Reliability of a commercially available threshold loading device in healthy subjects and in patients with chronic obstructive pulmonary disease

Inspiratory muscle training in addition to conventional physical rehabilitation in hospitalized patients undergoing hematopoietic stem cell transplantation: a randomized controlled trial

PURPOSE

To investigate the effect of inspiratory muscle training (IMT) in addition to conventional physical rehabilitation on muscle strength, functional capacity, mobility, hemodynamics, fatigue, and quality of life in hospitalized patients undergoing hematopoietic stem cell transplantation (HSCT).

METHODS

We conducted a randomized controlled trial in 57 inpatients with hematological diseases undergoing HSCT. Conventional inpatient physical rehabilitation was delivered to the IMT (n = 27) and control (CON; n = 30) groups according to usual care, and the first group additionally performed IMT. The IMT was prescribed according to clinical and laboratory parameters at 40% of maximal inspiratory pressure (MIP), 5 days/week throughout the hospitalization, in sessions of 10-20 min. The primary outcome was MIP and the secondary outcomes were maximal expiratory pressure (MEP), peripheral muscle strength (handgrip and sit-to-stand tests), functional capacity (6-min step test), mobility (timed up and go test), blood pressure, quality of life (EORTC-QLQ-C30), and fatigue (FACT-F) at admission and hospital discharge.

RESULTS

The population was predominately autologous HSCT. The IMT group significantly increased the MIP (P < 0.01) and decreased both fatigue (P = 0.01) and blood pressure (P < 0.01) compared with control. No differences were found between admission and hospital discharge in peripheral and expiratory muscle strength, functional capacity, mobility, and quality of life in both groups (P > 0.05).

CONCLUSIONS

Our results support the effectiveness of IMT as part of rehabilitation for HSCT inpatients, improving inspiratory muscle strength, and reducing fatigue and blood pressure.

TRIAL REGISTRATION

NCT03373526 (clinicaltrials.gov).

Tailored patient self-management and supervised, home-based, pulmonary rehabilitation for mild and moderate chronic obstructive pulmonary disease

[Purpose] Our study aimed to estimate the effects of a supervised, intensive, home-based-pulmonary-rehabilitation (HBPR) program for mild and moderate chronic-obstructive-pulmonary-disease (COPD) patients. [Participants and Methods] A retrospective, case-control study. Forty-three (N=43) patients were observed, divided into Treatment-Group (TG) and Control-Group (CG). The TG (N=23) underwent a 4-week training program, consisting of endurance and strength training sessions, performed 4-times per week. In addition, inspiration muscle training was performed, with a threshold device. The primary outcome was dyspnea improvements, measured by the modified-Borg-scale (mBS), and the secondary outcome was the determination of diaphragm excursion and function, using ultrasound (US) assessment to measure clinical parameters. [Results] The results suggested significantly improved mBS scores, measured for the ΔT0-T1 and ΔT0-T2 time points; improved diaphragm-excursion (Dia-Ex) at ΔT0-T1 and ΔT0-T2; and improved maximum Dia-Ex at ΔT0-T1 and ΔT1-T2 in the TG compared with the CG. Moreover, the results showed improvements over time for all parameters in the TG versus CG, suggesting a constant improvement in respiratory pathology. [Conclusion] A supervised HBPR plan was effective in reducing dyspnea by the mBS, and improving diaphragmatic function, as determined by US evaluation, and lastly improving quality of life in patients with mild-to-moderate COPD.

Respiratory Muscle Rehabilitation in Patients with Prolonged Mechanical Ventilation: A Targeted Approach

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2020. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Dynamic respiratory muscle function in late-onset Pompe disease

Maximal inspiratory pressure (PI_MAX) reflects inspiratory weakness in late-onset Pompe disease (LOPD). However, static pressure tests may not reveal specific respiratory muscle adaptations to disruptions in breathing. We hypothesized that dynamic respiratory muscle functional tests reflect distinct ventilatory compensations in LOPD. We evaluated LOPD (n = 7) and healthy controls (CON, n = 7) during pulmonary function tests, inspiratory endurance testing, dynamic kinematic MRI of the thorax, and ventilatory adjustments to single-breath inspiratory loads (inspiratory load compensation, ILC). We observed significantly lower static and dynamic respiratory function in LOPD. PI_MAX, spirometry, endurance time, and maximal diaphragm descent were significantly correlated. During single-breath inspiratory loads, inspiratory time and airflow acceleration increased to preserve volume, and in LOPD, the response magnitudes correlated to maximal chest wall kinematics. The results indicate that changes in diaphragmatic motor function and strength among LOPD subjects could be detected through dynamic respiratory testing. We concluded that neuromuscular function significantly influenced breathing endurance, timing and loading compensations.

