Relationship Between Diaphragm Thickness, Thickening Fraction, Dome Excursion, and Respiratory Pressures in Healthy Subjects: An Ultrasound Study.

PURPOSE: Diaphragm ultrasonography is used to identify causes of diaphragm dysfunction. However, its correlation with pulmonary function tests, including maximal inspiratory (MIP) and expiratory pressures (MEP), remains unclear. This study investigated this relationship by measuring diaphragm thickness, thickening fraction (TF), and excursion (DE) using ultrasonography, and their relationship to MIP and MEP. It also examined the influence of age, sex, height, and BMI on these measures. METHODS: We recruited healthy Japanese volunteers and conducted pulmonary function tests and diaphragm ultrasonography in a seated position. Diaphragm ultrasonography was performed during quiet breathing (QB) and deep breathing (DB) to measure the diaphragm thickness, TF, and DE. A multivariate analysis was conducted, adjusting for age, sex, height, and BMI. RESULTS: Between March 2022 and January 2023, 109 individuals (56 males) were included from three facilities. The mean (standard deviation) MIP and MEP [cmH2O] were 72.2 (24.6) and 96.9 (35.8), respectively. Thickness [mm] at the end of expiration was 1.7 (0.4), TF [%] was 50.0 (25.9) during QB and 110.7 (44.3) during DB, and DE [cm] was 1.7 (0.6) during QB and 4.4 (1.4) during DB. Multivariate analysis revealed that only DE (DB) had a statistically significant relationship with MIP and MEP (p = 0.021, p = 0.008). Sex, age, and BMI had a statistically significant influence on relationships between DE (DB) and MIP (p = 0.008, 0.048, and < 0.001, respectively). CONCLUSION: In healthy adults, DE (DB) has a relationship with MIP and MEP. Sex, age, and BMI, but not height, are influencing factors on this relationship.

Can inspiratory muscle training benefit patients with COVID-19? A systematic review and meta-analysis.

The possible benefits of inspiratory muscle training (IMT) on mechanical and clinical outcomes in patients with Coronavirus disease-2019 (COVID-19) remain controversial. We conducted a meta-analysis to evaluate the effect of IMT in the rehabilitation strategy of patients with COVID-19. The Pubmed, Embase, Web of Science (WOS), and Cochrane Central Register of Controlled Trials (CENTRAL) were searched to identify trials evaluating the efficacy of IMT in the treatment of patients with COVID-19. The primary outcome included change from baseline of VO2 max, maximal inspiratory pressure (PImax), 6-min walk test(6MWT), forced expiratory volume in the first second predicted (FEV1%pred), and quality of life (QOL). Six studies with 349 participants were analyzed. Significant improvements were found in change from baseline of VO2 max (MD: 4.54, 95% confidence interval [CI]: 1.79-7.30, Z = 3. 32, I2 = 0, p = 0.001), PImax (MD: 21.43, 95% CI: 1.33-41.52, Z = 2.09, I2 = 90%, p = 0.04), 6MWD (MD: 40.13, 95% CI: 24.92-55.35, Z = 5.17, I2 = 0, p < 0.00001) and FEV1%pred (MD: 8.73, 95% CI 3.07-14.39, Z = 3.02, p = 0.002) while no statistical improvements were found in QOL (SMD: 0.70, 95% CI: 0.37-1.03, Z = 4.15, I2 = 89% p = 0.32) between IMT group and control group. The application of IMT might elicit mechanical and clinical improvement in patients with COVID-19. IMT could be recommended as an effective strategy of pulmonary rehabilitation for COVID-19. However, the proper timing, optimal duration, as well as appropriate frequency and intensity of IMT remain uncertain and further studies are needed.

Effects of Modified Diaphragmatic Training on Gastroesophageal Reflux Disease Questionnaire Score, Diaphragmatic Excursion, and Maximum Inspiratory Pressure in Adults with Gastroesophageal Reflux Disease After COVID-19: A Single-Blinded Randomized Control.

