Dyspnea in Parkinson's disease: an approach to diagnosis and management

Effects of high-intensity respiratory muscle training on respiratory muscle strength in individuals with Parkinson's disease: Protocol of a randomized clinical trial

OBJECTIVE

To investigate the efficacy of high-intensity respiratory muscle training (combined inspiratory and expiratory muscle training) in improving inspiratory and expiratory muscle strength, inspiratory muscle endurance, peak cough flow, dyspnea, fatigue, exercise capacity, and quality of life in this population.

METHODS

A randomized controlled trial, concealed allocation, blinded assessments, and intention-to-treat analysis will be carried out. Altogether, 34 individuals with PD (age ≥ 50 years old, with maximum inspiratory pressure (MIP) <80cmH2O or maximum expiratory pressure (MEP) <90cmH2O) will be recruited. Patients will be randomly assigned to either (1) high-intensity respiratory muscle training (experimental group, 60% of MIP and MEP) or (2) sham training (control group, 0cmH2O). Individuals will perform a home-based intervention, with indirect home supervision, consisting of two daily 20-min sessions (morning and afternoon), seven times a week, during eight weeks. Primary outcomes are MIP and MEP. Secondary outcomes are inspiratory muscle endurance, peak cough flow, dyspnea, fatigue, exercise capacity, and quality of life. The effects of the training will be analyzed from the collected data using intention-to-treat. Between-group differences will be measured using a two-way ANOVA with repeated measures (2*3), considering baseline, post-intervention, and 12-week follow-up.

IMPACT

The results of this trial will provide valuable new information on the efficacy of high-intensity respiratory muscle training in improving muscle strength, functional outcomes, and quality of life in individuals with PD. Performing combined inspiratory and expiratory muscle training using a single equipment is cheaper and feasible, takes less time and is easy to use. In addition, this intervention will be carried out in the home environment that increases accessibility, reduces time, and costs of transport, which increases the feasibility to reproduce their findings in clinical practice.

TRIAL REGISTRATION

NCT05608941. Registered on November 8, 2022.

Respiratory Abnormalities in Parkinson's Disease: What Do We Know from Studies in Humans and Animal Models?

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disease characterized by movement disorders due to the progressive loss of dopaminergic neurons in the ventrolateral region of the substantia nigra pars compacta (SNpc). Apart from the cardinal motor symptoms such as rigidity and bradykinesia, non-motor symptoms including those associated with respiratory dysfunction are of increasing interest. Not only can they impair the patients’ quality of life but they also can cause aspiration pneumonia, which is the leading cause of death among PD patients. This narrative review attempts to summarize the existing literature on respiratory impairments reported in human studies, as well as what is newly known from studies in animal models of the disease. Discussed are not only respiratory muscle dysfunction, apnea, and dyspnea, but also altered central respiratory control, responses to hypercapnia and hypoxia, and how they are affected by the pharmacological treatment of PD.

Key concepts and opportunities

Neuropalliative care is an emerging field dedicated to applying palliative care approaches to meet the needs of persons living with neurologic illness and their families. The development of this field acknowledges the unique needs of this population, including in terms of neuropsychiatric symptoms, the impact of neurologic illness on personhood, and the logistics of managing neurologic disability. In defining the goals of this field, it is important to distinguish between neuropalliative care as an approach to care, as a skillset, as a medical subspecialty, and as a public health goal as each of these constructs offers their own contributions and opportunities. As a newly emerging field, there are nearly unlimited opportunities to improve care through research, clinical care, education, and advocacy.

Breathing disorders in neurodegenerative diseases

Neurodegenerative disorders are a diverse group of conditions caused by progressive degeneration of neurons resulting in cognitive, motor, sensory, and autonomic dysfunction, leading to severe disability and death. Pulmonary dysfunction is relatively common in these conditions, may be present early in the disease, and is less well recognized and treated than other symptoms. There are variable disorders of upper and lower airways, central control of ventilation, strength of respiratory muscles, and breathing during sleep which further impact daily activities and quality of life and have the potential to injure vulnerable neurons. Laryngopharyngeal dysfunction affects speech, swallowing, and clearance of secretions, increases the risk of aspiration pneumonia, and can cause stridor and sudden death. In Parkinson's disease, L-Dopa benefits some pulmonary symptoms but there are limited pharmacological treatment options for pulmonary dysfunction. Targeted treatments include strengthening of respiratory muscles, positive airway pressure in sleep and techniques to improve cough efficacy. Well-designed clinical trials are needed to evaluate the long-term benefits of these interventions. Challenges for the future include earlier identification of pulmonary dysfunction in the clinic, institution of the most effective treatments (based on clinical trials that measure long-term meaningful outcomes) and the development of neuroprotective treatment.

Exercise Intolerance and Oxygen Desaturation in Patients with Parkinson's Disease: Triggers for Respiratory Rehabilitation?

The role that oxygen desaturation plays in exercise tolerance and its rehabilitative implications in patients with Parkinson's disease (PD) are unclear. We aimed to test exercise tolerance and oxygen saturation levels both during exercise and at night in PD patients to better define their rehabilitative needs. In clinically stable PD patients, undergoing inpatient rehabilitation, and in "ON" phase, we prospectively assessed clinical data, sleepiness, comorbidities, PD severity (Hoehn&Yahr, HY), motor function (ADLs, UPDRSII and UPDRSIII, Barthel Index, Functional Independence Measure), balance, spirometry, respiratory muscles (MIP/MEP), peak cough expiratory flow (PCEF), continuous night oxygen monitoring, and meters at 6MWT. Of 55 patients analyzed (28 with moderate-severe PD, HY ≥ 2.5), 37% and 23% showed moderate-severe impairment on UPDRSII and UPDRSIII, respectively; 96% had reduced exercise tolerance and severe respiratory muscles impairment (MIP/MEP < 45% pred.); 21.8% showed desaturations during exercise; and 12.7% showed nocturnal desaturations. At multiple regression, low exercise tolerance and low mean nocturnal and exercise-induced saturation correlated with several respiratory and motor function and disability indices (all p < 0.03). Exercise tolerance, exercise-induced desaturations, and nocturnal desaturations were extremely frequent in PD patients and were worse in more severe PD patients. This suggests considering a combined role for motor and respiratory rehabilitation in these patients.