Inspiratory Muscle Weakness Research Articles

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

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. This systematic review and meta-analysis aims to determine the effects of inspiratory muscle training (IMT) in healthy older adults. 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 (>60years) without a long-term condition. 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). 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.

Responses to progressive exercise in subjects with chronic dyspnea and inspiratory muscle weakness

Inspiratory muscle weakness (IMW) is a potential cause of exertional dyspnea frequently under-appreciated in clinical practice. Cardiopulmonary exercise testing (CPET) is usually requested as part of the work-up for unexplained breathlessness, but the specific pattern of exercise responses ascribed to IMW is insufficiently characterized. To identify the physiological and sensorial responses to progressive exercise in dyspneic patients with IMW without concomitant cardiorespiratory or neuromuscular diseases. Twenty-three subjects (18 females, 55.2±16.9 years) complaining of chronic daily life dyspnea (mMRC = 3 [2-3]) plus maximal inspiratory pressure < the lower limit of normal and 12 matched controls performed incremental cycling CPET. FEV1/FVC<0.7, significant abnormalities in chest CT or echocardiography, and/or an established diagnosis of neuromuscular disease were among the exclusion criteria. Patients presented with reduced aerobic capacity (peak V̇O2: 79±26 vs 116±21 %predicted), a tachypneic breathing pattern (peak breathing frequency/tidal volume = 38.4 ± 22.7 vs 21.7 ± 14.2 breaths/min/L) and exercise-induced inspiratory capacity reduction (-0.17 ± 0.33 vs 0.10 ± 0.30 L) (all P < .05) compared to controls. In addition, higher ventilatory response (ΔV̇E/ΔV̇CO2 = 34.1±6.7 vs 27.0±2.3 L/L) and symptomatic burden (dyspnea and leg discomfort) to the imposed workload were observed in patients. Of note, pulse oximetry was similar between groups. Reduced aerobic capacity in the context of a tachypneic breathing pattern, inspiratory capacity reduction and preserved oxygen exchange during progressive exercise should raise the suspicion of inspiratory muscle weakness in subjects with otherwise unexplained breathlessness.

Inspiratory Muscle Training in Patients With Heart Failure: What Is New? Systematic Review and Meta-Analysis.

The benefits of inspiratory muscle training (IMT) have already been demonstrated in patients with heart failure (HF), but the best mode of training and which patients benefit from this intervention are not clear. The purpose of this study was to review the effects of IMT on respiratory muscle strength, functional capacity, pulmonary function, quality of life, and dyspnea in patients with HF; IMT isolated or combined with another intervention (combined IMT), the presence of inspiratory muscle weakness, training load, and intervention time were considered. The search included the databases MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Physiotherapy Evidence Database, and LILACS database through September 2019. The review included randomized studies that assessed IMT in isolation or combined with another intervention-in comparison with a control group, a placebo, or another intervention-in patients with HF. Fourteen studies were included, 13 for meta-analysis (10 for isolated IMT and 3 for combined IMT). Isolated IMT demonstrated an increase in maximal inspiratory pressure (MIP) (25.12cm H2O; 95% CI=15.29 - 34.95), 6-Minute Walk Test (81.18m; 95% CI=9.73 - 152.63), maximum oxygen consumption (12weeks: 3.75mL/kg/min; 95% CI=2.98 to 4.51), and quality of life (-20.68; 95% CI=-29.03 to -12.32). The presence of inspiratory muscle weakness, higher loads, and longer intervention times resulted in greater increases in MIP. IMT combined with another intervention demonstrated an increase only in MIP. Isolated IMT resulted in an increase in inspiratory muscle strength, functional capacity, and quality of life. IMT combined with another intervention resulted only in a small increase in inspiratory strength. Isolated IMT with higher loads can be considered an adjuvant intervention, especially for those who do not adhere to conventional rehabilitation and who have respiratory muscle weakness. A systematic review was necessary to review the effects of IMT on respiratory muscle strength, lung function, functional capacity, quality of life, and dyspnea in patients with HF. Various clinical issues important for a better training prescription were considered; these included whether the performance of the training IMT as a form of isolated training benefits patients with HF, whether the combination of IMT with another intervention has additional effects, whether any patient with HF can benefit from IMT (alone or combined with another intervention), and whether only patients who already have respiratory muscle weakness benefit. Also important was establishing which training load provides the best result and the best intervention time, so that health care can be provided more efficiently. For people with heart failure, IMT by itself, without being combined with other exercise, can improve ease of breathing, increase the amount of distance that they can walk, and improve quality of life. Inspiratory training with higher loads might be helpful for those with respiratory muscle weakness who are unable to do conventional exercise.

