Reduction In Respiratory Muscle Strength Research Articles

Reduction of respiratory muscle strength in subjects with rheumatoid arthritis

Objetivo: Avaliar a força muscular respiratória de pacientes com Artrite Reumatoide (AR) em comparação a indivíduos saudáveis e correlacionar com o nível de atividade da doença (DAS-28) e índice de massa corporal (IMC). Método: Estudo transversal onde foram avaliadas 18 mulheres, com média de idade de 57,94 anos, sendo 8 com AR (Grupo AR) e 10 saudáveis (Grupo Controle), pareadas por idade. Todas foram submetidas às seguintes avaliações: ficha cadastral - dados de identificação e clínicos; exame físico - massa corporal, estatura e IMC; DAS-28; dosagem de proteína C-reativa (PCR) e determinação dos valores de Pressão Inspiratória Máxima (PImáx) e Pressão Expiratória Máxima (PEmáx), por meio de um manovacuômetro. Foi adotado o nível de significância de 5%. Resultados: Houve diferença estatisticamente significativa entre os grupos AR e Controle em relação à PImáx (-46,25 ± 17,67 cmH2O vs. -81,00 ± 19,69 cmH2O; p ≤ 0,01) e PEmáx (58,75 ± 17,26 cmH2O vs. 78,00 ± 6,32 cmH2O; p ≤ 0,01). Também verificou-se diferença entre o grupo AR e valores preditos para a idade em relação à PImáx (-46,25 ± 17,67 cmH2O vs. -81,06 ± 4,11 cmH2O; p ≤ 0,01) e PEmáx (58,75 ± 17,26 cmH2O vs. 78,92 ± 5,33 cmH2O; p ≤ 0,01). Adicionalmente, foi encontrada correlação significativa entre a PEmáx e IMC (p = 0,03). Não houve correlação significativa entre as variáveis PImáx - PCR, DAS-28 e IMC, e entre PEmáx - DAS e PCR. Conclusão: Esses dados reforçam o caráter sistêmico da AR e levantam a necessidade de uma avaliação global do paciente, que não foque apenas no componente articular, mas verifique também a força dos músculos respiratórios desses indivíduos, para determinação de estratégias terapêuticas mais específicas e adequadas.

Respiratory Muscle Strength, the Six-Minute Walk Test and Quality of Life in Chagas Cardiomyopathy

Patients with heart failure disease develop respiratory and functional limitations and suffer from the negative influence on their quality of life. This study was designed to evaluate respiratory muscle strength and its relationship to functional capacity, quality of life and rate of perceived exertion in patients with Chagas cardiomyopathy. We evaluated 32 patients divided into groups with and without Chagas heart disease. We measured the Minnesota Living with Heart Failure Questionnaire, the maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), distance walked during the 6-minute walk test, rating of perceived exertion (RPE), heart rate, blood pressure, respiratory rate, oxygen saturation and ejection fraction (EF). The group with Chagas heart disease showed decreased quality of life (overall score: p = 0.001; physical domain: p = 0.002; role-emotional domain: p = 0.031 and general health domain: p < 0.001) and MIP (p < 0.001) when compared with the control group. There was no difference between the distance walked in both groups. The RPE was greater in the group with Chagas heart disease (p = 0.001). The MIP correlated with MEP (r = 0.631, p = 0.009) and EF (r = 0.524, p = 0.037). The inspiratory muscle strength is reduced, and the decreased quality of life has a negative influence on the physical and emotional aspects of the patients with Chagas cardiomyopathy. No correlation was found between perceived exertion and the reduction of respiratory muscle strength.

