Relationship between inspiratory muscle strength and balance in women: A cross-sectional study.

BACKGROUND: There is scarce evidence on changes at the functional level associated with the respiratory area in women. This study aims to analyse the relationship between inspiratory muscle strength and balance in women. MATERIAL AND METHODS: In this cross-sectional observational study, the sample consisted of groups according to the results obtained in the balance test. Inspiratory muscle weakness was defined as maximum inspiratory pressure (MIP) ≤ 80% of the predictive value. MIP was carried out using through a mouthpiece, with an electronic manometer. Logistic regression model was used to examine if MIP predicts balance. RESULTS: 159 women participated in the study. Approximately 20% of them achieved balance ≤ 2 seconds and 18% presented MIP≤80%. MIP was associated with the time achieved in the one-leg support test. Subjects with MIP ≤ 80% of the predictive value show 3 times more risk of having a lower performance in the balance test (OR = 3.26). CONCLUSIONS: Inspiratory muscle weakness is associated with deficient balance in this sample. It shows the need for multidimensional assessment and rehabilitation strategies for patients identified as having MIP weakness and/or balance disorders.

Maximal inspiratory pressure is associated with health-related quality of life and is a reliable method for evaluation of patients on hemodialysis.

OBJECTIVE: To evaluate the association between Maximal Inspiratory Pressure (MIP) and health-related quality of life (HRQoL) and to verify the reliability of the MIP in patients on hemodialysis. METHODS: In a repeated-measures design, patients on hemodialysis performed MIP and specific HRQoL questionnaire (trial 1). The MIP was repeated after 6 to 8 weeks (trial 2) and reliability was assessed using Intra-class Correlation Coefficient. Standard Error of Measurement and Minimal Detectable Change scores were calculated. RESULTS: Sixty-one individuals (68.9% men) were evaluated in trial 1. MIP was associated with specific domains "Symptoms" (r = 0.45; R2 adjusted = 0.192) and the kidney disease component summary (r = 0.38; R2 adjusted = 0.138). Regarding generic domains, the MIP was associated with "Physical Functioning" (r = 0.57; R2 adjusted = 0.375) and Physical component summary (r = 0.47; R2 adjusted = 0.258). Thirty-three patients were randomly selected to perform a second MIP test (trial 2). The Intra-class Correlation Coefficient was 0.94 (95%CI 0.88-0.97). By Bland-Altman analysis, the bias was 3.2 cmH2O, which represents a difference of 3.7%. The Standard Error of Measurement and Minimal Detectable Change for MIP were 5.9 cmH2O and 13.8 cmH2O, respectively. CONCLUSION: The MIP is a reliable test, associated with physical domains of HRQoL in patients on hemodialysis. Thus, it is a useful method for respiratory evaluation in this population.

Use of volume controlled vs. pressure controlled volume guaranteed ventilation in elderly patients undergoing laparoscopic surgery with laryngeal mask airway.

BACKGROUND: The peak inspiratory pressure (PIP) is crucial in mechanical ventilation with supraglottic airway device (SAD). Pressure-controlled ventilation volume-guaranteed (PCV-VG), delivering a preset tidal volume with the lowest required airway pressure, is being increasingly used during general anesthesia. In this study, we compared respiratory mechanics and circulatory parameters between volume-controlled ventilation (VCV) and PCV-VG in elderly patients undergoing laparoscopic surgery using the laryngeal mask airway supreme (LMA). METHODS: Eighty participants scheduled for laparoscopic surgery were enrolled in this prospective, randomized clinical trial. The participants were randomly assigned to receive VCV or PCV-VG. PIP, dynamic compliance (Cdyn) and mean inspiratory pressure (Pmean) were recorded at 5 min after induction of anesthesia (T1), 5 min after pneumoperitoneum(T2), 30 and 60 min after pneumoperitoneum (T3 and T4). Data including other respiratory variables, hemodynamic variables, and arterial blood gases were also collected. The difference in PIP between VCV and PCV-VG was assessed as the primary outcome. RESULTS: PIP was significantly lower at T2, T3, and T4 in both groups compared with T1 (all P <  0.0001), and it was significantly lower in the PCV-VG group than the VCV group at T2, T3, and T4 (all P <  0.001). Cydn was decreased at T2, T3, and T4 in two groups compared with T1 (all P <  0.0001), but it was higher in PCV-VG group than in VCV group at T2, T3, and T4 (all P <  0.0001). There were on statistically significant differences were found between the groups for other respiratory and hemodynamic variables. CONCLUSION: In elderly patients who underwent laparoscopic surgery using an LMA, PCV-VG was superior to VCV in its ability to provide ventilation with lower peak inspiratory pressure and greater dynamic compliance.

Efficacy of inspiratory muscle training on inspiratory muscle function, functional capacity, and quality of life in patients with asthma: A randomized controlled trial.