Effect of inspiratory muscle training on respiratory muscle strength and functional capacity in patients with type 2 diabetes mellitus: A randomized clinical trial.

Type 2 diabetes mellitus (T2DM) is usually associated with respiratory manifestations including inspiratory muscle weakness which affects exercise capacity. The present study aimed to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and exercise capacity in patients with Type 2 diabetes mellitus (T2DM). This was a randomized controlled trial in patients with type 2 diabetes mellitus with no previous cardiopulmonary or neuromuscular diseases. Patients had no back pain. Patients were randomized into interventional or placebo groups. Sniff nasal inspiratory pressure (SNIP), maximum inspiratory pressure (MIP), and six-minute walking test (6MWT) were measured at baseline and 8 weeks post incremental inspiratory muscle training. At baseline, interventional and placebo groups were similar in age, body mass index, sex inspiratory muscle strength, and exercise capacity. After 8 weeks of incremental inspiratory muscle training at 40% of MIP, the interventional group had a significant increase in the SNIP (mean difference: 18.5 ± 5.30 cm H2O vs 2.8 ± 4.8 cm H2O) and MIP (mean difference: 19.4 ± 4.3 Vs 5.4 ± 3.6 cm H2O) compared to the placebo group, respectively. The interventional group showed improvement in the 6MWT (mean difference: 70 ± 29 m vs 34 ± 24 m) compared to the placebo group, P < .05. Incremental inspiratory muscle training increased the diaphragm strength in patients with T2DM and improved exercise capacity.

What is the prevalence of inspiratory muscle weakness in preoperative cardiac surgery patients? An observational study

BackgroundIn patients undergoing elective cardiac surgery, the prevalence of inspiratory muscle weakness is not well-understood. This information could guide pre-operative therapy. ObjectivesTo determine the prevalence of inspiratory muscle weakness in preoperative cardiac surgery patients, and describe relationships between pre-operative factors (including maximal inspiratory pressure, MIP) and post-operative pulmonary complications (PPCs). MethodsProspective study of elective cardiac surgery patients. Pre-operative MIP was measured (cmH2O) and PPC data were extracted from medical records (Melbourne Group Score) while age, height, weight, frailty and physical activity levels were captured via questionnaire. Backwards-stepwise logistic regression was used to describe associations. Results24 participants were recruited (79% male, age 70 ± 10.7, BMI 26.8 ± 4.14). The prevalence of inspiratory muscle weakness (MIP < 60% predicted) was 25% (n = 6). PPCs were associated with body mass index (BMI) (r = 0.464, p = 0.022). ConclusionThe prevalence of pre-operative inspiratory muscle weakness was 25%. BMI may be an important determinant of PPCs in elective cardiac surgery patients.