C.P.6 Study of a novel autosomal recessive minicore disease

Minicore disease is a congenital myopathy of early onset, defined pathologically by the presence of multiple areas of reduced mitochondrial oxidative activity in muscle biopsies. There are currently three types of minicore disease defined; minicore myopathy with external ophthalmoplegia, caused by mutations in the RYR1 gene; minicore disease, severe classic form, caused by mutations in the SEPN1 gene and minicore myopathy, antenatal onset with arthrogryposis, with no associated disease gene. A family with three affected sibs was studied. The parents are unaffected and not known to be related, and the phenotype is consistent. The affected sibs presented at birth with extreme generalised hypotonia. There was marked delay in motor milestones, with walking only achieved after 2years of age. Neck, trunk and facial weakness was moderate, and there was moderate reduction in respiratory muscle strength. The heart was unaffected and intelligence preserved. Muscle biopsy of the quadriceps showed minicores on oxidative stains. This phenotype was not consistent with the described phenotypes of minicore disease, suggesting that this is a novel minicore disease phenotype. We combined linkage analysis with exome capture and next generation sequencing to attempt to identify the causative mutation in this family. SNP linkage analysis under a recessive model eliminated all known congenital myopathy, minicore disease and muscular dystrophy genes except for TTN, POMT1, SGCA, DMN2, and COL6A1. Subsequently, whole exome sequencing data eliminated all genes in the list except for TTN, in which two heterozygous variants were identified. Further investigation of these variants in the family found that both variants were inherited from the unaffected father, suggesting that these variants are not the cause of the disease in this family. Thus, it is suspected that a novel disease gene is the cause of this family’s disease.

Efeito do treinamento muscular respiratório em pacientes submetidos à colecistectomia

As cirurgias abdominais altas, como as colecistectomias, tendem a evoluir no pós operatório com distúrbios ventilatórios restritivos. O objetivo deste trabalho foi avaliar a evolução da força muscular inspiratória após o treinamento da musculatura respiratória, por meio do uso de aparelho com carga linear pressórica em pacientes submetidos à colecistectomia convencional. Foram estudados 10 pacientes do sexo feminino, com indicação de colecistectomia, e elas realizaram avaliação da força muscular inspiratória através da medida da Pressão Inspiratória Máxima (PImáx). Deles, seis foram avaliados no pré e pós-operatório (G1 – grupo 1) e realizaram o Treinamento Muscular Respiratório (TMR) com uso do Theshold® (2 vezes ao dia no 1º e no 2º pós-operatório utilizando 40% da PImáx), e quatro pacientes foram acompanhados no pós-operátorio como grupo controle (G2 – grupo 2). Os resultados indicam que, apesar da diminuição da PImáx no pós-operatório, houve recuperação da força muscular inspiratória já no primeiro dia de TRM, de 36,7 ± 13,7 cmH2O para 48,0 ± 13,7 cmH2O e este aumento foi estatisticamente significante (p&lt;0,05), o que não ocorreu no grupo controle. Conclui-se que há uma redução na força muscular respiratória após colecistectomia e que o TMR foi satisfatório na melhora de força muscular respiratória.

Maximal respiratory pressure in healthy 20 to 89 year-old sedentary individuals of central São Paulo State

To evaluate respiratory muscle strength (RMS) in a sample composed exclusively of healthy sedentary individuals and to compare with predicted values, to investigate the relationship between maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) and age, weight and height, and propose predictive equations of MIP and MEP for this population.Subjects were 140 healthy and sedentary individuals: 70 males (55+/-20 years) and 70 females (54+/-21 years), separated into groups according to age. The RMS was obtained with an aneroid vacuum manometer (+/-300 cmH2O).There was a significant reduction in RMS with increasing age (ANOVA one-way, p<0.05). Moreover, the RMS values decreased significantly from age 40 compared to the predicted values (Student t test, p<0.05). There were also significant correlations of RMS with age, weight and height (Pearson correlation, p<0.05). The predictive equations using linear regression for maximal respiratory pressures according to sex showed that age in males and females and weight in females influenced the prediction of the MIP and MEP values.Our results showed that age and anthropometric characteristics influence RMS values. In addition, the RMS values were lower compared to the predicted values from age 40 because the sample was composed exclusively of sedentary individuals. In this context, we propose equations to predict the MIP and MEP values exclusively for healthy, sedentary individuals from 20 to 89 years of age.

