure (MEP), and peak cough flow (PCF) during reflex and voluntary cough were measured on all participants. RESULTS: The analysis revealed that peak SGP had a moderate but significant linear association with MEP (r = 0.38; P = 0.013), voluntary (r = 0.31; P = 0.051), and reflex PCF (r = 0.40; P = 0.012), but not with maximum inspiratory pressure (r = 0.23; P = 0.145). Higher values in peak SGP were associated with higher values in MEP, voluntary PCF, and reflex PCF. No linear association was detected between peak SGP and spirometric indices. CONCLUSIONS: Peak SGP has a direct association with voluntary and reflex PCF, and expiratory muscle strength, but not with inspiratory muscle strength. The association with peak SGP is higher for reflex PCF than for voluntary PCF.

Could reflex cough induced through nebulized capsaicin achieve airway clearance in patients with acute retention of lung secretions?

Nasotracheal suctioning (NTS) is a procedure commonly performed by respiratory physiotherapists and nurses to remove excess respiratory secretions from the tracheobronchial tree in a self-ventilating, non-intubated and non-tracheotomized patient. NTS is an important treatment modality for patients with acute secretion retention who are at high risk of progressive respiratory deterioration and arrest. However, NTS is a blind invasive procedure with risk of serious adverse events, and the patient experience of NTS is often extremely negative. Capsaicin, a substance extracted from cayenne pepper, elicits reflex coughs when inhaled. It is hypothesized that capsaicin-induced reflex cough may offer an alternative treatment option to NTS. It is suggested that repeated reflex cough bouts, elicited through inhalation of nebulized capsaicin via a facemask, could achieve clearance of retained secretions from the tracheobronchial tree to the oropharynx, thereby avoiding the need for NTS. This hypothesis is supported by preliminary cough flow data from a stroke trial. Stroke patients underwent assessments of peak cough flow (PCF, a measure of cough effectiveness) of both maximal volitional cough and capsaicin-induced reflex cough. In a sub-group of 20 stroke patients with weak volitional cough (mean PCF 220 L/min, SD 80), PCF of capsaicin-induced reflex cough was on average 184 L/min (SD 130) higher than PCF of subjects' maximal volitional cough effort. Cough flow traces indicate a pattern of cough augmentation during consecutive reflex cough bouts. It is suggested that the hypothesis may best be tested in a pragmatic applied clinical study, i.e. through the application of nebulized capsaicin in relevant clinical situations, as opposed to observational or experimental physiological studies.

Clinical Criteria for Tracheostomy Decannulation in Subjects with Acquired Brain Injury.

BACKGROUND: Patients with acquired brain injury (ABI) often require long periods of having a tracheostomy tube for airway protection and prolonged mechanical ventilation. It has been recognized that fast and safe decannulation improves outcomes and facilitates the recovery process. Nevertheless, few studies have provided evidence for decannulation criteria, despite the high prevalence of ABI subjects with tracheostomies. The aim of our study was to assess which clinical parameters are the best predictors for decannulation in subjects with ABI. METHODS: In this cross-sectional study, we recruited 74 consecutive ABI subjects (mean age 51.52 ± 16.76) with tracheostomy tubes. First, the subjects underwent the original decannulation assessment for cannula removal. Second, they underwent our experimental decannulation protocol. The experimental protocol included: voluntary cough (cough peak flow ≥160 L/min), reflex cough, tracheostomy tube capping (≥72 h), swallowing instrumental assessment (penetration aspiration scale ≤5), blue dye test, number of trachea suctions, endoscopic assessment of airway patency (lumen diameter ≥50%), saturation (SpO2 >95%), and level of consciousness evaluation (Glasgow coma scale ≥8). The reference standard was clinical removal of the tracheostomy tube within 48 h. RESULTS: Parameters showing the highest values of sensitivity and specificity, respectively, were tracheostomy tube capping (80%, 100%), endoscopy assessment of airway patency (100%, 30%), swallowing instrumental assessment (85%, 96%), and the blue dye test (65%, 85%). All these were combined in a clinical cluster parameter, which had higher sensitivity (100%) and specificity (82%). CONCLUSION: These results suggest that the best clinical prediction rule for decannulation in acquired brain injury subjects is a combination of the following assessments: (1) tracheostomy tube capping, (2) endoscopic assessment of patency of airways, (3) swallowing instrumental assessment, and (4) blue dye test.