Inspiratory muscle dysfunction and restrictive lung function impairment in congenital heart disease: Association with immune inflammatory response and exercise intolerance

BackgroundIn adult patients with congenital heart disease (ACHD), both underlying disease and lung restriction contribute to exercise intolerance. In ACHD the yet incompletely understood mechanism underlying restricted ventilation may be inspiratory muscle weakness. Therefore, this study comprehensively evaluated inspiratory muscle function in ACHD and associations with systemic inflammation and the clinical severity of exercise intolerance. Methods30 ACHD patients (21 men, 35 ± 12 years) and 30 healthy controls matched for age, gender and body mass index underwent spirometry, measurement of mouth occlusion pressures, and diaphragm ultrasound. Six-minute walking distance (6MWD) and New York Heart Association functional class were used to quantify exercise intolerance. Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) levels were measured using enzyme-linked immunosorbent assays. ResultsACHD patients showed lower forced vital capacity (FVC), and maximum inspiratory (PImax) and expiratory (PEmax) pressures compared with controls (all p < 0.05). On ultrasound, ACHD patients showed a lower diaphragm thickening ratio (2.3 ± 0.5 vs. 2.8 ± 0.9, p < 0.01) and lower diaphragm excursion velocity during a voluntary sniff maneuver (5.7 ± 2.2 vs. 7.6 ± 2.0 cm/s, p < 0.01). Respiratory parameters, such as FVC (r = 0.53; p < 0.01) and PImax (r = 0.43; p = 0.02), correlated with 6MWD. Furthermore, amino terminal pro B-type natriuretic peptide levels were inversely correlated with FVC (r = −0.54; p < 0.01). Circulating pro-inflammatory cytokines were markedly increased, and IL-6 was correlated with 6MWD, dyspnea, and biomarkers of heart, lung and inspiratory muscle function (all p < 0.05). ConclusionsOur findings show that diaphragm dysfunction is present in ACHD and relates to restrictive ventilation disorder and exercise intolerance, possibly mediated by increased IL-6 levels.

Evidence of diaphragmatic dysfunction with severe alveolar hypoventilation syndrome in mitochondrial respiratory chain deficiency

Diaphragmatic dysfunction has been reported in congenital myopathies, muscular dystrophies, and occasionally, mitochondrial respiratory chain deficiency. Using a minimally invasive procedure in 3 young girls, 1 with a heteroplasmic MT-CYB mutation and 2 with biallelic pathogenic TK2 variants, we provided functional evidence of diaphragmatic dysfunction with global respiratory muscle weakness in mitochondrial respiratory chain deficiency. Analysis of respiratory muscle performance using esogastric pressures revealed paradoxical breathing and severe global inspiratory and expiratory muscle weakness with a sniff esophageal inspiratory pressure and a gastric pressure during cough averaging 50% and 40% of predicted values, respectively. This diaphragmatic dysfunction was responsible for severe undiagnosed nocturnal hypoventilation, requiring noninvasive ventilation. Our results underline the interest of this minimally invasive procedure for the evaluation of respiratory muscle performance and its potential value for the monitoring of future clinical trials in respiratory chain deficiency.

Inspiratory Muscle Training in Patients with Heart Failure.

Background: Prior systematic reviews and meta-analysis addressed that inspiratory muscle training (IMT) improved inspiratory muscle weakness, cardiorespiratory fitness and quality of life similar to conventional exercise training as a first alternative in deconditioned patients with heart failure (HF) lead to a better adaptation to posterior exercise training. The heterogeneity and variability in a wide range of new studies about this topic led to the necessity of an updated and comprehensive narrative review. The present review aimed to analyze and update the most relevant studies about IMT in patients who suffer from HF. Methods: A narrative review was carried out about IMT in HF patients including 26 experimental studies divided into 21 clinical trials and 5 quasi-experimental studies identified through database searching in PubMed, Cochrane and PEDro. Results: There is enough evidence to state that IMT produces improvements in functional capacity of patients with HF. Nevertheless, there is not enough evidence to support that IMT could improve cardiovascular parameters, blood biomarkers or quality of life in these patients. Conclusions: Thus, IMT may be recommended to improve functional capacity in patients who suffer from HF; nevertheless, more evidence is needed regarding cardiovascular parameters, biomarkers and quality of life. Furthermore, mortality or HF hospitalization was not evaluated and most studies were not longer than 3 months. According to IMT protocols and study designs heterogeneity and mid-term follow-up, further investigations through high-quality long-term randomized clinical trials should be performed to achieve systematic reviews and meta-analysis to support strong evidence for IMT in HF patients.

