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.

Agreement between clinical and non-clinical digital manometer for assessing maximal respiratory pressures in healthy subjects.

Measurement of respiratory muscles strength such as maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) are used to detect, diagnose and treat respiratory weakness. However, devices used for these measurements are not widely available and are costly. Currently, the use of a digital manometer is recommended. In industry, several inexpensive devices are available, but these have not been validated for clinical use. Our objective was to determine the agreement between maximal respiratory pressures obtained with a clinical digital manometer and that with a non-clinical digital manometer in healthy volunteers. We assessed the height, weight, lung function, MIP, and MEP of healthy volunteers. To compare pressures obtained by each type of digital manometer, a parallel approach configuration was used. The agreement was measured with the Intraclass Coefficient Correlation (ICC) and the Bland-Altman plot. Twenty-seven participants (14 men) were recruited with a median age of 22 (range: 21-23) years. Each participant underwent three measurements to give a total of 81 measurements. The mean MIPs were 90.8 ± 26.4 (SEM 2.9) and 91.1 ± 26.4 (SEM 2.9) cmH2O for the clinical and non-clinical digital manometers, respectively. The mean MEPs were 113.8 ± 40.4 (SEM 4.5) and 114.5 ± 40.5 (SEM 4.5) cmH2O for the clinical and non-clinical digital manometers, respectively. We obtained an ICC of 0.998 (IC 0.997-0.999) for MIP and 0.999 (IC 0.998-0.999) for MEP. There is a high agreement in the values obtained for MIP and MEP between clinical and non-clinical digital manometers in healthy volunteers. Further validation at lower pressures and safety profiling among human subjects is needed.

Análisis comparativo de los valores de las presiones respiratorias máximas con los valores de referencia en una población adulta sana / Comparative analysis of maximal respiratory pressures with the reference values of a healthy adult population

Antecedentes y objetivo: La determinación de las presiones respiratorias máximas es un procedimiento no invasivo de gran utilidad clínica para la evaluación de la fuerza de los músculos respiratorios. El objetivo es analizar en qué medida las ecuaciones predictivas existentes para población española, se ajustan a los valores observados de presión inspiratoria y espiratoria máximas (PEM y PIM) en una muestra de sujetos adultos sanos. Material y métodos: Estudio descriptivo observacional de corte transversal en el que se reclutaron 63 sujetos sanos mediante muestreo probabilístico aleatorizado simple entre la comunidad universitaria de la Universidade da Coruña. Las presiones respiratorias máximas se efectuaron con un transductor de presiones conectado a una boquilla de submarinista, siguiendo las recomendaciones de la Sociedad Española de Neumología y Cirugía Torácica (SEPAR). Se compararon los resultados con las ecuaciones de Morales de 1997. Resultados: Se presentan los datos de 24 mujeres y 39 hombres (45,94 ± 16,71 años). Existe una diferencia estadísticamente significativa en las mujeres de -19,08 ± 23,57 cmH2O y de -28,13 ± 29,93 cmH2O para la PIM y la PEM, respectivamente, entre el valor observado y el valor predicho. Asimismo, en el caso de los hombres se observó una diferencia estadísticamente significativa de -25,18 ± 24,31 cmH2O para la PIM y de -39,53 ± 44,38 cm H2O para la PEM. Conclusiones: Las ecuaciones predictivas disponibles para las presiones respiratorias máximas sobreestiman considerablemente los valores alcanzados de la PIM y la PEM. Los resultados del presente estudio ponen de manifiesto la necesidad de realizar nuevas ecuaciones de referencia a través de un estudio multicéntrico representativo de toda la población española

Background and aim: The determination of maximal respiratory pressures is a non-invasive process of high clinical value for assessing respiratory muscle strength. The aim is to analyse to what extent the existing predictive equations for the Spanish population are adjusted to the maximal inspiratory and expiratory pressures (MIP and MEP) values observed in a sample of healthy adult subjects. Material and methods: A cross-sectional study was conducted on a sample of 63 healthy subjects recruited from the A Coruña University community using a simple random probabilistic method. Maximal respiratory pressures were performed using a pressure transducer connected to a scuba mouthpiece according to the standards of Spanish Society of Pulmonology and Thoracic Surgery (SEPAR). The results were compared with predictive equations proposed by Morales in 1997. Results: The study included the results from 24 females and 39 males (45.94 ± 16.71 years). Females showed a statically significant difference between the observed and predictive values, with -19.08 ± 23.57 cm H2O and -28.13 ± 29.93 cm H2O for MIP and MEP. A statistically significant difference was also observed for males with -25.18 ± 24.31 cm H2O for MIP and -39.53 ± 44.38 cm H2O for MEP. Conclusions: Predictive equations to calculate the theoretical values of maximal respiratory pressures in a healthy Spanish adult population overestimate considerably the real values of MIP and MEP. The results of this study highlight the need to create new reference equations by conducting a multicentre study representative of the entire Spanish population

