Clinical and Physiologic Evaluation of Respiratory Muscle Function

Effectiveness of simultaneous bilateral visual diaphragm biofeedback under low back pain: influence of age and sex

Introduction: The aim of the present study was to determine the effectiveness of simultaneous bilateral visual diaphragm biofeedback (BFB) from ultrasonography in conjunction with inspiratory muscle training (IMT) on diaphragmatic thickness during normal breathing and respiratory and clinical outcomes in patients with non-specific low back pain (NSLBP) and determine the influence of age and sex. Methods: A single-blind randomized clinical trial was carried out (NCT04582812). A total sample of 96 patients with NSLBP was recruited and randomized by sex-based stratification into IMT (n = 48) and BFB + IMT (n = 48) interventions over 8 weeks. Bilateral diaphragmatic thickness at maximum inspiration (Tins) and expiration (Texp), respiratory pressures, lung function, pain intensity, bilateral pressure pain threshold (PPT), disability, and quality of life were measured at baseline and after 8 weeks. Results: The BFB + IMT group showed significant differences (p < 0.05) with increased left hemidiaphragm thickness at Tins and Tins-exp (d = 0.38-053), and right and left PPT (d = 0.71-0.74) versus the IMT group. The interaction with sex was statistically significant (p = 0.007; F(1,81) = 7.756; ηp 2 = 0.087) and higher left hemidiaphragm thickness at Tins was predicted by the BFB + IMT group (R 2 = 0.099; β = 0.050; F(1,82) = 8.997; p = 0.004) and male sex (R 2 = 0.079; β = 0.045; F(1,81) = 7.756;p = 0.007). Furthermore, greater left hemidiaphragm thickness at Tins-exp was predicted by younger age (R 2 = 0.052; β = -0.001; F(1,82) = 4.540; p = 0.036). Discussion: The simultaneous bilateral visual diaphragm biofeedback by ultrasonography in conjunction with IMT was effective in both increasing the left diaphragmatic thickness during inspiration, which was positively influenced and predicted by male sex and younger age, and increasing the bilateral PPT of the paraspinal muscles in patients with NSLBP.

Normal values for maximal respiratory pressures in children and adolescents: A systematic review with meta-analysis

BACKGROUND

The non-invasive assessment of maximal respiratory pressures (MRP) reflects the strength of the respiratory muscles.

OBJECTIVE

To evaluate the studies which have established normative values for MRP in healthy children and adolescents and to synthesize these values through a meta-analysis.

METHODS

The searches were conducted until October 2023 in the following databases: ScienceDirect, MEDLINE, CINAHL, SciELO, and Web of Science. Articles that determined normative values and/or reference equations for maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in children and adolescents published in English, Portuguese, or Spanish regardless of the year of publication were included. Two reviewers selected titles and abstracts, in case of conflict, a third reviewer was consulted. Articles that presented sufficient data were included to conduct the meta-analysis.

RESULTS

Initially, 252 studies were identified, 28 studies were included in the systematic review and 19 in the meta-analysis. The sample consisted of 5798 individuals, and the MIP and MEP values were stratified by sex and age groups of 4-11 and 12-19 years. Values from females 4-11 years were: 65.8 cmH2O for MIP and 72.8 cmH2O for MEP, and for males, 75.4 cmH2O for MIP and 84.0 cmH2O for MEP. In the 12-19 age group, values for females were 82.1 cmH2O for MIP and 90.0 cmH2O for MEP, and for males, they were 95.0 cmH2O for MIP and 105.7 cmH2O for MEP.

CONCLUSIONS

This meta-analysis suggests normative values for MIP and MEP in children and adolescents based on 19 studies.

Association of Diaphragm Contractility and Postural Control in a Chronic Ankle Instability Population: A Preliminary Study

BACKGROUND

Altered reorganization of the sensorimotor system after an initial lateral ankle sprain may lead to a chronic neuromuscular maladaptation in multiple body locations. Specifically, decreased diaphragm contractility has been observed in patients with chronic ankle instability (CAI). The diaphragm has an essential role in postural control. Decreased diaphragm contractility could associate with diminished postural control commonly observed in patients with CAI. However, no study has determined if diaphragm contractility contributes to postural control in a CAI population.

HYPOTHESIS

Decreased diaphragm contractility would be negatively associated with static postural control in patients with CAI.