Inspiratory Muscle Strength as a Determinant of Functional Capacity Early After Coronary Artery Bypass Graft Surgery

Stein R, Maia CP, Silveira AD, Chiappa GR, Myers J, Ribeiro JP. Inspiratory muscle strength as a determinant of functional capacity early after coronary artery bypass graft surgery. Objective To evaluate the effects of a 6-day postoperative in-hospital cardiopulmonary rehabilitation program on inspiratory muscle strength and its potential association with improved functional capacity after coronary artery bypass graft (CABG) surgery. Design Prospective, randomized controlled trial. Setting Tertiary public hospital in Brazil. Participants Men (N=20) after CABG were randomized to cardiopulmonary rehabilitation (n=10; age, 64±8y) or to usual care (n=10; age, 63±7y). Interventions Ten subjects underwent a 6-day postoperative in-hospital program, which included the use of expiratory positive airway pressure mask and bronchial hygiene techniques, coupled with progressive distance walking and calisthenics as well as cardiopulmonary training. Ten controls were followed by their own physicians and received routine nursing assistance but were not exposed to any specific respiratory or motor physical intervention. Main Outcome Measures Maximal inspiratory and expiratory pressure were measured by a pressure transducer, and the highest pressure obtained in 6 measurements was used for analysis (before surgery, and 7 and 30d after surgery). The six-minute walk test (6MWT) was performed 7 days after surgery, and maximal cardiopulmonary exercise testing was performed 30 days after CABG. Results After randomization, clinical and functional characteristics were similar in the 2 groups. Rehabilitation resulted in maintenance of maximal inspiratory pressure (PImax) measured at 7 and 30 days postoperatively, respectively (from 68±19% at baseline to 58±22% and to 61±22% predicted), while it was significantly reduced in the control group. 6MWT distance was longer 7 days after CABG in rehabilitation subjects (416±78m) than controls (323±67m). Peak oxygen uptake (V o 2peak) at day 30 was also higher (28%) in the rehabilitation group and was correlated with PImax ( r=.90). Conclusions A 6-day rehabilitation program attenuated the postoperative reduction in respiratory muscle strength and also improved the recovery of functional capacity after CABG. The correlation between PImax and V o 2peak during the late postoperative period suggests that inspiratory muscle strength is an important determinant of functional capacity after CABG.

THE MEASUREMENT OF RESPIRATORY MUSCLE FUNCTION IN ADOLESCENT IDIOPATHIC SCOLIOSIS

PURPOSE: Restrictive lung disease is the most commonly reported pulmonary abnormality in adolescents with idiopathic scoliosis(IS). There is limited data on respiratory muscle function in IS. Since spinal deformity and decrease in lung volumes may lead to reduction in respiratory muscle strength, we studied these relationships.

Correlações entre os níveis de L-carnitina plasmática, o estado nutricional e a função ventilatória de portadores de doença pulmonar obstrutiva crônica

OBJETIVO: Avaliar os níveis de L-carnitina livre no plasma, o estado nutricional, a função pulmonar e a tolerância ao exercício em pacientes com doença pulmonar obstrutiva crônica e verificar as correlações entre a composição corporal e as frações de L-carnitina no plasma. MÉTODOS: Quarenta pacientes entre 66,2±9 anos, com diagnóstico clínico de doença pulmonar obstrutiva crônica, foram divididos em dois grupos: G1, com índice de massa corporal menor que 20kg/m², e G2, com índice de massa corporal maior que 20kg/m². Foram mensurados os parâmetros espirométricos, a tolerância ao exercício no teste de caminhada, a força muscular respiratória, a composição corporal por meio da impedância bioelétrica e as dosagens da L-carnitina plasmática, através de amostras de sangue. RESULTADOS: Foram observados menores valores das variáveis espirométricas (p&lt;0,01), da força muscular respiratória e dos níveis de L-carnitina nos pacientes do G1; porém, não houve diferença entre os grupos quanto à capacidade de realizar exercício físico dinâmico de baixa intensidade. Correlações significativas entre o percentual de gordura e os níveis de L-carnitina plasmática foram observadas nos pacientes (r=0,53 com p&lt;0,002); sendo que, nos pacientes com índice de massa corporal menor que 18kg/m², essa relação aumentou (r&lt;0,73 com p&lt;0,01). CONCLUSÃO: Na doença pulmonar obstrutiva crônica, a desnutrição está associada tanto aos prejuízos da função pulmonar e da força muscular respiratória, quanto aos baixos níveis de L-Carnitina plasmática.

