Suspected statin-induced respiratory muscle myopathy during long-term inspiratory muscle training in a patient with diaphragmatic paralysis

Effects of inspiratory muscle training on exertional breathlessness in patients with unilateral diaphragm dysfunction: a randomised trial

Background

Unilateral diaphragm dysfunction (UDD) is an underdiagnosed cause of dyspnoea. Inspiratory muscle training (IMT) is the only conservative treatment for UDD, but the mechanisms of improvement are unknown. We characterised the effects of IMT on dyspnoea, exercise tolerance and respiratory muscle function in people with UDD.

Methods

15 people with UDD (73% male, 61±8 years) were randomised to 6 months of IMT (50% maximal inspiratory mouth pressure (PI,max), n=10) or sham training (10% PI,max, n=5) (30 breaths twice per day). UDD was confirmed by phrenic nerve stimulation and persisted throughout the training period. Symptoms were assessed by the transitional dyspnoea index (TDI) and exercise tolerance by constant-load cycle tests performed pre- and post-training. Oesophageal (Pes) and gastric (Pga) pressures were measured with a dual-balloon catheter. Electromyography (EMG) and oxygenation (near-infrared spectroscopy) of respiratory muscles were assessed continuously during exercise.

Results

The IMT group (from 45±6 to 62±23% PI,max) and sham group (no progression) completed 92 and 86% of prescribed sessions, respectively. PI,max, TDI scores and cycle endurance time improved significantly more after IMT versus sham (mean between-group differences: 28 (95% CI 13-28) cmH2O, 3.0 (95% CI 0.9-5.1) points and 6.0 (95% CI 0.4-11.5) min, respectively). During exercise at iso-time, Pes, Pga and EMG of the scalene muscles were reduced and the oxygen saturation indices of the scalene and abdominal muscles were higher post- versus pre-training only in the IMT group (all p<0.05).

Conclusion

The effects of IMT on dyspnoea and exercise tolerance in UDD were not mediated by an improvement in isolated diaphragm function, but may reflect improvements in strength, coordination and/or oxygenation of the extra-diaphragmatic respiratory muscles.

Statin Use in Relation to COVID-19 and Other Respiratory Infections: Muscle and Other Considerations

Statins have been widely advocated for use in COVID-19 based on large favorable observational associations buttressed by theoretical expected benefits. However, past favorable associations of statins to pre-COVID-19 infection outcomes (also buttressed by theoretical benefits) were unsupported in meta-analysis of RCTs, RR = 1.00. Initial RCTs in COVID-19 appear to follow this trajectory. Healthy-user/tolerator effects and indication bias may explain these disparities. Moreover, cholesterol drops in proportion to infection severity, so less severely affected individuals may be selected for statin use, contributing to apparent favorable statin associations to outcomes. Cholesterol transports fat-soluble antioxidants and immune-protective vitamins. Statins impair mitochondrial function in those most reliant on coenzyme Q10 (a mevalonate pathway product also transported on cholesterol)-i.e., those with existing mitochondrial compromise, whom data suggest bear increased risks from both COVID-19 and from statins. Thus, statin risks of adverse outcomes are amplified in those patients at risk of poor COVID-19 outcomes-i.e., those in whom adjunctive statin therapy may most likely be given. High reported rates of rhabdomyolysis in hospitalized COVID-19 patients underscore the notion that statin-related risks as well as benefits must be considered. Advocacy for statins in COVID-19 should be suspended pending clear evidence of RCT benefits, with careful attention to risk modifiers.

Unilateral diaphragmatic paralysis: inspiratory muscles, breathlessness and exercise capacity

Background

Patients with unilateral diaphragmatic paralysis (UDP) may present with dyspnoea without specific cause and limited ability to exercise. We aimed to investigate the diaphragm contraction mechanisms and nondiaphragmatic inspiratory muscle activation during exercise in patients with UDP, compared with healthy individuals.