STUDY DESIGN

Cross-sectional study design.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 15 participants with CAI participated voluntarily. An ultrasonography assessment was performed to quantify the right and left hemidiaphragm thickness at the end of resting inspiration and expiration in supine while breathing quietly. The degree of diaphragm contractility was calculated from the diaphragm thickness. Participants performed 3 eyes-open trials of a 20-second single-leg balance task on the involved limb. Static postural control measures included the center of pressure velocity (COPV) and mean of time-to-boundary (TTB) minima in the anteroposterior (AP) and mediolateral directions.

RESULTS

Moderate correlations of the right hemidiaphragm contractility were observed with COPV (ρ = -0.54) and TTB mean minima (ρ = 0.56) (P < 0.05) in the AP direction. The left hemidiaphragm contractility was moderately correlated with COPV (ρ = -0.56) and TTB mean minima (ρ = 0.60) (P < 0.05) in the AP direction.

CONCLUSION

Lower diaphragm contractility may be associated with diminished static postural control in the AP direction in patients with CAI.

CLINICAL RELEVANCE

This study highlights diaphragm contractility could be a potential connection with diminished static postural control in patients with CAI. Our data raise new avenues for future exploration including potential beneficial effects of implementation of diaphragm breathing exercises and techniques for restoring static postural control in patients with CAI.

Macronutrient and Micronutrient Intake in Children with Lung Disease

This review article aims to summarize the literature findings regarding the role of micronutrients in children with lung disease. The nutritional and respiratory statuses of critically ill children are interrelated, and malnutrition is commonly associated with respiratory failure. The most recent nutrition support guidelines for critically ill children have recommended an adequate macronutrient intake in the first week of admission due to its association with good outcomes. In children with lung disease, it is important not to exceed the proportion of carbohydrates in the diet to avoid increased carbon dioxide production and increased work of breathing, which potentially could delay the weaning of the ventilator. Indirect calorimetry can guide the process of estimating adequate caloric intake and adjusting the proportion of carbohydrates in the diet based on the results of the respiratory quotient. Micronutrients, including vitamins, trace elements, and others, have been shown to play a role in the structure and function of the immune system, antioxidant properties, and the production of antimicrobial proteins supporting the defense mechanisms against infections. Sufficient levels of micronutrients and adequate supplementation have been associated with better outcomes in children with lung diseases, including pneumonia, cystic fibrosis, asthma, bronchiolitis, and acute respiratory failure.

Point Prevalence of the Biomechanical Dimension of Dysfunctional Breathing Patterns Among Competitive Athletes

ABSTRACT

Shimozawa, Y, Kurihara, T, Kusagawa, Y, Hori, M, Numasawa, S, Sugiyama, T, Tanaka, T, Suga, T, Terada, RS, Isaka, T, and Terada, M. Point prevalence of the biomechanical dimension of dysfunctional breathing patterns among competitive athletes. J Strength Cond Res 37(2): 270-276, 2023-There is growing evidence of associations between altered biomechanical breathing patterns and numerous musculoskeletal and psychological conditions. The prevalence of dysfunctional and diaphragmatic breathing patterns is unknown among athletic populations. The purpose of this study was to examine the prevalence of dysfunctional and diaphragmatic breathing patterns among athletic populations with a clinical measure to assess the biomechanical dimension of breathing patterns. Using a cross-sectional design, 1,933 athletes across multiple sports and ages were screened from 2017 to 2020. Breathing patterns were assessed using the Hi-Lo test in the standing position. Scores of the Hi-Lo test were determined based on the presence or absence of abdominal excursion, anterior-posterior chest expansion, superior rib cage migration, and shoulder elevation. The Hi-Lo test scores were used to categorize observational breathing mechanics as dysfunctional and diaphragmatic breathing patterns. The prevalence of athletes with dysfunctional breathing patterns was 90.6% (1,751 of 1,933). Athletes with diaphragmatic breathing patterns accounted for 9.4% of all athletes in our sample (182 of 1,933). There were no differences in the proportion of breathing patterns between male and female athletes ( p = 0.424). Breathing patterns observations were associated with sport-setting categories ( p = 0.002). The highest percentages of dysfunctional breathers were in middle school student athletes (93.7%), followed by elementary school student athletes (91.2%), high school student athletes (90.6%), professional/semiprofessional athletes (87.5%), and collegiate athletes (84.8%). The current study observed that dysfunctional breathing patterns (90.6%) in the biomechanical dimension were more prevalent than diaphragmatic breathing pattern (9.4%) among competitive athletes. These results suggest that clinicians may need to consider screening breathing patterns and implementing intervention programs aimed to improve the efficiency of biomechanical dimensions of breathing patterns in athletic populations. This study may help raise awareness of impacts of dysfunctional breathing patterns on athletes' health and performance.

