Respiratory Muscle Function In Patients Research Articles

Effectiveness of Myofascial Release on Respiratory Muscle in COPD Patients: A Narrative Review

Introduction: The Chronic Obstructive Pulmonary Disease (COPD) can stiffen the diaphragm, limiting its movement and compliance. Myofascial Release (MFR) techniques may help loosen restrictions in the fascia surrounding the diaphragm, allowing for better mobility and more efficient breathing. While some studies suggest benefits of MFR for COPD patients, the overall research base is limited. Aim: To evaluate the current evidence on effectiveness of MFR techniques in improving respiratory muscle function in patients with COPD. Materials and Methods: A narrative review was conducted from September 2023 to January 2024 and following searches were performed in PubMed, Physiotherapy Evidence Database (PEDro) and Cochrane using keywords like “manual diaphragm release”, “respiratory muscles”, “COPD” and “diaphragmatic myofascial release”. After probing the databases only four studies were found to be in line with the aim, where the participants were both male and female with COPD according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Results: Findings of the Randomised Controlled Trials (RCTs) were included in the present review. The studies employed Myofascial release over Respiratory muscles which shows that MFR have beneficial effects on respiratory muscle functions in COPD patients, potentially improving breathing mechanics, muscle strength and exercise tolerance. Conclusion: The review supports the potential effectiveness of myofascial release as a complementary therapy for improving respiratory muscle function in individuals with COPD. The MFR could be a valuable non invasive and drug-free technique to complement existing COPD management strategies like medication and pulmonary rehabilitation. It might offer additional benefits for symptom management and overall well-being.

Effect of chest wall mobilization on respiratory muscle function in patients with severe chronic obstructive pulmonary disease (COPD): A randomized controlled trial

BackgroundClinical trials have demonstrated positive correlation between pulmonary function and chest wall expansion in COPD. Decrease in chest wall expansion in patients with COPD compromises rib cage mobility and functional length of respiratory muscles that ultimately jeopardize the efficacy and function of respiratory system. MethodThirty male adults (mean age: 74.97 ± 6.29) suffered with severe COPD were randomly allocated to either experimental group (chest wall mobilizations) or control group. Both groups received standardized education and walking exercise (twice/week) for 6 weeks. Patients in experimental group received additional chest wall mobilizations that include stretching and joints mobilization. Pulmonary function, respiratory muscle strength, thoracic excursion, cervical and thoracic range of movement were evaluated at baseline, post-program and at 3-month follow-up. ResultsThere were significantly greater improvements in respiratory muscle strength, thoracic excursion and thoracic range of movement (p < 0.01) except thoracic flexion. Lower thoracic excursion is strongly associated with increase in maximum inspiratory pressure (β = 13.64, p < 0.001) and maximum expiratory pressure (β = 16.23, p < 0.001). Thoracic range of movement especially extension (p < 0.001) and bilateral rotation (p < 0.01) exhibit a strong relationship with increase in lower thoracic excursion (adjusted R2 = 0.876) as shown in multiple regression analysis. ConclusionAdditional chest wall mobilization in the rehabilitation of patients with COPD is likely to enhance thoracic extension and rotation which increase lower thoracic excursion. This significant improvement in chest expansion capacity allows respiratory muscles to work at an optimal functional length which result in greater respiratory muscle strength in patients with severe COPD.

Bronchoscopic lung volume reduction with endobronchial valves improves respiratory muscle function in patients with severe emphysema

Bronchoscopic lung volume reduction with endobronchial valves improves respiratory muscle function in patients with severe emphysema