OBJECTIVE: To evaluate the efficacy of an inspiratory muscle training protocol on inspiratory muscle function, functional capacity, and quality of life in patients with asthma. DESIGN: A single-blind, randomized controlled clinical trial. SETTING: Community-based. SUBJECTS: Patients with asthma, aged between 20 and 70 years old, non-smokers. INTERVENTIONS: Participants were randomized into two groups: inspiratory muscle training group performed inspiratory muscle training 5 days a week for 8 weeks, consisting of six sets of 30 breaths per day with a training load ⩾50% of maximal inspiratory pressure, plus an educational program; the control group only received the educational program. MAIN MEASUREMENTS: Maximal inspiratory pressure, inspiratory muscle endurance, and the distance performed on the incremental shuttle walking test were assessed pre-intervention, post-intervention and at follow-up (3 months after the end of the intervention). The asthma quality of life questionnaire was applied pre and post-intervention. RESULTS: Data from 39 participants were analyzed. Maximal inspiratory pressure in percentage of predicted and endurance test duration were significantly higher post-intervention in the inspiratory muscle training group (∆ post-pre: 50.8% vs 7.3% of predicted - P < 0.001 and ∆ post-pre: 207.9 seconds vs 2.7 seconds - P < 0.001, respectively). There was no significant difference in the incremental shuttle walking distance between groups (∆ post-pre: 30.9 m vs -8.1 m, P = 0.165). Quality of life was perceived as significantly better, without a difference between groups (P > 0.05). CONCLUSIONS: About 8 weeks of inspiratory muscle training in patients with controlled asthma significantly increased inspiratory muscle strength and endurance.

Maximal Dynamic Inspiratory Pressure Evaluation in Heart Failure: A Comprehensive Reliability and Agreement Study.

OBJECTIVE: The purpose of this study was to analyze the reliability (interrater and intrarater) and agreement (repeatability and reproducibility) properties of tapered flow resistive loading (TFRL) measures in patients with heart failure (HF). METHODS: For this cross-sectional study, participants were recruited from the cardiopulmonary rehabilitation program at the University of Brasilia from July 2015 to July 2016. All patients participated in the study, and 10 were randomly chosen for intrarater and interrater reliability testing. The 124 participants with HF (75% men) were 57.6 (SD = 1.81) years old and had a mean left ventricular ejection fraction of 38.9% (SD = 15%) and a peak oxygen consumption of 13.05 (SD = 5.3) mL·kg·min-1. The main outcome measures were the maximal inspiratory pressure (MIP) measured with a standard manovacuometer (SM) and the MIP and maximal dynamic inspiratory pressure (S-Index) obtained with TFRL. The S-Index reliability (interrater and intrarater) was examined by 2 evaluators, the S-Index repeatability was examined with 10 repetitions, and the reproducibility of the MIP and S-Index was measured with SM and TFRL, respectively. RESULTS: The reliability analysis revealed high S-Index interrater and intrarater reliability values (intraclass correlation coefficients [ICCs] of 0.89 [95% CI = 0.58-0.98] and 0.97 [95% CI = 0.89-0.99], respectively). Repeatability analyses revealed that 8 maneuvers were required to reach the maximum S-Index in 75.81% (95% CI = 68.27-83.34) of the population. The reproducibility of TFRL measures (S-Index = 68.8 [SD = 32.8] cm H2O; MIP = 66 [SD = 32.3] cm H2O) was slightly lower than that of the SM measurement (MIP = 70.1 [SD = 35.9] cm H2O). CONCLUSIONS: The TFRL device provided a reliable intrarater and interrater S-Index measure in patients with HF and had acceptable repeatability, requiring 8 maneuvers to produce a stable S-Index measure. The reproducibilities of the S-Index, MIP obtained with SM, and MIP obtained with TRFL were similar. IMPACT: TRFL is a feasible method to assess both MIP and the S-index as measures of inspiratory muscle strength in patients with HF and can be used for inspiratory muscle training, making the combined testing and training capabilities important in both clinical research and the management of patients with HF.

Evaluation of Respiratory Muscle Strength and Diaphragm Ultrasound: Normative Values, Theoretical Considerations, and Practical Recommendations.

BACKGROUND: Reference values derived from existing diaphragm ultrasound protocols are inconsistent, and the association between sonographic measures of diaphragm function and volitional tests of respiratory muscle strength is still ambiguous. OBJECTIVE: To propose a standardized and comprehensive protocol for diaphragm ultrasound in order to determine lower limits of normal (LLN) for both diaphragm excursion and thickness in healthy subjects and to explore the association between volitional tests of respiratory muscle strength and diaphragm ultrasound parameters. METHODS: Seventy healthy adult subjects (25 men, 45 women; age 34 ± 13 years) underwent spirometric lung function testing, determination of maximal inspiratory and expiratory pressure along with ultrasound evaluation of diaphragm excursion and thickness during tidal breathing, deep breathing, and maximum voluntary sniff. Excursion data were collected for amplitude and velocity of diaphragm displacement. Diaphragm thickness was measured in the zone of apposition at total lung capacity (TLC) and functional residual capacity (FRC). All participants underwent invasive measurement of transdiaphragmatic pressure (Pdi) during different voluntary breathing maneuvers. RESULTS: Ultrasound data were successfully obtained in all participants (procedure duration 12 ± 3 min). LLNs (defined as the 5th percentile) for diaphragm excursion were as follows: (a) during tidal breathing: 1.2 cm (males; M) and 1.2 cm (females; F) for amplitude, and 0.8 cm/s (M) and 0.8 cm/s (F) for velocity, (b) during maximum voluntary sniff: 2.0 cm (M) and 1.5 cm (F) for amplitude, and 6.7 (M) cm/s and 5.2 cm/s (F) for velocity, and (c) at TLC: 7.9 cm (M) and 6.4 cm (F) for amplitude. LLN for diaphragm thickness was 0.17 cm (M) and 0.15 cm (F) at FRC, and 0.46 cm (M) and 0.35 cm (F) at TLC. Values for males were consistently higher than for females, independent of age. LLN for diaphragmatic thickening ratio was 2.2 with no difference between genders. LLN for invasively measured Pdi during different breathing maneuvers are presented. Voluntary Pdi showed only weak correlation with both diaphragm excursion velocity and amplitude during forced inspiration. CONCLUSIONS: Diaphragm ultrasound is an easy-to-perform and reproducible diagnostic tool for noninvasive assessment of diaphragm excursion and thickness. It supplements but does not replace respiratory muscle strength testing.