Factors Affecting Lymphatic Absorption in Chinese Patients on Continuous Ambulatory Peritoneal Dialysis (CAPD)

The pathways and physiology of lymph absorption (LA) from the peritoneal cavity are well documented; however, much uncertainty still exists as to the various clinical and demographic factors affecting LA. We studied LA measured by the albumin instillation method, in adult Chinese CAPD patients, and showed that it was independent of age, sex, body surface area, duration of dialysis, intrinsic renal disease, use of intraperitoneal drugs (heparin/antibiotics/deferroxamine) and frequency of past bacterial peritonitis. High lymph absorbers had a relatively highertranscapillary cumulative ultrafiltration than low lymph absorbers. An enhanced LA was associated with a high initial intraperitoneal volume. Assessment of diaphragmatic strength by the decrement in vital capacity on changing from an erect to a supine position failed to distinguish patients with high and low LA.

Differences in Respiratory Muscle Strength Measures in Well-Nourished and Malnourished Hospitalized Patients

BACKGROUND

Objective indicators of nutritional status are essential for accurate identification of malnutrition. Previous research has indicated an association between measures of respiratory muscle strength (RMS) and nutritional status. Measurement of RMS-including maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP)-may provide evidence to support the assessment of nutritional status in hospitalized patients.

OBJECTIVE

The purpose of this study was to determine whether there was a difference in MIP, MEP, and SNIP between well-nourished and malnourished hospitalized patients.

DESIGN

A cross-sectional study was conducted.

PARTICIPANTS/SETTING

Patients were screened for eligibility criteria on admission by means of electronic medical records in general medical or surgical units at a tertiary care hospital in Chicago, IL, from January 2016 to January 2017. A total of 140 patients were included for analysis.

MAIN OUTCOMES MEASURED

The primary outcome was detection of differences in measures of RMS between malnourished and well-nourished hospitalized patients. Nutritional status was assessed using subjective global assessment and Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition (Academy/ASPEN) criteria recommended to identify malnutrition. The MIP, MEP, and SNIP measures were obtained and reported as absolute values (expressed in centimeters of water) and percent of predicted values.

STATISTICAL ANALYSIS

Independent t tests or Mann-Whitney U tests were used to determine differences in RMS measures between patients assessed as well nourished and those assessed as malnourished, depending on normality.

RESULTS

Compared with well-nourished patients, malnourished patients identified by subjective global assessment criteria had significantly lower absolute SNIP (73.7±28.7 vs 59.5±27.1 cm H₂O, P=0.004) and percent of predicted SNIP (78.6%±26.3% vs 64.8%± 30.0% predicted, P=0.006). Similarly, compared with well-nourished patients when Academy/ASPEN guidelines were used, malnourished individuals had significantly lower absolute SNIP (76.5±28.6 vs 58.3±26.3 cm H₂O, P<0.001), percent of predicted SNIP (81.4%±26.4% vs 63.5%±28.7% predicted, P<0.001), absolute MIP (83.5±34.6 vs 71.1±33.6 cm H₂O, P=0.05), and absolute MEP (108.7±36.6 vs 94.2±39.9 cm H₂O, P=0.04).

CONCLUSION

Differences in RMS between well-nourished and malnourished patients were observed when SNIP measures were used. However, there were no differences in MIP and MEP measures. Further research is needed to build on the findings from this study.

Diaphragm Contractility in Individuals with Chronic Ankle Instability

INTRODUCTION/PURPOSE

Previous investigations have identified impaired trunk and postural stability in individuals with chronic ankle instability (CAI). The diaphragm muscle contributes to trunk and postural stability by modulating the intra-abdominal pressure. A potential mechanism that could help to explain trunk and postural stability deficits may be related to altered diaphragm function due to supraspinal sensorimotor changes with CAI. The purpose of this study was to examine the diaphragm contractility in individuals with CAI and healthy controls.

METHODS

Twenty-seven participants with self-reported CAI and 28 healthy control participants volunteered. A portable ultrasound unit was used to visualize and measure the right and left hemidiaphragm thickness at the end of resting inspiration and expiration in supine while breathing quietly. The diaphragm movement was imaged and recorded on B-mode ultrasonography. The degree of diaphragm contractility was calculated from the mean of three images from the end of resting inspiration and expiration. Independent t-tests were used to compare the degree of diaphragm thickness of right and left sides between the CAI and the control groups.

RESULTS

The CAI group had a smaller degree of left hemidiaphragm contractility compared with the control group (P = 0.03). There was no between-group difference in other diaphragm variables.