BACKGROUND: Although diaphragmatic training has been shown to improve gastroesophageal reflux disease (GERD) symptoms, its effectiveness in adults with GERD after COVID-19 has not been evaluated. This study examined the effectiveness of modified diaphragmatic training (MDT) on GERD questionnaire (GERDQ) score, diaphragmatic excursion, and maximum inspiratory pressure (MIP) in adults with GERD after COVID-19. METHODS: This single-blinded randomized control trial was conducted at Persahabatan Hospital from February to April 2023. The medical records of 364 patients with persistent gastrointestinal symptoms were evaluated; among these potential participants, 302 had symptoms before, and 62 after, COVID-19 infection. Fifty of these patients fulfilled the study inclusion and exclusion criteria and were randomly assigned to the intervention (n = 25) or control (n = 25) groups. Four weeks of diaphragmatic training were followed by MDT or standard diaphragmatic training. A follow-up assessment was conducted 30 days after the beginning of the training. RESULTS: The GERDQ score was significantly decreased in the pre-post-intervention group (10.44 ± 2.00 vs 1.84 ± 2.17) and the control group (8.64 ± 0.57 vs 3.32 ± 1.49), with p < 0.001. The intervention group showed significant improvements in the right diaphragmatic excursion (RDE) (44% vs 11.87%), left diaphragmatic excursion (LDE) (46.61% vs 13.62%), and MIP (75.26% vs 23.97%) compared with the control group. CONCLUSION: MDT in adults after COVID-19 with GERD enhanced diaphragmatic excursion and MIP and decreased symptoms of gastroesophageal reflux by 8.60 points of GERDQ. Respiratory symptoms and other side effects were comparable between the groups.

Impairment of Inspiratory Muscle Function after COVID-19.

BACKGROUND: Persistent symptoms after acute coronavirus-disease-2019 (COVID-19) are common, and there is no significant correlation with the severity of the acute disease. In long-COVID (persistent symptoms >4 weeks after acute COVID-19), respiratory symptoms are frequent, but lung function testing shows only mild changes that do not explain the symptoms. Although COVID-19 may lead to an impairment of the peripheral nervous system and skeletal muscles, respiratory muscle function has not been examined in this setting. METHODS: In this study, we assessed the severity of dyspnea (NYHA-function class) in long-COVID patients and analyzed its association with body mass index (BMI), FEV1, forced vital capacity, other parameters of body plethysmography, diffusing capacity for carbon monoxide (DLCO), arterial blood gases, and inspiratory muscle function, assessed by airway occlusion pressure (P0.1) and maximal inspiratory pressure (PImax) in two respiratory clinics in Germany between Oct 2020 and Aug 2021. RESULTS: A total of 116 patients were included in the study. The mean age was 50.2 ± 14.5 years; BMI, 26.7 ± 5.87 kg/m2; NYHA class I, 19%; II, 27%; III, 41%; and IV, 14%. While lung function values and computed tomography or conventional X-ray of the chest were in the normal range, inspiratory muscle function was markedly impaired. P01 was elevated to 154 ± 83%predicted and PImax was reduced to 41 ± 25%predicted. PImax reduction was strongly associated with the severity of dyspnea but independent of BMI, time after acute COVID-19 and most of the other parameters. CONCLUSIONS: This study shows that in long-COVID patients, respiratory symptoms may be mainly caused by reduced inspiratory muscle strength. Assessment of PImax and P0.1 might better explain dyspnea than classical lung function tests and DLCO. A prospective study is needed to confirm these results.

Inspiratory muscle training for improving inspiratory muscle strength and functional capacity in older adults: a systematic review and meta-analysis.

BACKGROUND: The ageing process can result in the decrease of respiratory muscle strength and consequently increased work of breathing and associated breathlessness during activities of daily living in older adults. OBJECTIVE: This systematic review and meta-analysis aims to determine the effects of inspiratory muscle training (IMT) in healthy older adults. METHODS: A systematic literature search was conducted across four databases (Medline/Pubmed, Web of Science, Cochrane Library CINAHL) using a search strategy consisting of both MeSH and text words including older adults, IMT and functional capacity. The eligibility criteria for selecting studies involved controlled trials investigating IMT via resistive or threshold loading in older adults (>60 years) without a long-term condition. RESULTS: Seven studies provided mean change scores for inspiratory muscle pressure and three studies for functional capacity. A significant improvement was found for maximal inspiratory pressure (PImax) following training (n = 7, 3.03 [2.44, 3.61], P = <0.00001) but not for functional capacity (n = 3, 2.42 [-1.28, 6.12], P = 0.20). There was no significant correlation between baseline PImax and post-intervention change in PImax values (n = 7, r = 0.342, P = 0.453). CONCLUSIONS: IMT can be beneficial in terms of improving inspiratory muscle strength in older adults regardless of their initial degree of inspiratory muscle weakness. Further research is required to investigate the effect of IMT on functional capacity and quality of life in older adults.

