MIP) And Expiratory Research Articles

Exercise Improves Respiratory Function, Body Fluid and Nitric Oxide in Hemodialysis Patients.

Emerging evidence suggests that resistance training (RT) can mitigate respiratory muscle weakness in hemodialysis (HD) patients. However, the underlying mechanisms responsible for these beneficial effects remain unclear. The purpose of this study was to assess the impact of periodized RT on respiratory muscle strength and its relationship with handgrip strength (HGS), fat-free mass (FFM), nitric oxide (NO), and interdialytic weight gain (IWG) in HD patients. Thirty-three patients were randomly assigned to two groups: control (CTL; n=18) and RT (n=15). The RT group did not perform any additional exercise training specific to the respiratory tract. Maximal inspiratory (MIP) and expiratory (MEP) pressures, peak expiratory flow (PEF), HGS, FFM, NO, and IWG were measured before and after the intervention period. Participants in the RT group engaged in a 24-week RT program, three times per week. RT resulted in significant improvements in MIP, MEP, PEF, as well as enhancements in HGS, FFM, NO, and IWG (p<0.05). Notably, inverse correlations were observed between MIP (r=-0.37, p=0.03) and PEF (r=-0.4, p=0.02) with IWG. Thus, the amelioration of HGS and FFM coincided with a reduction in respiratory muscle weakness among HD patients. Decreased IWG and increased circulating NO are plausible mechanisms contributing to these improvements.

A Secondary Analysis of Gender Respiratory Features for Ultrasonography Bilateral Diaphragm Thickness, Respiratory Pressures, and Pulmonary Function in Low Back Pain.

The aim of the present study was to determine the gender respiratory differences of bilateral diaphragm thickness, respiratory pressures, and pulmonary function in patients with low back pain (LBP). A sample of 90 participants with nonspecific LBP was recruited and matched paired by sex (45 women and 45 men). Respiratory outcomes included bilateral diaphragm thickness by ultrasonography, respiratory muscle strength by maximum inspiratory (MIP) and expiratory (MEP) pressures, and pulmonary function by forced expiratory volume during 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC spirometry parameters. The comparison of respiratory outcomes presented significant differences (p < 0.001), with a large effect size (d = 1.26-1.58) showing means differences (95% CI) for MIP of -32.26 (-42.99, -21.53) cm H2O, MEP of -50.66 (-64.08, -37.25) cm H2O, FEV1 of -0.92 (-1.18, -0.65) L, and FVC of -1.00 (-1.32, -0.69) L, with lower values for females versus males. Gender-based respiratory differences were presented for maximum respiratory pressures and pulmonary function in patients with nonspecific LBP. Women presented greater inspiratory and expiratory muscle weakness as well as worse lung function, although these differences were not linked to diaphragm thickness during normal breathing.

Assessment of maximal inspiratory and expiratory pressures in skeletal Class II patients with different growth patterns.

To evaluate maximal inspiratory (MIP) and expiratory (MEP) pressures, which are reflective of respiratory muscle strength, in skeletal Class II patients with different growth patterns (horizontal, average, and vertical) and to correlate those with airway dimension. Patients with a Class II skeletal base seeking orthodontic treatment were assigned to the following groups: average, horizontal, and vertical growth pattern. The control group (n = 14) comprised patients with a Class I skeletal base and average growth pattern. Airway dimensions were obtained using cone-beam computed tomography scans, and a spirometer with a pressure transducer was used for assessment of MIP and MEP. Routine spirometry for assessment of lung function was also performed. No significant differences were found in maximal inspiratory and expiratory pressures for the study groups in comparison with the control group. Class I patients had significantly greater oropharyngeal and nasopharyngeal airway volumes compared with the study groups. No significant difference in minimal cross-section area of the airway was observed among groups. A weak positive correlation between maximal inspiratory pressure and airway volume was observed. Although Class I patients displayed significantly greater oropharyngeal and nasopharyngeal airway volumes, there was no significant difference in respiratory muscle strength or airway function between Class II patients with different growth patterns and the Class I control group. The findings underscore the significance of exploring factors beyond craniofacial growth patterns that may contribute to sleep-related breathing disorders.