Respiratory muscle function in patients with nemaline myopathy

In this cross-sectional study, we comprehensively assessed respiratory muscle function in various clinical forms of nemaline myopathy (NM) including non-volitional tests for diaphragm function. Forty-two patients with NM were included (10 males (25-74 y/o); 32 females (11-76 y/o)). The NM forms were typical (n=11), mild (n=7), or childhood-onset with slowness of movements (n=24). Forced vital capacity (FVC) and maximal inspiratory pressure were decreased in typical NM in comparison with childhood-onset NM with slowness (32.0 [29.0-58.5] vs 81.0 [75.0-87.0]%, p<0.01, and 35.0 [24.0-55.0] vs 81.0 [65.0-102.5] cmH2O, p<0.01). Eight patients with childhood-onset NM with slowness had respiratory muscle weakness. There was a low correlation between FVC and Motor Function Measure scores (r=0.48, p<0.01). End-inspiratory diaphragm thickness and twitch mouth pressure were decreased in patients requiring home mechanical ventilation compared to non-ventilated patients with normal lung function (1.8 [1.5-2.4] vs 3.1 [2.0-4.6] mm, p=0.049, and -7.9 [-10.9- -4.0] vs -14.9 [-17.3- -12.6], p=0.04). Our results show that respiratory muscle weakness is present in all NM forms, including childhood-onset NM with slowness, and may be present irrespective of the degree of general motor function impairment. These findings highlight the importance for screening of respiratory function in patients with NM to guide respiratory management.

Inspiratory Muscle Training on Glucose Control in Diabetes: A Randomized Clinical Trial.

This study evaluated the effects of inspiratory muscle training (IMT) in glucose control and respiratory muscle function in patients with diabetes. It was a randomized clinical trial conducted at the Physiopathology Laboratory of the Hospital de Clínicas de Porto Alegre. Patients with Type 2 diabetes were randomly assigned to IMT or placebo-IMT (P-IMT), performed at 30% and 2% of maximal inspiratory pressure, respectively, every day for 12 weeks. The main outcome measures were HbA1c, glycemia, and respiratory muscle function. Thirty patients were included: 73.3% women, 59.6 ± 10.7 years old, HbA1c 8.7 ± 0.9% (71.6 ± 9.8mmol/mol), and glycemia 181.8 ± 57.8mg/dl (10.5 ± 3.2mmol/L). At the end of the training, HbA1c was 8.2 ±0.3% (66.1 ± 3.3mmol/mol) and 8.7 ± 0.3% (71.6 ± 3.3mmol/mol) for the IMT and P-IMT groups, respectively (p = .8). Fasting glycemia decreased in both groups with no difference after training although it was lower in IMT at 8 weeks: 170.0 ± 11.4 mg/dl(9.4 ± 0.6 mmol/L) and 184.4 ± 15.0mg/dl (10.2 ± 0.8mmol/L) for IMT and P-IMT, respectively (p < .05). Respiratory endurance time improved in the IMT group (baseline = 325.9 ± 51.1s and 305.0 ± 37.8s; after 12 weeks = 441.1 ± 61.7s and 250.7 ± 39.0s for the IMT and P-IMT groups, respectively; p < .05). Considering that glucose control did not improve, IMT should not be used as an alternative to other types of exercise in diabetes. Higher exercise intensities or longer training periods might produce better results. The clinical trials identifier is NCT03191435.

Heart Failure Results in Inspiratory Muscle Dysfunction Irrespective of Left Ventricular Ejection Fraction

Background: Exercise intolerance in heart failure with reduced ejection fraction (HFrEF) or heart failure with preserved ejection fraction (HFpEF) results from both cardiac dysfunction and skeletal muscle weakness. Respiratory muscle dysfunction with restrictive ventilation disorder may be present irrespective of left ventricular ejection fraction and might be mediated by circulating pro-inflammatory cytokines. Objective: To determine lung and respiratory muscle function in patients with HFrEF/HFpEF and to determine its associations with exercise intolerance and markers of systemic inflammation. Methods: Adult patients with HFrEF (n = 22, 19 male, 61 ± 14 years) and HFpEF (n = 8, 7 male, 68 ± 8 years) and 19 matched healthy control subjects underwent spirometry, measurement of maximum mouth occlusion pressures, diaphragm ultrasound, and recording of transdiaphragmatic and gastric pressures following magnetic stimulation of the phrenic nerves and the lower thoracic nerve roots. New York Heart Association (NYHA) class and 6-min walking distance (6MWD) were used to quantify exercise intolerance. Levels of circulating interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured using ELISAs. Results: Compared with controls, both patient groups showed lower forced vital capacity (FVC) (p < 0.05), maximum inspiratory pressure (PI_max), maximum expiratory pressure (PE_max) (p < 0.05), diaphragm thickening ratio (p = 0.01), and diaphragm strength (twitch transdiaphragmatic pressure in response to supramaximal cervical magnetic phrenic nerve stimulation) (p = 0.01). In patients with HFrEF, NYHA class and 6MWD were both inversely correlated with FVC, PI_max, and PE_max. In those with HFpEF, there was an inverse correlation between amino terminal pro B-type natriuretic peptide levels and FVC (r = −0.77, p = 0.04). In all HF patients, IL-6 and TNF-α were statistically related to FVC. Conclusions: Irrespective of left ventricular ejection fraction, HF is associated with respiratory muscle dysfunction, which is associated with increased levels of circulating IL-6 and TNF-α.