Ultrasonographic modeling of diaphragm function: A novel approach to respiratory assessment.

OBJECTIVES: Bedside ultrasound techniques have the unique ability to produce instantaneous, dynamic images, and have demonstrated widespread utility in both emergency and critical care settings. The aim of this article is to introduce a novel application of this imaging modality by utilizing an ultrasound based mathematical model to assess respiratory function. With validation, the proposed models have the potential to predict pulmonary function in patients who cannot adequately participate in standard spirometric techniques (inability to form tight seal with mouthpiece, etc.). METHODS: Ultrasound was used to measure diaphragm thickness (Tdi) in a small population of healthy, adult males at various points of the respiratory cycle. Each measurement corresponded to a generated negative inspiratory force (NIF), determined by a handheld meter. The data was analyzed using mixed models to produce two representative mathematical models. RESULTS: Two mathematical models represented the relationship between Tdi and NIFmax, or maximum inspiratory pressure (MIP), both of which were statistically significant with p-values <0.005: 1. log(NIF) = -1.32+4.02×log(Tdi); and 2. NIF = -8.19+(2.55 × Tdi)+(1.79×(Tdi2)). CONCLUSIONS: With validation, these models intend to provide a method of estimating MIP, by way of diaphragm ultrasound measurements, thereby allowing evaluation of respiratory function in patients who may be unable to reliably participate in standard spirometric tests.

Comparison of balance changes after inspiratory muscle or Otago exercise training.

The inspiratory muscles contribute to balance via diaphragmatic contraction and by increasing intra-abdominal pressure. We have shown inspiratory muscle training (IMT) improves dynamic balance significantly with healthy community-dwellers. However, it is not known how the magnitude of balance improvements following IMT compares to that of an established balance program. This study compared the effects of 8-week of IMT for community-dwellers, to 8-week of the Otago exercise program (OEP) for care-residents, on balance and physical performance outcomes. Nineteen healthy community-dwellers (74 ± 4 years) were assigned to self-administered IMT. Eighteen, healthy care-residents (82 ± 4 years) were assigned to instructor-led OEP. The IMT involved 30 breaths twice-daily at ~50% of maximal inspiratory pressure (MIP). The OEP group undertook resistance and mobility exercises for ~60 minutes, twice-weekly. Balance and physical performance were assessed using the mini Balance Evaluation System Test (mini-BEST) and time up and go (TUG). After 8-week, both groups improved balance ability significantly (mini-BEST: IMT by 24 ± 34%; OEP by 34 ± 28%), with no between-group difference. Dynamic balance sub-tasks improved significantly more for the IMT group (P < 0.01), than the OEP group and vice versa for static balance sub-tasks (P = 0.01). The IMT group also improved MIP (by 66 ± 97%), peak inspiratory power (by 31 ± 12%) and TUG (by -11 ± 27%); whereas the OEP did not. IMT and OEP improved balance ability similarly, with IMT eliciting greater improvement in dynamic balance, whilst OEP improved static balance more than IMT. Unlike IMT, the OEP did not provide additional benefits in inspiratory muscle function and TUG performance. Our findings suggest that IMT offers a novel method of improving dynamic balance in older adults, which may be more relevant to function than static balance and potentially a useful adjunct to the OEP in frailty prevention.

Inspiratory Muscle Training After Heart Valve Replacement Surgery Improves Inspiratory Muscle Strength, Lung Function, and Functional Capacity: A RANDOMIZED CONTROLLED TRIAL.

PURPOSE: The aim of this study was to analyze the effects of inspiratory muscle training (IMT) as a therapeutic strategy after heart valve replacement surgery (HVRS). METHODS: A double-blind, randomized, clinical trial that included patients undergoing elective HVRS, without post-operative complications, were allocated to 2 groups: IMT group (IMT-G) and IMT placebo group (IMT-PG). The IMT started 3 d after surgery and was performed twice daily for 4 wk. Lung function, maximum inspiratory pressure (MIP) as a measure of inspiratory muscle strength, functional capacity, and quality of life were assessed pre-operatively and at the end of training. RESULTS: The IMT-G recovered pre-operative MIP and lung function values after 4 wk of training. This group also increased the distance walked during the 6-min walk test (6MWD). In the IMT-PG, the values of MIP were below those found pre-operatively, with impairment of lung function and lower 6MWD in the final evaluation. At the end of IMT, MIP was correlated with the 6MWD and with the spirometry variables. CONCLUSIONS: IMT performed for 4 wk after HVRS was effective in restoring the values of inspiratory muscle strength and lung function to the pre-operative level and increasing the functional capacity assessed by the 6MWD. Furthermore, an association between lung function and functional capacity was observed, demonstrating the clinical relevance of the use of IMT in the rehabilitation process of these patients.