Respiratory Muscle Strength in Brazilian Adolescents: Impact of Body Composition

(1) Introduction: Studies on respiratory muscle strength (RMS) in adolescents are controversial. Few studies so far have investigated respiratory muscle strength in Brazilian adolescents and the impact of body composition on it. (2) Objective: to evaluate the respiratory muscle strength of Brazilian adolescents and compare this with nationally and internationally predicted normality values. (3) Method: A cross-sectional study (CAEE: 34634414.5.0000.5479) was carried out with 98 adolescents, where both sexes were divided into four groups: eutrophic (n = 44); overweight (n = 15), obese (n = 25), and severely obese (n = 14). All were submitted to an anthropometric assessment, body composition analysis and manovacuometry. To interpret the results, Analysis of Variance (ANOVA) with Turkey’s post hoc test was used. The Kruskal–Wallis test and Friedman’s post hoc test were used to compare the observed vs. proposed results. A p-value &lt; 0.05 was considered statistically significant. (4) Results: There were no differences among the groups for maximal inspiratory (MIP) and expiratory (MEP) pressures. However, when considering the total sample, we could say that RMS was higher among boys, and there were no significant differences in RMS in relation to the maturational stage. The values obtained for MIP were lower than those suggested for the national equation and higher than those proposed for the international equation. Similarly, the values obtained for MEP were lower than those suggested for the national and international equation. (5) Conclusions: RMS was similar in adolescents with different body compositions and different maturation stages. Adiposity did not interfere with RMS in adolescents. Boys had higher MIP and MEP values compared to girls. Therefore, the reference values proposed by the equations do not consistently match RMS in the adolescents studied. This context reinforces the need for new studies that are related to RMS to establish normality values and propose equations that represent the youth population.

Respiratory phenotypes in ALS as determined by respiratory questions of the ALSFRS-R and their relation to respiratory tests.

Respiratory insufficiency and its complications are the main cause of death in amyotrophic lateral sclerosis (ALS). Respiratory symptoms are scored in questions Q10 (dyspnoea) and Q11 (orthopnoea) of the revised ALS functional rating scale (ALSFRS-R). The association of respiratory test alterations with respiratory symptoms is unclear. Patients with ALS and progressive muscular atrophy were included. We recorded retrospectively demographic data, ALSFRS-R, forced vital capacity (FVC), maximal inspiratory (MIP) and expiratory (MEP) pressures, mouth occlusion pressure at 100ms (P0.1), nocturnal oximetry (SpO2 mean), arterial blood gases, phrenic nerve amplitude (PhrenAmpl). Three groups were categorized: G1- normal Q10 and Q11; G2- abnormal Q10; G3- abnormal Q10 and Q11 or only abnormal Q11. A binary logistic regression model explored independent predictors. We included 276 patients (153 men, onset-age 62.6±11.0yrs, disease duration 13.0±9.6mo, spinal-onset 182) with mean survival 40.1±26.0mo. Gender, onset-region and disease duration were similar in G1 (n=149), G2 (n=78) and G3 (n=49). Time to NIV was shorter in G3 (p<0.001), but survival was similar. ALSFRS-R subscores were significantly different (G1>G2>G3, p<0.001), except for lower limb subscore (p=0.077). G2 and G3 patients were older than G1 (p<0.001), had lower FVC, MIP, MEP, PhrenAmpl and SpO2 mean. Independent predictors for G2 were MIP and SpO2 mean; for G3 was only PhrenAmpl. These three distinct ALS phenotypic respiratory categories represent progressive stages of ventilatory dysfunction, supporting ALSFRS-R clinical relevance. Orthopnea is a severe symptom that should prompt NIV, being phrenic nerve response an independent predictor. Early NIV promotes similar survival for G2 and G3.

