Associations between laryngeal and cough dysfunction in motor neuron disease with bulbar involvement.

True vocal fold (TVF) dysfunction may lead to cough ineffectiveness. In individuals with motor neuron disease (MND), cough impairment in the context of dysphagia increases risk for aspiration and respiratory failure. This study characterizes differences and associations between TVF kinematics and airflow during cough in individuals with bulbar MND. Sequential glottal angles associated with TVF movements during volitional cough were analyzed from laryngeal video endoscopy examinations of adults with bulbar MND (n = 12) and healthy controls (n = 12) and compared with simultaneously collected cough-related airflow measures. Significant group differences were observed with airflow and TVF measures: volume acceleration (p ≤ 0.001) and post-compression abduction TVF angle average velocity (p = 0.002) were lower and expiratory phase rise time (p = 0.001) was higher in the MND group. Reductions in maximum TVF angle during post-compression abduction in the MND group approached significance (p = 0.09). All subjects demonstrated complete TVF and supraglottic closure during the compression phase of cough, except for incomplete supraglottic closure in 2/12 MND participants. A strong positive relationship between post-compression maximum TVF abduction angle and peak expiratory cough flow was observed in the MND group, though it was not statistically significant (r = 0.55; p = 0.098). Reductions in the speed and extent of TVF abduction are seen during the expulsion phase of cough in individuals with MND. This may contribute to cough impairment and morbidity.

Pulmonary issues in patients with chronic neuromuscular disease.

Patients with chronic neuromuscular diseases such as spinal cord injury, amyotrophic lateral sclerosis, and muscular dystrophies experience respiratory complications that are cared for by the respiratory practitioner. An organized anatomical approach for evaluation and treatment is helpful to provide appropriate clinical care. Effective noninvasive strategies for management of hypoventilation, sleep-disordered breathing, and cough insufficiency are available for these patients.

Equipment options for cough augmentation, ventilation, and noninvasive interfaces in neuromuscular respiratory management.

This is a summary of the presentation on equipment options for cough augmentation, ventilation, and noninvasive interfaces in neuromuscular respiratory management presented as part of the program on pulmonary management of pediatric patients with neuromuscular disorders at the 30th annual Carrell-Krusen Neuromuscular Symposium on February 20, 2008.

Limits of effective cough-augmentation techniques in patients with neuromuscular disease.

BACKGROUND: Manual and mechanical cough-augmentation techniques can improve peak cough flow (PCF) in patients with respiratory insufficiency caused by neuromuscular disease. METHODS: We studied cough-augmentation techniques in 179 clinically stable patients with various neuromuscular diseases. We measured vital capacity (VC), maximum expiratory pressure (MEP), and PCF, with and without 3 cough-augmentation techniques: manually assisted cough (MAC); breath-stacking (in a subgroup of 60 patients receiving noninvasive mechanical ventilation); and breath-stacking in combination with MAC (also in the 60-patient subgroup). We analyzed the data with the receiver operating characteristic (ROC), to predict the lower limits (assisted PCF > or = 180 L/min) and upper limits (assisted PCF < unassisted PCF) of effectiveness of the 3 cough-augmentation techniques. RESULTS: The lower limit of effective assisted cough with MAC, breath-stacking, and breath-stacking plus MAC was best predicted by VC > 1,030 mL (ROC 0.86, P < .001), VC > 558 mL (ROC 0.92, P < .001), and VC > 340 mL (ROC 0.90, P < .001). The upper limit of effective MAC was best predicted by MEP > 34 cm H(2)O (ROC 0.89, P < .001), whereas the ROC prediction of the upper limit of effective cough with breath-stacking and with breath-stacking plus MAC was not better than random. With each of the cough-augmentation techniques the benefits decreased linearly with increasing MEP and VC (P < .001). Compared to MAC and breath-stacking alone, breath-stacking plus MAC best improved unassisted PCF (P < .001). CONCLUSIONS: In clinically stable patients with neuromuscular diseases, the effectiveness of cough-augmentation techniques can be predicted with measurements of maximum respiratory capacity. Patients with VC > 340 mL and MEP < 34 cm H(2)O would optimally benefit from the combination of breath-stacking plus manually assisted cough to improve PCF to > 180 L/min.

Respiratory treatment of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis is a progressive neurodegenerative disease with no known cure. The major cause of mortality and major morbidities is related to the effects of the disease on the muscles of the respiratory system (ie, the inspiratory, expiratory, and upper airway muscles). Dyspnea, swallowing difficulties, sialorrhea, and impaired cough are all symptoms that can be palliated through pharmacologic and nonpharmacologic means. Noninvasive positive pressure ventilation, in particular, is a technique that not only relieves dyspnea but may also extend the lives of patients who have this disease. It should be offered to all patients who have amyotrophic lateral sclerosis with a forced vital capacity of less than 50 percent.

American College of Chest Physicians consensus statement on the respiratory and related management of patients with Duchenne muscular dystrophy undergoing anesthesia or sedation.