Methodologies of inspiratory muscle training techniques in obstructive lung diseases

Background: Inspiratory muscle training (IMT) is a non-pharmacological, non-invasive therapeutic method that can improve the quality of life in patients with obstructive lung diseases. The effectiveness of IMT may depends on the type of the device used in the training and the parameters of the training programme. Objectives: The aim of the review was to present different techniques and protocols of IMT used in patients with obstructive lung diseases. Methods: The MEDLINE and EMBASE were searched to identify the potentially eligible publications from the previous 5 years. The various protocols of IMT used in different studies were analysed and described in detail. Results: A database search identified 333 records, of which 22 were included into the final analysis. All of the finally analysed studies were conducted in patients with chronic obstructive pulmonary disease (COPD). The protocols of IMT used in the studies differed in the type of the device used, the duration of the training programme, the number and the duration of training sessions, the initial load, and the rate at which the load was changed during the training. Conclusions: IMT is used mainly in studies on patients with COPD and not with asthma. There is no one approved training programme for IMT. The most predominant type of IMT is a training with threshold loading. The most frequently used devices for IMT are POWERbreath and Threshold IMT. The protocols of IMT used in the studies are very diverse.

Identificação de equipamentos e procedimentos utilizados por fisioterapeutas brasileiros para testes de endurance muscular inspiratória

RESUMO A avaliação da função dos músculos inspiratórios por meio do teste de endurance muscular inspiratória (EMI), definida como a capacidade de sustentação dessa tarefa ao longo do tempo, atualmente apresenta ampla variedade de instrumentos e procedimentos para sua mensuração. Este estudo teve como objetivo identificar os diferentes equipamentos, procedimentos e forma de avaliação dos testes de EMI entre fisioterapeutas brasileiros. É um estudo transversal realizado por meio de questionário enviado por correio eletrônico individualmente a cada participante. Cento e treze fisioterapeutas de diferentes regiões do país, grande parte com atuação conjunta na clínica e na docência (52,1%), responderam realizar poucas vezes a medida de EMI (48,7%). O manovacuômetro aneroide foi o aparelho mais utilizado por 42,5% dos profissionais. O clipe nasal e o bocal tubular de plástico rígido ou papel foram os acessórios mais utilizados durante o teste, correspondendo a 51,8% e 33%, respectivamente. O teste de ventilação voluntária máxima foi o mais utilizado para avaliação da endurance inspiratória, relatado por 23% dos respondentes. O teste de carga constante para avaliação da endurance foi adotado por 51,2% dos fisioterapeutas, sendo que 54,9% associaram comandos verbais à demonstração para explicação do teste. A interpretação dos valores aferidos era feita através de valores de referência por 25,7% dos entrevistados. Identificou-se que os fisioterapeutas brasileiros entrevistados não apresentaram a mesma conduta para os testes de EMI. No entanto os equipamentos, procedimentos e a forma de avaliação são utilizados com base nas diretrizes sobre o tema e de acordo com a disponibilidade de recursos do serviço.

Breathing techniques in patients with chronic obstructive pulmonary disease (COPD)

Background:Breathing techniques are included in the rehabilitation program of patients with chronic obstructive pulmonary disease (COPD). The efficacy of breathing techniques aiming at improving symptoms of dyspnea and eliciting physiological effects is discussed in this paper. In patients with COPD, breathing techniques aim to relieve symptoms and ameliorate adverse physiological effects by: 1) increasing strength and endurance of the respiratory muscles; 2) optimizing the pattern of thoracoabdominal motion; and 3) reducing dynamic hyperinflation of the rib cage and improving gas exchange. Evidence exists to support the effectiveness of pursed lips breathing, forward leaning position, active expiration and inspiratory muscle training, but not for diaphragmatic breathing. Careful patient selection, proper and repeated instruction and control of the techniques, and assessment of the effects are necessary. Despite the evidence that breathing techniques are effective, several problems need to be resolved. The limited evidence for the transfer of the effects of breathing techniques during resting conditions to exercise conditions raises several questions. Do breathing techniques have to be practiced during activities of daily living?