Methods

Pulmonary function, as well as volitional and nonvolitional inspiratory muscle strength were evaluated in 35 patients and in 20 healthy subjects. Respiratory pressures and electromyography of scalene and sternocleidomastoid muscles were continuously recorded during incremental maximal cardiopulmonary exercise testing until symptom limitation. Dyspnoea was assessed at rest, every 2 min during exercise and at the end of exercise with a modified Borg scale.

Main results

Inspiratory muscle strength measurements were significantly lower for patients in comparison to controls (all p<0.05). Patients achieved lower peak of exercise (lower oxygen consumption) compared to controls, with both gastric (−9.8±4.6 cmH₂O versus 8.9±6.0 cmH₂O) and transdiaphragmatic (6.5±5.5 cmH₂O versus 26.9±10.9 cmH₂O) pressures significantly lower, along with larger activation of both scalene (40±22% EMGmax versus 18±14% EMGmax) and sternocleidomastoid (34±22% EMGmax versus 14±8% EMGmax). In addition, the paralysis group presented significant differences in breathing pattern during exercise (lower tidal volume and higher respiratory rate) with more dyspnoea symptoms compared to the control group.

Conclusion

The paralysis group presented with exercise limitation accompanied by impairment in transdiaphragmatic pressure generation and larger accessory inspiratory muscles activation compared to controls, thereby contributing to a neuromechanical dissociation and increased dyspnoea perception.

The exercise capacity limitation in patients with unilateral diaphragmatic paralysis is characterised by an inefficient hemidiaphragm contraction. Consequently, there is a neuromechanical dissociation with an overload of inspiratory accessory muscles and higher breathlessness.https://bit.ly/2XxAR4K

Polypharmacy Increases Risk of Dyspnea Among Adults With Serious, Life-Limiting Diseases

BACKGROUND

Polypharmacy is associated with dyspnea in cross-sectional studies, but associations have not been determined in longitudinal analyses. Statins are commonly prescribed but their contribution to dyspnea is unknown. We determined whether polypharmacy was associated with dyspnea trajectory over time in adults with advanced illness enrolled in a statin discontinuation trial, overall, and in models stratified by statin discontinuation.

METHODS

Using data from a parallel-group unblinded pragmatic clinical trial (patients on statins ≥3 months with life expectancy of 1 month to 1 year, enrolled in the parent study between June 3, 2011, and May 2, 2013, n = 308/381 [81%]), we restricted analyses to patients with available baseline medication count and ≥1 dyspnea score. Polypharmacy was assessed by self-reported chronic medication count. Dyspnea trajectory group, our primary outcome, was determined over 24 weeks using the Edmonton Symptom Assessment System.

RESULTS

The mean age of the patients was 73.8 years (standard deviation [SD]: ±11.0) and the mean medication count was 11.6 (SD: ±5.0). We identified 3 dyspnea trajectory groups: none (n = 108), mild (n = 130), and moderate-severe (n = 70). Statins were discontinued in 51.8%, 48.5%, and 42.9% of patients, respectively. In multivariable models adjusting for age, sex, diagnosis, and statin discontinuation, each additional medication was associated with 8% (odds ratio [OR] = 1.08 [1.01-1.14]) and 16% (OR = 1.16 [1.08-1.25]) increased risk for mild and moderate-severe dyspnea, respectively. In stratified models, polypharmacy was associated with dyspnea in the statin continuation group only (mild OR = 1.12 [1.01-1.24], moderate-severe OR = 1.24 [1.11-1.39]) versus statin discontinuation (mild OR = 1.03 [0.95-1.12], and moderate-severe OR = 1.09 [0.98-1.22]).

CONCLUSION

Polypharmacy was strongly associated with dyspnea. Prospective interventions to decrease polypharmacy may impact dyspnea symptoms, especially for statins.