Força muscular respiratória e desempenho no Modified Shuttle Walk Test em escolares com fibrose cística / Fuerza muscular respiratoria y rendimiento en el Modified Shuttle Walk Test en escolares con fibrosis quística / Respiratory muscle strength and Modified Shuttle Walk Test performance in schoolers with cystic fibrosis

RESUMO O Modified Shuttle Walk Test (MSWT) é um teste de exercício potencialmente máximo que, associado à avaliação da força muscular respiratória (FMR), reflete a condição respiratória e a capacidade de exercício de escolares com fibrose cística (FC). O objetivo desta pesquisa foi investigar a relação entre FMR e distância percorrida (DP) no MSWT realizado por escolares com FC e comparar os dados obtidos com valores preditos na literatura. Trata-se de um estudo observacional transversal que incluiu escolares com FC. Realizou-se avaliação antropométrica, espirometria e FMR, utilizando as pressões inspiratória máxima (PImáx) e expiratória máxima (PEmáx) por meio da manovacuometria. Dois MSWT foram realizados, com intervalo de 30 minutos entre eles. Verificou-se a distribuição dos dados pelo teste de Shapiro-Wilk e aplicou-se teste t pareado para comparação entre valores das avaliações e predito, bem como para comparação entre gêneros. Aplicou-se teste de Pearson para correlação entre PImáx e PEmáx e DP no MSWT. Aceitou-se significância de 5%. Participaram 28 crianças (9,9±1,9 anos) destas, 57,14% apresentaram PImáx abaixo do predito (15 crianças) e 53,57% da PEmáx (16 crianças). A média da DP foi 730,4±266,1m, abaixo do predito na literatura. Não houve relação entre DP e FMR. Identificou-se correlação moderada entre valores de PImáx e PEmáx (r=0,58 e p=0,01). Não houve relação entre FMR e desempenho no MSWT nos escolares com FC estudados. A FMR, bem como o DP no MSWT, apresentou-se abaixo do predito na literatura.

RESUMEN El Modified Shuttle Walk Test (MSWT) es una prueba de ejercicio potencialmente máxima que, asociada a la evaluación de la fuerza muscular respiratoria (FMR), refleja la condición respiratoria y la capacidad de ejercicio de escolares con fibrosis quística (FQ). El objetivo de esta investigación fue investigar la relación entre FMR y distancia recorrida (DP) en el MSWT realizado por escolares con FQ y comparar los datos obtenidos con valores predichos en la literatura. Se trata de un estudio observacional transversal que incluyó a los escolares con FQ. Se realizó una evaluación antropométrica, espirometría y FMR, utilizando las presiones inspiratoria máxima (PImáx) y espiratoria máxima (PEmáx) por medio de la manovacuometría. Se realizaron dos MSWT, con un intervalo de 30 minutos entre ellos. Se verificó la distribución de los datos por la prueba de Shapiro-Wilk y se aplicó una prueba t pareada para la comparación entre los valores de las evaluaciones y el predicado, así como para la comparación entre los géneros. Se aplicó una prueba de Pearson para la correlación entre PImáx y PEmáx y DP en el MSWT. Se aceptó una significación del 5%. Participaron del estudio 28 niños (9,9±1,9 años); 57,14% presentaron PImáx por debajo del pronóstico (15 niños) y 53,57% por debajo del pronóstico para PEmáx (16 niños). El promedio de la DP fue 730,4±266,1m, por debajo del predicho en la literatura. No hubo relación entre DP y FMR. Se identificó una correlación moderada entre valores de PImáx y PEmáx (r=0,58 y p=0,01). No hubo relación entre FMR y desempeño en el MSWT en los escolares con FC. La FMR, así como la DP en el MSWT, se presentó abajo del predicho en la literatura.

ABSTRACT Modified Shuttle Walk Test (MSWT) is a potentially maximal exercise test that, together with the assessment of respiratory muscle strength (RMS), reflects the respiratory condition and exercise capacity of schoolchildren with cystic fibrosis (CF). This study aimed to investigate the relationship between the RMS and the performance in the MSWT by schoolchildren with CF and to compare the data obtained with the values predicted in the literature. This is a cross-sectional observational study that included schoolchildren with CF. Anthropometric evaluation, spirometry and RMS evaluation were performed, using the maximal inspiratory (MIP) and expiratory (MEP) pressures (Globalmed MVD300® manovacuometer) (ATS/ERS) (2002). Two MSWT were performed, with an interval of 30 minutes between them. The distribution of the data by the Shapiro-Wilk test was applied and paired t-test was used to compare the values of the evaluations with those predicted, as well as for comparison between genders. Pearson test was used for correlation between MIP and MEP and the performance in the MSWT. Significance of 5% was accepted. 28 children (9.9±1.9 years) participated; 57.14% showed MIP below the predicted (15 children) and 53.57% showed MEP below the predicted (16 children). The mean performance was 730.4±266.1m, which is lower than the values predicted in the literature. No relationship between performance and RMS was observed. A moderate correlation was observed between MIP and MEP values (r=0.58, p=0.01). No relationship between the RMS and the MSWT performance was observed in schoolchildren with CF of this study. The RMS and the performance in the MSWT were below the predicted in the literature.