CONCLUSION

Individuals with CAI appear to have altered diaphragm contractility, which may be an illustration of diaphragm dysfunction and central nervous system changes in CAI population. The association between CAI and altered diaphragm contractility provides clinicians a more comprehensive awareness of proximal impairments associated with CAI. Future investigation is needed to determine whether altered contractility of the diaphragm contributes to functional impairments, activity limitations, and participant restrictions commonly observed in patients with CAI.

Analysis of Pulmonary Function Test in Korean Patients With Duchenne Muscular Dystrophy: Comparison of Foreign and Korean Reference Data

Objective

To determine the abnormal pulmonary function value in Korean Duchenne muscular dystrophy (DMD) patients, we performed a comparative analysis of the patients' pulmonary function value expressed as % of the overseas reference data and Korean healthy children and adolescent reference data.

Methods

We performed pulmonary function test (PFT) in a total of 27 DMD patients. We compared the patients' FVC% and FEV1% of the overseas reference data with those of the Korean children and adolescent reference data. Also, we compared the patients' MIP% and MEP% of the prediction equation data with those of the Korean children and adolescent reference data.

Results

Age of the subjects ranged from 8 to 16 years (12.03±2.27 years). The mean maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak cough flow (PCF) were 36.93±9.5 cmH₂O, 45.79±17.46 cmH₂O, 1.4±0.43 L, 1.45±0.45 L, 1.40±0.41 L, and 206.25±61.21 L/min, respectively. The MIP%, MEP%, and FVC% of the Korean children and adolescent reference data showed statistically significant higher values than those of the prediction equation data.

Conclusion

We observed a clear numeric difference between Korean DMD patients' pulmonary function value expressed as % of the overseas data and inland data. To perform a precise assessment of respiratory function and to determine appropriate respiratory therapy, pulmonary function values of Korean DMD patients should be interpreted taking into account the inland normal pulmonary function test data.

Maximal respiratory pressure reference values for Navajo children ages 6-14

BACKGROUND

Since anthropometric variables are critical to the creation of pulmonary nomograms for FVC, FEV1, and other volumes and capacities, it is logical that anthropometric variables also influence the values of the maximal respiratory pressures (MRPs). Since nomograms are race-specific, it is important that tribe-specific tables of normal maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) be developed. To date normal tables for MRPs do not exist for Navajo children.

OBJECTIVE

Therefore the purpose of this study was to derive MRP normative reference values for Navajo children in the age range of 6-14 years.

METHODS-PARTICIPANTS AND MEASUREMENTS

A cross-sectional study was undertaken with a representative sample of 534 healthy children, ages 6-14 years, attending Navajo Nation elementary schools in Arizona. MIP and MEP were measured.

RESULTS

Test results from 275 girls and 259 boys met American Thoracic Society quality control standards and showed that MRPs all increased with height. Mean MIP in cm H2 O was 77 for boys and 67 for girls with lower limits of 44 and 40, respectively. Mean MEP in cm H2 O was 75 for boys and 66 for girls with the lower limits of 42 and 38, respectively.

CONCLUSION

Since the data were collected from the population of interest, the resulting MIP and MEP reference equations should be used when testing Navajo children ages 6-14 years.

Força muscular respiratória e perfil postural e nutricional em crianças com doenças neuromusculares

INTRODUÇÃO: As doenças neuromusculares infantis são crônicas, degenerativas e determinam alterações funcionais, musculares e nutricionais. OBJETIVOS: Avaliar sistematicamente a força muscular respiratória e o perfil postural e nutricional de crianças com doenças neuromusculares em seguimento multidisciplinar institucional. MATERIAIS E MÉTODOS: Foram estudados pacientes com diferentes doenças neuromusculares por meio da verificação da força muscular respiratória, da avaliação nutricional de massa muscular, do índice de massa corpórea e da porcentagem (%) de gordura corporal, além de avaliação postural e dos padrões de movimento. RESULTADOS: Foram avaliados 41 sujeitos. As crianças do sexo masculino predominaram na população em estudo, sendo 82,9% dela (n = 34), e os outros 17,1% (n = 7) eram do sexo feminino. A média de idade encontrada foi de 9,65 ± 3,11 anos. O principal diagnóstico encontrado foi Distrofia Muscular de Duchenne, 43,9% (n = 18), seguido de Atrofia Muscular Espinhal, 9,75% (n = 4), Distrofia Congênita, 7,31% (n = 3), Distrofia Muscular de Cinturas, Polineuropatia e Miopatia Congênita, todos com 4,9% (n = 2), além de Distrofia Muscular Progressiva, Miastenia Grávis, Charcoot Marie Toot, Emery Dreifuss, encontrados em 2,43% (n = 1). Foi verificada uma diminuição da força muscular respiratória (PImáx = 81 ± 24,3 cmH2O, 91% predito e PEmáx = 70 ± 29,6 cmH2O, 72% predito), mais evidente nos músculos expiratórios. A Hiperlordose lombar foi encontrada em 26 pacientes (64%) e 9 pacientes (22%) já haviam perdido a capacidade de deambular. Em relação ao perfil nutricional, 90% dos pacientes (n = 30) mostraram uma alta incidência de perda de reserva muscular e 52% deles (n = 13) apresentaram a porcentagem de gordura corporal abaixo do aceitável. CONCLUSÃO: A avaliação multidisciplinar das doenças neuromusculares pediátricas podem auxiliar no estabelecimento de tratamento precoce da Fisioterapia para melhorar a qualidade de vida dos pacientes e cuidadores.