Reliability of an Electronic Inspiratory Loading Device for Assessing Pulmonary Function in Post-Stroke Patients

Background

The purpose of this study was to examine the inter- and intra-rater reliability of an electronic inspiratory loading device for the assessment of pulmonary functions: maximum inspiratory pressure, peak inspiratory flow, and vital capacity.

Material/Methods

Subjects were 50 patient volunteers in a rehabilitation hospital who had experienced their first episode of unilateral stroke with hemiparesis during the previous 6 months (26 men, 24 women; mean age [±SD], 55.96 [±12.81] years), with no use of medications that could induce drowsiness, evidence of restrictive lung disease, history of asthma, use of psychotropic drugs, or alcohol consumption habit.

Maximum inspiratory pressure, peak inspiratory flow, and vital capacity for pulmonary functions were assessed using an electronic inspiratory loading device (PowerBreathe, K5, 2010) by 2 examiners, with patients in an unassisted sitting position, and 1 examiner re-assessed with same patients at the same time of a day after 1 week. Intra-class correlation coefficients were used to assess reliability.

Results

Intra-rater reliability ranged from intra-class correlation coefficients (ICCs)=0.959 to 0.986 in variables. For the inter-rater reliability between 2 examiners, the ICCs ranged from 0.933 to 0.985. Intra-rater and inter-rater reliability were good in variables (maximal inspiratory pressure, peak inspiratory flow, and vital capacity).

Conclusions

The intra- and inter-examiner reliability of the pulmonary function measurements, maximum inspiratory pressure, peak inspiratory flow, and vital capacity, for the post-stroke patients was very high. The results suggest that the electronic inspiratory loading device would be useful for clinical rehabilitative assessment of pulmonary function.

Improvement in Neural Respiratory Drive Estimation From Diaphragm Electromyographic Signals Using Fixed Sample Entropy

Diaphragm electromyography is a valuable technique for the recording of electrical activity of the diaphragm. The analysis of diaphragm electromyographic (EMGdi) signal amplitude is an alternative approach for the quantification of the neural respiratory drive (NRD). The EMGdi signal is, however, corrupted by electrocardiographic (ECG) activity, and this presence of cardiac activity can make the EMGdi interpretation more difficult. Traditionally, the EMGdi amplitude has been estimated using the average rectified value (ARV) and the root mean square (RMS). In this study, surface EMGdi signals were analyzed using the fixed sample entropy (fSampEn) algorithm, and compared to the traditional ARV and RMS methods. The fSampEn is calculated using a tolerance value fixed and independent of the standard deviation of the analysis window. Thus, this method quantifies the amplitude of the complex components of stochastic signals (such as EMGdi), and being less affected by changes in amplitude due to less complex components (such as ECG). The proposed method was tested in synthetic and recorded EMGdi signals. fSampEn was less sensitive to the effect of cardiac activity on EMGdi signals with different levels of NRD than ARV and RMS amplitude parameters. The mean and standard deviation of the Pearson's correlation values between inspiratory mouth pressure (an indirect measure of the respiratory muscle activity) and fSampEn, ARV, and RMS parameters, estimated in the recorded EMGdi signal at tidal volume (without inspiratory load), were 0.38±0.12, 0.27±0.11 , and 0.11±0.13, respectively. Whereas at 33 cmH2O (maximum inspiratory load) were 0.83±0.02, 0.76±0.07, and 0.61±0.19 , respectively. Our findings suggest that the proposed method may improve the evaluation of NRD.

Effect of training on inspiratory load compensation in weaned and unweaned mechanically ventilated ICU patients

BACKGROUND

While inspiratory muscle weakness is common in prolonged mechanical ventilation, inspiratory muscle strength training (IMST) can facilitate strengthening and ventilator weaning. However, the inspiratory load compensation (ILC) responses to threshold loads are not well characterized in patients. We retrospectively compared ILC responses according to the clinical outcomes of IMST (ie, maximum inspiratory pressure [PImax], weaning outcome), in difficult-to-wean ICU patients.