Driving Pressure: Defining the Range.

BACKGROUND: Recent literature suggests that optimization of tidal driving pressure (ΔP) would be a better variable to target for lung protection at the bedside than tidal volume (VT) or plateau pressure (Pplat), the traditional indicators of ventilator-induced lung injury. However, the usual range or variability of ΔP over time for any subject category have not been defined. This study sought to document the ΔP ranges observed in current practice among mechanically ventilated subjects receiving routine care for diverse acute conditions in a community hospital environment. METHODS: This was a retrospective, observational study in a university-affiliated and house staff-aided institution with respiratory care protocols based on extant lung-protective guidelines for VT. Demographic characteristics and measured parameters related to mechanical ventilation and hemodynamics were extracted from electronic records of intubated subjects for each 8-h period of the first 24 h in the ICU. Pplat values reported by the ventilator were validated by the respiratory therapist before those data were entered into the electronic medical record. RESULTS: The mean ΔP was significantly higher at Time 1 (mean 16.1, range 7.0-31.0 cm H2O) compared to both Time 2 (mean 14.5, range 7.0-35.0 cm H2O) (P < .001) and Time 3 (mean 14.8, range 8.0-32 cm H2O) (P < .001). At all time points, the median ΔP was higher for completely passive breathing compared to triggered breathing. The widest difference between presumed entirely passive and presumed intermittently or consistently triggered breaths occurred at Time 1 (mean ΔP = 17.2 vs 14.9 cm H2O, respectively) (P = .01). CONCLUSIONS: Suggested safety thresholds for ΔP are often violated by a strategy that focuses on only VT and Pplat. Our data suggest that ΔP is lower for passive versus triggered breathing cycles. Vigilance is especially important in the initial stages of mechanical ventilator support, and attention should be paid to triggering efforts when interpreting and comparing machine-determined numerical values for ΔP.

Clinical implication of maximal voluntary ventilation in myotonic muscular dystrophy.

Patients with myotonic muscular dystrophy type 1 (DM1) tend to exhibit earlier respiratory insufficiency than patients with other neuromuscular diseases at similar or higher forced vital capacity (FVC). This study aimed to analyze several pulmonary function parameters to determine which factor contributes the most to early hypercapnia in patients with DM1.We analyzed ventilation status monitoring, pulmonary function tests (including FVC, maximal voluntary ventilation [MVV], and maximal inspiratory and expiratory pressure), and polysomnography in subjects with DM1 who were admitted to a single university hospital. The correlation of each parameter with hypercapnia was determined. Subgroup analysis was also performed by dividing the subjects into 2 subgroups according to usage of mechanical ventilation.Final analysis included 50 patients with a mean age of 42.9 years (standard deviation = 11.1), 46.0% of whom were male. The hypercapnia was negatively correlated with MVV, FVC, forced expiratory volume in 1 second (FEV1), and their ratios to predicted values in subjects with myotonic muscular dystrophy type 1. At the same partial pressure of carbon dioxide, the ratio to the predicted value was lowest for MVV, then FEV1, followed by FVC. Moreover, the P values for differences in MVV and its ratio to the predicted value between ventilator users and nonusers were the lowest.When screening ventilation failure in patients with DM1, MVV should be considered alongside other routinely measured parameters.

Assessing Inspiratory Muscle Strength for Early Detection of Respiratory Failure in Motor Neuron Disease: Should We Use MIP, SNIP, or Both?

BACKGROUND: Motor neuron disease (MND) invariably impacts on inspiratory muscle strength leading to respiratory failure. Regular assessment of sniff nasal inspiratory pressure (SNIP) and/or maximal mouth inspiratory pressure (MIP) contributes to early detection of a requirement for ventilatory support. OBJECTIVES: The aim of this study was to compare the feasibility, agreement, and performance of both tests in MND. METHODS: Patients with MND followed by a multidisciplinary consultation were prospectively included. Pulmonary follow-up included forced expiratory volumes, vital capacity (VC) seated and supine, MIP, SNIP, pulse oximetry, and daytime arterial blood gases. RESULTS: A total of 61 patients were included. SNIP and MIP could not be performed in 14 (21%) subjects; 74% of the subjects showed a decrease in MIP or SNIP at inclusion versus 31% for VC. Correlation between MIP and SNIP (Pearson's rho: 0.68, p < 0.001) was moderate, with a non-significant bias in favor of SNIP (3.6 cm H2O) and wide limits of agreement (-34 to 41 cm H2O). Results were similar in "bulbar" versus "non-bulbar" patients. At different proposed cut-off values for identifying patients at risk of respiratory failure, the agreement between MIP and SNIP (64-79%) and kappa values (0.29-0.53) was moderate. CONCLUSIONS: MIP and SNIP were equally feasible. There was no significant bias in favor of either test, but a considerable disparity in results between tests, suggesting that use of both tests is warranted to screen for early detection of patients at risk of respiratory failure and avoid over diagnoses. SNIP, MIP, and VC all follow a relatively linear downhill course with a steeper slope for "bulbar" versus "non-bulbar" patients.

