PM R 7 (2015) 677-684

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Original ResearcheCME

Feasibility of Lung Volume Recruitment in Early Neuromuscular Weakness: A Comparison Between Amyotrophic Lateral Sclerosis, Myotonic Dystrophy, and Postpolio Syndrome Marta Kaminska, MD, MSc, Franceen Browman, RRT, Daria A. Trojan, MD, MSc, Angela Genge, MD, Andrea Benedetti, PhD, Basil J. Petrof, MD

Abstract Background: Lung volume recruitment (LVR) is a cough assistance technique used in persons with neuromuscular disorders (NMDs), most typically in those requiring noninvasive ventilation (NIV). Whether it may be useful in persons with NMDs who have milder respiratory impairment is unknown. Objective: To assess the feasibility, impact on quality of life (QOL), and preliminary physiological effects of daily LVR in different categories of persons with NMDs who have an early stage of respiratory impairment. Design: Feasibility study. Setting: Academic tertiary care center. Participants: Outpatients diagnosed with amyotrophic lateral sclerosis (n ¼ 8), postpolio syndrome (n ¼ 10), and myotonic dystrophy (n ¼ 6) who had restrictive respiratory defects but were not yet using NIV. Methods: Participants were asked to perform LVR up to 4 times daily and log their LVR use in a diary. Physiological measurements and questionnaires were completed at baseline and after 3 months. Main Outcome Measurements: Compliance with LVR use was assessed, along with QOL and willingness to continue the treatment. Physiological measurements included forced vital capacity (FVC), lung insufflation capacity (LIC), and the LIC minus FVC difference. Results: Of the 24 recruited subjects, 7 with amyotrophic lateral sclerosis, 7 with postpolio syndrome, and 5 with myotonic dystrophy completed the study (n ¼ 19). At baseline, mean values for FVC and spontaneous peak cough flow were 59.9% predicted and 373.1 L/min, respectively. For subjects completing the study, 74% were willing to continue long-term LVR use, and QOL scores were not adversely affected by LVR in any NMD subgroup. The LIC-FVC difference increased from baseline to follow-up by a mean of 0.243 L (P ¼ .006) in all subjects (n ¼ 19), suggesting a possible improvement in respiratory system mechanics. Conclusions: In patients with NMDs who have early restrictive respiratory defects but do not yet require NIV, regular use of LVR is feasible with no negative impact on QOL over a 3-month period and may have physiological benefits. Further work is needed to determine whether early institution of LVR can improve respiratory system mechanics and help delay ventilatory failure in persons with NMDs.

Introduction Respiratory compromise is the leading cause of morbidity and mortality in persons with neuromuscular disorders (NMDs) [1]. Respiratory muscle weakness can lead to ventilatory impairment and cough insufficiency with retention of pulmonary secretions, predisposing to complications such as atelectasis

and respiratory infections [2,3]. Long-term home noninvasive ventilation (NIV) is now the mainstay of respiratory support for patients with hypoventilation due to severe respiratory muscle weakness. In addition, to facilitate secretion clearance, various coughassistance techniques have been devised, including the lung volume recruitment (LVR) technique, also known as breath stacking or deep lung insufflation.

1934-1482/$ - see front matter ª 2015 by the American Academy of Physical Medicine and Rehabilitation http://dx.doi.org/10.1016/j.pmrj.2015.04.001

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Lung Volume Recruitment Feasibility

Although supporting literature (reviewed in reference 2) is scant, the use of these techniques has become the standard of care in persons currently or imminently requiring NIV [4,5]. LVR involves the administration of a series of stacked breaths using a resuscitator bag. This technique allows expansion of the lungs to a volume greater than the spontaneous inspiratory capacity, which is reduced in the setting of respiratory muscle weakness. By initiating the expiratory phase of cough from this higher lung volume, one can take advantage of the larger respiratory system elastic recoil pressure to generate a greater cough flow. LVR has been shown to increase peak cough flow (PCF) [6-10] in persons with various NMDs. Increased PCF improves secretion clearance and is believed to help both prevent and treat pulmonary infections [5]. In addition, over time the reduced tidal volumes, sighs, and poor cough effectiveness in persons with NMDs lead to reduced compliance (stiffening) of the lungs and chest wall, further contributing to respiratory insufficiency [11]. Indeed, the increased elastic loads imposed by these changes are strongly associated with CO2 retention [12]. In this context, the regular use of LVR has been proposed as a “range-of-motion” exercise for the respiratory system [13] to maintain normal compliance of the respiratory system and possibly delay the onset of ventilatory failure. The optimal timing for institution of LVR is not clear, but it is usually initiated in patients with advanced stages of respiratory impairment who are receiving NIV [4,5]. However, earlier, preventive intervention may provide an advantage. Furthermore, potential benefits of LVR may depend upon unique characteristics of the specific NMD in question [8,14-16]. In the present investigation, we performed a feasibility study of LVR use in patients with NMDs who had relatively early pulmonary restrictive defects. Our primary objectives were to determine (1) the feasibility and acceptability of LVR in patients with NMDs who did not have severe pulmonary compromise and were not receiving NIV and (2) whether the applicability and physiological parameters related to LVR would vary between different NMD categories. With regard to the latter objective, we studied 3 types of NMD, consisting of 2 relatively stable diseases (postpolio syndrome [PPS] and myotonic dystrophy [MD]) and one more rapidly progressive disorder (amyotrophic lateral sclerosis [ALS]).

restrictive pulmonary function attributable to an NMD as defined by forced vital capacity (FVC)

Feasibility of Lung Volume Recruitment in Early Neuromuscular Weakness: A Comparison Between Amyotrophic Lateral Sclerosis, Myotonic Dystrophy, and Postpolio Syndrome.

Lung volume recruitment (LVR) is a cough assistance technique used in persons with neuromuscular disorders (NMDs), most typically in those requiring n...
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