Pulmonary and Inspiratory Muscle Function Response to a Mountain Ultramarathon.

The study aimed to provide within-race data on the time course of pulmonary function during a mountain ultramarathon (MUM). Additionally, we wanted to assess possible sex differences regarding pre- to post-race change in pulmonary and inspiratory muscle function. Lastly, we were interested in evaluating whether changes in respiratory function were associated with relative running speed and due to general or specific fatigue. 47 athletes (29 males and 18 females; 41 ± 5 years) were submitted to a cardiopulmonary exercise test (CPET) before a 107-km MUM. Spirometric variables: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC and peak expiratory flow (PEF); maximal inspiratory pressure (MIP); squat jump (SJ) and handgrip strength (HG) were assessed before and after the race. Additionally PEF was measured at three aid stations (33rd, 66th and 84th km) during the race. PEF declined from the 33rd to the 66th km (p = 0.004; d = 0.72) and from the 84th km to the finish line (p = 0.003; d = 0.90), while relative running speed dropped from the first (0-33 km) to the second (33-66 km) race section (p < 0.001; d = 1.81) and from the third (66-84 km) to the last race section (p < 0.001; d = 1.61). Post-race, a moderate reduction was noted in FVC (-13%; p < 0.001; d = 0.52), FEV1 (-19.5%; p < 0.001; d = 0.65), FEV1/FVC (-8.4%; p = 0.030; d = 0.59), PEF (-20.3%; p < 0.001; d = 0.58), MIP (-25.3%; p < 0.001; d = 0.79) and SJ (-31.6%; p < 0.001; d = 1.42). Conversely, HG did not change from pre- to post-race (-1.4%; p = 0.56; d = 0.05). PEF declined during the race in parallel with running speed drop. No sex differences were noted regarding post-race respiratory function, except that FEV1/FVC decay was significantly greater among women. The magnitude of pre- to post-race respiratory function decline was uncorrelated with relative running speed.

Impact of moderate-severe persistent allergic rhinitis on thoraco-abdominal kinematics and respiratory muscle function.

Objective: To assess thoraco-abdominal kinematics, respiratory muscle strength and electromyographic activity of the diaphragm (EAdi) in moderate-severe allergic rhinitis (AR) patients. Methods: A cross-sectional study involving 40 individuals (20 in the AR group) and 20 in the control group [CG]) was conducted. Ventilatory pattern and chest wall volume distribution (optoelectronic plethysmography), respiratory muscle strength (manovacuometry and sniff nasal inspiratory pressure [SNIP]), and EAdi were assessed in both groups. Results: The AR patients had impaired thoraco-abdominal kinematics (reduced total chest wall volume) (p = 0.004), lower values of total respiratory cycle time (p = 0.014) and expiratory time (p = 0.006). They also presented an increase of percentage contribution of the abdominal rib cage (p = 0.475) and respiratory rate (p = 0.019). A positive correlation among pulmonary rib cage tidal volume and MIP (r = 0.544; p < 0.001), SNIP (r = 0.615; p < 0.001), and MEP (r = 0.604; p < 0.001) was observed. After adjusting for age, BMI and gender through multivariate analysis, the individuals with AR presented lower values ​​of MIP (ß = -24.341; p < 0.001), MEP (ß = -0.277; p < 0.001), SNIP (ß = -34.687; p < 0.001) and RMS (ß = -0.041; p = 0.017). Conclusions: The individuals with moderate-severe persistent AR had worse respiratory muscle strength, diaphragm activation and chest wall volume distribution with a higher abdominal contribution to tidal volume than the control group. These findings reinforce the notion that the upper and lower airways work in an integrated and synergistic manner.

Effectiveness of Incentive Spirometry on Inspiratory Muscle Strength After Coronary Artery Bypass Graft Surgery.