Community-dwelling individuals with stroke, who have inspiratory muscle weakness, report greater dyspnea and worse quality of life

The objective of the present study was to investigate if different levels of inspiratory muscle strength would be associated with dyspnea, walking capacity, and quality of life after stroke. For this exploratory study, the dependent outcome was strength of the inspiratory muscles, measured by maximal inspiratory pressure. Individuals with maximal inspiratory pressure ≥80 cmH2O were classified as non-weak, those with maximal inspiratory pressure between 45 and 80 cmH2O were classified as weak, and those with maximal inspiratory pressure ≤45 cmH2O were classified as very weak. Related outcomes included dyspnea, measured by the modified Medical Research Council scale; walking capacity, measured by the 6-minute walk test; and quality of life, measured by the Stroke-Specific Quality of Life scale. Fifty-three participants, who had a mean age of 62 years (SD 12) and a mean time since the onset of the stroke of 20 (SD 17) months were included. Significant differences were found only between the weak/very weak and non-weak groups. The mean differences between the non-weak and weak/very weak participants were -1.8 points (95% confidence interval -2.7 to -0.9) for dyspnea and 55 points (95% confidence interval 22-88) for quality of life. Significant correlations were found between measures of inspiratory strength and dyspnea (r = -0.54; P < 0.01) and quality of life (r = 0.56; P < 0.01). There were not found any significant differences or correlations regarding walking capacity. The findings demonstrated that individuals with stroke, who had weakness of the inspiratory muscles, reported greater dyspnea and worse quality of life, compared with those, who did not have weakness. The results regarding walking capacity remain unclear.

Controlled Study of Central Hemodynamic Changes in Inspiratory Exercise with Different Loads in Heart Failure.

Background Inspiratory muscle weakness contributes to exercise intolerance and decreased quality of life in patients with heart failure. Studies with inspiratory muscle training show improvement in inspiratory muscle strength, functional capacity and quality of life. However, little is known about the central hemodynamic response (CHR) during inspiratory exercise (IE). Objective To evaluate CHR in a single IE session with different loads (placebo, 30% and 60%) in heart failure. Methods Randomized placebo-controlled clinical trial in patients with heart failure with reduced ejection fraction, functional class II and III. Twenty patients aged 65 ± 11 years completed a single session of inspiratory exercise, in 3 cycles of 15 minutes, with a 1-hour washout, involving loads of 30% (C30), 60% (C60) and placebo, using a linear load resistor (PowerBreathe Light). The noninvasive hemodynamic study was performed by cardiothoracic bioimpedance (Niccomo™ CardioScreen®). Statistical analysis was performed with Student's t-test and Pearson's correlation, and P≤0.05 was considered significant. Results An increase in heart rate (HR) was observed with C30 (64 ± 15 vs 69 ± 15 bpm; p = 0.005) and C60 (67 ± 14 vs 73 ± 14 bpm, p = 0.002). A decrease was observed in systolic volume (SV) with C30 (73 ± 26 vs 64 ± 20 ml; p = 0.004). Cardiac output (CO), on its turn, increased only with C60 (4.6 ± 1.5 vs 5.3 ± 1.7 l/min; p = -0.001). Conclusion When using the 60% load, in a single IE session, changes in CHR were observed. HR and CD increased, as did the Borg scales and subjective sensation of dyspnea. The 30% load reduced the SV. (Arq Bras Cardiol. 2020; 114(4):656-663).

A randomized controlled trial of high-intensity interval training and inspiratory muscle training for chronic heart failure patients with inspiratory muscle weakness.