METHODS

Sixteen tracheostomized subjects (10 weaned, 6 unweaned) from a previous clinical trial underwent IMST 5 days/week, at the highest tolerated load, in conjunction with daily, progressive spontaneous breathing trials. PImax and ILC with a 10 cm H2O load were compared in the subjects before and after IMST. Changes in ILC performance were further characterized (5, 10, 15 cm H2O loads) in the trained subjects who weaned.

RESULTS

Demographics, respiratory mechanics, and initial PImax (52 ± 26 cm H2O vs 42 ± 13 cm H2O) did not significantly differ between the groups. Upon enrollment, PImax significantly correlated with flow ILC responses with the 10 cm H2O load (r = 0.64, P = .008). After IMST, PImax significantly increased in the entire sample (P = .03). Both before and after IMST, subjects who weaned generated greater flow and volume ILC than subjects who failed to wean. Additionally, ILC flow, tidal volume, and duty cycle increased upon ventilator weaning, at loads of 5, 10, and 15 cm H2O.

CONCLUSIONS

Flow ILC at a threshold load of 10 cm H2O in ventilated, tracheostomized subjects positively correlated with PImax. Although PImax improved in both groups, the flow and volume ILC responses of the weaned subjects were more robust, both before and after IMST. The results suggest that ILC response is different in weaned and unweaned subjects, reflecting dynamic inspiratory muscular efforts that could be influential in weaning.

Mechanical ventilation, diaphragm weakness and weaning: a rehabilitation perspective

Most patients are easily liberated from mechanical ventilation (MV) following resolution of respiratory failure and a successful trial of spontaneous breathing, but about 25% of patients experience difficult weaning. MV use leads to cellular changes and weakness, which has been linked to weaning difficulties and has been labeled ventilator induced diaphragm dysfunction (VIDD). Aggravating factors in human studies with prolonged weaning include malnutrition, chronic electrolyte abnormalities, hyperglycemia, excessive resistive and elastic loads, corticosteroids, muscle relaxant exposure, sepsis and compromised cardiac function. Numerous animal studies have investigated the effects of MV on diaphragm function. Virtually all these studies have concluded that MV use rapidly leads to VIDD and have identified cellular and molecular mechanisms of VIDD. Molecular and functional studies on the effects of MV on the human diaphragm have largely confirmed the animal results and identified potential treatment strategies. Only recently potential VIDD treatments have been tested in humans, including pharmacologic interventions and diaphragm "training". A limited number of human studies have found that specific diaphragm training can increase respiratory muscle strength in FTW patients and facilitate weaning, but larger, multicenter trials are needed.

Specific inspiratory muscle training is safe in selected patients who are ventilator-dependent: a case series

BACKGROUND

Mechanical ventilation of intensive care patients results in inspiratory muscle weakness. Inspiratory muscle training may be useful, but no studies have specifically described the physiological response to training.

RESEARCH QUESTIONS

Is inspiratory muscle training with a threshold device safe in selected ventilator-dependent patients? Does inspiratory muscle strength increase with high-intensity inspiratory muscle training in ventilator-dependent patients?

DESIGN

Prospective cohort study of 10 medically stable ventilator-dependent adult patients.

SETTING

Tertiary adult intensive care unit.

METHODS

Inspiratory muscle training 5-6 days per week with a threshold device attached to the tracheostomy without supplemental oxygen.

OUTCOME MEASURES

Physiological response to training (heart rate, mean arterial pressure, oxygen saturation and respiratory rate), adverse events, training pressures.

RESULTS

No adverse events were recorded in 195 sessions studied. For each patient's second training session, no significant changes in heart rate (Mean Difference 1.3 bpm, 95% CI -2.7 to 5.3), mean arterial pressure (Mean Difference -0.9 mmHg, 95% CI -6.4 to 4.6), respiratory rate (Mean Difference 1.2 bpm, 95% CI -1.1 to 3.5 bpm) or oxygen saturation (Mean Difference 1.2%, 95% CI -0.6 to 3.0) were detected Training pressures increased significantly (Mean Difference 18.6 cmH(2)O, 95% CI 11.8-25.3).