Effects of creative dance on functional capacity, pulmonary function, balance, and cognition in COPD patients: A randomized controlled trial

BackgroundExercise training is key to the comprehensive management of patients with chronic obstructive pulmonary disease (COPD). Creative dance can be an innovative approach as effective as traditional exercise training. ObjectivesThis study aimed to investigate effect of creative dance-based exercise (CDE) training on functional capacity, postural stability and balance, pulmonary and cognitive functions, respiratory and peripheral muscle strength in COPD patients. MethodsTwenty-four patients with COPD were randomly allocated to either “chest physiotherapy and home-based walking program” (PT) or “CDE alongside home-based chest physiotherapy group” (PT+CDE). Both groups performed chest PT program twice a day for 5 days per week for 8 weeks. PT+CDE group received CDE training 2 days a week for 8 weeks. Primary outcome was six minute walk test (6MWT). Secondary outcomes were postural stability and balance, pulmonary function, maximum inspiratory (MIP) and expiratory (MEP) pressure, peripheral muscle strength, Montreal Cognitive Assessment (MoCA), COPD Assessment Test (CAT), and BODE index. Outcome measures were assessed at baseline and after 8 weeks of training. ResultsBoth groups showed statistically significant improvements in 6MWT distance, MIP, MEP, MoCA score, CAT, and BODE index (p < 0.05). Only with CDE training was achieved improvements in postural stability and balance scores, pulmonary function, and peripheral muscle strength (p < 0.05). The improvements in 6 MWT distance, MEP, MoCA score, and CAT were greater in PT+CDE group (p < 0.05). ConclusionUse of creative dance training in addition to home-based chest PT program was more effective than chest PT program regarding primary and secondary outcomes in COPD patients.

Roles of alpha-7 nicotinic acetylcholine receptors and spleen in the lung injury induced by a repeated saline lavage in rat

BackgroundThe study aimed to determine whether or notα7 nicotinic acetylcholine receptors (α7nAChR) induce anti-inflammatory effects directly in the lung or through the spleen pathway in a sterile model of lung injury by saline lavage.MethodsMale Sprague Dawley rats were divided into seven groups; Sham, splenectomy (SPX), saline lavage (LAV), LAV treated with α7nAChR agonist nicotine (LAV + NIC), and LAV treated with NIC and a selective α7nAChR antagonist MLA (LAV+MLA+NIC), LAV and splenectomy (LAV+SPX), and LAV+SPX treated with nicotine (LAV+SPX+NIC). Tracheostomy and catheterization of the femoral artery were performed under deep anesthesia. Animals were subjected to volume-controlled ventilation and lung injury by 10 repeated saline lavages. Splenectomy was achieved one week before the induction of lung injury. The recovery phase lasted for 3 h, and drugs were injected 1 h after the last lavage.ResultsMean arterial blood pressure (MBP), heart rate (HR), PaO2, PaO2/FiO2 ratio, and pH decreased, whereas, maximal inspiratory (MIP) and expiratory (MEP) pressures, and PaCO2 increased 1 h after the saline lavage. Nicotine corrected entirely all the above parameters in the LAV + NIC group. MLA or SPX prevented the effects of nicotine on the above parameters, except that MLA had no extra effect on MIP or MEP. In addition, nicotine improved lung compliance in the LAV + NIC and LAV + SPX + NIC groups, though it was inhibited by MLA in the LAV + MLA + NIC group. The increases of plasma and lung tissue malondialdehyde (MDA) in the LAV group were diminished by nicotine, whereas, MLA and SPX prevented these reductions. Besides, nicotine could reduce plasma MDA in the LAV + SPX + NIC group. Total BAL cell count, protein BAL/protein plasma ratio, and lung histological scores were attenuated by nicotine in the LAV + NIC group, whereas, MLA reversed the mentioned alterations in the LAV + MLA + NIC group. However, splenectomy could not stop the decreasing effect of nicotine on the total BAL cell in the LAV + SPX + NIC group.ConclusionsIn this study, we indicated that α7nAChR and spleen play roles in cholinergic anti-inflammatory pathways in saline lavage-induced lung injury. However, our results are in favor of at least some direct effects of α 7nAChR in the lung.

