The utility of using peak expiratory flow and forced vital capacity to predict poor expiratory cough flow in children with neuromuscular disorders

Abstract

Background Approximately one in every 1200 South Africans is affected by a neuromuscular disease (NMD). Weak respiratory muscles and ineffective cough contribute to the development of respiratory morbidity and mortality. Early identification of individuals at risk of respiratory complications, through peak expiratory cough flow (PCF) measurement, may improve patient outcomes through timely initiation of cough augmentation therapy. Objectives The aim of this study was to investigate the relationship between peak expiratory flow (PEF), forced vital capacity (FVC) and PCF in South African children with neuromuscular disorders. Methods A retrospective descriptive study of routinely collected data was conducted. Results Forty-one participants (aged 11.5 ± 3.6 years; 75.6% male) were included. There was a strong linear correlation between PCF and PEF ( R = 0.78; p = 0.0001) and between PCF and FVC ( R = 0.61; p = 0.0001). There was good agreement between PCF and PEF, with intraclass correlation coefficient of 0.8 (95% confidence interval, 0.7–0.9; p < 0.0001). Peak expiratory flow < 160 L.min −1 and FVC < 1.2 L were significantly predictive of PCF < 160 L.min −1 (suggestive of cough ineffectiveness), whilst PEF < 250 L.min −1 was predictive of PCF < 270 L.min −1 , the level at which cough assistance is usually implemented. Conclusion PEF and FVC may be surrogate measures of cough effectiveness in children with neuromuscular disorders. Clinical implications PEF and FVC may be considered for clinical use as screening tools to identify patients at risk for pulmonary morbidity related to ineffective cough.

Daytime predictors of nocturnal hypercapnic hypoventilation in children with neuromuscular disorders

“…There was a strong linear correlation between PEF and FVC in our cohort, similar to the findings of other studies. 36,37 Our findings support the importance of regular spirometry measurements in children with NMD where possible.…”

The role of physiotherapy in the respiratory management of children with neuromuscular diseases: A South African perspective

“…Characterised by progressive muscle weakness, including cardiac and respiratory muscles, children with NMD often present with respiratory morbidity because of hypoventilation and an impaired cough (Chatwin et al 2018;Farrero et al 2013;Finkel et al 2018). An ineffective cough leads to secretion retention and the potential for subsequent lower respiratory tract infection, airway obstruction, hypoventilation, dyspnea and sleep disturbances that can adversely affect health-related quality of life (Chatwin et al 2018;Finkel et al 2018;Morrow et al 2019;Panitch 2006;Toussaint et al 2018).…”

“…Proximal ACT (cough augmentation) assists inspiration, expiration or both phases of the cough mechanism through a variety of manual and/or mechanical techniques such as manually assisted cough (MAC), lung volume recruitment (LVR) techniques and mechanical insufflation-exsufflation (MI-E) (Finder 2010;Finder et al 2004;Toussaint et al 2018). Airway clearance techniques are recommended in patients whose mucociliary escalator, mucus rheology, structural defects and/or poor cough mechanics, caused by muscle weakness, compromise their secretion mobilisation and expectoration (Farrero et al 2013;McCool & Rosen 2006;Morrow et al 2019;Toussaint et al 2018).…”

“…anterior horn cell) (Yang & Finkel 2010 ). The types of NMD commonly seen in the paediatric population are muscular dystrophies (Duchenne and Becker muscular dystrophy [DMD and BMD]), spinal muscular atrophy (SMA) and congenital myopathies, with DMD presenting with the highest prevalence of one in every 3000–6000 live male births (Finder et al 2004 ; Morrow et al 2019 ; Yang & Finkel 2010 ). Spinal muscular atrophy is not as common as muscular dystrophies, with an estimated incidence of one in 10 000 live births for all types of SMA (Verhaart et al 2017 ).…”

Influence of β2 adrenergic receptor genotype on longitudinal measures of forced vital capacity in patients with Duchenne muscular dystrophy

“…The clinical progression of this respiratory derangement begins with the loss of respiratory muscle strength, followed by functional impairments in lung volumes and flow generation [2] . This loss of respiratory function initially presents as reduced cough efficiency, increasing the risk of both lower and upper respiratory tract illnesses [3] . As respiratory muscle weakness progresses, patients may lose the ability to generate sufficient respiratory pressures to maintain an adequate level of alveolar ventilation [4][5][6] .…”