CONCLUSION

Threshold-based inspiratory muscle training can be delivered safely in selected ventilator-dependent patients without supplemental oxygen. Inspiratory muscle training is associated with increased muscle strength, which may assist ventilatory weaning.

Protocol: inspiratory muscle training for promoting recovery and outcomes in ventilated patients (IMPROVe): a randomised controlled trial

INTRODUCTION

Inspiratory muscle weakness is a known consequence of mechanical ventilation and a potential contributor to difficulty in weaning from ventilatory support. Inspiratory muscle training (IMT) reduces the weaning period and increases the likelihood of successful weaning in some patients. However, it is not known how this training affects the residual inspiratory muscle fatigability following successful weaning nor patients' quality of life or functional outcomes.

METHODS AND ANALYSIS

This dual centre study includes two concurrent randomised controlled trials of IMT in adult patients who are either currently ventilator-dependent (>7 days) (n=70) or have been recently weaned from mechanical ventilation (>7 days) in the past week (n=70). Subjects will be stable, alert and able to actively participate and provide consent. There will be concealed allocation to either treatment (IMT) or usual physiotherapy (including deep breathing exercises without a resistance device). Primary outcomes are inspiratory muscle fatigue resistance and maximum inspiratory pressures. Secondary outcomes are quality of life (Short Form-36v2, EQ-5D), functional status (Acute Care Index of Function), rate of perceived exertion (Borg Scale), intensive care length of stay (days), post intensive care length of stay (days), rate of reintubation (%) and duration of ventilation (days).

ETHICS AND DISSEMINATION

Ethics approval has been obtained from relevant institutions, and results will be published with a view to influencing physiotherapy practice in the management of long-term ventilator-dependent patients to accelerate weaning and optimise rehabilitation outcomes.

TRIAL REGISTRATION NUMBER

ACTRN12610001089022.

Inspiratory muscular training in chronic stroke survivors: a randomized controlled trial

OBJECTIVE

To assess the effectiveness of inspiratory muscular training (IMT) on measures of strength, resistance, functional performance, and quality of life (QOL) for chronic stroke survivors.

DESIGN

Double-blinded randomized controlled trial.

SETTING

Research laboratory.

PARTICIPANTS

Subjects (N=21) with stroke (11 men, 10 women; maximal inspiratory pressure [MIP] <90% of predicted values) were randomly assigned to the experimental (n=11) and control groups (n=10); 18 participants completed all testing and training.

INTERVENTIONS

Interventions were based on home-based training, with resistance adjusted biweekly to 30% of MIP for the experimental group. The control group underwent the same protocol without the threshold resistance valve. Both groups received home training 30 minutes a day 5 times a week for 8 weeks.

MAIN OUTCOME MEASURES

MIP, inspiratory muscular endurance (IME), functional performance, and QOL.

RESULTS

There were significant between-group differences for the MIP and IME measures. Significant changes were observed for only the experimental group for MIP (67.8±14.6 at baseline to 102.2±26.0cmH(2)O at posttraining) and IME (31.8±19.3 to 49.2±21.1cmH(2)O). No statistically significant differences were observed for measures of functional performance and QOL.

CONCLUSIONS

Significant short-term effects of the IMT program for inspiratory strength and endurance were observed in chronic stroke survivors. These findings gave some indications that IMT may benefit people with stroke, and it is feasible to be included in rehabilitation interventions with this population.

Inspiratory muscle training in a child with nemaline myopathy and organ transplantation

OBJECTIVE

To report the use of inspiratory muscle strength training to treat repeated ventilatory insufficiency in a child with nemaline myopathy who underwent cardiac and renal transplantation.

DESIGN

Case report.

SETTING

Pediatric intensive care unit of a tertiary care university teaching hospital.

PATIENT

A 16-yr-old female with nemaline myopathy affecting cardiorespiratory function, recent organ transplantation, and delayed postoperative ventilatory recovery.

INTERVENTION

Inspiratory muscle strength training was provided 5 days weekly for 2 wks, accompanied by progressive weaning from noninvasive ventilation.