RESPIRATORY MUSCLE FUNCTION AFTER EXERCISE IN COMPETITIVE FEMALE CYCLISTS

Previous studies have shown significant reductions in respiratory muscle strength, as evidenced by maximal sustained inspiratory (PImax) and expiratory (PEmax) mouth pressures, in subjects demonstrating average fitness following maximal exercise. However, studies utilizing trained endurance athletes have shown non-signficant reductions in both PImax and PEmax following maximal exercise. PURPOSE: To examine the effects of prior endurance training on respiratory muscle strength following short-term maximal exercise in competitive female athletes. METHODS: Seven competitive female cyclists (20.9 ± 2.3 yr) performed progressive intensity exercise to voltional fatigue on their personal cycles utilizing a Computrainer device. Maximal oxygen consumption (VO2max) was determined via open circuit spirometry (MedGraphics CPX/D). PImax and PEmax values were obtained before and immediately after the maximal cycle test. The highest value of 3–4 consistent trials was used for analysis. Differences in pre- and post-exercise values for PImax and PEmax were analyzed with a paired t-test (α = 0.05). RESULTS: The progressive intensity exercise test revealed a mean VO2max of 49.4 ± 7.3 ml/kg/min for the group. No significant reduction in PImax (p = 0.39) or PEmax (p = 0.71) were detected after the maximal exercise bout when compared to pre-exercise values. CONCLUSION: These results suggest that the respiratory musculature does not fatigue in aerobically trained female cyclists during short-term maximal exercise. These findings confirm the results of other studies utilizing female cyclists of similar fitness that suggest a possible adaptation of the respiratory musculature to endurance exercise training.

Influence of excessive weight loss after gastroplasty for morbid obesity on respiratory muscle performance.

BACKGROUND: Morbidly obese subjects are known to have impaired respiratory function and inefficient respiratory muscles. A study was undertaken to investigate the influence of excessive weight loss on pulmonary and...

Respiratory muscle weakness and normal ventilatory drive in dilative cardiomyopathy.

In dilative cardiomyopathy several factors influence dyspnoea. Patients with chronic heart failure may demonstrate impairment of breathing pattern, ventilatory drive and respiratory muscle strength, as well as reduction of ventilatory efficiency. The purpose of this study was to evaluate whether dilative cardiomyopathy is accompanied by changes in breathing pattern, respiratory muscle weakness and ventilatory neural drive. We investigated 47 patients (36 men, mean age = 47.8 +/- 11.2 years) with chronic heart failure due to dilative cardiomyopathy, and 30 healthy subjects (10 men, mean age = 35.4 +/- 11.7 years) served as controls. Patients and controls underwent evaluation of left ventricular ejection fraction by 2D echocardiography, spirometry, body plethysmography, mouth occlusion pressure and respiratory muscle strength, as well as by submaximal treadmill exercise testing with gas exchange measurements. The patients' results were compared to controls and predicted standard normal values, and evaluated for differences according to the degree of severity of functional impairment. Patients with dilative cardiomyopathy demonstrated a slight reduction in lung volumes (15% of the patients with obstructive and 15% with restrictive lung function pattern) and diffusion capacity (20.4 +/- 6.8 vs 15.4 +/- 6.7 ml.min-1.kPa-1; P < 0.01). In neural drive, as assessed by mouth occlusion pressure, there was no significant difference between patients and controls. There was a slight but significant reduction in respiratory muscle strength, as assessed by measuring maximal inspiratory pressure in patients with dilative cardiomyopathy (6.7 +/- 2.4 kPa vs 8.6 +/- 3.5 kPa; P < 0.01). The observed changes were more pronounced in the severe chronic heart failure patients (with a reduction in ventilatory efficiency) whereas no relationship among indices of cardiac or respiratory function was found. Patients with chronic heart failure due to dilative cardiomyopathy develop respiratory muscle weakness without changes in neural ventilatory drive, and slight changes in breathing pattern related to the severity of the disease.

Effect of upper respiratory tract infection in patients with neuromuscular disease.

