This January the Journal is happy to kick off a new initiative that we hope will continue each January, Special Issues! We are pleased to bring you an issue on skeletal muscle dysfunction in individuals with cardiovascular or pulmonary conditions. Please allow me to take a moment to thank Sunita Mathur and Darlene Reid for this idea as well as for identifying the topic and taking the lead on this particular special issue.
We are already planning a Special Issue on Social Determinants of Health that will also kick off a new section of the Journal on this topic. The Special Issue is planned for January 2020 and more information follows with an Invited Editorial by our new Associate Editor, Dr. Todd Davenport.
I truly hope you enjoy this issue and want to thank all of guest editors, authors and reviewers for the extra work it has taken to put this issue together.
Thank you for allowing me to continue to serve as your Editor-in-Chief!
Wishing you and yours a very Happy New Year!
Introduction to the Special Issue
Over the last 20 years, there has been an increasing awareness of the systemic complications associated with cardiopulmonary conditions, and a rise in the number of publications focusing on skeletal muscle dysfunction in conditions such as chronic obstructive pulmonary disease, heart failure and critical illness. As physical therapists, we are well positioned to understand skeletal muscle pathology and its implications on mobility and exercise tolerance, and to address skeletal muscle dysfunction through carefully prescribed exercise training. However, physical therapists are often educated on skeletal muscle injury, testing and training in the context of musculoskeletal rehabilitation. This area has now become a key component of practice for physical therapists working in acute and rehabilitation settings for cardiac and pulmonary patients, as well in the intensive care unit.
In this Special Issue of CPTJ, we bring together a series of review papers on topics relevant to understanding skeletal muscle dysfunction, how to evaluate it, and how to address it through training interventions. Kasawara et al. provide an overview of the impairments observed in skeletal muscle structure and function and the contributing factors to muscle dysfunction across several common cardiovascular and respiratory conditions. Two reviews focused on evaluations of muscle dysfunction. Mathur et al discuss reliable and valid tests used to assess skeletal muscle strength, physical function and mobility in people with chronic obstructive pulmonary disease (COPD) and describe the practical issues related to conducting these tests in the clinical setting. Parry et al review the methodological issues related to ultrasound imaging in the evaluation of skeletal muscle size, structure and composition with a focus on the current literature in critical illness and COPD. We have also included 2 reviews on different aspects of exercise training. An important consequence of muscle weakness is impaired balance, McLay et al have reviewed the literature on balance and muscle dysfunction in COPD, and provide guidelines on the assessment and training of balance in this population. In the review by Ahmed et al., respiratory muscle dysfunction in discussed in the context of individuals with diaphragmatic dysfunction due to mechanical ventilation. The authors provide a review of the mechanisms of respiratory muscle dysfunction in this population, as well as guidelines for training the respiratory muscles. We hope that you will find this Special Issue relevant to your clinical practice and will challenge your thinking related to the assessment and treatment of muscle dysfunction in cardiopulmonary populations.
Special Issue 2020: Social Determinants of Health
The Cardiopulmonary Physical Therapy Journal is pleased to announce a new section for submissions on the social determinants of health (SDOH). Social determinants of health are “the structural determinants and conditions in which people are born, grow, live, work and age.” They include factors like socioeconomic status, education, the physical environment, employment, and social support networks, as well as access to health care. SDOH are becoming an increasingly well-acknowledged predictor of health outcomes throughout clinical research and practice. The American Physical Therapy Association Vision Statement emphasizes the role for physical therapists to mitigate the effects of SDOH on health.
Invitation to Submit
The Journal will publish a Special Issue on Social Determinants of Health in January 2020. The Journal invites manuscripts focused on the SDOH as they relate to cardiovascular or pulmonary prevention, conditions and/or outcomes, including movement system interactions with the musculoskeletal, neuromuscular, autonomic and/or metabolic systems. Articles in this section can include all currently accepted types for the journal including research reports, systematic reviews, qualitative studies, case reports and clinical perspectives. Manuscripts are preferred that are considered likely to further our understanding of social determinants of health in the primary, secondary or tertiary prevention of disease, impairment or disability through interventions across the spectrum from clinical settings through community, occupational or population health settings. Potential contexts include environmental, social, physical, behavioral, or nutritional interventions in wellness, prevention, and treatment throughout the human life span. Submissions should follow the instructions for authors for the appropriate type of manuscript being submitted.
Todd Davenport, PT, DPT, MPH, OCS
Ventilation, Respiration, Skeletal Muscle, and More—What, a Link?