BACKGROUND: Although the use of incentive spirometry with a deep breathing exercise (DBE) is widely used in clinical practice in patients who have undergone coronary artery bypass graft (CABG) surgery, the effect of this combination therapy has not been conclusively elucidated. The aim of this study was to investigate the effect of postoperative combined incentive spirometry and DBE versus DBE alone on inspiratory muscle strength following CABG. METHOD: This randomised clinical trial was conducted in patients scheduled to undergo CABG surgery at Siriraj Hospital, Bangkok Thailand. The study group received incentive spirometry and DBE, and the control group received DBE only. Maximal inspiratory pressure (MIP) before surgery and at day 4 after surgery was assessed by a respiratory pressure meter. Secondary outcomes, including postoperative pulmonary complication and duration of postoperative hospitalisation, were obtained from the medical records. RESULTS: Ninety (90) patients were included, with 47 and 43 patients assigned to the study and control groups, respectively. In both groups, there was a significant reduction in MIP from preoperative baseline to postoperative day 4; however, the MIP in the incentive spirometry group had a significantly smaller reduction in MIP compared with the control group (33.0±23.2% vs 47.2±20.1%, respectively; p=0.006, 95% confidence interval, 3.9-23.3). There was no difference between groups regarding secondary outcomes. CONCLUSIONS: Patients in the study group had significantly better recovery of inspiratory muscle strength on day 4 post-CABG than patients in the control group. There was no significant difference between groups for either postoperative pulmonary complications or length of hospital stay.

[Evaluation of the relationship between the parameters of peripheral skeletal and respiratory muscles in patients with chronic obstructive pulmonary disease].

Chronic obstructive pulmonary disease (COPD) is a group of diseases with high levels of comorbidity. Pathological changes of peripheral skeletal and respiratory muscles in COPD patients, which are often underestimated, occupy a special place. AIM: To study the relationship between functional and quantitative parameters of the peripheral (limb muscle) and respiratory muscles in COPD patients. MATERIALS AND METHODS: 127 patients (98 men/29 women, mean age 67.68.2 years) were under observation without acute COPD. All COPD patients were classified according to GOLD (2019) into groups A, B, C, D. The algorithm of the European Working Group on Sarcopenia in Older People (EWGSOP2) was used to diagnose sarcopenia. The muscle mass was measured using dual energy X-ray absorptiometry (DXA) and the appendicular lean mass index (ASM) was estimated. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured by body plethysmograph MasterScreen Body. Quantitative assessment of thoracic muscle cross-sectional areas were performed using the CT scan using Vidar Dicom Viewer software. RESULTS: Sarcopenia was diagnosed in 43.3% of COPD patients. Respiratory muscle dysfunction was determined in 66.1% of patients with COPD, its probability increased in groups C and D in comparison with groups A and B [chance ratio 6.6 (95% confidence interval 2.915.0); p0.0001]. Correlations between the functional parameters of sarcopenia and respiratory muscle strength as well as between the mass of peripheral skeletal muscles and respiratory muscle area have been established according to the data of computerized tomography (р0.01). Sarcopenia as well as respiratory muscle dysfunction was observed more frequently in persons with severe and extremely severe airway obstruction and in patients with predominantly emphysematic COPD phenotype (p0.01). CONCLUSION: Sarcopenia is a frequent comorbidity in COPD and its development is connected with the severity of the course of the main disease. Correlation between parameters of peripheral (limb muscle) and respiratory muscles in patients with COPD has been determined.

Effects of inspiratory muscle strength and inspiratory resistance on neck inspiratory muscle activation during controlled inspirations.

NEW FINDINGS: What is the central question of this study? What factors influence the onset and magnitude of activation of the neck inspiratory muscles during inspiration? What is the main finding and its importance? Recruitment of the sternocleidomastoid and scalene muscles during inspiration, measured by means of surface EMG, was strongly correlated with maximal inspiratory pressure. This result indicates that muscle recruitment depends on the capacity of an individual to generate inspiratory pressure. Surface measurements of neck inspiratory muscle EMG activity might complement tests currently used for the screening of respiratory-related disease. ABSTRACT: The aims of the present study were as follows: (i) to examine the relationship between the onset of recruitment of the neck inspiratory muscles and inspiratory muscle strength; and (ii) to clarify the effect of inspiratory resistance on neck inspiratory muscle activation during inspiration at specific flow rates and to specific lung volumes. Inspiratory muscle strength, as indicated by maximal inspiratory pressure (MIP), and peak inspiratory flow rate (PFR) were measured in healthy participants. Subsequently, participants inspired at target inspiratory flow rates between 20 and 100% of PFR as closely as possible, with and without artificial inspiratory resistance. Electromyographic activity (EMGRMS ) of the sternocleidomastoid and scalene muscles was measured from surface electrodes at each target flow rate for each 10% increment of forced vital capacity (FVC) between 20 and 50% of FVC. Recruitment onset for each muscle was determined from %PFR-EMGRMS curves at each lung volume (%FVC). Finally, linear regression analyses were performed for MIP and recruitment onset for each muscle at each %FVC. Recruitment onset during inspiration without inspiratory resistance was strongly correlated with MIP (r > 0.60, P < 0.040). Specifically, a lower MIP was associated with earlier muscle recruitment (i.e. recruitment at a lower flow rate), especially for the sternocleidomastoid muscle (r > 0.75, P < 0.005). Recruitment of both neck inspiratory muscles at a given flow rate was also earlier when inspiratory resistance was added (P = 0.002). These results indicate that the recruitment and activation of the neck inspiratory muscles depends on both inspiratory muscle strength and inspiratory resistance.