Respiratory muscle strength during acute upper respiratory tract infection (URI) was assessed in patients with various forms of neuromuscular disease. Vital capacity (VC), oxygen saturation, end-tidal PCO2, maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) were determined in 25 stable patients with various forms of neuromuscular disease. Thirteen episodes of URI developed in 10 patients. Respiratory parameters were reassessed within 24-36 h following the onset of symptoms in each patient. In patients with URI, mean baseline VC, MIP, and MEP were 1.16 L +/- 0.14, 49.2 cm H2O +/- 6.8, and 35.5 cm H2O +/- 3.8 and fell to 1.01 L +/- 0.15, 37.1 cm H2O +/- 6.2, and 25.5 cm H2O +/- 3.0 during URI (p < 0.05 for each), respectively. Mean baseline PCO2 and oxygen saturation were 39.1 mm Hg +/- 1.1 and 95.1% +/- 1.0, and during URI, 43.9 mm Hg +/- 2.1 (p < 0.05) and 95.0% +/- 1.0 (NS), respectively. Five episodes of significant hypercapnia were observed in 4 patients. All parameters returned to near baseline values following recovery. We conclude that patients with various forms of neuromuscular disease develop reductions in respiratory muscle strength in association with URI. Unlike normal subjects, however, these decrements in respiratory muscle function may result in symptoms of shortness of breath, reductions in vital capacity, and acute hypercapnia in this patient population.

Lung volumes and respiratory muscle strength in adult patients with childhood- or adult-onset growth hormone deficiency: effect of 12 months' growth hormone replacement therapy.

We have described impairment of the respiratory function in adult patients with childhood-onset growth hormone (GH) deficiency. The aim of the present study was to evaluate lung volumes and respiratory muscle strength in patients diagnosed as GH deficient before and after 6 and 12 months of recombinant GH treatment. Ten adults diagnosed as GH deficient in childhood, ten adults diagnosed as GH deficient in adulthood and ten healthy subjects entered the study. For each subject, evaluation of respiratory function followed the same standard approach, consisting of respiratory muscle strength assessment, record of flow-volume curves, measurement of static lung volumes and lung diffusing capacity. Childhood-onset GH-deficient patients had a significant reduction of maximal inspiratory (p < 0.01) and maximal expiratory (p < 0.05) mouth pressures. Total lung capacity, vital capacity and functional residual capacity were significantly reduced compared to healthy subjects (p < 0.05). Conversely, residual volume and diffusing lung capacity did not show any significant change. No significant change of the ratio between the percentage forced expiratory volume in 1 s and the forced vital capacity was observed. The decrease of respiratory mouth pressures was not correlated to the decrease of lung volumes. Adult-onset GH-deficient patients had only a significant reduction of maximal expiratory pressure compared to healthy subjects (p < 0.05). After 6 months of treatment no significant differences in any of the evaluated parameters were found. After 12 months of treatment patients with childhood-onset GH deficiency show a significant improvement of lung volumes (p < 0.01) and maximal respiratory mouth pressures (p < 0.005), whereas adult-onset GH-deficient patients show a significant improvement of maximal expiratory pressure (p < 0.05). In conclusion, the results of this study showed that adult patients affected with childhood-onset GH deficiency suffer from an impairment of the ventilatory function due to a reduction of lung volumes and a decrease of respiratory pressures probably due to a reduction of respiratory muscle strength. This impairment was reversed after 12 months of treatment with recombinant GH. Conversely, adult-onset GH-deficient patients had only an impairment of the maximal expiratory pressure, probably due to respiratory muscle weakness re-established after 12 months of GH therapy.

Impairment of lung volumes and respiratory muscle strength in adult patients with growth hormone deficiency

Little is known of the respiratory function in patients with growth hormone (GH) deficiency. The aim of the present study was to evaluate lung volumes and respiratory muscle strength in patients diagnosed as GH deficient in childhood. Ten patients diagnosed as GH deficient in childhood and ten healthy subjects entered the study. For each subject the evaluation of respiratory function followed the same standard approach, consisting of respiratory muscle strength assessment, recording of flow-volume curves, measurement of static lung volumes and lung diffusing capacity. Both maximal inspiratory and expiratory mouth pressures were decreased in GH deficiency. Vital capacity, N2 functional residual capacity and total lung capacity were significantly reduced when compared to healthy subjects. Conversely, the residual volume and diffusing lung capacity to CO did not show any significant change. No significant change of percentage forced expiratory volume in 1 s/forced vital capacity ratio was observed. The decrease of respiratory mouth pressures was not correlated to the decrease of lung volumes. In conclusion, the results of this study show that adult patients affected with childhood onset GH deficiency suffer from impairment of ventilatory function and a decrease of respiratory muscle pressures, probably due to reduction of respiratory muscle strength.