Respiratory function tests in amyotrophic lateral sclerosis: The role of maximal voluntary ventilation

BackgroundPulmonary function tests are routinely used to measure progression in ALS. This study aimed to assess the change of various respiratory tests, in particular maximal voluntary ventilation (MVV), which evaluates respiratory endurance. MethodsA group of 51 patients were assessed 3 times (T1, T2, T3, separated by 5.4 months), including slow (SVC) and forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), maximal inspiratory (MIP) and expiratory (MEP) pressures, MVV, and sniff nasal inspiratory pressure (SNIP). In addition, body mass index (BMI), ALSFRS-R and phrenic nerve responses were obtained 4 times. Patients with dementia and marked bulbar involvement were excluded. ResultsMean ALSFRS-R was high at entry (42.9) and its decline was moderately slow at 0.4/month. FVC and FEV1 declined significantly in the three time frames analysed. MVV reduced significantly only between T1–T3 and SVC between T2–T3, and MIP, MEP, PEF and SNIP did not change significantly. The amplitude and the latency of the motor response of the phrenic nerve changed significantly, and BMI declined significantly in most time periods, and ALSFRS-R changed significantly in the 4 time periods. We found a strong correlation between MVV, and FVC, SVC, FEV1, SNIP, phrenic nerve amplitude/area (p < 0.001), and markedly with PEF (rho = 0.821) and ALSFRS-R (rho = 0.713). ConclusionsOur study of early affected patients supports the use of a set of volitional and non-volitional respiratory tests to assess disease progression, rather than any single test. We found MVV a potentially useful marker of pulmonary function in ALS.

Pulmonary Function and Respiratory Muscle Strength in Patients with Multiple Sclerosis.

Background In patients with multiple sclerosis (MS), there is a decline in muscle strength and physical capacity due to demyelination and axonal loss in the central nervous system. In patients with advanced MS or in a later stage of the disease, also respiratory impairment may occur. The degree of pulmonary dysfunction in the earlier stages of MS has not been thoroughly described. Therefore, the primary aims of this study are to describe pulmonary function and respiratory muscle strength in patients with a moderate disease course and to identify associations between respiratory muscle strength and functional capacity. Methods A sample of 48 patients with a diagnosis of MS and mean age 56 ± 11 years was studied using a descriptive cross-sectional design. The patients had a disease duration of 24 ± 11 years and a median Expanded Disability Status Scale (EDSS) score of 4.5 (interquartile range 4.0-6.5). Pulmonary function assessed by spirometry, respiratory muscle strength, peak cough flow and peripheral oxygen saturation, subjective breathing and coughing ability, and physical capacity measured using the 6MWT were evaluated. Results The patients had normal pulmonary function with no significant abnormalities in dynamic spirometry (vital capacity 103 ± 16% predicted, forced expiratory volume in 1 second 95 ± 15% predicted). Peak expiratory flow rate 89 ± 17% predicted was in the lower limit of normal. Respiratory muscle strength, determined by maximal inspiratory (MIP) and expiratory (MEP) static pressures, was normal but with large differences between individuals. MIP ranged from 26 to 143 cmH2O (98 ± 31% predicted); the MEP values ranged from 43 to 166 cmH2O (104 ± 29% predicted), with two patients having values below the lower limit of normal. Significant positive associations between MIP as well as MEP were found in several pulmonary function variables. A significant negative association was found between EDSS score and MEP (r = −0.312, p = 0.031). Mean peak cough flow was 389 ± 70 L/min, which is comparable with the values reported for healthy adults. The patients did not experience a severely decreased ability to take deep breaths or cough. There was a moderate correlation between MEP and physical capacity, as assessed by the 6MWT (r = 0.399, p = 0.010) and between peak expiratory flow (PEF) and the 6MWT (r = 0.311, p = 0.048). Conclusion Respiratory muscle strength, pulmonary function assessed by spirometry, and peak cough flow were normal in patients with mild to moderate MS; however, there were large individual differences demonstrating low respiratory muscle strength in some patients. Significant associations between MEP and functional capacity and between MEP and disease severity were found, indicating that patients with impaired respiratory muscle strength have lower functional capacity and more severe disease.

