Research in Focus: Effect of Lung Volume Recruitment on Pulmonary Function in Progressive Childhood-Onset Neuromuscular Disease

  •   January 7, 2021

Full Citation: O’Sullivan R, Carrier J, Cranney H, Hemming R. Effect of Lung Volume Recruitment on Pulmonary Function in Progressive Childhood-Onset Neuromuscular Disease: A Systematic Review. Archives of Physical Medicine and Rehabilitation 2020. https://doi.org/10.1016/j.apmr.2020.07.014

Background

Individuals with neuromuscular diseases (NMD) experience progressive declines in respiratory function over time secondary to disease progression, the effects of aging and the implications of skeletal growth and rib cage deformities (in the case of individuals with childhood onset NMDs). Non-invasive ventilation is used by individuals with NMDs to support tidal volume breathing and increase life expectancy. Lung volume recruitment (LVR) is used in this population to supplement inspiratory volumes, either before a cough or routinely to replace spontaneous deep breathing activities such as sigh breaths, and yawns, which have been theorized to play a role in maintaining lung expansion, compliance, and secretion clearance.1

The purpose of this study was to address the question: “Does LVR have an effect on pulmonary function test parameters in individuals with progressive childhood-onset NMDs?”

Methods

  • Systematic Review
  • Search Strategy and Results:
    • Databases: EBSCO, SCOPUS, AMED, MEDLINE, EMCARE and Open Grey
    • Forward and backward citation chaining
    • Due to the niche topic, only nine relevant studies were identified; three studies were subsequently excluded due to high risk of bias
  • Inclusion Criteria:
    • Population Studied:
      • Subjects > six years old
      • Diagnosis of progressive childhood-onset NMD
    • Intervention:
      • LVR using volume-controlled ventilator or manual resuscitator bag
    • Comparison
      • LVR to baseline function or no treatment
    • Outcomes of Interest:
      • Peak Cough Flow (PCF),
      • Forced Vital Capacity (FVC) or
      • Maximum Inspiratory Capacity (MIC)
  • Exclusion Criteria:
    • Mixed patient populations (childhood and adult onset NMDs)
    • LVR using other recruitment strategies (e.g., manual insufflation/exsufflation, intermittent positive pressure breathing)
    • Pediatric participants less than six years of age
    • Case series and case study designs
    • Inclusion of acutely ill patients
    • Publication not in English
    • Studies assessed as “significantly high risk of bias”

Findings

  • Heterogeneity of study methodology precluded meta-analysis
  • All studies provided evidence of immediate effect of LVR on PCF
    • Findings related to LVR impact on PCF may relate to baseline characteristics of study participants, with some analysis suggesting that greatest immediate effects of LVR are seen in individuals with lowest baseline function.
    • Evidence is lacking regarding characteristics of responders vs non-responders to LVR, however there was “no clear evidence in the studies analyzed, nor in the wider literature, to suggest that the presence of scoliosis affects the effectiveness of LVR”.
    • “Evidence from both this review and the wider literature suggests that, clinically, resources should be prioritized to ensure that individuals with lower PCF values have access to LVR.”
  • Three studies included analysis of long-term implications of daily LVR on respiratory function
    • Longitudinal effects of LVR on PCF were inconsistent with 1/3 studies reporting statistically significant increases in PCF
    • One study reported a small increase in FVC over the study duration while two studies reported a statistically significant difference in the rate of predicted decline in FVC over time.
    • As stated by the authors, the extended duration of two studies “may provide time for the progressive nature of the NMDs studied to have influenced the results… Given that FVC is a variable directly related to mortality, any positive effect on its longitudinal progression is clinically advantageous.”

Limitations

  • Niche topic with only nine relevant studies identified, of which three were excluded due to risk of bias.
  • Included studies were of relatively low quality.
  • Two of the included studies were conducted from the same center, and despite different study designs and populations the SR authors assessed that there was some risk that there was overlap between included subjects of the two studies.
  • Rate of decline in respiratory function is non-linear with this patient population and this serves as a confounding variable with the analysis of LVR impact.

Relevance to physiotherapy practice in Alberta

As individuals with NMDs demonstrate a typically progressive decline in respiratory function which can ultimately impact life expectancy, interventions which can either improve or delay these changes have significant impact on morbidity and mortality. Physiotherapists who work with individuals with pediatric onset NMDs should be aware of the state of research regarding LVR. Although more high-quality research is needed, given the patient population in question and niche research topic, additional evidence may be slow to develop.

Disclaimer: The purpose of this summary is to highlight recently published research findings that are not openly accessible. Every effort is made to ensure accuracy and clarity of the summary. Readers are encouraged to review the published article in full for further information.


  1. O’Sullivan R, Carrier J, Cranney H, Hemming R. Effect of Lung Volume Recruitment on Pulmonary Function in Progressive Childhood-Onset Neuromuscular Disease: A Systematic Review. Archives of Physical Medicine and Rehabilitation 2020. https://doi.org/10.1016/j.apmr.2020.07.014