MEASUREMENTS AND MAIN RESULTS

Maximal inspiratory pressure increased from -36.7 cm H2O to -77.8 cm H2O, accompanied by improved inspiratory flow, volume, pressure activation and power. During the training period, the patient was weaned from continuous noninvasive ventilatory assist to her preoperative level of ventilatory function.

CONCLUSION

Inspiratory muscle training may be a beneficial component of care for children with nemaline myopathy who experience acute ventilatory insufficiency.

Comparison of 2 Methods for Inspiratory Muscle Training in Patients With Chronic Obstructive Pulmonary Disease

OBJECTIVE

The aim of this study was to compare the use of threshold and resistive load devices for inspiratory muscle training in patients with chronic obstructive pulmonary disease (COPD). A randomized prospective trial was designed to compare use of the 2 devices under training or control conditions.

PATIENTS AND METHODS

Thirty-three patients with moderate or severe COPD were randomly assigned to home treatment with a threshold device, a resistive load device, or a control situation in which either of those devices was maintained at a minimum load throughout the study. Training was performed daily in 2 sessions of 15 minutes each for 6 weeks. In the patients who underwent training with threshold (n=12) and resistive load (n=11) devices, the loads used were adjusted weekly until the maximum tolerated load was reached to ensure that the interventions were as equivalent as possible. Respiratory function, respiratory muscle function, and quality of life were assessed before and after training and the different inspiratory pressure profiles were compared between training groups.

RESULTS

Both peak inspiratory pressure and scores on the Chronic Respiratory Questionnaire (CRQ) improved in the groups that received inspiratory muscle training compared with control subjects: maximal static inspiratory pressure increased from 86 cmH2O to 104.25 cmH2O (P< .01) in the threshold device group and from 91.36 cm H2O to 105.7 cmH2O (P< .01) in the resistive load device group. The resistive load group showed the largest increase in CRQ quality-of-life scores. Differences between the dyspnea score on the CRQ at the beginning and end of the training period were as follows: 3 points in the resistive load group, 2.58 in the threshold group, and 2.5 in the control group. Significant differences in duty cycle measured during training sessions were observed between groups at the end of training (0.31 in the threshold group and 0.557 in the resistive load group), but the mean pressure-time index was similar (0.11) in both groups because of the greater peak and mean inspiratory pressures in the threshold device group.

CONCLUSIONS

Load readjustment allowed equivalent training intensities to be achieved with different inspiratory pressure profiles. Our study demonstrated the effectiveness of inspiratory muscle training without control of breathing pattern but showed no superiority of one training method over another.

Respiratory muscles training in COPD patients

It is known that respiratory muscles undergo adaptation in response to overload stimuli during exercise training in stable COPD patients, thus resulting in significant increase of respiratory muscle function as well as the individual's improvements. The present article reviews the most updated evidence with regard to the use of respiratory muscle training (RMT) methods in COPD patients. Basically, three types of RMT (resistive training, pressure threshold loading, and normocapnic hyperpnea) have been reported. Frequency, duration, and intensity of exercise must be carefully considered for a training effect. In contrast with the plentitude of existing data inherent to inspiratory muscle training (IMT), literature is still lacking in showing clinical and physiological studies related to expiratory muscle training (EMT). In particular, while it seems that IMT is slightly superior to EMT in providing additional benefits other than respiratory muscle function such as a reduction in dyspnea, both the effects and the safety of EMT is still to be definitively elucidated in patients with COPD.

Home respiratory muscle training in patients with chronic obstructive pulmonary disease

OBJECTIVE AND BACKGROUND

The benefits of inspiratory muscle strength training in decreasing symptoms, disability or handicap of patients affected by COPD are not well established. The objective of this study was to assess the efficacy of the constant use of a new flow-volumetric inspiratory exerciser, named Respivol, in improving respiratory functional parameters in COPD patients.

METHODS

Twenty consecutive ambulatory patients affected by COPD were enrolled. Each patient was assessed, before and after 3 and 6 months inspiratory exercise with Respivol, for the following clinical parameters: maximal inspiratory pressure, maximal expiratory pressure, dyspnoea grade, quality of life by a self-administered St George questionnaire and a 6-min walking test. After a brief progressive ambulatory training programme, inspiratory exercise with Respivol was performed at home for 6 months. All patients used Respivol together with medical treatment.