Comparative Effect of Liuzijue Qigong and Conventional Respiratory Training on Trunk Control Ability and Respiratory Muscle Function in Patients at an Early Recovery Stage From Stroke: A Randomized Controlled Trial

ObjectivesTo compare the effects of Liuzijue Qigong and conventional respiratory training on trunk control ability and respiratory muscle functions in patients at an early recovery stage from stroke. DesignA single-blind, randomized controlled trial. SettingA hospital. ParticipantsPatients (N=60) within 2 months poststroke. InterventionsThe experimental group (n=30) received conventional rehabilitation training combined with Liuzijue exercise, and the control group (n=30) received conventional rehabilitation training combined with conventional respiration training. The training in the 2 groups was conducted 5 times per week for 3 weeks. Main Outcome MeasuresTrunk Impairment Scale (TIS), maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), maximum expiratory mid-flow (MMEF), diaphragmatic movement, the change of intra-abdominal pressure (IAP), Berg Balance Scale (BBS), and Modified Barthel Index (MBI). All outcome measures were assessed twice (at baseline and 3 weeks). ResultsBoth groups significantly improved in TIS, MIP, FVC, PEF, and the change of IAP, BBS, and MBI when pre- and postassessments (P<.05) were compared. Compared with the control group, there was a significant difference in the experimental group in the static sitting balance subscale (P=.014), dynamic balance subscale (P=.001), coordination subscale (P<.001), TIS total scores (P<.001; effect size [ES]=0.9), MIP (P=.012; 95% confidence interval [CI], 2.23-17.69; ES=0.67), MEP (P=.015; 95% CI, 1.85-16.57; ES=0.65), change of IAP (P=.001), and MBI (P=.016; 95% CI, 1.51-14.16; ES=0.64). No significant differences were found between the 2 groups in FEV1 (P=.24), FVC (P=.43), PEF (P=.202), MMEF (P=.277), the diaphragmatic movement of quiet breathing (P=.146), deep breathing (P=.102), and BBS (P=.124). ConclusionsLiuzijue exercise showed more changes than conventional respiratory training in improving trunk control ability, respiratory muscle functions, and activities of daily living ability in patients at an early recovery stage from stroke.

Effects of levosimendan on respiratory muscle function in patients weaning from mechanical ventilation

PurposeRespiratory muscle weakness frequently develops in critically ill patients and is associated with adverse outcome, including difficult weaning from mechanical ventilation. Today, no drug is approved to improve respiratory muscle function in these patients. Previously, we have shown that the calcium sensitizer levosimendan improves calcium sensitivity of human diaphragm muscle fibers in vitro and contractile efficiency of the diaphragm in healthy subjects. The main purpose of this study is to investigate the effects of levosimendan on diaphragm contractile efficiency in mechanically ventilated patients.MethodsIn a double-blind randomized placebo-controlled trial, mechanically ventilated patients performed two 30-min continuous positive airway pressure (CPAP) trials with 5-h interval. After the first CPAP trial, study medication (levosimendan 0.2 µg/kg/min continuous infusion or placebo) was administered. During the CPAP trials, electrical activity of the diaphragm (EAdi), transdiaphragmatic pressure (Pdi), and flow were measured. Neuromechanical efficiency (primary outcome parameter) was calculated.ResultsThirty-nine patients were included in the study. Neuromechanical efficiency was not different during the CPAP trial after levosimendan administration compared to the CPAP trial before study medication. Tidal volume and minute ventilation were higher after levosimendan administration (11 and 21%, respectively), whereas EAdi and Pdi were higher in both groups in the CPAP trial after study medication compared to the CPAP trial before study medication.ConclusionsLevosimendan does not improve diaphragm contractile efficiency.