Effects of inspiratory muscle training on postural stability, pulmonary function and functional capacity in children with cystic fibrosis: A randomised controlled trial.

BACKGROUND: Previous research has found conflictive results regarding the benefits of inspiratory muscle training (IMT) for cystic fibrosis (CF) patients. Also, involvement of postural stability is a rising concern in chronic lung diseases but its role in CF patients is poorly understood. Our aim was to investigate the effects of IMT in CF patients as well as analysing the factors which may be related to postural stability. METHODS: Thirty-six children aged between 8 and 18 years with CF were randomly allocated to either "comprehensive chest PT" group (PT) or "IMT alongside comprehensive chest PT" group (PT+IMT). Both groups trained for 8 weeks. Dynamic and static postural stability tests on Biodex Balance system®, spirometry, respiratory muscle strength and 6-min walk distance (6MWD) was assessed at baseline and after 8 weeks of training. Determinants of postural stability was also analysed on baseline values. RESULTS: Maximum expiratory pressure (MEP) was found to be an independent predictor for overall limits of stability (LOS) score explaining %26 of variance (R = 0.514, p = 0.003). Overall LOS score, FVC, FEV1, peak expiratory flow, MEP and 6MWD significantly improved in both groups, with no significant differences between groups. Maximum inspiratory pressure (MIP) also improved in both groups but the magnitude of improvement in MIP was greater in PT+IMT group (38 cmH2O vs 13 cmH2O; p < 0.001). CONCLUSIONS: Combining IMT with chest PT failed to provide further improvements, except for MIP, suggesting that a comprehensive chest PT program may be individually effective in improving overall LOS score, spirometry, respiratory muscle strength and 6MWD. TRIAL REGISTRATION: www.ClinicalTrials.gov; registration number: NCT03375684.

Quanto tempo de oclusão é necessário para avaliar a pressão inspiratória máxima pelo método da válvula expiratória unidirecional em sujeitos sem via aérea artificial? / ¿Cuánto tiempo de oclusión es necesario para evaluar la presión inspiratoria máxima por el método de la válvula espiratoria unidireccional en sujetos sin vía aérea artificial? / How much occlusion time is necessary to assess maximal inspiratory pressure by the unidirectional expiratory valve method in subjects without artificial airway?

RESUMO O objetivo desse estudo foi determinar o tempo de oclusão necessário para avaliar a pressão inspiratória máxima (PIMáx) obtida pelo método da válvula expiratória unidirecional em sujeitos sem via aérea artificial. Foram avaliados 31 sujeitos, com idade entre 18 e 60 anos. A PIMáx foi avaliada pelo método convencional (PIMáxconv) e pelo método da válvula expiratória unidirecional (PIMáxuni), sendo a ordem de avaliação definida por meio de sorteio. Para a medida da PIMáxuni, um manovacuômetro digital foi acoplado a uma válvula expiratória unidirecional e máscara orofacial por 20 segundos de oclusão. Nesse período, todos os sujeitos foram encorajados a realizar esforços inspiratórios máximos. Para definir a ótima duração da manobra, o tempo de esforço foi dividido a cada intervalo de 5 segundos (0-5s, 0-10s, 0-15s, 0-20s). Os intervalos de tempo para obtenção da PIMáxuni foram comparados por meio do teste de ANOVA One-way. Para comparação das médias dos valores de PIMáxconv e PIMáxuni, foi utilizado o teste t de Student. O nível de significância foi de 5%. A média dos valores da PIMáxconv foi de -102,5±23,9 cmH2O, enquanto que a PIMáxuni foi de -117,3±24,8 cmH2O (p<0,001). O valor absoluto máximo da PIMáxuni foi alcançado dentro do intervalo de 0-20 segundos, que foi significativamente superior ao valor absoluto máximo obtido nos primeiros 5 segundos (p=0,036). O tempo de oclusão necessário para avaliar a PIMáx pelo método da válvula expiratória unidirecional em sujeitos colaborativos sem via aérea artificial deve ser de pelo menos 20 segundos.