Control of breathing in patients with limb girdle dystrophy: a controlled study.

In patients with limb girdle dystrophy the relative contribution of peripheral factors (respiratory muscle weakness, and lung and/or airway involvement) and central factors (blunted and/or inadequate chemoresponsiveness) in respiratory insufficiency has not yet been established. To resolve this, lung volumes, arterial blood gas tensions, respiratory muscle strength, breathing pattern and neural respiratory drive were investigated in a group of 15 patients with limb girdle dystrophy. An age-matched normal group was studied as a control. Respiratory muscle strength was assessed as an arithmetic mean of maximal inspiratory (MIP) and expiratory (MEP) pressures. Breathing pattern was evaluated in terms of volume (ventilation VE, tidal volume VT) and time (respiratory frequency Rf, inspiratory time TI, expiratory time TE) components of the respiratory cycle. Neural respiratory drive was assessed as the mean inspiratory flow (VT/TI), mouth occlusion pressure (P0.1) and electromyographic activity (EMG) of the diaphragm (EMGd) and the intercostal parasternal (EMGp) muscles. In 10 of the 15 patients the responses to carbon dioxide (PCO2) stimulation were also evaluated. Most patients exhibited a moderate decrease in vital capacity (VC) (range 37-87% of predicted), MIP (range 23-84% of predicted), and/or MEP (range 13-41% of predicted). The arterial carbon dioxide tension (PaCO2) was increased in three patients breathing room air, while PaO2 was normal in all. Compared with the control group Rf was higher, and VT, TI and TE were lower in the patients. EMGd and EMGp were higher whilst VT/TI and P0.1 were normal in the patients. Respiratory muscle strength was inversely related to EMGd and EMGp. PaCO2 was found to relate primarily to VC and duration of illness, but not to respiratory muscle strength. During hypercapnic rebreathing delta VE/delta PCO2, delta VT/delta PCO2, and delta P0.1/delta PCO2 were lower than normal, whilst delta EMGd/delta PCO2 and delta EMGp/delta PCO2 were normal in most patients. A direct relation between respiratory muscle strength and delta VT/delta PCO2 was found. The respiratory muscles, especially expiratory ones, are weak in patients with limb girdle dystrophy. Reductions in respiratory muscle strength are associated with increased neural drive and decreased ventilatory output (delta VT/delta PCO2). The decrease in VC, together with the duration of disease, influence PaCO2. VC is a more useful test than respiratory muscle strength for following the course of limb girdle dystrophy.

Respiratory muscle function and exercise capacity in multiple sclerosis.

Patients with multiple sclerosis (MS) show a poor exercise tolerance. A reduction in respiratory muscle strength has also been reported. The purpose of this study was to evaluate whether reduction in exercise tolerance was related to respiratory muscle dysfunction. Twenty four multiple sclerosis patients (mean +/- SD age: 48 +/- 9 yrs, duration of illness 12.2 +/- 6 yrs, severity of illness as assessed by Expanded Disability Scale Score (EDSS) 5.3 +/- 2), underwent detailed evaluation of lung function tests, arterial blood gas analysis, respiratory muscle strength and endurance, and exercise test on an arm ergometer. Sixteen of the 24 patients were able to perform the exercise test (Group I), whilst the other eight were not (group II). Arterial blood gases and lung function tests were normal for both groups. Respiratory muscle strength as assessed both by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) was significantly reduced (MIP 18-76 cmH2O; MEP 16-82 cmH2O) compared to predicted values. Inspiratory muscle endurance time was significantly reduced in Group II in comparison to Group I (247 +/- 148 vs 397 +/- 154 s, respectively). Both MIP and MEP were significantly related to inspiratory muscle endurance time. Endurance time, MIP and MEP were inversely significantly related to duration of illness, whilst only endurance time was significantly related to Expanded Disability Scale Score.(ABSTRACT TRUNCATED AT 250 WORDS)

Dyspnea-limited response in chronic obstructive pulmonary disease: reduced unsupported arm activities.