Influence of Lung Hyperinflation on Respiratory Muscles Pressures During a Submaximal Test in Patients With COPD: A Clinical Perspective

Background and Objective: Reduction of exercise tolerance is associated with expiratory flow-limitation (EFL) and lung hyperinflation; those are only partially reversible to bronchodilator. Lung hyperinflation lowers the diaphragm muscle provoking a mechanical disadvantage that, eventually, reduces maximal inspiratory (MIP) and expiratory (MEP) pressures. We aimed to assess the influence of the dynamic lung hyperinflation on respiratory pressures changes at rest and after a submaximal exercise test in COPD patients with and without a bronchodilator. Methods:: We prospectively analyzed 16 COPD patients (FEV1 36.4±10% pred.; age 61.0±8 years, height 165±12 cm and BMI 25.9±6 kg/m2). MIP and MEP were measured before and after performing the six minutes walking test (6MWT) with and without bronchodilator (400 mcg of albuterol). Results:: Nine of 16 patients increased IC more than 150 ml after bronchodilator use. Right after the 6MWT was accomplished without bronchodilator, IC decreased by 7.05% as compared to the 6MWT baseline value (p&lt;0.01). Nine patients decreased IC more than 150ml. After bronchodilator use, patients performed the 6MWT without any IC significant reduction (p&gt;0.05). Twelve patients increased the MIP (ranging from 70±11cmH2O to 77±10cmH2O, p = 0.0043) using 400mcg of albuterol. Thirteen patients reduced MIP after the 6MWT without bronchodilator use (p &lt;0.007). There was no significant reduction (p&gt; 0.05) in MIP when patients performed the 6MWT after bronchodilator use. We also found a significant correlation between MIP and inspiratory capacity (IC) and MEP and the IC before and after the 6MWT (r=0.61, p=0.0054; r=0.60, p=0.0031, respectively). Conclusions:: Dynamic pulmonary hyperinflation directly interferes with the ability of respiratory muscles to generate inspiratory and expiratory pressures. The previous use of bronchodilators in patients with COPD reduced dynamic hyperinflation when accomplishing a sub-maximal exercise.

RESPIRATORY MUSCLE IMPAIRMENT EVALUATED WITH MEP/MIP RATIO IN CHILDREN AND ADOLESCENTS WITH CHRONIC RESPIRATORY DISEASE.

ABSTRACTObjective: To evaluate the strength of respiratory muscles and to compare maximum inspiratory (MIP) and expiratory (MEP) pressure and MEP/MIP ratio between patients with chronic respiratory diseases and healthy individuals.Methods: Case-control study. Individuals with neuromuscular disease and post-infectious bronchiolitis obliterans were considered. In addition, they were also matched according to anthropometric and demographic characteristics with healthy children and adolescents. MIP, MEP in the three groups, and pulmonary function only in patients with chronic respiratory diseases were recorded.Results: A total of 52 subjects with CRD (25 with neuromuscular disease, and 27 with post-infectious bronchiolitis obliterans) and 85 healthy individuals were included, with an average age of 11.3±2.1 years. Patients with neuromuscular disease and post-infectious bronchiolitis obliterans presented lower MIP and MEP when compared with healthy individuals, although MEP/MIP ratio was lower in patients with neuromuscular disease (0.87±0.3) and higher in patients with post-infectious bronchiolitis obliterans (1.1±0.3) compared to the healthy group (0.97±0.2). Only in patients with neuromuscular disease a negative correlation was observed between MEP/MIP ratio and age (r=-0.50; p=0.01).Conclusions: Differences in the pattern of muscular weakness between patients with chronic respiratory diseases were observed. In patients with neuromuscular disease, a decrease in the MEP/MIP ratio depending on MIP was verified; and in those patients with post-infectious bronchiolitis obliterans, an increase in the MEP/MIP ratio depending on MIP was also observed.