Combined aerobic exercise and high-intensity respiratory muscle training in patients surgically treated for non-small cell lung cancer: a pilot randomized clinical trial.

Lung resection surgery further decreases exercise capacity and negatively affects respiratory muscle function in patients with non-small cell lung cancer (NSCLC). The best design for exercise interventions in these patients has not been determined yet. To assess the impact of aerobic exercise and high-intensity respiratory muscle training on patient outcomes following lung cancer resection surgery. Prospective, single-blind, pilot randomized controlled trial. Outpatient cardiopulmonary rehabilitation unit of two university hospitals. Thirty-seven patients with NSCLC after tumor resection. Patients were randomly assigned to exercise training or usual post-operative care. The training program consisted of aerobic exercises and high-intensity respiratory muscle training (24 supervised sessions, 3 per week, 8 weeks). Primary outcome was exercise capacity assessed with peak oxygen uptake (VO2peak) during cardiopulmonary exercise test. Secondary outcomes included changes in respiratory muscle strength, levels of serum insulin growth factor I (IGF-I) and IGF binding protein 3 (IGFBP-3), and quality of life assessed with the European Organization for Research and Treatment of Cancer (EORTC QLQ-C30) questionnaire. The 8-week training program was associated with significant improvement in VO2peak (2.13 mL/Kg/min [95%CI 0.06 to 4.20]), maximal inspiratory and expiratory pressures (18.96 cmH2O [95% CI 2.7 to 24.1] and 18.58 cmH2O [95% CI 4.0 to 33.1], respectively) and IGFBP-3 (0.61 µg/mL [%95 CI 0.1 to 1.12]). No significant differences were observed in the EORTC QLQ-C30. An 8-week exercise program consisting of aerobic exercise and high-intensity respiratory muscle training improved exercise capacity, respiratory muscle strength, and serum IGFBP-3 levels in NSCLC patients after lung resection. There was no impact on the other outcomes assessed. A combination of aerobic exercise and respiratory muscle training could be included in the rehabilitation program of deconditioned patients with NSCLC after lung resection surgery.

Feasibility of Exercise Training in Cancer Patients Scheduled for Elective Gastrointestinal Surgery

Background/Aims: This study examines the feasibility of a preoperative exercise program to improve the physical fitness of a patient before gastrointestinal surgery. Methods: An outpatient exercise program was developed to increase preoperative aerobic capacity, peripheral muscle endurance and respiratory muscle function in patients with pancreatic, liver, intestinal, gastric or esophageal cancer. During a consult at the outpatient clinic, patients were invited to participate in the exercise program when their surgery was not scheduled within 2 weeks. Results: The 115 participants followed on average 5.7 (3.5) training sessions. Adherence to the exercise program was high: 82% of the planned training sessions were attended, and no adverse events occurred. Mixed model analyses showed a significant increase of maximal inspiratory muscle strength (84.1-104.7 cm H₂O; p = 0.00) and inspiratory muscle endurance (35.0-39.5 cm H₂O; p = 0.00). No significant changes were found in aerobic capacity and peripheral muscle strength. Conclusion: This exercise program in patients awaiting oncological surgery is feasible in terms of participation and adherence. Inspiratory muscle function improved significantly as a result of inspiratory muscle training. The exercise program however failed to result in improved aerobic capacity and peripheral muscle strength, probably due to the limited number of training sessions as a result of the restricted time interval between screening and surgery.

