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• Response to “Clinical Experience Using LVR for Patients with DMD”
  Sherri L Katz, Douglas McKim
  Published on: 25 July 2022
• Clinical Experience Using LVR for Patients with DMD
  Somnath V. Ganapa, John R. Bach, Yuka Ishikawa and Daniel Wang
  Published on: 25 July 2022

• Published on: 25 July 2022

  Response to “Clinical Experience Using LVR for Patients with DMD”

  • Sherri L Katz, Division Chief, Pediatric Respirology, Associate Professor, Senior Scientist Children's Hospital of Eastern Ontario/University of Ottawa/Children's Hospital of Eastern Ontario Research Institute
  • Other Contributors:
    • Douglas McKim, Respirologist and Sleep Centre Director, Medical Director of CANVent Respiratory Rehabilitation Services, Professor

  We appreciate Dr. Ganapa and colleagues’ letter in response to our randomized controlled trial of lung volume recruitment (LVR) in Duchenne muscular dystrophy (DMD). We wholeheartedly agree that LVR has a critical role in the management of individuals with DMD during acute exacerbations and in individuals with advanced neuromuscular disease, especially in those with respiratory failure. The use of LVR in this context is supported by international clinical care guidelines [1-6] and data which demonstrates improvement in lung function decline and maximum insufflation capacity with routine twice-daily LVR.[7-9]

  In our cohort with relatively preserved lung function (baseline median FVC 84.8%, IQR 73.3, 95.5%), the median age of our group (baseline median 11.5 years, IQR 9.5, 13.5 years) is slightly younger than that described by Dr. Ganapa, in whom routine LVR is initiated. Recent data from the Cooperative International Neuromuscular Research Group’s Duchenne Natural History Study indicates, however, that peak median FVC occurs at age 17.0-17.9 years in those with glucocorticoid exposure for greater than one year, compared to age 12.0-12.9 years in those not treated with glucocorticoids.[10] Eighty-nine percent of our cohort were treated with systemic steroids, which likely explains why many had normal FVC at baseline and why it was challenging to show improvements in the rate of decline of FVC over two years with LVR treatment.

  Despite the clear benefits of L...

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  We appreciate Dr. Ganapa and colleagues’ letter in response to our randomized controlled trial of lung volume recruitment (LVR) in Duchenne muscular dystrophy (DMD). We wholeheartedly agree that LVR has a critical role in the management of individuals with DMD during acute exacerbations and in individuals with advanced neuromuscular disease, especially in those with respiratory failure. The use of LVR in this context is supported by international clinical care guidelines [1-6] and data which demonstrates improvement in lung function decline and maximum insufflation capacity with routine twice-daily LVR.[7-9]

  In our cohort with relatively preserved lung function (baseline median FVC 84.8%, IQR 73.3, 95.5%), the median age of our group (baseline median 11.5 years, IQR 9.5, 13.5 years) is slightly younger than that described by Dr. Ganapa, in whom routine LVR is initiated. Recent data from the Cooperative International Neuromuscular Research Group’s Duchenne Natural History Study indicates, however, that peak median FVC occurs at age 17.0-17.9 years in those with glucocorticoid exposure for greater than one year, compared to age 12.0-12.9 years in those not treated with glucocorticoids.[10] Eighty-nine percent of our cohort were treated with systemic steroids, which likely explains why many had normal FVC at baseline and why it was challenging to show improvements in the rate of decline of FVC over two years with LVR treatment.

  Despite the clear benefits of LVR during exacerbations and in individuals with lower pulmonary function, the optimal timing for routine LVR therapy was not identified in our study of younger individuals with preserved lung function. While it would be ideal to conduct a randomized trial of LVR therapy in individuals with DMD beginning at the apex of their vital capacity trajectory,[9] a lengthy and costly study would be needed to evaluate changes over several years in order to determine the benefits of LVR. In contrast, such a study is not needed in individuals with advanced disease, in whom there is sufficient evidence to justify regular treatment. Given that uptake of routine LVR therapy for individuals with neuromuscular disease is not uniform, additional evidence is still needed to guide best practices for clinical care. Further exploration is required to ensure that LVR is introduced when it will be of benefit to individuals with neuromuscular disease.

  References
  1. Birnkrant DJ, Bushby KM, Amin RS, et al. The respiratory management of patients with duchenne muscular dystrophy: a DMD care considerations working group specialty article. Pediatric Pulmonology 2010;45(8):739-48.
  2. Amin RM, I; Zielinski,D; Adderley,R; Carnevale,F; Chiang,J; Cote,A; Daniels,C; Daigneault,P; Harrison.C; Katz,S; Keilty,K; Majaesic,C; Moraes.T.J; Price,A; Radhakrishnan,D; Rapoport,A; Spier,S; Thavagnanam,S; Witmans,M; Canadian Thoracic Society. Pediatric home mechanical ventilation: A Canadian Thoracic Society clinical practice guideline executive summary. Canadian Journal of Respiratory, Critical Care and Sleep Medicine 2017;1(1):7-36.
  3. Hull J, Aniapravan R, Chan E, et al. British Thoracic Society guideline for respiratory management of children with neuromuscular weakness. Thorax 2012;67 Suppl 1:i1-40.
  4. Finder JD, Birnkrant D, Carl J, et al. Respiratory care of the patient with Duchenne muscular dystrophy: ATS consensus statement. Am J Respir Crit Care Med 2004;170(4):456-65.
  5. Birnkrant DJ, Bushby K, Bann CM, et al. Diagnosis and management of Duchenne muscular dystrophy, part 2: respiratory, cardiac, bone health, and orthopaedic management. Lancet Neurol 2018;17(4):347-61. doi: 10.1016/s1474-4422(18)30025-5 [published Online First: 2018/02/06]
  6. Birnkrant DJ. The American College of Chest Physicians consensus statement on the respiratory and related management of patients with Duchenne muscular dystrophy undergoing anesthesia or sedation. Pediatrics 2009;123 Suppl 4:S242-S44.
  7. McKim DA, Katz SL, Barrowman N, et al. Lung Volume Recruitment Slows Pulmonary Function Decline in Duchenne Muscular Dystrophy. Archives of Physical Medicine and Rehabilitation 2012;93(7):1117-22.
  8. Katz SL, Barrowman N, Monsour A, et al. Long-Term Effects of Lung Volume Recruitment on Maximal Inspiratory Capacity and Vital Capacity in Duchenne Muscular Dystrophy. Ann Am Thorac Soc 2016;13(2):217-22.
  9. Chiou M, Bach JR, Jethani L, et al. Active lung volume recruitment to preserve vital capacity in Duchenne muscular dystrophy. J Rehabil Med 2017;49(1):49-53. doi: 10.2340/16501977-2144 [published Online First: 2016/09/16]
  10. McDonald CM, Gordish-Dressman H, Henricson EK, et al. Longitudinal pulmonary function testing outcome measures in Duchenne muscular dystrophy: Long-term natural history with and without glucocorticoids. Neuromuscul Disord 2018;28(11):897-909. doi: 10.1016/j.nmd.2018.07.004 [published Online First: 2018/10/20]