Respiratory function in chronic primary fibromyalgia

Since patients with severe chronic primary fibromyalgia (CPF) report effort dyspnoea, respiratory function was studied in 87 consecutive women with CPF according to Yunus' criteria. Bernstein spirometry, maximum inspiratory (MIP) and expiratory (MEP) pressures were obtained in patients, and in a reference group of 61 healthy women. MIP was considerably lower in patients than in controls (3.6 +/- 2.0 vs. 8.0 +/- 2.2 kPa, p less than 0.0001), as was MEP (3.1 +/- 2.1 vs. 8.3 +/- 2.2 kPa, p less than 0.0001). Patients who had previously reported dyspnoea at a bicycle exercise test showed significantly lower values of respiratory pressures than patients without dyspnoea. Respiratory pressures were reproducibly low in CPF patients. Spirometric values were normal among patients and controls. We conclude that maximum expiratory and inspiratory pressures are low in CPF, a finding which may indicate respiratory muscle dysfunction in this syndrome.

Assessment of the respiratory muscles strength at patients with chronic obstructive pulmonary disease with various forms of comorbidity

To evaluate the RM power of COPD patients with various variants of comorbidity and to determine the role of comorbidity in the development of respiratory muscle dysfunction. RM strength of 64 men with exacerbation of COPD was studied. The severity of comorbidity was assessed by the Charlson index. Depending on the prevalence of comorbidity, patients were divided into 3 groups: cardiovascular, cerebrovascular and metabolic. Maximum inspiratory (MIP) and expiratory (MEP) pressures in the oral cavity, maximum rate of pressure development (MRPD), sniff nasal inspiratory pressure (SNIP), MEP/MIP and SNIP/MIP indexes were determined with MicroRPM device (UK). Measured values of MIP, MEP and SNIP were compared with the proper ones. The most noticeable decrease of RM strength was defined in the group of patients with severe comorbidity. In case of a mild comorbidity MEP and SNIP values were 68 and 78% of the predicted values and MIP value corresponded to the personified standard. RM strength of patients with COPD depended on the clinical variant of comorbidity. Thus, in the group of patients with cardiovascular variant of comorbidity auxiliary inspiratory muscles strength decreased. In the group of patients with cerebrovascular variant of comorbidity the expiratory muscles dysfunction predominated. In the group of patients with metabolic variant of comorbidity diaphragm dysfunction predominated. The pathogenetic significance of various factors of COPD comorbidity in the development of RM dysfunction was confirmed by the results of the correlation analysis.

Correlation of the sit-to-stand test, the walk test and waist circumference before cardiac surgery

The postoperative period of cardiac surgery interferes with peripheral muscle strength, which can be assessed by a 1-minute sit-to-stand test (STST). Our objective was to correlate STST and preoperative physical-functional variables and secondarily to correlate with gender, clinical and surgical variables, comorbidities, risk factors and postoperative complications. Cross-sectional and analytical study of patients undergoing elective cardiac surgery between 2010 and 2017. On the day before surgery, an evaluation was performed to quantify performance of the STST and the functional physical variables (six-minute walk test - 6MWT, respiratory muscle strength assessed by maximal inspiratory (MIP) and expiratory (MEP) pressure and waist circumference). Clinical and surgical variables (ejection fraction, time on mechanical ventilation, length of stay in the intensive care unit and total length of stay), comorbidities and risk factors (hypertension, diabetes mellitus, chronic obstructive pulmonary disease, acute myocardial infarction, smoking, alcoholism, physical inactivity and stress) and postoperative complications were collected from patient’s medical records. A population of 154 individuals obtained a mean of 17.32±5.02 repetitions in STST. There was a direct correlation with the 6MWT (r= 0.330; p= 0.004), the percentage of MIP (r= 0.115; p= 0.001) and MEP (r= 0.212; p= 0.004) and an inverse correlation with waist circumference (r= -0.238; p= 0.003) and age (r= -0.294; p= 0.001). There was a better performance of STST correlated with males (p= 0.032) and those with lower stress levels (p= 0.012). It is concluded that there is a correlation between the STST and the 6MWT, respiratory muscle strength and waist circumference, as well as male gender and stress.