Assessing the effects of inspiratory muscle training in a patient with unilateral diaphragm dysfunction

A 55-year-old man was referred to the outpatient pulmonary department of our hospital because of dyspnoea during exertion and when bending forward, which had been present for at least 6 months. He reported experiencing severe symptoms of breathlessness and many of his daily activities had to be adapted or interrupt due to symptoms (as documented by the Baseline Dyspnea Index (BDI)) (table 1). Recent infectious episodes or episodes of neck or shoulder pain were absent. His medical history included systemic arterial hypertension, obesity (body mass index (BMI) 36 kg·m⁻²), and obstructive sleep apnoea for which he was treated with night-time continuous positive airway pressure therapy (8 cmH₂O). He was a former smoker (18 pack-years) who quit smoking 15 years ago. 8 months ago, he underwent abdominal surgery (transabdominal epigastric hernia repair). The presence of cardiopulmonary disease and other aetiologies, such as neuromuscular disease, was excluded. Chest radiograph showed an elevated left hemidiaphragm and impaired left phrenic nerve conduction (i.e. increased latency and compound muscle action potential (CMAP) duration) after electrical stimulation (table 1) [1].

Patients with diaphragm dysfunction experience exertional dyspnoea. Respiratory muscle function assessments can identify breathing abnormalities and IMT might help to reduce symptoms (mostly via improvements in non-diaphragmatic muscles).http://bit.ly/2QdxNFP

A novel investigation of statins myotoxic mechanism: effect of atorvastatin on respiratory muscles in hypoxic environment

Myopathy is a well-known adverse effect of statins, affecting a large sector of statins users. The reported experimental data emphasized on mechanistic study of statin myopathy on large muscles. Clinically, both large muscles and respiratory muscles are reported to be involved in the myotoxic profile of statins. However, the experimental data investigating the myopathic mechanism on respiratory muscles are still lacking. The present work aimed to study the effect of atorvastatin treatment on respiratory muscles using rat isolated hemidiaphragm in normoxic & hypoxic conditions. The contractile activity of isolated hemidiaphragm in rats treated with atorvastatin for 21 days was investigated using nerve stimulated technique. Muscle twitches, train of four and tetanic stimulation was measured in normoxic, hypoxic and reoxygenation conditions. Atorvastatin significantly increased the tetanic fade, a measure of muscle fatigability, in hypoxic conditions. Upon reoxygenation, rat hemidiaphragm regains its normal contractile profile. Co-treatment with coenzyme Q10 showed significant improvement in defective diaphragmatic contractility in hypoxic conditions. This work showed that atorvastatin treatment rapidly deteriorates diaphragmatic activity in low oxygen environment. The mitochondrial respiratory dysfunction is probably the mechanism behind such finding. This was supported by the improvement of muscle contractile activity following CoQ10 co-treatment.

Novel methods of inspiratory muscle training via the Test of Incremental Respiratory Endurance (TIRE)

The favorable effects of inspiratory muscle training (IMT) in health and disease are becoming much more apparent. A variety of IMT methods exist, but few studies have compared IMT methods. The purpose of this article is to review the methods and outcomes of the Test of Incremental Respiratory Endurance (TIRE).

Inspiratory muscle training in heart disease and heart failure: a review of the literature with a focus on method of training and outcomes

Evidence to date strongly suggests that poor inspiratory muscle performance is associated with dyspnea, poor exercise tolerance and poor functional status in patients with heart failure (HF). A growing body of literature has examined the effects of inspiratory muscle training (IMT) in HF patients with the majority of studies reporting favorable effects on several of the above limitations and a substantial number of related deficiencies due to inadequate inspiration and inspiratory muscle strength and endurance. The domains and manifestations of HF, which were significantly improved by IMT in one or more of the 18 out of 19 studies of IMT, included dyspnea, quality of life, balance, peripheral muscle strength and blood flow, peripheral muscle sympathetic nervous activity, heart rate, respiratory rate, peak VO₂, 6-min walk test distance, ventilation, VE/VCO₂ slope, oxygen uptake efficiency, circulatory power, recovery oxygen kinetics and several indices of cardiac performance. This paper will also review the available IMT literature with a focus on methods of IMT and clinical outcomes. Key differences between available IMT methods will be highlighted with a goal to improve IMT efforts and decrease the pathophysiological manifestations of heart disease and HF.