Titration of Mechanical Insufflation-Exsufflation Optimal Pressure Combinations in Neuromuscular Diseases by Flow/Pressure Waveform Analysis / Titulación de las combinaciones de presión óptima de insuflación-exuflación mecánica en las enfermedades neuromusculares mediante análisis de la onda de fujo/presión

Introduction: The aim of this study was to assess several air-pressure settings for MI-E to determine their effect on peak cough flow (PCF), and to compare the best pressures with those are more common used in the literature (±40cmH2O) in patients with neuromuscular disorders (NMD). Methods: Adults with NMD in whom MI-E was indicated were recruited. Assisted PCF was measured by an external pneumotachograph. The protocol included 9 PCF measures per patient: 1 baseline (non-assisted), 4 with increasing inspiratory pressures without negative pressure (10, 20, 30 and 40cmH2O or maximum tolerated), and then 4 adding expiratory pressures (-10, -20, -30 and -40cm H2O or maximum tolerated) with maximum inspiratory pressure previously achieved. Results: Twenty one patients were included, 61% with amyotrophic lateral sclerosis (ALS). Mean PCFs with recommended pressures (± 40 cmH2O) were lower than the scored in the individualized steps of the titration protocol (197.7 ± 67l/min vs 214.2 ± 60 l/min, p < 0.05). Regarding subgroups, mean PCFmax values in ALS patients with bulbar symptoms were significantly higher than those achieved with recommended pressures (163.6 ± 80 vs 189 ± 66l/min, p < 0.05). Conclusion: The PCFmax obtained with the protocol did not always match the recommended settings. It may be advisable to perform MI-E titration assessed by non-invasive PCF monitoring in patients with NMD, especially in ALS with bulbar involvement to improve the therapy detecting airway collapse induced by high pressures

Introducción: El objetivo del estudio fue evaluar varios ajustes de presión para insuflación-exuflación mecánica (IEM) para determinar su efecto sobre el flujo pico de tos (FPT), y comparar las mejores presiones con aquellas que son habitualmente utilizadas en la literatura (± 40 cmH2O) en pacientes con enfermedades neuromusculares (ENM). Métodos: Se reclutaron adultos con ENM en los que se indicó IEM. Se midió el FPT asistido mediante un neumotacógrafo externo, y se registraron las curvas de presión y flujo/tiempo. El protocolo incluía 9 medidas de FPT por paciente: una basal (no asistida), 4 con presiones inspiratorias crecientes sin presión negativa (10, 20, 30 y 40 cmH2O o máximo tolerado), y luego 4 presiones espiratorias (-10, -20, -30, -40 cmH2O o máxima tolerada) con la presión inspiratoria máxima conseguida. Resultados: Se incluyeron 21 pacientes, 61% con esclerosis lateral amiotrófica (ELA). Las altas presiones (>±35 cmH2O) lograron el mejor FPT solo en el 50% de los sujetos. Los FPT medios con presiones recomendadas de ± 40 cmH2O (197,7 ± 67 l/min) fueron más bajos que los conseguidos con presiones de titulación individualizadas con el protocolo (214,2 ± 60 l/min, p < 0,05). Con respecto a los subgrupos, los valores medios de FPT máximos en los pacientes con ELA con síntomas bulbares fueron significativamente mayores que los logrados con las presiones recomendadas (163,6±80 frente a 189 ± 66 l/min p < 0,05). Conclusión: El FPT máximo obtenido con el protocolo no siempre coincide con las presiones más altas. Puede ser aconsejable realizar una valoración de IEM evaluada mediante monitorización no invasiva de FPT en pacientes con ENM, especialmente en ELA con afectación bulbar, para mejorar la terapia que detecta el colapso de la vía aérea inducida por altas presiones

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.