RESUMEN Este estudio busca determinar cuánto tiempo de oclusión es necesario para obtener la presión inspiratoria máxima (PIMáx) por medio del método de la válvula espiratoria unidireccional en individuos sin vía aérea artificial. Se evaluaron 31 sujetos de entre 18 y 60 años de edad. La PIMáx se evaluó mediante el método estándar (PIMáxest) y el método de válvula espiratoria unidireccional (PIMáxuni), siendo que el orden de evaluación se estableció por medio de un sorteo. Para el PIMáxuni, un manovacuómetro digital se ha conectado a una válvula espiratoria unidireccional y una máscara orofacial durante 20 segundos de oclusión. Durante este período, se alentó a los individuos a hacer esfuerzos respiratorios máximos. Para definir la óptima duración de la maniobra, el tiempo de esfuerzo se dividió en intervalos de cinco segundos (0-5s, 0-10s, 0-15s, 0-20s). Los intervalos del tiempo para el PIMáxuni se compararon mediante la prueba ANOVA one-way. Las medias de los valores de PIMáxest y de PIMáxuni se compararon mediante la prueba pareada t de Student. El nivel de significancia se estableció en el 5%. La media de los valores de PIMáxest (-102,5±23,9 cmH2O) presentó una diferencia estadísticamente significativa en comparación con la media de los valores de PIMáxuni (-117,3±24,8 cmH2O, p<0,001). El valor absoluto máximo obtenido de PIMáxuni estaba dentro del intervalo de 0-20 segundos, que fue significativamente superior del valor absoluto máximo durante los primeros 5 segundos (p=0,036). El tiempo de oclusión necesario para registrar la PIMáx por el método de válvula espiratoria unidireccional en individuos colaborativos sin vía aérea artificial debe ser de al menos 20 segundos.

ABSTRACT The aim of this study was to determine how much occlusion time is necessary to obtain maximal inspiratory pressure (MIP) by the unidirectional expiratory valve method in subjects without artificial airway. Thirty-one subjects aged 18-60 years were evaluated. MIP was evaluated by the standard method (MIPstan) and by the unidirectional expiratory valve method MIPuni, with the order of evaluation determined randomly by lot. For MIPuni measurement, a digital vacuum manometer was attached to a unidirectional expiratory valve and an orofacial mask for 20 seconds of occlusion. During this period, all subjects were encouraged to make maximal respiratory efforts. To define the optimum duration of the maneuver, the 20 seconds of effort were partitioned at every five-second interval (0-5s, 0-10s, 0-15s, 0-20s). The time intervals for obtaining MIPuni were compared with the one-way ANOVA test. The mean values of the standard method and the unidirectional expiratory valve method were compared using the paired Student's t-test. The significance level was established at 5%. The mean values for the MIPstan (-102.5±23.9 cmH2O) presented a statistically significant difference as compared to the mean values for MIPuni (-117.3±24.8 cmH2O; p<0.001). Maximal peak values for MIPuni were achieved within the 20-second time window, which differed significantly from the peak values obtained during the first five seconds (p=0.036). The occlusion time necessary to record MIP by the unidirectional expiratory valve method in collaborative subjects without artificial airway should be of at least 20 seconds.

Beyond inspiratory muscle strength: Clinical utility of single-breath work capacity assessment in veterans with COPD.

BACKGROUND: Inspiratory muscle function in COPD has been traditionally described in terms of maximal inspiratory pressure (MIP). Arguably, however, is the day-to-day relevance of MIP, given that individuals rarely need maximal inspiratory forces to perform general tasks, but rather repeated breathing muscle contractions which demand endurance. The sustained maximal inspiratory pressure (SMIP) reflects the ability of the respiratory muscles to maintain force over time (i.e. single-breath work capacity). We investigated the relationships between SMIP and COPD-related clinical outcomes, hypothesizing that SMIP would have superior correlational and discriminatory value when compared to MIP. METHODS: 61 males with mild-to-very severe airflow obstruction underwent measures of spirometry, whole-body plethysmography, symptomatology, comorbidity, quality of life, exacerbations and mental health. MIP and SMIP were obtained via the Test of Incremental Respiratory Endurance. RESULTS: The mean ±â€¯SD MIP and SMIP were 77.2 ±â€¯22.9 cmH2O and 407.9 ±â€¯122.8 PTU. Both MIP and SMIP positively correlated with pulmonary function, with SMIP displaying the highest correlations. We found significant differences in spirometry, hyperinflation, symptomatology, exacerbation frequency, comorbidity, quality of life and anxiety in subjects grouped as having reduced or normal single-breath work capacity. Finally, significantly lower SMIP values were found in individuals with an IC/TLC ratio ≤25%. CONCLUSIONS: The assessment of SMIP appears to have superior clinical value than MIP in COPD. Our analyses revealed that subjects whose SMIP was reduced experienced more severe airflow obstruction, greater hyperinflation, as well as worse health and mental status with increased symptomatology and impaired quality of life.

Impairment of respiratory muscle strength in Berardinelli-Seip congenital lipodystrophy subjects.

BACKGROUND: Berardinelli-Seip Congenital Generalized Lipodystrophy (BSCL) is an ultra-rare metabolic disease characterized by hypertriglyceridemia, hyperinsulinemia, hyperglycemia, hypoleptinemia, and diabetes mellitus. Although cardiovascular disturbances have been observed in BSCL patients, there are no studies regarding the Respiratory Muscle Strength (RMS) in this type of lipodystrophy. This study aimed to evaluate RMS in BSCL subjects compared with healthy subjects. METHODS: Eleven individuals with BSCL and 11 healthy subjects matched for age and gender were included in this study. The Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP), and Peripheral Muscle Strength (PMS) were measured for three consecutive years. BSCL subjects were compared to healthy individuals for MIP, MEP, and PMS. Correlations between PMS and MIP were also analyzed. The genetic diagnosis was performed, and sociodemographic and anthropometric data were also collected. RESULTS: BSCL subjects showed significantly lower values for MIP and MEP (p <  0.0001 and p = 0.0002, respectively) in comparison to healthy subjects, but no changes in handgrip strength (p = 0.15). Additionally, we did not observe changes in MIP, MEP, and PMS two years after the first analysis, showing maintenance of respiratory dysfunction in BSCL subjects (p = 0.05; p = 0.45; p = 0.99). PMS and MIP were not correlated in these subjects (r = 0.56; p = 0.18). CONCLUSION: BSCL subjects showed lower respiratory muscle strength when compared with healthy subjects; however, PMS was not altered. These findings were maintained at similar levels during the two years of evaluation. Our data reveal the first association of BSCL with the development of respiratory muscle weakness.