RESULTS

Maximal inspiratory pressure and maximal expiratory pressure values were significantly increased after 3 and 6 months of exercise. Dyspnoea grade was significantly reduced and the 6-min walking test showed an increase in effort tolerance, after 6 months of home training. Quality of life assessment showed an improvement, associated with a decrease of respiratory disease symptoms.

CONCLUSIONS

Inspiratory muscle strength training with Respivol seems to be efficient in reducing symptoms and improving quality of life in adults with COPD.

Physiologic correlates of dyspnea in patients with morbid obesity

OBJECTIVE

Mechanisms of dyspnea in obesity remain unclear. This study was undertaken to determine the relationships between dyspnea and pulmonary function including inspiratory muscle endurance (IME) in morbidly obese patients before bariatric surgery.

RESEARCH METHODS AND PROCEDURES

Fifty-five patients with a mean+/-s.d. body mass index (BMI) of 49.4+/-7.0 kg/m(2) were included. Dyspnea was evaluated by the Baseline Dyspnea Index (BDI; 0-12, 0=maximal dyspnea). Pulmonary function tests included a plethysmography, maximal inspiratory pressure (PImax) and IME was assessed by the incremental threshold loading test, determining the maximal pressure sustained for 2 min (Plim(2)) and Plim(2)/PImax ratio. Patients were classified according to their BMI in two groups: BMI < or =49 (n=27) and >49 kg/m(2) (n=28).

RESULTS

Breathlessness was higher in the BMI >49 kg/m(2) group compared to the BMI < or =49 kg/m(2) group (BDI score at 6.9+/-2.2 in the BMI >49 kg/m(2) group vs 8.9+/-2.5 in the BMI < or =49 kg/m(2) group, P<0.01). Patients with BMI >49 kg/m(2) had significantly higher PaCO(2) level and significantly lower vital capacity, inspiratory capacity and PImax values compared with the BMI < or =49 kg/m(2) group. Correlations between BDI and lung function were moderate: forced expiratory volume in 1 s (FEV(1))% pred: Rho=0.27; P=0.05; vital capacity % pred: Rho=0.40; P=0.004; and Plim(2)/PImax: Rho=0.40; P=0.003. Higher correlations with dyspnea were found in the BMI < or =49 kg/m(2) group: FEV(1)% pred: Rho=0.38; P=0.05; and Plim(2)/PImax: Rho=0.49; P=0.01.

DISCUSSION

Inspiratory muscle performance is moderately reduced in morbid obesity. Dyspnea in these patients remains moderately related to lung function and inspiratory muscle performance. However, inspiratory muscles performance correlates more significantly with dyspnea in patients with a BMI < or =49 kg/m(2).

Inspiratory muscular activation during threshold® therapy in elderly healthy and patients with COPD

Inspiratory muscles training in COPD is controversial not only in relation to the load level required to produce muscular conditioning effects but also in relation to the group of patients benefiting from the training. Consequently, inspiratory muscular response assessment during Threshold therapy may help optimizing training strategy. The objective of this study was to evaluate the participation of the diaphragm and the sternocleidomastoid (SMM) muscle to overcome with a 30% Threshold load using surface electromyography (sEMG) and to analyze the correlation between SMM activation, maximum strength level of inspiratory muscles (MIP) and obstruction degree in COPD patients (FEV1). We studied seven healthy elderly subjects, mean age of 68+/-4 years and seven COPD patients, FEV1 45+/-17% of the predicted value, with mean age 66+/-8 years. sEMG analysis of SMM muscles and diaphragm were obtained through RMS (root-mean-square) during three stages: pre-loading, loading and post-loading.

RESULTS

In the COPD group, the RMS of the SMM increased 28% during load (p<0.05) while the RMS of the diaphragm remained constant. In the elderly there was a trend of a 11% increase in diaphragm activity and of 7% in SMM activity but, without reaching significance levels. SMM activity demonstrated good correlation with the obstruction level (r=-0.537).

CONCLUSION

To overcome the load required by Threshold therapy, COPD patients demonstrated an increase of accessory muscles activity, represented by SMM. For the same relative load this increase seems to be proportional to the degree of pulmonary obstruction.