Assessment of the respiratory muscles strength at various stages of ischemic stroke

To assess the power of RM in patients with IS at different stages of the disease. Power characteristics of RM of 56 patients with IS with different severity of the disease were examined after 2-4, 5-6 and 13-14 months of IS onset. Maximum inspiratory (MIP) and expiratory (MEP) pressures in the oral cavity, maximum rate of pressure development (MRPD) and sniff nasal inspiratory pressure (SNIP) were determined. A decrease in expiratory and inspiratory RM strength was shown in the early and late periods of IS, severity of which was depended on the severity of neurologic disorders. The bronchial obstruction resulted in RM dysfunction. Expiratory muscles weakness only was observed in the remote period while one third of patients had obstructive disorders of breathing. The functional activity of different RM at different IS stages was correlated with the smoking index, forced expiratory volume in the first second, forced vital capacity, skeletal muscles mass and severity of dyspnea, asthenia and disturbances of vital functions. These differences were the most obvious in elderly group of people. RM power examination of IS patients is an important mechanism of early diagnosis and rehabilitation.

Presiones inspiratoria y espiratoria máximas: Recomendaciones y procedimiento

The measurement of maximal inspiratory (MIP) and expiratory (MEP) pressures assess the strength of the respiratory muscles. These test are a simple, quick, and noninvasive. It consists that the patient must generate peak inspiratory (from residual volume) and expiratory pressure (from total lung capacity) against an occluded system. MIP assesses the diaphragmatic strength; while MEP assess the intercostal and abdominal muscles. Maximum respiratory pressures are of great clinical utility in the diagnosis and monitoring of diseases affecting the respiratory muscles. In order to improve quality and facilitate the realization of the measurement of MIP-MEP, we review international recom- mendations on this procedure and issue local guidelines that contribute to a better standardization process.

Unilateral diaphragm paralysis: a dysfunction restricted not just to one hemidiaphragm

BackgroundMost patients with unilateral diaphragm paralysis (UDP) have unexplained dyspnea, exercise limitations, and reduction in inspiratory muscle capacity. We aimed to evaluate the generation of pressure in each hemidiaphragm separately and its contribution to overall inspiratory strength.MethodsTwenty-seven patients, 9 in right paralysis group (RP) and 18 in left paralysis group (LP), with forced vital capacity (FVC) < 80% pred, and 20 healthy controls (CG), with forced expiratory volume in 1 s (FEV1) > 80% pred and FVC > 80% pred, were evaluated for lung function, maximal inspiratory (MIP) and expiratory (MEP) pressure measurements, diaphragm ultrasound, and transdiaphragmatic pressure during magnetic phrenic nerve stimulation (PdiTw).ResultsRP and LP had significant inspiratory muscle weakness compared to controls, detected by MIP (− 57.4 ± 16.9 for RP; − 67.1 ± 28.5 for LP and − 103.1 ± 30.4 cmH2O for CG) and also by PdiTW (5.7 ± 4 for RP; 4.8 ± 2.3 for LP and 15.3 ± 5.7 cmH2O for CG). The PdiTw was reduced even when the non-paralyzed hemidiaphragm was stimulated, mainly due to the low contribution of gastric pressure (around 30%), regardless of whether the paralysis was in the right or left hemidiaphragm. On the other hand, in CG, esophagic and gastric pressures had similar contribution to the overall Pdi (around 50%). Comparing both paralyzed and non-paralyzed hemidiaphragms, the mobility during quiet and deep breathing, and thickness at functional residual capacity (FRC) and total lung capacity (TLC), were significantly reduced in paralyzed hemidiaphragm. In addition, thickness fraction was extremely diminished when contrasted with the non-paralyzed hemidiaphragm.ConclusionsIn symptomatic patients with UDP, global inspiratory strength is reduced not only due to weakness in the paralyzed hemidiaphragm but also to impairment in the pressure generated by the non-paralyzed hemidiaphragm.