Validation of a protocol to evaluate maximal expiratory pressure using a pressure transducer and a signal conditioner

The respiratory muscles can present fatigue and even chronic inability to generate force. So, reliable devices are necessary to their evaluation. The aim of this study is to evaluate the MEP (Maximal Expiratory Pressure) values of individuals between 20 and 25 years old and to validate a protocol using a pressure transducer and a signal conditioner comparing it with the digital manometer. We evaluated the MEP of 10 participants. They remained seated and made six respiratory maneuvers from Total Lung Capacity (TLC) to Residual Volume (RV). The results in the study showed no statistically significant differences when compared to values reported in the literature, and that the pressure transducer provides reliable values for MEP.

Natural history of thoracic insufficiency syndrome: a spondylothoracic dysplasia perspective

BACKGROUND

Spondylothoracic dysplasia is a condition in which bilateral chest wall deformity due to costovertebral rib fusion with shortening of the thoracic spine results in severe thoracic insufficiency syndrome and early death. Little is known about the long-term respiratory natural history of this disorder and the specific anatomic deformity.

METHODS

We conducted a multicenter prospective and retrospective study of patients with spondylothoracic dysplasia. Medical evaluations, respiratory history, physical examination findings, radiographs, computed tomographic scans, and pulmonary function tests were studied. Anatomic, radiographic, and functional parameters for the disorder were established to determine the natural history of the thoracic insufficiency syndrome.

RESULTS

Twenty-eight patients were identified. Eight patients had died in the neonatal period, and twenty were evaluated (eleven prospectively and nine retrospectively). The survivors were doing well clinically, but the average spirometric values were 27.9% of the predicted normal value for the forced vital capacity (FVC), 29.5% of the predicted normal value for the forced expiratory volume in the first second (FEV1), and 0.92 for the FEV1/FVC ratio, demonstrating a severe restrictive respiratory pattern. The computed tomographic scan lung volumes were an average of 28% of the expected values for age and gender. The thorax was stiff from rib fusion and was severely shortened posteriorly, averaging 24.2% of the predicted normal length. The thoracic spine was predominantly composed of block vertebrae, whereas in the lumbar region there were multiple hemivertebrae. Minimal scoliosis was seen, and there were no neurological deficits.

CONCLUSIONS

Spondylothoracic dysplasia has a unique pathoanatomy of volume depletion deformity of the thorax with chest wall stiffness, resulting in thoracic insufficiency syndrome. Clinical tolerance of the restrictive lung disease in this disorder is impressive, but no clear reason has yet been identified for the clinical pulmonary health in the face of severe restrictive lung disease. Patients who survive infancy show no progression of congenital anomalies and can have a good quality of life. This disease may serve as a model of the natural history of thoracic insufficiency syndrome due to growth inhibition of the thoracic spine either as a result of congenital causes or secondary to surgical fusion early in life.

Changes of Pulmonary Function for Patients With Osteoporotic Vertebral Compression Fractures After Kyphoplasty

One of the consequences of osteoporotic vertebral compression fractures (OVCFs) is progressive collapse of the fractured osteoporotic vertebral body. This can lead to spinal kyphosis that may cause restriction of respiratory function. The balloon kyphoplasty procedure can reduce kyphosis and relieve the pain. There are few studies that have appropriate data and follow-up to evaluate the effect of deformity correction on pulmonary function after the kyphoplasty procedure. The current study explores changes of pulmonary function of 30 older women who suffered from OVCFs in the thoracolumbar segment after kyphoplasty. After kyphoplasty was performed on these women, thoracic kyphotic angle, local kyphotic angle, pain scores, and pulmonary function parameters-vital capacity, inspiratory capacity, residual volume, functional residual capacity, total lung capacity, forced vital capacity (FVC), and maximum voluntary ventilation (MVV) were measured. All measurements were taken before, 3 days after, and 1 month after the kyphoplasty. The height of the vertebral body was restored, the local kyphotic angle was improved, and pain scores were significantly decreased after kyphoplasty. FVC and MVV were significantly increased 3 days after the procedures; whereas only MVV had gone on to improve 1 month later. The decreased values of pain scores had a remarkably positive correlation with the percentage of improvement of FVC (r=0.536) and MVV (r=0.614) measured 3 days after kyphoplasty. In patients with OVCFs, kyphoplasty could partially improve their impaired lung function.