Respiratory muscle performance as a possible determinant of exercise capacity in patients with ankylosing spondylitis

Reduction of exercise capacity in patients with ankylosing spondylitis is associated with skeletal muscle performance. The contribution of respiratory muscle performance is questionable. This pilot study was designed to investigate the relationship between respiratory muscle performance and exercise capacity in ankylosing spondylitis. Subjects were 12 patients with ankylosing spondylitis. Measurements of maximal respiratory pressures and inspiratory muscle endurance were performed and correlated with maximal exercise capacity. Lung function and chest wall expansion were reduced on average. Maximal inspiratory and expiratory pressures were reduced to 82 +/- 20% of predicted values and 75 +/- 22% of predicted values respectively. On average there was no reduction in inspiratory muscle endurance which remained at 103 +/- 36% of predicted values. No overall reduction was found in maximal exercise capacity, either expressed as maximal workload or as peak oxygen uptake; however, a wide range was found. Maximal workload and peak oxygen uptake correlated significantly with maximal respiratory pressures and respiratory muscle endurance. The best regression model for explaining the total variation of maximal workload and peak oxygen uptake selected maximal inspiratory pressures as the independent variable (r(2) = 59.6%, p = 0.003 and r(2) = 62.5%, p = 0.05 respectively.) These data suggest respiratory pressure and respiratory muscle endurance, in particular maximal inspiratory pressure, may be determinants of exercise capacity in patients with ankylosing spondylitis.

Coupling of breathing and movement during manual wheelchair propulsion

The hypothesis of this study was that stable coordination patterns may be found both within and between physiological subsystems. Many studies have been conducted on both monofrequency and multifrequency coordination, with a focus on both the frequency and phase relations among the limbs. In the present study, locomotor-respiratory coupling was observed in the maintenance of small-integer frequency ratios (2:1, 3:1, and 4:1) and in the consistent placement of the inspiratory phase just after the onset of the movement cycle during wheelchair propulsion. Level of experience and various motor and respiratory parameters were manipulated. Coupling was observed across levels of experience. Increases in movement frequency were accompanied by a shift to larger-integer ratios, suggesting that a single modeling strategy (e.g., the Farey tree; D. L. González & O. Piro, 1985) may be used for coordination both within the motor subsystem and between it and other physiological subsystems.

Inspiratory muscle training in patients with cystic fibrosis

Little information is available about the effects of inspiratory muscle training in patients with cystic fibrosis (CF). In this study the effects of inspiratory-threshold loading in patients with CF on strength and endurance of the inspiratory muscles, pulmonary function, exercise capacity, dyspnoea and fatigue were evaluated. Sixteen patients were assigned to one of two groups using the minimization method: eight patients in the training group and eight patients in the control group. The training was performed using an inspiratory-threshold loading device. Patients were instructed to use the threshold trainer 20 min a day, 5 days a week for 6 weeks. Patients in the training group trained at inspiratory threshold loads up to 40% of maximal static inspiratory pressure (Pimax) and patients in the control group got 'sham' training at a load of 10% of Pimax. No significant differences were found among the two groups in gender, age, weight, height, pulmonary function, exercise capacity, inspiratory-muscle strength and inspiratory-muscle endurance before starting the training programme. Mean (SD) age in the control group was 19 (5.5) years, mean (SD) age in the training group was 17 (5.2) years. Mean FEV1 in both groups was 70% predicted, mean inspiratory-muscle strength in both groups was above 100% predicted. All patients except one, assigned to the training group, completed the programme. After 6 weeks of training, mean inspiratory-muscle endurance (% Pimax) in the control group increased from 50% to 54% (P = 0.197); in the training group mean inspiratory muscle endurance (% Pimax) increased from 49% to 66% (P = 0.003). Statistical analysis showed that the change in inspiratory-muscle endurance (% Pimax) in the training group was significantly higher than in the control group (P = 0.012). After training, in the training group there was a tendency of improvement in Pimax with an increase from 105 to 123% predicted, which just fell short of statistical significance (P = 0.064). After training no significant differences were found in changes from baseline in pulmonary function, exercise capacity, dyspnoea and fatigue. It is concluded that low-intensity inspiratory-threshold loading at 40% of Pimax was sufficient to elicit an increased inspiratory-muscle endurance in patients with CF.