Caring for the older person with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a common disease in elderly patients, is characterized by high symptom burden, health care utilization, mortality, and unmet needs of patients and caregivers. Respiratory failure and dyspnea may be exacerbated by heart failure, pulmonary embolism, and anxiety; by medication effects; and by other conditions, including deconditioning and malnutrition. Randomized controlled trials, which provide the strongest evidence for guideline recommendations, may underestimate the risk of adverse effects of interventions for older patients with COPD. The focus of guidelines on disease-modifying therapies may not address the full spectrum of patient and caregiver needs, particularly the high rates of bothersome symptoms, risk of functional and cognitive decline, and need for end-of-life care planning. Meeting the many needs of older patients with COPD and their families requires that clinicians supplement guideline-recommended care with treatment decision making that takes into account older persons' comorbid conditions, recognizes the trade-offs engendered by the increased risk of adverse events, focuses on symptom relief and function, and prepares patients and their loved ones for further declines in the patient's health and their end-of-life care. A case of COPD in an 81-year-old man hospitalized with severe dyspnea and respiratory failure highlights both the challenges in managing COPD in the elderly and the limitations in applying guidelines to geriatric patients.

Physical therapists referring patients to physicians: a review of case reports and series

STUDY DESIGN

Descriptive.

BACKGROUND

An important role for physical therapists in the healthcare delivery system is to recognize when patient referral to a physician or other healthcare provider is indicated. Few studies exist describing physical therapists' evaluative and diagnostic processes leading to patient referral to a physician.

OBJECTIVE

To summarize published patient case reports that described physical therapist/patient episodes of care that resulted in the referral of the patient to a physician and a subsequent diagnosis of medical disease.

METHODS

A literature search identified 78 case reports describing physical therapist referral of patients to physicians with subsequent diagnosis of a medical condition. Two evaluators reviewed the cases and summarized (1) how and when patients accessed physical therapy services, (2) timing of patient referral to a physician, (3) resultant medical diagnoses, (4) physical therapists' role in referral of patients for diagnostic testing, and (5) relevant patient symptom description, health history, review of systems, and physical examination findings.

RESULTS

Fifty-eight (74.4%) of 78 patients had been referred to a physical therapist by their physician, while the remaining 20 patients accessed physical therapy services via direct access. The patients' primary presenting symptoms included pain (n = 60), weakness (n = 4), tingling/numbness (n = 2), or a combination (n = 12). Patient referrals to a physician occurred at the initial physical therapy session in 58 (74.4%) of 78 cases. A majority of patient referrals to a physician (n = 65) were related to primary presenting symptoms, including manifestations inconsistent with physician diagnosis, recent worsening without cause, unusual accompanying symptoms such as fatigue and/or weakness, and inadequate response to treatment. Resultant diagnoses included neuromusculoskeletal disorders (n = 53; fractures and tumors most common), visceral disorders (n = 14; cardiovascular involvement most common), and medication-related disorders (n = 3).

CONCLUSIONS

This review of published patient case reports provides numerous examples of physical therapists using effective multifactorial screening strategies for referred and direct-access patients, leading to timely patient referrals to physicians. The therapist-initiated patient referral to a physician led to subsequent diagnosis of a wide range of conditions and pathological processes.

Effects of statins on skeletal muscle: a perspective for physical therapists

Hyperlipidemia, also known as high blood cholesterol, is a cardiovascular health risk that affects more than one third of adults in the United States. Statins are commonly prescribed and successful lipid-lowering medications that reduce the risks associated with cardiovascular disease. The side effects most commonly associated with statin use involve muscle cramping, soreness, fatigue, weakness, and, in rare cases, rapid muscle breakdown that can lead to death. Often, these side effects can become apparent during or after strenuous bouts of exercise. Although the mechanisms by which statins affect muscle performance are not entirely understood, recent research has identified some common causative factors. As musculoskeletal and exercise specialists, physical therapists have a unique opportunity to identify adverse effects related to statin use. The purposes of this perspective article are: (1) to review the metabolism and mechanisms of actions of statins, (2) to discuss the effects of statins on skeletal muscle function, (3) to detail the clinical presentation of statin-induced myopathies, (4) to outline the testing used to diagnose statin-induced myopathies, and (5) to introduce a role for the physical therapist for the screening and detection of suspected statin-induced skeletal muscle myopathy.