Voluntary upregulation of reflex cough is possible in healthy older adults and Parkinson's disease.

Cough is an airway-protective mechanism that serves to detect and forcefully eject aspirate material. Existing research has identified the ability of healthy young adults to suppress or modify cough motor output based on external cueing. However, no study has evaluated the ability of people with Parkinson's disease (PD) and healthy older adults (HOAs) to upregulate cough motor output. The goal of this study was to evaluate the ability of people with PD and healthy age-matched controls (HOAs) to upregulate reflex and voluntary cough function volitionally with verbal instruction and visual biofeedback of airflow targets. Sixteen participants with PD and twenty-eight HOAs (56-83 yr old) were recruited for this study. Experimental procedures used spirometry to evaluate 1) baseline reflex cough (evoked with capsaicin) and voluntary sequential cough and 2) reflex and voluntary cough with upregulation biofeedback. Cough airflow was recorded and repeated-measures ANOVA was used to analyze differences in cough airflow parameters. Cough peak expiratory airflow rate and cough expired volume were significantly greater in the cueing condition for both induced reflex (P < 0.001) and voluntary cough (P < 0.001) compared with baseline measures. This is the first study to demonstrate the ability of people with PD and HOAs to upregulate induced reflex and voluntary cough motor output volitionally. These results support the development of studies targeting improved cough effectiveness in patients with airway-protective deficits.NEW & NOTEWORTHY Aspiration pneumonia is a leading cause of death in Parkinson's disease (PD) and results from concurrent dysphagia and dystussia (cough dysfunction). This is the first study to demonstrate that people with PD and healthy age-matched controls can volitionally upregulate induced reflex and voluntary cough effectiveness when presented with novel cueing strategies. Thus targeting upregulation of cough effectiveness via biofeedback may be a viable way to enhance airway protection in people with PD.

A novel reflex cough testing device.

BACKGROUND: The reflex cough test is useful for detecting silent aspiration, a risk factor for aspiration pneumonia. However, assessing the risk of aspiration pneumonia requires measuring not only the cough reflex but also cough strength. Currently, no reflex cough testing device is available that can directly measure reflex cough strength. We therefore developed a new testing device that can easily and simultaneously measure cough strength and the time until the cough reflex, and verified whether screening with this new instrument is feasible for evaluating the risk of aspiration pneumonia. METHODS: This device consists of a special pipe with a double lumen, a nebulizer, and an electronic spirometer. We used a solution of prescription-grade L-tartaric acid to initiate the cough reflex. The solution was inhaled through a mouthpiece as a microaerosol produced by an ultrasonic nebulizer. The peak cough flow (PCF) of the induced cough was measured with the spirometer. The 70 patients who participated in this study comprised 49 patients without a history of pneumonia (group A), 21 patients with a history of pneumonia (group B), and 10 healthy volunteers (control group). RESULTS: With the novel device, PCF and time until cough reflex could be measured without adverse effects. The PCF values were 118.3 ± 64.0 L/min, 47.7 ± 38.5 L/min, and 254.9 ± 83.8 L/min in group A, group B, and the control group, respectively. The PCF of group B was significantly lower than that of group A and the control group (p < 0.0001), while that of group B was significantly lower than that of the control group (p < 0.0001). The time until the cough reflex was 4.2 ± 5.9 s, 7.0 ± 7.0 s, and 1 s in group A, group B, and the control group, respectively. This duration was significantly longer for groups A and B than for the control group (A: p < 0.001, B: p < 0.001), but there was no significant difference between groups A and B (p = 0.0907). CONCLUSION: Our newly developed device can easily and simultaneously measure the time until the cough reflex and the strength of involuntary coughs for assessment of patients at risk of aspiration pneumonia.