The relation between leptin and inflammatory markers with respiratory and peripheral muscle strength in tuberculosis: A case-control study.

BACKGROUND: Muscle weakness is a part of the wasting syndrome associated with TB. Cytokines are candidates as the initial causative agents of the metabolic changes in TB. The objective of this study is to assess the peripheral and respiratory muscle strength in patients with TB and controls and relate these findings with leptin, IL-6 and TNF-α serum levels. METHODS: Case-control study. Hospitalized patients with pulmonary TB and controls were included. Maximal voluntary handgrip strength (HS), maximal inspiratory pressure (MIP) and maximum expiratory pressure (MEP) were measured. Leptin, IL-6 and TNF-α dosage were performed. RESULTS: We included 35 cases and 35 controls. Leptin was lower and TNF-α levels were higher in TB patients than in controls (P < .0001 for both). Body mass index (BMI), HS, MIP and MEP were all significantly lower in cases than in controls (P < .0001). Lower leptin and higher TNF-α levels are associated with malnutrition and reduced MIP, MEP and HS. Patients who reported fever and those with positive culture for Mycobacterium tuberculosis had higher serum levels of IL-6. CONCLUSION: Peripheral and respiratory muscle strength and leptin levels were reduced in patients with active TB. Lower levels of leptin and higher levels of TNF-α were associated with malnutrition and with reduced MIP, MEP and HS.

Assessment of Respiratory Muscle Weakness in Subjects With Neuromuscular Disease.

INTRODUCTION: Neuromuscular diseases (NMD) are a group of rare heterogeneous disorders that may be accompanied by respiratory muscle weakness. The simplest measurements of respiratory muscle strength are maximum inspiratory pressure (PImax) and maximum expiratory pressure (PEmax) of the mouth. Inspiratory muscle weakness can also be evaluated by the sniff test (sniff nasal inspiratory pressure method). This study tested the agreements in PImax and PEmax (measured by using a plethysmograph and portable equipment) as well as the correlations of PImax and PEmax by using the sniff nasal inspiratory pressure method, lung function, and arterial blood gas parameters in subjects with NMD. METHODS: This prospective, noninterventional study measured respiratory parameters in all the subjects with NMD who underwent measurement of maximum respiratory pressures. RESULTS: A total of 55 subjects with NMD were included. There were no statistically significant differences in PImax and PEmax measured by using a plethysmograph and portable equipment. Moreover, PImax showed a good correlation with the sniff nasal inspiratory pressure method. CONCLUSIONS: Measurements of PImax and PEmax by using portable equipment were equivalent to those performed by using the accepted standard, plethysmography, in the subjects with NMD. Noninvasive evaluation of the sniff test with the portable equipment correlates with PImax, which makes this approach a good method for measuring the maximum strength of inspiratory muscles in patients with NMD.

Assessment of Maximum Dynamic Inspiratory Pressure.

BACKGROUND: Inspiratory muscle strength has been considered an important marker of ventilatory capacity and a predictor of global performance. A new tool has become available for dynamically evaluating the maximum inspiratory pressure (the S-Index). However, the proper assessment of this parameter needs to be determined. Thus, the aim of the present study was to investigate the number of inspiratory maneuvers necessary to reach a maximum and reliable S-Index and the influence of inspiratory muscle warm-up on this assessment. METHOD: We performed a retrospective study from the database of 432 healthy subjects who underwent S-Index tests and inspiratory muscle warm-up or sham. The effect of repeated maneuvers on the S-Index and the impact of inspiratory muscle warm-up were analyzed by using the intraclass correlation coefficient and unpaired t test. RESULTS: We analyzed 81 subjects, (55% men), mean ± SD age 38.1 ± 9.6 y, 43 subjects in the inspiratory muscle warm-up group. Maximum and reliable S-Indexes were reached at the eighth maneuver in both groups preceding inspiratory muscle warm-up or sham, 102 cm H2O (95% CI 95-109 cm H2O); intraclass correlation coefficient 0.96; P < .001. Only the inspiratory muscle warm-up group presented a significant increase in the S-Index after warm-up, 13.5 cm H2O (95% CI 10-17), P < .001. CONCLUSIONS: Eight maneuvers were necessary to reach maximum and reliable values of the S-Index preceding inspiratory muscle warm-up or sham. Moreover, inspiratory muscle warm-up preceding S-Index assessment improved inspiratory muscle performance.