Chronic heart failure is a major public health problem in which supervised exercise programs are recommended as part of non-pharmacological management. There are various reports of the success of high-intensity aerobic interval training (HI-AIT) and inspiratory muscle training (IMT) in the management of chronic heart failure patients. This study tested the hypothesis that the combination of HI-AIT and IMT could result in additional benefits over the IMT and the HI-AIT alone in terms of inspiratory muscle function, exercise capacity, and quality of life in patients with chronic heart failure and inspiratory muscle weakness. Forty patients with ejection fraction ≤45% and inspiratory muscle weakness described by maximal inspiratory pressure <70% predicted, underwent three exercise training sessions per week for 12 weeks. Patients were randomly allocated to one of four groups: the HI-AIT group, the IMT group, the combined (HI-AIT & IMT) group, and the control group. Before and after completing their training period, all patients underwent different tests that are mentioned above. No changes were detected in the control group. However, the combined group, when compared to HI-AIT and IMT groups, respectively, resulted in additional significant improvement in maximal inspiratory training (62%, 24%, 25%), exercise time (62%, 29%, 12%), the 6-minute walk test (23%, 15%, 18%), and the Minnesota Living with Heart Failure Questionnaire (56%, 47%, 36%). In patients with chronic heart failure and inspiratory muscle weakness, the combination of the HI-AIT and the IMT resulted in additional benefits in respiratory muscle function, exercise performance, and quality of life compared to that of HI-AIT or IMT alone.Trial Registration number: NCT03538249.

Respiratory Muscle and Lung Function in Lung Allograft Recipients: Association with Exercise Intolerance

Background: In lung transplant recipients (LTRs), restrictive ventilation disorder may be present due to respiratory muscle dysfunction that may reduce exercise capacity. This might be mediated by pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Objective: We investigated lung respiratory muscle function as well as circulating pro-inflammatory cytokines and exercise capacity in LTRs. Methods: Fifteen LTRs (6 female, age 56 ± 14 years, 63 ± 45 months post-transplantation) and 15 healthy controls matched for age, sex, and body mass index underwent spirometry, measurement of mouth occlusion pressures, diaphragm ultrasound, and recording of twitch transdiaphragmatic (twPdi) and gastric pressures (twPgas) following magnetic stimulation of the phrenic nerves and the lower thoracic nerve roots. Exercise capacity was quantified using the 6-min walking distance (6MWD). Plasma IL-6 and TNF-α were measured using enzyme-linked immunosorbent assays. Results: Compared with controls, patients had lower values for forced vital capacity (FVC; 81 ± 30 vs.109 ± 18% predicted, p = 0.01), maximum expiratory pressure (100 ± 21 vs.127 ± 17 cm H₂O, p = 0.04), diaphragm thickening ratio (2.2 ± 0.4 vs. 3.0 ± 1.1, p = 0.01), and twPdi (10.4 ± 3.5 vs. 17.6 ± 6.7 cm H₂O, p = 0.01). In LTRs, elevation of TNF-α was related to lung function (13 ± 3 vs. 11 ± 2 pg/mL in patients with FVC ≤80 vs. >80% predicted; p < 0.05), and lung function (forced expiratory volume after 1 s) was closely associated with diaphragm thickening ratio (r = 0.81; p < 0.01) and 6MWD (r = 0.63; p = 0.02). Conclusion: There is marked restrictive ventilation disorder and respiratory muscle weakness in LTRs, especially inspiratory muscle weakness with diaphragm dysfunction. Lung function impairment relates to elevated levels of circulating TNF-α and diaphragm dysfunction and is associated with exercise intolerance.

Inspiratory Muscle Training in COPD.