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.

A Rapid, Handheld Device to Assess Respiratory Resistance: Clinical and Normative Evidence.

INTRODUCTION: Following reports of respiratory symptoms among service members returning from deployment to South West Asia (SWA), an expert panel recommended pre-deployment spirometry be used to assess disease burden. Unfortunately, testing with spirometry is high cost and time-consuming. The airflow perturbation device (APD) is a handheld monitor that rapidly measures respiratory resistance (APD-Rr) and has promising but limited clinical data. Its speed and portability make it ideally suited for large volume pre-deployment screening. We conducted a pilot study to assess APD performance characteristics and develop normative values. MATERIALS AND METHODS: We prospectively enrolled subjects and derived reference equations for the APD from those without respiratory symptoms, pulmonary disease, or tobacco exposure. APD testing was conducted by medical technicians who received a 10-min in-service on its use. A subset of subjects performed spirometry and impulse oscillometry (iOS), administered by trained respiratory therapists. APD measures were compared with spirometry and iOS. RESULTS: The total study population included 199 subjects (55.8% males, body mass index 27.7 ± 6.0 kg/m2, age 49.9 ± 18.7 yr). Across the three APD trials, mean inspiratory (APD-Ri), expiratory (APD-Re), and average (APD-Ravg) resistances were 3.30 ± 1.0, 3.69 ± 1.2, and 3.50 ± 1.1 cm H2O/L/s. Reference equations were derived from 142 clinically normal volunteers. Height, weight, and body mass index were independently associated with APD-Ri, APD-Re, and APD-Ravg and were combined with age and gender in linear regression models. APD-Ri, APD-Re, and APD-Ravg were significantly inversely correlated with FEV1 (r = -0.39 to -0.42), FVC (r = -0.37 to -0.40), and FEF25-75 (r = -0.31 to -0.35) and positively correlated with R5 (r = 0.61-0.62), R20 (r = 0.50-0.52), X5 (r = -0.57 to -0.59), and FRES (r = 0.42-0.43). Bland-Altman plots showed that the APD-Rr closely approximates iOS when resistance is normal. CONCLUSION: Rapid testing was achieved with minimal training required, and reference equations were constructed. APD-Rr correlated moderately with iOS and weakly with spirometry. More testing is required to determine whether the APD has value for pre- and post-deployment respiratory assessment.

Optimal method for assessment of respiratory muscle strength in neuromuscular disorders using sniff nasal inspiratory pressure (SNIP).

BACKGROUND: The ability to accurately determine respiratory muscle strength is vitally important in patients with neuromuscular disorders (NMD). Sniff nasal inspiratory pressure (SNIP), a test of inspiratory muscle strength, is easier to perform for many NMD patients than the more commonly used determination of maximum inspiratory pressure measured at the mouth (MIP). However, due to an inconsistent approach in the literature, the optimal technique to perform the SNIP maneuver is unclear. Therefore, we systematically evaluated the impact of performing the maneuver with nostril contralateral to the pressure-sensing probe open (SNIPOP) versus closed (SNIPCL), on determination of inspiratory muscle strength in NMD patients as well as control subjects with normal respiratory muscle function. METHODS: NMD patients (n = 52) and control subjects without respiratory dysfunction (n = 52) were studied. SNIPOP, SNIPCL, and MIP were measured during the same session and compared using ANOVA. Agreement and bias were assessed with intraclass correlation coefficients (ICC) and Bland-Altman plots. RESULTS: Mean MIP values were 58.2 and 94.0 cmH2O in NMD and control subjects, respectively (p<0.001). SNIPCL was greater than SNIPOP in NMD (51.9 ±31.0 vs. 36.9 ±25.4 cmH2O; p<0.001) as well as in controls (89.2 ±28.1 vs. 69.2 ±29.2 cmH2O; p<0.001). In both populations, the ICC between MIP and SNIPCL (NMD = 0.78, controls = 0.35) was higher than for MIP and SNIPOP (NMD = 0.53, controls = 0.06). In addition, SNIPCL was more often able to exclude inspiratory muscle weakness than SNIPOP. CONCLUSIONS: SNIPCL values are systematically higher than SNIPOP in both normal subjects and NMD patients. Therefore, SNIPCL is a useful complementary test for ruling out inspiratory muscle weakness in individuals with low MIP values.