ChronicPseudomonas aeruginosaInfection and Respiratory Muscle Impairment in Cystic Fibrosis

Chronic infection with Pseudomonas aeruginosa in patients with cystic fibrosis (CF) is associated with increased morbidity. Chronic infection can cause limb and respiratory muscle compromise. Respiratory muscle function can be assessed via maximal inspiratory pressure (PImax), maximal expiratory pressure (PEmax), and the pressure-time index of the respiratory muscles (PTImus). We studied the effect of chronic P. aeruginosa infection on respiratory muscle function in patients with CF. This cross-sectional study assessed PImax, PEmax, PTImus, FEV1, FVC, maximum expiratory flow during the middle half of the FVC maneuver, body mass index, and upper arm muscle area in 122 subjects with CF, in 4 subgroups matched for age and sex at different stages of P. aeruginosa infection, according to the Leeds criteria. We compared respiratory muscle function in the subgroups according to P. aeruginosa infection state. Median PImax was significantly lower in CF subjects with chronic P. aeruginosa infection (PImax = 62 cm H2O), compared to subjects who were never infected (PImax = 86 cm H2O, P = .02), free of infection (PImax = 74 cm H2O, P = .01), or intermittently infected (PImax = 72 cm H2O, P = .02). Median PTImus was significantly increased in CF subjects with chronic P. aeruginosa infection (PTImus = .142), compared to subjects who were free of infection (PTImus = .102, P = .006). Median upper-arm muscle area was significantly lower in CF subjects with chronic P. aeruginosa infection (upper-arm muscle area = 2,219 mm(2)), compared to subjects who were never infected (2,754 mm(2), P = .03), free of infection (2,678 mm(2), P = .01), or intermittently infected (2,603 mm(2), P = .04). Multivariate logistic regression revealed P. aeruginosa state of infection as a significant determinant of PTImus (P = .03) independently of sex, upper-arm muscle area, and FEV1. CF subjects with chronic P. aeruginosa infection exhibited impaired respiratory muscle function and decreased inspiratory muscle strength, and chronic P. aeruginosa infection independently impacts respiratory muscle function in subjects with CF.

Longitudinal course of lung function and respiratory muscle strength in spinal muscular atrophy type 2 and 3

BackgroundSpinal muscular atrophy (SMA) is a common genetic disorder that causes severe hypotonia and weakness, and often fatal restrictive lung disease. The aim of the study was to describe the natural history of the respiratory involvement in patients with SMA type 2 and 3 in order to assess the relevance of the clinical classification and identify the parameters associated with the earliest and most rapid decline over time. MethodsThirty-one patients aged 3–21 years were followed over a 10-year period. Lung function, blood gases, respiratory mechanics and muscle strength with recording of oesogastric pressures were measured during routine follow-up. ResultsAt least two measurements were available in 16 patients (seven type 2 and nine type 3). Among all the volitional and non-volitional, invasive and non-invasive tests, forced vital capacity (FVC) and sniff nasal inspiratory pressure (SNIP) were shown to be the most informative parameters, showing lower values in SMA type 2, with however a similar rate of decline in patients with SMA type 2 and 3. ConclusionOur results confirm an earlier decline in lung and respiratory muscle function in patients classified as SMA type 2 as compared with patients classified as type 3. This decline can be assessed by two simple non-invasive tests, FVC and SNIP, with the last maneuver being feasible and reliable in the youngest children, underlying its interest for the monitoring of children with SMA.

Aerobic exercise and respiratory muscle strength in patients with cystic fibrosis

The beneficial role of exercise in maintaining health in patients with cystic fibrosis (CF) is well described. Few data exist on the effect of exercise on respiratory muscle function in patients with CF. Our objective was to compare respiratory muscle function indices in CF patients that regularly exercise with those CF patients that do not. This cross-sectional study assessed nutrition, pulmonary function and respiratory muscle function in 37 CF patients that undertook regular aerobic exercise and in a control group matched for age and gender which consisted of 44 CF patients that did not undertake regular exercise. Respiratory muscle function in CF was assessed by maximal inspiratory pressure (Pimax), maximal expiratory pressure (Pemax) and pressure-time index of the respiratory muscles (PTImus). Median Pimax and Pemax were significantly higher in the exercise group compared to the control group (92 vs. 63 cm H2O and 94 vs. 64 cm H2O respectively). PTImus was significantly lower in the exercise group compared to the control group (0.089 vs. 0.121). Upper arm muscle area (UAMA) and mid-arm muscle circumference were significantly increased in the exercise group compared to the control group (2608 vs. 2178 mm2 and 23 vs. 21 cm respectively). UAMA was significantly related to Pimax in the exercising group. These results suggest that CF patients that undertake regular aerobic exercise maintain higher indices of respiratory muscle strength and lower PTImus values, while increased UAMA values in exercising patients highlight the importance of muscular competence in respiratory muscle function in this population.