Evaluation of pulmonary function and bicycle ergometry tests in patients with Behçet's disease

Behçet's disease (BD) has well-defined pulmonary complications, but cardiopulmonary exercise testing and the strength of the respiratory muscles have not been studied in detail. We aimed to investigate the pulmonary functions tests, inspiratory and expiratory muscle strength and endurance, cardiopulmonary exercise test response, and the relationship of these parameters in patients with BD. Forty BD patients and 20 healthy control subjects were recruited for this study. Mean age was 32.95 +/- 7.66 years for the BD group and 33.85 +/- 6.63 years for the control group with no statistically significant difference. The ratios of slight obstructive ventilatory impairment were 32.5% for the BD group. When the values of pulmonary function tests were compared, no statistically significant difference was found in FEV(1)/FVC (Forced expiratory volume during the first second/forced vital capacity), or maximal midexpiratory flow rate (all in percent) values between patient and control groups. Maximal inspiratory and expiratory pressures, peak expiratory flow rate (in percent) and maximal voluntary ventilation (in percent) values were significantly lower than those of the control group. Body's consumption of peak oxygen (VO(2peak)), oxygen consumption (milliliters per kilogram per minute), anaerobic threshold (AT), maximum exercise ventilation (VE(max)), work load values, and exercise test time in the bicycle exercise test were significantly higher in control groups than in patients with BD. The values of heart rate reserve, breathing reserve, and VE/VCO(2) at the AT of BD patients were within normal limits We conclude that respiratory and aerobic exercise may be recommended to improve respiratory muscle strength and endurance as well as the aerobic capacity and maximal ventilatory capacity in patients with BD.

Pulmonary function tests, respiratory muscle strength, and endurance of patients with osteoporosis

BACKGROUND

It has been shown that patients with thoracic kyphosis due to osteoporosis have diminished pulmonary function. The aim of this study was to determine the pulmonary function, respiratory muscle strength, and endurance of patients with osteoporosis who did not have compression fractures.

METHODS

The patient group consisted of 88 recently diagnosed postmenopausal osteoporotic women without spinal fractures. They were matched for age and body mass index with 54 healthy women, who formed the control group. Bone mineral density, pulmonary function test (PFT), maximum voluntary ventilation (MVV), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) measurements of both groups were performed.

RESULTS

There were no significant differences between the two groups regarding PFT parameters and MIP and MEP. However, osteoporotic patients had significantly lower MW values.

CONCLUSION

Women with postmenopausal osteoporosis without spinal compression fractures have normal PFT, MIP, and MEP values, but they have reduced respiratory muscle endurance.

Outcome assessment in the adult and juvenile idiopathic inflammatory myopathies

Through the recent efforts of multi-center collaborative study groups, a number of measures have been developed and partially validated to assess disease activity, disease damage, and health-related quality of life in adult and juvenile patients with IIM. Preliminary core set domains and core set measures of activity and damage have also been developed for adult and juvenile patients with myositis. Validated definitions of improvement and disability should be forthcoming in the next few years. These extraordinary developments will enable much-needed standardization in the assessment of the IIM, particularly in therapeutic and other clinical research studies. Despite this substantial progress, there is a need to develop more sensitive measures to assess IIM disease activity and damage, to further validate the existing tools, to define their performance characteristics in various IIM subgroups, to develop improved imaging techniques that are also quantitative, and to validate activation markers as surrogate measures. The ongoing cooperation of multiple specialists with expertise in these disorders, combined with emerging novel technologies, should continue to enhance the assessment of myositis. Improved clinical care and more rapid development of new therapies for patients with myositis will be the ultimate gains realized from these efforts.