This statement on the management of patients with Duchenne muscular dystrophy (DMD) undergoing procedural sedation or general anesthesia represents the consensus opinion of a multidisciplinary panel convened under the auspices of the American College of Chest Physicians. Expert recommendations on this subject are needed for several reasons. First, patients with DMD have an increased risk of complications when they undergo sedation or general anesthesia. In addition, due to improved cardiopulmonary therapies, patients with DMD are experiencing an unprecedented duration of survival. As a result, it is more common for them to require procedures involving sedation or general anesthesia. The risks related to anesthesia and sedation for DMD patients include potentially fatal reactions to inhaled anesthetics and certain muscle relaxants, upper airway obstruction, hypoventilation, atelectasis, congestive heart failure, cardiac dysrhythmias, respiratory failure, and difficulty weaning from mechanical ventilation. This statement includes advice regarding the highly interrelated areas of respiratory, cardiac, GI, and anesthetic management of patients with DMD undergoing general anesthesia or procedural sedation. The statement is intended to aid clinicians involved in the care of patients with DMD and to be a resource for other stakeholders in this field, including patients and their families. It is an up-to-date summary of medical literature regarding this topic and identifies areas in need of future research.

Management of airway clearance in neuromuscular disease.

The clearance of airway secretions from the lungs is normally supported by the mucociliary escalator and by cough. These protective mechanisms provide an effective means of pulmonary-hygiene maintenance in healthy individuals. Patients with neuromuscular disease that affects the respiratory pump (the muscles of breathing) can experience mild to profound limitation in both ventilation and cough. Neuromuscular respiratory insufficiency, when left untreated, can substantially impact quality of life and life expectancy. In most cases of neuromuscular disease, respiratory failure and pneumonia are the primary causes of death. Invasive mechanical ventilation and tracheal suctioning have been successfully used when needed to support respiratory insufficiency in this population. These modalities, though supportive, have been associated with substantial morbidity when used in patients with neuromuscular disease. The advent of noninvasive ventilation as a means of supporting chronic neuromuscular respiratory insufficiency has spurred the development of noninvasive cough-augmentation therapy to support airway clearance. Unfortunately, the need to support cough clearance is not always addressed, and few guidelines for the management of cough insufficiency have existed until relatively recently. An understanding of neuromuscular respiratory pathophysiology and the modes of effective noninvasive cough support are key in the evaluation and management of neuromuscular diseases. This review is meant to provide a basic understanding of cough mechanics, and the pathophysiology and management of neuromuscular cough insufficiency.

An evaluation of home volume ventilators that support open-circuit mouthpiece ventilation.

BACKGROUND: Open-circuit mouthpiece ventilation (MPV) is a form of noninvasive ventilation that can be used to provide portable daytime ventilatory support for neuromuscular patients with chronic respiratory failure. MPV has been reported to reduce the risk of respiratory infection due to tracheostomy, and to improve cough and voice function and patient quality of life. Despite these potential benefits, mouthpiece ventilation is not widely used. This may be due in part to the fact that little information is available as to which ventilators can support this application. OBJECTIVE: To determine which volume-cycled portable home ventilators currently available in the United States will support MPV, and what peak inspiratory flow rates create adequate circuit pressure to prevent low-pressure alarming. METHODS: We used a commercially available MPV breathing circuit with a set tidal volume range of 500\N1,000 mL with each of 8 ventilators currently available in the United States. RESULTS: Six of the 8 ventilators supported MPV: Respironics Lifecare PLV-100 and PLV Continuum, Mallinckrodt Achieva PSO2, Pulmonetics LTV800, Newport HT50, and Uni-Vent Eagle 754.

Standardized procedure for measurement of nasal potential difference: an outcome measure in multicenter cystic fibrosis clinical trials.

Patients with cystic fibrosis (CF) can be discriminated from healthy subjects by measurement of the nasal potential difference, which has become a useful outcome measure for therapies directed toward correcting defective electrolyte transport in CF. A standard operating procedure was developed by a CF Foundation clinical trials network, to be followed by all sites performing collaborative studies. Key variables in the measurement included type of voltmeter, exploring probe, reference electrodes, and solutions used to assess both sodium transport and chloride conductance. Eight sites submitted data on 3-8 normal and 4-5 CF subjects. Baseline voltage, an index of sodium transport, was -18.2 +/- 8.3 mV (mean +/- SD) for normals, and -45.3 +/- 11.4 mV for CF patients. There was no CFTR-mediated chloride secretion in CF subjects, as evidenced by the lack of response to perfusion with zero chloride + beta agonist solutions (+3.2 +/- 3.5 mV) vs. that in normals (-23.7 +/- 10.2 mV). The standardized nasal potential difference measurement minimizes variability between operators and study sites. Valid and consistent results can be attained with trained operators and attention to technical details. These data demonstrate the procedure to be sufficient for multicenter studies in the CF Foundation network.