Reflex Cough and Disease Duration as Predictors of Swallowing Dysfunction in Parkinson's Disease.

Patients with Parkinson's disease (PD) have progressive and pervasive disorders of airway protection. Recent work has highlighted the relationship between reflex and voluntary cough and swallowing safety. The goal of this study was to test the sensitivity and specificity of several airway protective and disease-specific factors for predicting swallowing safety outcomes in PD. Sixty-four participants (44 males) completed measures of voluntary and reflex cough, and swallowing safety. Clinical predictors included disease severity and duration, and cough airflow and sensitivity measures. ROC and Chi-square analyses identified predictors of swallowing safety (penetration-aspiration score) in PD. Disease duration significantly discriminated between patients with normal and abnormal swallowing safety (p = 0.027, sensitivity: 71 %, specificity: 55.4 %). Cough reflex sensitivity significantly discriminated between patients who penetrated above the level of the vocal folds and those with more severe penetration/aspiration (p = 0.021, sensitivity: 71.0 %, specificity 57.6 %). Urge-to-cough sensitivity (log-log linear slope) was the only variable which significantly discriminated between patients with penetration versus aspiration (p = 0.017, sensitivity: 85.7 %, specificity 73.2 %). It is important to identify the factors which influence airway protective outcomes in PD especially given that aspiration pneumonia is a leading cause of death. Results from this study highlight the ecological validity of reflex cough in the study of airway protection and this study further identifies important factors to consider in the screening of airway protective deficits in PD.

Comparison of voluntary and reflex cough effectiveness in Parkinson's disease.

INTRODUCTION: Multiple airway protective mechanisms are impacted with Parkinson's disease (PD), including swallowing and cough. Cough serves to eject material from the lower airways, and can be produced voluntarily (on command) and reflexively in response to aspirate material or other airway irritants. Voluntary cough effectiveness is reduced in PD however it is not known whether reflex cough is affected as well. The goal of this study was to compare the effectiveness between voluntary and reflex cough in patients with idiopathic PD. METHODS: Twenty patients with idiopathic PD participated. Cough airflow data were recorded via facemask in line with a pneumotachograph. A side delivery port connected the nebulizer for delivery of capsaicin, which was used to induce cough. Three voluntary coughs and three reflex coughs were analyzed from each participant. A two-way repeated measures analysis of variance was used to compare voluntary versus reflex cough airflow parameters. RESULTS: Significant differences were found for peak expiratory flow rate (PEFR) and cough expired volume (CEV) between voluntary and reflex cough. Specifically, both PEFR and CEV were reduced for reflex as compared to voluntary cough. CONCLUSION: Cough PEFR and CEV are indicative of cough effectiveness in terms of the ability to remove material from the lower airways. Differences between these two cough types likely reflect differences in the coordination of the respiratory and laryngeal subsystems. Clinicians should be aware that evaluation of cough function using voluntary cough tasks overestimates the PEFR and CEV that would be achieved during reflex cough in patients with PD.

Cough expired volume and airflow rates during sequential induced cough.

Cough effectiveness is determined by a combination of volume of air expired and maximum expiratory airflow rate. Studies of cough sensitivity identify cough thresholds based on at least 2 or 5-cough re-accelerations to a stimulus, however, to date no study has examined the interplay between the distribution of cough expired air and cough airflow rates for these induced sequential coughs. The goal of this study was to investigate the relationship between reflex cough re-accelerations, cough airflow and cough inspired and expired volume. Twenty adults (18-40 years, four men) volunteered for study participation, and were outfitted with a facemask in-line with a pneumotachograph and a one-way valve for capsaicin delivery on inspiration. Cough inspired and expired volume (Liters of air) as well as airflow parameters (peak expiratory flow rates L/s) were measured for each cough response. Results demonstrate significant linear relationships between cough expired volume, flow rates, and the total number of coughs produced. Thus, as the number of coughs in an epoch increase, the mechanical effectiveness of coughs within the epoch may decrease according to peak expiratory flow rates and cough expired volume, particularly for coughs comprised of more than 3 re-accelerations.