Although the muscle hypothesis of chronic heart failure proposed by Andrew Coats in the mid-1990’s posits skeletal muscle abnormalities as a major factor associated with heart failure (HF),1 the effects of skeletal muscle abnormalities in respiratory and many other disorders and diseases is becoming increasingly apparent.2-6 What is the link in this viscous cycle of many cardiorespiratory diseases and skeletal muscle dysfunction? This issue of the Journal explores the link and provides a foundation from which the examination and management of cardiorespiratory disorders can be better appreciated, performed, and interpreted.2-6 In fact, this issue of the Journal provides distinct examples of the link among the skeletal muscles of not just the diaphragm, but all skeletal muscle and their role in ventilation, respiration, and much more including functional tasks, balance, and quality of life in cardiorespiratory diseases.2-6
The first paper describes in detail the pathophysiology of skeletal muscle dysfunction in HF, chronic obstructive pulmonary disease (COPD), interstitial lung disease, cystic fibrosis, the intensive care unit and associated immobilization, as well as aging providing a framework for each of the subsequent papers.2 The second paper describes the use of ultrasound in the examination of quadriceps muscle dysfunction in respiratory disease and provides a thorough overview of the methods and key findings of ultrasound studies in chronic respiratory disease and critical illness.3 The ultrasound methods described in this paper reveal the need for standardization of ultrasound measurements as well as the assessment of competency to ensure meaningful and reliable results. Although the focus of this second paper was on the use of ultrasound in the evaluation of the quadriceps muscle,3 a substantial literature exists on the use of thoracic ultrasound in the evaluation of diaphragm excursion, speed of diaphragm contraction, diaphragm thickness, and many other measures which may be particularly useful in the physical therapy assessment and management of cardiorespiratory disorders.7-10 Also, a recent study demonstrated similar good intra-rater and inter-rater reliability in expert and trained novice sonographers for both limb and diaphragm thickness in critically-ill children with greater reliability in limb muscle thickness compared to diaphragm thickness (ICC > 0.9 vs ICC > 0.8) and found atrophy detected >13% in limb and >38% in diaphragm muscles.11 The above results highlight the importance of standardization, training, and use of ultrasound in physical therapy.3,7-11
The third paper in this series presents a variety of methods by which strength and function of the limb muscles can be measured and provides clinically relevant and extremely useful information by describing in detail the devices to assess limb muscle strength as well as tests to examine function in people with COPD.4 The methods and equipment needed, advantages, limitations, reliability, correlations, and reference values for strength measurements and functional tests are keenly outlined in the tables of the paper.4 Although a brief discussion of limb muscle endurance is provided, more information and research about methods to incorporate endurance, fatigability, and power measures in cardiorespiratory disease appears needed.4,12,13 The fourth paper provides a very nice overview of the role skeletal muscle strength has on balance and methods to manage balance disorders when skeletal muscle abnormalities exist in COPD.5 The role of skeletal muscle endurance and power is discussed more in this paper and the authors highlight the fact that with aging, skeletal muscle power decreases earlier and faster than skeletal muscle strength and appears to have a greater influence on postural control.5 A discussion of the 6 underlying components of the Systems Framework of Postural Control is provided,5 but this conceptual model and paper does not fully integrate the possible role of respiratory muscle dysfunction as a determinant of postural control despite ample evidence–especially when comorbid conditions like low back pain exist.14-16 Furthermore, although evidence suggests that respiratory muscle dysfunction may worsen postural control no mention of respiratory muscle training was presented.14-17
The fifth and final paper in this series provides a narrative review of the role inspiratory muscle strength training (IMST) has in patients receiving prolonged mechanical ventilation.6 The authors highlight in the paper that diaphragm muscle fiber composition, thinning, and atrophy ensues early after mechanical ventilation and is associated with signs of increased oxidative stress and proteolysis.6 The role of IMST in assisting the weaning process from mechanical ventilation as well as improving inspiratory muscle strength after weaning from mechanical ventilation is discussed, but the methods to perform and provide IMST in patients receiving mechanical ventilation is addressed only minimally.6 Information regarding the specific methods to administer IMST and necessary equipment for patients receiving mechanical ventilation can be found in a recent paper by Bissett et al.18
The weaning process does appear to be enhanced with IMST,6 and the findings from several recent ultrasound studies examining a variety of diaphragmatic ultrasound measures indirectly support the use of IMST to facilitate weaning from mechanical ventilation.19,20 For example, a meta-analysis of 13 studies with 742 subjects found that diaphragm excursion and thickness fraction were highly predictive of weaning success both of which could potentially be improved with IMST.19 Furthermore, an additional recent ultrasound study in patients with a COPD exacerbation undergoing noninvasive ventilation (NIV) found that diaphragmatic dysfunction (defined as a change in diaphragm thickness <20% during tidal volume breathing) was reliable and accurate in identifying patients at major risk of NIV failure and poorer prognosis.21 Therefore, ultrasound may be useful in determining not only mechanical ventilation weaning success and possible changes associated with IMST, but it may yield insight into the best form of ventilatory assistance to provide to patients with a COPD exacerbation.19-21
The 5 papers in this edition of the Journal provide important information about the role of skeletal muscle in the pathophysiology of cardiorespiratory disorders.2-6 Understandably missing in this series is the role of cardiac and smooth muscle in the pathophysiology of cardiorespiratory disease which are likely effected by skeletal muscle abnormalities and vice-versa as described in the muscle hypothesis of chronic heart failure.1 Nonetheless, this issue of the Journal provides a robust relationship among ventilation, respiration, skeletal muscle, and more, and yes–What a link it is!!