Respiratory muscle strength is decreased after maximal incremental exercise in trained runners and cyclists

The respiratory muscle fatigue seems to be able to limit exercise performance and may influence the determination of maximal oxygen uptake (V̇O2max) or maximum aerobic work rate during maximal incremental test. The aim of this study was therefore to investigate whether maximal incremental exercise decreases respiratory muscle strength. We hypothesized that respiratory muscle strength (maximal pressure) will decrease after maximal incremental exercise to exhaustion. 36 runners and 23 cyclists completed a maximal incremental test on a treadmill or a cycle ergometer with continuous monitoring of expired gases. Maximal inspiratory (MIP) and expiratory (MEP) pressure measurements were taken at rest and post- exercise. At rest, the MIP and MEP were 140±25 and 172±27 in runners vs. 115±26 and 146±33 in cyclists (p<0.05 between groups, respectively). The rest values of MIP and MEP were correlated to the V̇O2peak in all athletes, r=0.34, p<0.01 and r=0.36, p<0.01, respectively. At exhaustion, the MIP and MEP decreased significantly post- test by 13±7% and 13±5% in runners vs. 17±11% and 15±10% in cyclists (p>0.05), respectively. Our results suggest that respiratory muscle strength is decreased following maximal incremental exercise in trained runners and cyclists.

Comparison of slow and forced vital capacities on ability to predict survival in ALS

Introduction: Slow (SVC) and forced (FVC) vital capacities are the most used pulmonary function tests in amyotrophic lateral sclerosis (ALS). It is unknown if they equally predict survival in ALS. The aim of the present study was to compare both measures in predicting survival in this disease. Methods: Consecutive definite/probable ALS patients (2000–2014) in whom respiratory tests were performed at baseline and four months later were included. All patients were evaluated with the revised ALS functional rating scale (ALSFRS-R), respiratory (RofALSFRS-R), bulbar (ALSFRSb), upper and lower limb subscores, SVC, FVC, maximal inspiratory (MIP) and expiratory (MEP) pressures. King’s functional staging system was applied retrospectively. Survival analysis was carried out by univariate Kaplan-Meier log-rank test. Multivariate Cox proportional hazards model determined significant independent variables. Results: We included 469 patients (270 males; mean onset age 61.0 ± 11.5 years; mean disease duration from first symptoms to first visit: 15.8 ± 16.1months; 329 spinal and 140 bulbar onset). FVC and SVC were strongly correlated (r2 = 0.981, p < 0.001). Significant survival prognostic variables (Kaplan-Meier analyses) were onset region, age, disease duration, ALSFRS-R, ALSFRSb, RofALSFRS-R, ALSFRS-R decay, SVC, FVC, MIP, MEP and King’s staging (p ≤ 0.01). Final Cox model including the significant variables showed similar results for FVC and SVC (p < 0.001). Moreover, 1% decrease in either predicted values increased death probability by 1.02. Conclusion: FVC and SVC are inter-changeable in predicting survival in ALS.

Respiratory and locomotor muscle implications on the VO2 slow component and the VO2 excess in young trained cyclists

We investigated the impact of ramp and constant-load exercise on (i) respiratory muscle fatigue and locomotor muscle oxygenation, (ii) their relationship with the excess VO2 and VO2 slow component (SC). Fourteen male cyclists performed two tests to exhaustion: an incremental ramp and a constant-load exercise with continuous monitoring of expired gases and oxygenation of the vastus lateralis muscle on two separate days. Maximal inspiratory (MIP) and expiratory (MEP) pressure measurements were taken at rest and post- exercise. The VO2 excess represents the difference between VO2max observed and VO2max expected using linear equation between the VO2 and the intensity before gas-exchange threshold. During the ramp exercise, MIP and MEP declined by 13±8 and 19±10%, respectively (p<0.05). MIP and MEP were not correlated to the excess VO2 (0.09±0.05lmin−1). During the constant-load exercise, the VO2 SC (0.70±0.22lmin−1) was correlated (r=0.68, p<0.01) to deoxyhemoglobin SC (2.94±1.25AU) but not to the excess VO2 (r=0.30, p=0.2). Additionally, the significant decrease in MIP (20±9%) and MEP (23±11%) was correlated (r=0.55, p<0.05 and r=0.75, p<0.05, respectively) to the VO2 SC. Our results show that respiratory muscle fatigue was correlated to the VO2 SC in the constant-load exercise, whereas it was not correlated to the excess VO2 in ramp exercise may be because of our small excess VO2.