Maximum Rate of Pressure Development and Maximal Relaxation Rate of Respiratory Muscles in Patients with Cystic Fibrosis

Respiratory muscle function in patients with cystic fibrosis (CF) has been studied by measurement of maximal inspiratory pressure (P(Imax)), maximal expiratory pressure (P(Emax)), and the pressure-time index of the respiratory muscles (PTI(mus)). The maximum rate of pressure development (MRPD) during P(Imax) (MRPD-P(Imax)), MRPD during P(Emax) (MRPD-P(Emax)), maximal relaxation rate (MRR) during P(Imax) (MRR-P(imax)), and MRR during P(Emax) (MRR-P(Emax)) have not been studied in CF. Our aim was to study MRPD and MRR and investigate their possible application as accessory indices of respiratory muscle function in patients with CF. FEVY, FVC, and maximal expiratory flow between 25% and 75% of vital capacity, body mass index (BMI), upper arm muscle area, P(imax), P(Emax), PTI(mus), MRPD-P(Imax), MRPD-P(Emax), MRR-P(imax), and MRR-P(Emax) were assessed in 123 CF patients and in a control group of 123 healthy subjects matched for age and sex. MRR-P(Emax) was significantly increased and MRPD-P(Emax) was significantly decreased in the CF patients, compared to the healthy controls. In the CF patients MRR-P(Imax) was significantly related to PTI(mus) (P = .02), FEV1 (P = .03), FVC (P = .001), BMI (P < .001), and upper arm muscle area (P < .001). In the CF patients, MRPD-P(Imax) and MRPD- P(Emax) were significantly related to upper arm muscle area (P < .001), BMI (P < .001 and P = .01, respectively), P(Imax) (P < .001), and P(Emax) (P < .001). The CF patients exhibited increased MRR and decreased MRPD during maximal respiratory effort, compared to controls. The differences in MRR-P(imax) and MRPD-P(Imax) between the controls and the complete group of CF patients were not significant. MRPD and MRR were significantly related to nutritional and pulmonary function impairment in CF patients. MRPD strongly correlated to maximal respiratory muscle pressures, and MRR strongly correlated to PTI(mus) in patients with CF. These findings suggest that CF patients are at increased risk of respiratory muscle fatigue. Regular determination of MRPD and MRR may be clinically useful in CF patients and help to initiate inspiratory muscle training and noninvasive ventilation.

Respiratory muscle function in patients with cystic fibrosis

Respiratory muscle function in patients with cystic fibrosis (CF) can be assessed by measurement of maximal inspiratory pressure (Pimax ), maximal expiratory pressure (Pemax ), and pressure-time index of the respiratory muscles (PTImus ). We investigated the differences in maximal respiratory pressures and PTImus between CF patients with no gross hyperinflation and healthy controls and described the effects of pulmonary function and nutrition impairment on respiratory muscle function in this group of CF patients. Forced expiratory volume in 1 sec (FEV1 ), forced vital capacity (FVC) and maximal expiratory flow between 25% and 75% of VC (MEF25-75 ), body mass index (BMI), upper arm muscle area (UAMA), Pimax , Pemax , and PTImus were assessed in 140 CF patients and in a control group of 140 healthy subjects matched for age and gender. Median Pimax and Pemax were significantly lower in CF patients compared to the controls [Pimax = 74 (57-94) in CF vs. 84 (66-102) in controls, P = 0.009], [Pemax = 71 (50-95) in CF vs. 84 (66-102) in controls, P < 0.001]. Median PTImus in CF patients compared to controls was significantly increased [PTImus = 0.110 (0.076-0.160) in CF vs. 0.094 (0.070-0.137) in controls, P = 0.049] and it was significantly higher in CF patients with impaired pulmonary function. In CF patients, PTImus was significantly negatively related to upper arm muscle area (r = 0.184, P = 0.031). These findings suggest that CF patients with no severe lung disease compared to healthy subjects exhibit impaired respiratory muscle function, while CF patients with impaired pulmonary function and nutrition indices exhibit higher PTImus values.