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.

Respiratory Muscle Strength as a Predictive Biomarker for Survival in Amyotrophic Lateral Sclerosis.

RATIONALE: Biomarkers for survival in amyotrophic lateral sclerosis (ALS) would facilitate the development of novel drugs. Although respiratory muscle weakness is a known predictor of poor prognosis, a comprehensive comparison of different tests is lacking. OBJECTIVES: To compare the predictive power of invasive and noninvasive respiratory muscle strength assessments for survival or ventilator-free survival, up to 3 years. METHODS: From a previously published report respiratory muscle strength measurements were available for 78 patients with ALS. Time to death and/or ventilation were ascertained. Receiver operating characteristic analysis was used to determine the cutoff point of each parameter. MEASUREMENTS AND MAIN RESULTS: Each respiratory muscle strength assessment individually achieved statistical significance for prediction of survival or ventilator-free survival. In multivariate analysis sniff trans-diaphragmatic and esophageal pressure, twitch trans-diaphragmatic pressure (Tw Pdi), age, and maximal static expiratory mouth pressure were significant predictors of ventilation-free survival and Tw Pdi and maximal static expiratory mouth pressure for absolute survival. Although all measures had good specificity, there were differing sensitivities. All cutoff points for the VC were greater than 80% of normal, except for prediction of 3-month outcomes. Sequential data showed a linear decline for direct measures of respiratory muscle strength, whereas VC showed little to no decline until 12 months before death/ventilation. CONCLUSIONS: The most powerful biomarker for mortality stratification was Tw Pdi, but the predictive power of sniff nasal inspiratory pressure was also excellent. A VC within normal range suggested a good prognosis at 3 months but was of little other value.

Exercise Capacity and Respiratory Profile in Patients after Orthopedic Liver Transplantation: a Follow-up Study.

INTRODUCTION: We sought to describe: 1) The influence of orthotopic liver transplantation (OLT) on exercise capacity, pulmonary function and respiratory muscle strength after surgery, 2) The relationship between exercise capacity and symptoms of anxiety and depression. MATERIAL AND METHODS: This is a prospective follow up study conducted with patients submitted to OLT. All patients were assessed before and 1 month after surgery through measurements: six minute walk test (6MWT), 6 min step test (6MST) and HADS (Hospital Anxiety and Depression Scale). FEV1% (forced expiratory volume), maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured in the pre-operative and on 1st, 3rd, 5th day and 1 month after surgery. RESULTS: In 77 patients , 6MWD improved 20.2 m (95%CI 8.1-32.3) and 6MST improved 7.8 steps after surgery (95%CI 3.9-11.6). Change in 6 MWD and 6 MST did not correlated with change HADS. The FEV1% at each time point were 88.8 ± 21.3 before surgery, 32.9 ± 9.9 on 1st day, 39.6 ± 11.5 on 3rd day, 46 ± 12.1 on 5th day and 86.6 ± 21.1 one month after surgery. MIP and MEP values at each time point were -67.4 ± 23.2 and 79.7 ± 26 before surgery, -30.8 ± 12.3 and 36.4 ± 15.4 on 1st day, -38.6 ± 14.1 and 43.8 ± 17 on 3rd day, -45.8 ± 15.9 and 49.7 ± 18.7 on 5th day and -67.1 ± 29.4 and 80.9 ± 23.9 one month after surgery. CONCLUSION: Exercise capacity was modestly increased after OLT without any correlation with symptoms of anxiety and depression. Pulmonary function and respiratory muscle strength decreased immediately after liver transplantation, and progressively recovered, returning to baseline values after 1 month.