Reference values for lung function tests. II. Maximal respiratory pressures and voluntary ventilation

The strength of the respiratory muscles can be evaluated from static measurements (maximal inspiratory and expiratory pressures, MIP and MEP) or inferred from dynamic maneuvers (maximal voluntary ventilation, MVV). Although these data could be suitable for a number of clinical and research applications, no previous studies have provided reference values for such tests using a healthy, randomly selected sample of the adult Brazilian population. With this main purpose, we prospectively evaluated 100 non-smoking subjects (50 males and 50 females), 20 to 80 years old, selected from more than 8,000 individuals. Gender-specific linear prediction equations for MIP, MEP and MVV were developed by multiple regression analysis: age and, secondarily, anthropometric measurements explained up to 56% of the variability of the dependent variables. The most cited previous studies using either Caucasian or non-Caucasian samples systematically underestimated the observed values of MIP (P < 0.05). Interestingly, the self-reported level of regular physical activity and maximum aerobic power correlates strongly with both respiratory and peripheral muscular strength (knee extensor peak torque) (P < 0.01). Our results, therefore, provide a new frame of reference to evaluate the normalcy of some useful indexes of respiratory muscle strength in Brazilian males and females aged 20 to 80.

[Maximum static respiratory pressures in adults. The reference values for a Mediterranean Caucasian population]

The aim of this study was to establish reference values for PImax and PEmax for the Mediterranean adult population. Male and female individuals between 18 and 83 years old meeting the criteria for consideration as references and residing in the metropolitan area of Valencia were assigned by decades to six subgroups, each containing at least 20 men and 20 women. PEmax was obtained from the point of maximum expiration (residual volume) and PImax was the point of maximum inspiration (total lung capacity). The cohort, which finally included 264 subjects (129 men and 135 women), was separated a priori by sex for data analysis. The following types of variables were studied: sociological (employment, educational level and exercise), biometric (age, height and weight) and spirometric results. A linear correlation analysis was performed for each pair of variables and a Kolmogorov-Smirnov test of normality was performed. In order to check the accuracy of PImax and PEmax readings, intra-individual variability was determined by performing three consecutive procedures over 3 days in 39 randomly selected individuals (18 men and 21 women). Significant inter-day and inter-test effects for respiratory pressures were thus ruled out. Predictive equations were worked out using a simple linear model including all predictive variables and eliminating weaker variables in a stepwise manner. Mathematical goodness of fit was assessed by a coefficient for multiple determinations (R2); also determined were the estimated standard error and statistical significance. We also compared observed and estimated values and the behavior of residual values in terms of their independence, normality and homoscedasticity. Reference limits were established by defining percentiles. The equations finally arrived at for men were as follows: PImax (-cmH2O) - 1.03 x Age + 0.59 x Weight + 133.07, PEmax (cmH2O) - 1.31 x Age + 263.12. The equations for women were PImax (-cmH2O) - 0.64 x Age + 125.18, PEmax (cmH2O) - 0.57 x Age + 0.65 x Weight + 116.26. Agreement with the usual references (the Black and Hyatt equations) was analyzed.

Head position and its effect on pulmonary function in tetraplegic patients

To test the influence of head position on pulmonary function in tetraplegic individuals 15 subjects with chronic C4-C7 injuries participated in a one group pre-post test comparing the relationship between orthostatic position of the head (OPH) and standard pulmonary function tests (PFTs). Twelve subjects with habitual forward head posture and three with non-forward head posture performed PFTs in (1) their habitual posture, and (2) an experimental posture imposed by placement of thoracic and/or lumbar rolls behind their back. Results showed that changing head posture did not alter mid-forced expiratory flow or forced inspiratory vital capacity, but significantly affected forced vital capacity (t = 2.83; P < 0.05) and 12 s maximum voluntary ventilation (t = 2.07; P < 0.05). In cases where pulmonary function was altered by head position, the resulting performance was best in the subject's habitual posture, although no differences in resting pulmonary tests were observed between subjects with and without forward head position. These data show that temporary postural alterations affecting OPH, if not allowing sufficient time for muscular adaptation, adversely affect pulmonary function in tetraplegic patients.

Maximal inspiratory pressure: does reproducibility indicate full effort?

BACKGROUND

Maximal inspiratory pressure (MIP) is often relied upon as an index of inspiratory muscle strength, and reproducibility of MIP taken to indicate maximal effort. This study was designed to determine whether reproducibility is a valid indicator of maximal effort.

METHODS

Ten normal subjects were studied, all of whom were familiar with the MIP test but none was an experienced subject. They were told that the purpose was to measure how accurately they could generate 50% of their MIP. Each performed nine MIP efforts and nine submaximal efforts. Means and coefficients of variation of peak negative inspiratory pressure (Pmax) and the ranges of the best three efforts were calculated for each type.