Lawrence P. Cahalin, PhD, PT, CCS, FAHA
1. Coats A. The “muscle hypothesis” of chronic heart failure. J Mol Cell Cardiol. 1996;28(11):2255–2262.
2. Kasawara KT, Castellanos MM, Hanada M, Reid WD. Pathophysiology of muscle in pulmonary and cardiovascular conditions. Cardiopulm Phys Ther J. 2018;30:1–11.
3. Parry S, Burtin C, Denehy L, Puthucheary Z, Bear D. Ultrasound evaluation of quadriceps muscle dysfunction in respiratory disease: A narrative review. Cardiopulm Phys Ther J. 2018.
4. Mathur S, Dechman G, Bui KL, Camp PG, Saey D. Evaluation of limb muscle strength and function in people with chronic obstructive pulmonary disease. Cardiopulm Phys Ther J. 2018.
5. McLay R, O’Hoski S, Beauchamp MK. Role of muscle strength in balance assessment and treatment in chronic obstructive pulmonary disease. Cardiopulm Phys Ther J. 2018.
6. Ahmed S, Martin AD, Smith BK. Inspiratory muscle training in patients with prolonged mechanical ventilation: Narrative review. Cardiopulm Phys Ther J. 2018.
7. Jones AYM, Ngai SPC, Ying MTC, et al. Sonographic evaluation of diaphragmatic function during breathing control. Physiother Theory Pract. 2017;33(7):560–567.
8. Rocha FR, Bruggemann AK, Francisco DS, et al. Diaphragmatic mobility: Relationship with lung function, respiratory muscle strength, dyspnea, and physical activity in daily life in patients with COPD. J Bras Pneumol. 2017;43(1):32–37.
9. Corbellini C, Boussuges A, Villafane JH, Zocchi L. Diaphragmatic mobility loss in subjects with moderate to very severe COPD may improve after in-patient pulmonary rehabilitation. Respir Care. 2018;63(10):1271–1280.
10. Hayward SA, Janssen J. Use of thoracic ultrasound by physiotherapists: A scoping review of the literature. Physiotherapy. 2018. pii: S0031-9406(18)30001-4.
11. Ng KW, Dietz AR, Johnson R, Shoykhet M, Zaidman CM. Reliability of bedside ultrasound of limb and diaphragm muscle thickness in critically-ill children. Muscle Nerve. 2018. doi: [epub ahead of print].
12. Maltais F, Decramer M, Casaburi R, et al. An Official American thoracic Society/European respiratory Society Statement: Update on limb muscle dysfunction ini chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2014;189(9):e15–e62.
13. Bean JF, Kiely DK, LaRose S, Alian J, Frontera WR. Is stair-climb power a clinically relevant measure of leg power impairments in at-risk older adults? Arch Phys Med Rehabil. 2007;88(5):604–609.
14. Smith MD, Chang AT, Hodges PW. Balance recovery is compromised and trunk muscle activity is increased in chronic obstructive pulmonary disease. Gait Posture. 2016;43:101–107.
15. Smith MD, Chang AT, Seale HE, Walsh JR, Hodges PW. Balance is impaired in people with chronic obstructive pulmonary disease. Gait Posture. 2010;31(4):456–460.
16. Janssens L, Brumagne S, Polspoel K, Troosters T, McConnell A. The effect of inspiratory muscles fatigue on postural control in people with and without recurrent low back pain. Spine (Phila Pa 1976). 2010;35(10):1088–1094.
17. Janssens L, Brumagne S, McConnell A, et al. Proprioceptive changes impair balance control in individuals with chronic obstructive pulmonary disease. PLoS One. 2013;8(3):e57949.
18. Bissett B, Leditschke IA, Green M, Marzano V, Collins S, Van Haren F. Inspiratory muscle training for intensive care patients: A multidisciplinary practice guide for clinicians. Aust Crit Care. 2018;1–7.
19. Li C, Li X, Han H, Cui H, Wang G, Wang Z. Diaphragmatic ultrasonography for predicting ventilator weaning: A meta-analysis. Medicine (Baltimore). 2018;97(22):e10968.
20. Tenza-Lozano E, Llamas-Alvarez A, Jaimez-Navarro E, Fernandez-Sanchez J. Lung and diaphragm ultrasound as predictors of success in weaning from mechanical ventilation. Crit Ultrasound J. 2018;10(1):12.
21. Marchioni A, Castaniere I, Tonelli R, et al. Ultrasound-assessed diaphragmatic impairment is a predictor of outcomes in patients with acute exacerbation of chronic obstructive pulmonary disease undergoing noninvasive ventilation. Crit Care. 2018;22(1):109.