The effects of inspiratory muscle training on exercise capacity, dyspnea and respiratory functions in lung transplantation candidates: a randomized controlled trial.

OBJECTIVE: To investigate whether inspiratory muscle training would contribute to the improvement of exercise capacity, dyspnea perception and respiratory functions in lung transplantation candidates. DESIGN: Prospective randomized controlled trial. SETTING: Pulmonary Rehabilitation center. SUBJECTS: A total of 34 patients with severe lung disease requiring lung transplantation were randomly allocated to either pulmonary rehabilitation plus inspiratory muscle training group (PR + IMT group, n = 17) or pulmonary rehabilitation group (PR group, n = 17) before any lung transplantation operation. METHODS: All patients underwent supervised pulmonary rehabilitation program on two days per week for three months. The PR + IMT group received inspiratory muscle training in addition to the standard pulmonary rehabilitation program. The 6-minute walk test, maximal inspiratory pressure, modified Medical Research Concile dyspnea scores and spirometric parameters were measured for each patient. RESULTS: The PR + IMT group had statistically significantly increased in walking distance (100 m, P = 0.03), maximum inspiratory pressure (26 cmH2O, P = 0.001) and alveolar volume ratio of carbonmonoxide diffusion capacity (9%, P = 0.02) than PR group. Although both groups demonstrated a statistically significant decrease in the dyspnea score, no significant differences were found between the groups ( P = 0.075). There was no change in spirometric variables in both groups. CONCLUSION: A greater increase in exercise capacity was observed in the PR + IMT group. Our study showed that inspiratory muscle training improved exercise capacity even further and increased the benefits provided by pulmonary rehabilitation.

Respiratory weakness after mechanical ventilation is associated with one-year mortality - a prospective study.

BACKGROUND: Diaphragm dysfunction in mechanically ventilated patients is associated with poor outcome. Maximal inspiratory pressure (MIP) can be used to evaluate inspiratory muscle function. However, it is unclear whether respiratory weakness is independently associated with long-term mortality. The aim of this study was to determine if low MIP is independently associated with one-year mortality. METHODS: We conducted a prospective observational cohort study in an 18-bed ICU. Adults requiring at least 24 hours of mechanical ventilation with scheduled extubation and no evidence of pre-existing muscle weakness underwent MIP evaluation just before extubation. Patients were divided into two groups: low MIP (MIP ≤30 cmH2O) and high MIP (MIP >30 cmH2O). Mortality was recorded for one year after extubation. For the survival analysis, the effect of low MIP was assessed using the log-rank test. The independent effect of low MIP on post mechanical ventilation mortality was analyzed using a multivariable Cox regression model. RESULTS: One hundred and twenty-four patients underwent MIP evaluation (median age 66 years (25(th)-75(th) percentile 56-74), Simplified Acute Physiology Score (SAPS) 2 = 45 (33-57), duration of mechanical ventilation 7 days (4-10)). Fifty-four percent of patients had low MIP. One-year mortality was 31 % (95 % CI 0.21, 0.43) in the low MIP group and 7 % (95 % CI 0.02, 0.16) in the high MIP group. After adjustment for SAPS 2 score, body mass index and duration of mechanical ventilation, low MIP was independently associated with one-year mortality (hazard ratio 4.41, 95 % CI 1.5, 12.9, p = 0.007). Extubation failure was also associated with low MIP (relative risk 3.0, 95 % CI 1, -9.6; p = 0.03) but tracheostomy and ICU length of stay were not. CONCLUSION: Low MIP is frequent in patients on mechanical ventilation and is an independent risk factor for long-term mortality in ICU patients requiring mechanical ventilation. MIP is easily evaluated at the patient's bedside. TRIAL REGISTRATION: This study was retrospectively registered in www.clinicaltrials.gov (NCT02363231) in February 2015.

Effects of inspiratory muscle training on pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation: a randomized controlled trial.