170 Quantifying physical activity in leisure time in adults with cystic fibrosis and association with disease severity: a preliminary study

169 Exercise and respiratory muscle function in patients with cystic fibrosis T.G. Dassios1, A. Katelari2, S. Doudounakis2, G. Dimitriou3. 1Addenbrookes Hospital, Cambridge University Hospitals NHS Trust, Neonatal Intensive Care Unit, Cambridge, United Kingdom; 2“Aghia Sophia” Children’s Hospital, Department of Cystic Fibrosis, Athens, Greece; 3University of Patras Medical School, Department of Paediatrics, Patras, Greece

169 Exercise and respiratory muscle function in patients with cystic fibrosis

169 Exercise and respiratory muscle function in patients with cystic fibrosis

Effect of endurance exercise on respiratory muscle function in patients with cystic fibrosis

During exercise, patients with cystic fibrosis (CF) dynamically hyperinflate, which imposes both elastic and threshold loads on the inspiratory muscles and places them at a mechanical disadvantage due to muscle shortening. Conversely, dynamic hyperinflation imposes a progressively resistive load and lengthens the expiratory muscles potentially increasing their susceptibility to develop low frequency fatigue (LFF). The aim of the study was to determine whether high intensity endurance exercise leads to the development of LFF in either the diaphragm or expiratory abdominal wall muscles in patients with CF. Ten patients and ten healthy individuals were studied. Twitch transdiaphragmatic pressure (TwP(di)) and twitch abdominal pressure (TwT(10)) were measured before and after exhaustive endurance cycle exercise at 80% of their previously determined maximum work rate. There was no difference in TwP(di) or TwT(10) at 20, 40 or 60 min post exercise compared to pre-exercise resting values in any of the participants, indicating that overt LFF of the respiratory muscles did not develop.

The Calcium Sensitizer Levosimendan Improves Human Diaphragm Function

Acquired diaphragm muscle weakness is a key feature in several chronic conditions, including chronic obstructive pulmonary disease, congestive heart failure, and difficult weaning from mechanical ventilation. No drugs are available to improve respiratory muscle function in these patients. Recently, we have shown that the calcium sensitizer levosimendan enhances the force-generating capacity of isolated diaphragm fibers. To investigate the effects of the calcium sensitizer levosimendan on in vivo human diaphragm function. In a double-blind, randomized, crossover design, 30 healthy subjects performed two identical inspiratory loading tasks. After the first loading task, subjects received levosimendan (40 μg/kg bolus followed by 0.1/0.2 μg/kg/min continuous infusion) or placebo. Transdiaphragmatic pressure, diaphragm electrical activity, and their relationship (neuromechanical efficiency) were measured during loading. Magnetic phrenic nerve stimulation was performed before the first loading task and after bolus administration to assess twitch contractility. Center frequency of diaphragm electrical activity was evaluated to study the effects of levosimendan on muscle fiber conduction velocity. The placebo group showed a 9% (P=0.01) loss of twitch contractility after loaded breathing, whereas no loss in contractility was observed in the levosimendan group. Neuro-mechanical efficiency of the diaphragm during loading improved by 21% (P<0.05) in the levosimendan group. Baseline center frequency of diaphragm electrical activity was reduced after levosimendan administration (P<0.05). The calcium sensitizer levosimendan improves neuromechanical efficiency and contractile function of the human diaphragm. Our findings suggest a new therapeutic approach to improve respiratory muscle function in patients with respiratory failure.

231* Respiratory muscle function in patients with cystic fibrosis

231* Respiratory muscle function in patients with cystic fibrosis