Dyspnea, the sensation of uncomfortable breathing, is the primary activity-limiting symptom leading to reduced functional ability in chronic obstructive pulmonary disease (COPD). Patients with severe COPD report a marked increase in the sensation of dyspnea with routine tasks that require arm use, especially activities necessitating unsupported arm elevation. Dyspnea is associated with alterations in respiratory muscle function, such as an increase in muscle force requirement, a reduction in respiratory muscle strength and endurance, and an increase in the recruitment of the rib cage and accessory muscles. Unsupported arm exercise (UAE) further compromises respiratory muscle capacity for ventilation because it requires the muscles' concomitant recruitment in the maintenance of chest wall stabilization. This article presents respiratory muscle mechanisms leading to reduced UAE, methods of measuring unsupported arm endurance, and treatment strategies to improve unsupported arm activity endurance in patients with COPD.

Respiratory muscle function in cystic fibrosis.

Maximal static expiratory and inspiratory mouth pressures (PEmax and PImax) and quadriceps femoris muscle strength were measured in 25 patients aged 16-28 years with cystic fibrosis (mean FEV1 46% predicted). Mean (SD) PEmax was 64% (18%) predicted (below 75% predicted in 16 of the 25 patients), and PImax was 64% (24%) predicted (below 75% predicted in 14 patients). Quadriceps muscle strength was 68% (20%) predicted (below 75% predicted in 17 patients). The relatively small reduction in respiratory muscle strength in these patients was unlikely to have contributed appreciably to their respiratory problems.

The Effect of Hyperinflation on Respiratory Muscle Strength and Efficiency in Healthy Subjects and Patients with Asthma

We evaluated respiratory muscle strength and efficiency in 15 patients with asthma. There was a significant reduction in mean Plmax (89.3 +/- 4.7 versus 110.5 +/- 9.4 cm H2O, p less than 0.001) and efficiency (2.41 +/- 0.2 versus 4.2 +/- 0.6%, p less than 0.01). This reduction in strength and efficiency was seen only in the male patients. Following bronchodilator, there was a significant increase in Plmax (from 89.3 +/- 4.7 to 96.2 +/- 5.4 cm H2O, p less than 0.005) and efficiency (from 2.41 +/- 0.2 to 3.22 +/- 0.2%, p less than 0.001). There was no correlation between the change in strength and efficiency and the degree of improvement in FEV1 following bronchodilator. However, there was a significant correlation with the fall in lung volume. To determine whether hyperinflation would result in a reduction in respiratory muscle strength and efficiency, we induced a mean increase in end-expiratory lung volume of 0.66 L by applying continuous negative pressure around the chest in 10 healthy individuals. This was associated with a significant fall in Plmax (from 110.5 +/- 9.4 to 100.5 +/- 8.93 cm H2O, p less than 0.001) and efficiency (from 4.2 +/- 0.6 to 2.6 +/- 0.5%, p less than 0.005). The data suggest that the strength and efficiency of the respiratory muscles are reduced in asthmatic males but not in the females. The strength and efficiency of the respiratory muscles improve significantly following bronchodilator, and this improvement is related to reduction in lung volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary function and maximal transrespiratory pressures in ankylosing spondylitis.

Clinical measurements and pulmonary functions, including maximal transrespiratory pressures, were studied in 30 patients (age 43 (SD 10) years) with ankylosing spondylitis. Vital capacity (VC) was slightly reduced to 79 (16)% and forced expiratory volume in one second (FEV1) was similarly reduced to 82 (20)% such that the average FEV1/VC ratio was 77.8 (6.65). Total lung capacity was slightly reduced to 85 (13)%. Transfer factor of the lung for carbon monoxide (TLCO) averaged 88 (17)% and TLCO per unit lung volume was 114 (26)%. Reductions in lung volumes correlated well with clinical measurements. Both maximal expiratory pressures (PEmax) and inspiratory pressures (PImax) were clearly reduced to 56 (17)% and 76 (28)% respectively. This suggests that spirometrically determined volumes were better preserved than respiratory muscle strength in ankylosing spondylitis. It is speculated that the reduction in respiratory muscle strength may be due to intercostal muscle atrophy.