OBJECTIVE: To investigate the effects of inspiratory muscle training on pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation. DESIGN: Prospective randomized controlled single-blind study. SETTING: Cardiology department of a university hospital. SUBJECTS: A total of 38 patients with permanent atrial fibrillation were randomly allocated to either a treatment group (n = 19; age 66.2 years (8.8)) or a control group (n = 19; age 67.1 years (6.4)). METHODS: The training group received inspiratory muscle training at 30% of maximal inspiratory pressure for 15 minutes twice a day, 7 days a week, for 12 weeks alongside the standard medical treatment. The control group received standard medical treatment only. Spirometry, maximal inspiratory and expiratory pressures and 6-minute walking distance was measured at the beginning and end of the study. RESULTS: There was a significant increase in maximal inspiratory pressure (27.94 cmH2O (8.90)), maximal expiratory pressure (24.53 cmH2O (10.34)), forced vital capacity (10.29% (8.18) predicted), forced expiratory volume in one second (13.88% (13.42) predicted), forced expiratory flow 25%-75% (14.82% (12.44) predicted), peak expiratory flow (19.82% (15.62) predicted) and 6-minute walking distance (55.53 m (14.13)) in the training group (p < 0.01). No significant changes occurred in the control group (p > 0.05). CONCLUSION: Inspiratory muscle training can improve pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation.

Effects of fast expiration exercises without pressure on the respiratory muscle strength of healthy subjects.

[Purpose] The aim of this investigation was to determine the effects of 4 weeks of fast expiration exercises performed without pressure on respiratory muscle strength. [Subjects and Methods] Respiratory muscle strength of the training group that performed fast expiration exercises (n=12) was compared with that of a control group that performed no exercises (n=12). The fast expiration exercises were performed using a peak expiratory flow meter device and consisted of 20 fast expiration exercises performed 3 times per week for 4 weeks. Maximal expiratory and inspiratory pressures were evaluated as respiratory muscle strength using a spirometer pre- and post- intervention. [Results] There were significant increases in maximal expiratory pressure from 76.9 ± 29.1 to 96.1 ± 37.5 cmH2O and maximal inspiratory pressure from 80.8 ± 36.6 to 95.3 ± 37.6 cmH2O in the training group, but there was no significant difference in respiratory muscle strength between pre- and post-intervention in the control group. [Conclusion] Fast expiration exercises may be beneficial for increasing respiratory muscle strength. The findings of this study should be considered when prescribing a variation of the expiratory muscle strength training, as part of a pulmonary rehabilitation program.

Postural vital capacity difference with aging in duchenne muscular dystrophy.

INTRODUCTION: A change in vital capacity (VC) from standing to supine can be an index of diaphragm paralysis if it exceeds 25%. We aimed to verify whether the postural VC difference increases with age and reflects diaphragm weakness in DMD. METHODS: VCs were measured in DMD. Postural VC difference and percentage were calculated from the VC data. Maximal inspiratory pressure (MIP) and MIP percentage were measured as an indirect index of diaphragm weakness. RESULTS: A total of 220 patients and 544 measurements were collected. MIP and MIP percentage decreased significantly with age (P < 0.001 for both). Estimated postural VC difference and percentage also decreased (P < 0.001, P = 0.006, respectively). Age group comparisons showed a significant decrease in younger, but not older subjects. CONCLUSIONS: This study shows that the postural VC difference tended to decrease with age and might not reflect diaphragmatic weakness in DMD; however, this should be interpreted cautiously.

Evaluation of a new index of mechanical ventilation weaning: the timed inspiratory effort.

PURPOSE: The performance of most indices used to predict ventilator weaning outcomes remains below expectation. The purpose of this study was to evaluate a new weaning index, the timed inspiratory effort (TIE) index, which is based on the maximal inspiratory pressure and the occlusion time required to reach it. METHODS: This observational prospective study included patients undergoing mechanical ventilation. Patients ready to be weaned had their TIE index and 6 previously reported indices recorded. The primary end point was the overall predictive performance of the studied weaning indices (area under the receiver operating characteristic curves [AUCs]). The secondary end points were sensitivity, specificity, positive predictive value, and negative predictive value. P values <.05 were considered significant. RESULTS: From the 128 initially screened patients, the 103 patients selected for the study included 45 women and 58 men (mean age 60.8 ± 19.8 years). In all, 60 patients were weaned, 43 were not weaned, and 32 died during the study period. Tracheotomy was necessary in 61 patients. The mean duration of mechanical ventilation was 17.5 ± 17.3 days. The AUC of 3 weaning predictors (the TIE index, the integrative weaning index, and the frequency-to-tidal volume [f/Vt] ratio index) was higher than the other indices. The TIE index had the largest AUC. CONCLUSION: The TIE index performed better than the best weaning indices used in clinical practice.