RESULTS

Mean (SE) Pmax averaged-93.8 (6.0) cm H2O for the maximal efforts and -60.6 (7.7) cm H2O for the submaximal trials, with coefficients of variation averaging 8.71 (1.75)% and 14.58 (2.63)%, respectively and the ranges averaging 6.5 (1.1)% and 13.4 (3.5)%, respectively. There was no clear separation between the coefficients of variation or ranges of maximal and submaximal efforts. In four cases the ranges of the best three submaximal efforts were less than 5 cm H2O and less than 5% -criteria that have been used to validate MIP results. These four subjects had lower ranges for submaximal than maximal efforts, even when expressed as percentages of the means.

CONCLUSION

Reproducibility should not be relied upon to indicate a valid MIP test, especially for research purposes when relatively small changes in inspiratory muscle strength must be discriminated.

Dyspnea in a patient years after severe poliomyelitis. The role of cardiopulmonary exercise testing

Dyspnea after polio can occur for a variety of reasons, including neuromuscular disease and upper airway abnormalities resulting from prolonged intubation, including tracheal stenosis, tracheomalacia, and vocal cord paralysis. Routine studies such as spirometry and maximum voluntary ventilation (MVV) measurements can give similar results in these conditions. We present a 50-year-old woman who as a child developed poliomyelitis that required tracheostomy and negative pressure ventilation. Thirty-nine years later, she developed breathlessness with normal spirometry but decreased MVV. The flow volume loop showed flattening of the inspiratory and expiratory limbs, consistent with a fixed upper airway obstruction or neuromuscular weakness. Exercise testing with measurement of exercise flow volume loops and respiratory pressures was performed. The patient was ventilatory limited with increasing end-expiratory lung volume through exercise. Flow volume loops confirmed flow limitation. Respiratory pressures did not change after maximal exercise. Further evaluation confirmed left vocal cord paralysis and tracheomalacia. This patient demonstrates that the causes of dyspnea after poliomyelitis can be multifactorial, and that routine evaluation may fail to elucidate the limiting factor. In this case, exercise testing provided valuable insight into the limiting factor for this patient and provided useful data for counseling and for further management.

Review of the clinical efficacy of theophylline in the treatment of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is associated with significant morbidity and mortality. Therapeutic options are few and are often limited in efficacy. Theophylline is one option, but its use appears to have recently reached a threshold point of deemphasis. Given the consequences of further diminishing the available treatment of COPD, a reappraisal of theophylline's role is imperative. This report reviews the clinical efficacy of theophylline in managing patients with COPD. Special consideration is given to theophylline's effects on pulmonary function (i.e., bronchodilation, exercise capacity, and gas exchange), dyspnea, mucociliary clearance, respiratory muscle performance, cardiovascular function, and neuroinspiratory drive. Despite the lack of standardization in study design and methodology among the studies evaluating theophylline, the conflicting results, and the questions that remain to be answered, evidence indicates that theophylline can provide meaningful therapeutic benefit to patients with COPD. In addition, several studies in patients with COPD have shown that theophylline and inhaled beta-agonists interact in an additive fashion, and the combination therapy results in additional objective and subjective improvement over that achieved by either preparation alone.

Improvement in exercise capacity after nocturnal positive pressure ventilation and tracheostomy in a postpoliomyelitis patient

Progressive neuromuscular symptoms years after recovery from acute paralytic poliomyelitis have been termed the PPS. We describe a 52-year-old man who contracted poliomyelitis at age 9 years who fully recovered and 33 years later developed progressive dyspnea. Neurologic evaluation revealed bilateral paralysis of the vocal cords, generalized weakness, and accentuated mouth occlusion pressure and ventilatory responses to hypercapnic, hyperoxic breathing. An EMG and muscle biopsy showed changes consistent with acute and chronic denervation. Cardiopulmonary exercise evaluation demonstrated a pulmonary mechanical limit with excessive ventilation relative to CO2 output. Tracheostomy and nocturnal positive pressure ventilation resulted in increased respiratory muscle strength, normalization of ventilatory drive and marked improvement in exercise capacity.

Respiratory function in chronic hemiplegia

Dynamic spirometry was examined in 23 non-smoking hemiplegic patients after the acute phase. The decrease of slow inspiratory forced capacity is related to motor impairment and does not vary with time. The forced inspiratory and expiratory vital capacities are similar to the slow inspiratory vital capacity in the first 6 months of the disease, but significantly decrease later independent of the motor impairment. The peak expiratory flow is highly variable but is clearly decreased, and is related to motor impairment. These results point to a restrictive respiratory syndrome due to mechanical limitation of thorax excursions caused by weakness, hypotonicity, and incoordination of the trunk musculature. The importance of long-term physiotherapy of the trunk is emphasized.