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  Conflict of Interest:
  None declared.

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• Published on: 25 July 2022

  Clinical Experience Using LVR for Patients with DMD

  • Somnath V. Ganapa, Physician-resident Rutgers-New Jersey Medical School
  • Other Contributors:
    • John R. Bach, Physiatrist
    • Yuka Ishikawa, Pediatric Neurologist
    • Daniel Wang, Medical student

  We thank the authors for their contribution of a RCT of boys with DMD (FVC>60%) with the intervention of active LVR (air stacking) twice daily for two years. In our clinical practice, we have introduced LVR to thousands of patients with ventilatory pump failure and over 300 with DMD. Although we have not found LVR to preserve or improve vital capacity (VC), patients with 0 mL of VC can survive for decades using up to continuous noninvasive ventilatory support (CNVS). On the other hand, improvement of maximum insufflation capacity (MIC) is reported to improve significantly with practice of LVR, although this is also not crucial.1 What is certain is that tachypneic hypercapnic patients with shallow breathing associated with supplemental oxygen therapy often cannot normalize their blood gases by NVS settings until the O2 is discontinued and the patient practices LVR aggressively for several weeks to several months. At that point their lungs become more compliant and delivered air volumes can normalize their blood gases.2,3 Also, ventilator “unweanable” patients who practice air stacking via mouth and/or nose pieces are much easier to extubate to mouthpiece and nasal CNVS than patients who have not practiced this technique.3,4 Further, air stacking can improve peak cough flows (PCF), phonation, and time to swallow food.5 While McKim et al. suggested initiation of air stacking for DMD once VC decreases below 80%, we have usually begun once the absolute plateau VC is reached...

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  We thank the authors for their contribution of a RCT of boys with DMD (FVC>60%) with the intervention of active LVR (air stacking) twice daily for two years. In our clinical practice, we have introduced LVR to thousands of patients with ventilatory pump failure and over 300 with DMD. Although we have not found LVR to preserve or improve vital capacity (VC), patients with 0 mL of VC can survive for decades using up to continuous noninvasive ventilatory support (CNVS). On the other hand, improvement of maximum insufflation capacity (MIC) is reported to improve significantly with practice of LVR, although this is also not crucial.1 What is certain is that tachypneic hypercapnic patients with shallow breathing associated with supplemental oxygen therapy often cannot normalize their blood gases by NVS settings until the O2 is discontinued and the patient practices LVR aggressively for several weeks to several months. At that point their lungs become more compliant and delivered air volumes can normalize their blood gases.2,3 Also, ventilator “unweanable” patients who practice air stacking via mouth and/or nose pieces are much easier to extubate to mouthpiece and nasal CNVS than patients who have not practiced this technique.3,4 Further, air stacking can improve peak cough flows (PCF), phonation, and time to swallow food.5 While McKim et al. suggested initiation of air stacking for DMD once VC decreases below 80%, we have usually begun once the absolute plateau VC is reached and begins to decrease. For patients with DMD, this decline occurs around 13.5 (range-9-17) years of age.6 At this point, cough flows tend to drastically decrease, increasing the risk of pneumonia, but can be improved with air stacking.2,3 Therefore, it is our opinion that air stacking is not a burden but when to initiate is arguable.

  References

  1. Kang SW, Bach JR. Maximum insufflation capacity: vital capacity and cough flows in neuromuscular disease. Am J Phys Med Rehabil 2000;79(3):222-227.
  2. Bach JR, Kang SW. Disorders of ventilation: weakness, stiffness, and mobilization. Chest 2000; 117(2):301-303.
  3. Kang SW, Bach JR. Maximum insufflation capacity: vital capacity and cough flows in neuromuscular disease. Am J Phys Med Rehabil 2000;79(3):
  4. Rideau Y, Bach J. Efficacité therapeutique dans la dystrophie musculaire de Duchenne. J Readapt Med 1982;2(3):96-100.
  5. Deo P, Bach JR. Noninvasive ventilatory support to reverse weight loss in Duchenne muscular dystrophy: a case series. Pulmonol 2019;25(2):79-82.
  6. Bach J, Alba A, Lee M, Rideau Y. Long-term respiratory rehabilitation in the treatment of neuromuscular disease. Ann Readapt Med Phys 1983;26:101-109.

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  Conflict of Interest:
  None declared.

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