The benefits of inspiratory muscle training (IMT) for patients with COPD are documented in the literature, but its isolated effect or association with other interventions, the best training methods, and what type of patient benefits the most are not clear. We sought to assess the effects of IMT on respiratory muscle strength, pulmonary function, dyspnea, functional capacity, and quality of life for subjects with COPD, considering IMT isolated or association with other interventions, presence of inspiratory muscle weakness, training load, and intervention time. We searched the MEDLINE, EMBASE, PEDro, Cochrane CENTRAL, and LILACS databases in June 2018. We also performed a manual search of references in the studies found in the database search and included in this analysis. We included randomized controlled trials that investigated the above-mentioned outcomes and assessed IMT, either isolated or associated with other interventions, in comparison with a control group, placebo, or other interventions, in subjects with COPD. We used the GRADE approach to evaluate the quality of the evidence. Of 1,230 search results, 48 were included (N = 1,996 subjects). Isolated IMT increased PImax (10.64cm H2O, 95% CI 7.61-13.66), distance walked in 6-min-walk test (34.28 m; 95% CI 29.43-39.14), and FEV1 (0.08, 95% CI 0.02-0.13). However, there was no improvement in dyspnea and quality of life. The presence of inspiratory muscle weakness did not change the results; higher loads (60-80% of PImax) promoted a greater improvement in these outcomes, and a shorter intervention time (4 weeks) improved PImax, but longer intervention times (6-8 weeks) are required to improve functional capacity. IMT associated with other interventions only showed an increase in PImax (8.44cm H2O; 95% CI 4.98-11.91), and the presence of inspiratory muscle weakness did not change this result. Isolated IMT improved inspiratory muscle strength, functional capacity, and pulmonary function, without changing dyspnea and quality of life. Associated IMT only increased inspiratory muscle strength. These results indicate that isolated IMT can be considered as an adjuvant intervention in patients with COPD.

Continuous positive airway pressure improves respiratory mechanics and efficiency of neural drive in stable COPD: an exploratory study.

BackgroundContinuous positive airway pressure (CPAP) is a major treatment strategy for severe chronic obstructive pulmonary disease (COPD), especially with respiratory failure. However, it remains inconclusive whether CPAP affects respiratory mechanics and neural drive in stable COPD patients without respiratory failure.MethodsTwenty-two COPD patients without respiratory failure received CPAP starting from 4 to 10 cmH2O in 1 cmH2O increments. Respiratory pattern, end expiatory lung volume (EELV), dynamic PEEPi (PEEPidyn), airway resistance (Raw), pressure-time product of diaphragmatic pressure (PTPdi) and esophageal pressure (PTPeso), root mean square (RMS) of diaphragm electromyogram (EMGdi) and ratio of ventilation (Ve) to EMGdi (i.e., Ve/RMS) were measured before and at each level of continue positive airway pressure (CPAP). A subgroup analysis was performed between patients with and without inspiratory muscle weakness.ResultsNineteen patients completed the treatment. The respiratory pattern improved significantly after CPAP. Raw, PTPdi, and Pdi decreased significantly. ΔEELV decreased at 4 cmH2O (P<0.05), but increased significantly at >8 cmH2O. PEEPidyn decreased from 2.18±0.98 to 1.37±0.55 cmH2O. RMS increased while Ve/RMS improved significantly after CPAP (P<0.05). Besides, CPAP could significantly improve respiratory mechanics in patients with inspiratory muscle weakness.ConclusionsCPAP improves respiratory pattern, PEEPi, Raw, work of breathing and efficiency of neural drive in COPD patients without respiratory failure, but easily increases dynamic pulmonary hyperinflation. These effects on respiratory mechanics are significant in patients with inspiratory muscle weakness.

Risk Factors for Inspiratory Muscle Weakness in Chronic Heart Failure.

Chronic heart failure is commonly associated with inspiratory muscle weakness. However, few studies have investigated the risk factors for inspiratory muscle weakness in individuals with chronic heart failure and systolic dysfunction (left-ventricular ejection fraction [LVEF] <40%). Seventy subjects were recruited in a cardiac center. We assessed clinical parameters, smoking history, peripheral muscle strength, pulmonary function, echocardiographic variables, and brain natriuretic peptide. The subjects were classified with inspiratory muscle weakness when the maximum inspiratory pressure was <70% of predicted values. Thirty-six subjects (51%) had inspiratory muscle weakness. The subjects with inspiratory muscle weakness and the subjects with no inspiratory muscle weakness were similar in age, sex, body mass index, medication use, and physical activity. However, the subjects with inspiratory muscle weakness had lower LVEF (P = .003), systolic blood pressure (P = .01), diastolic blood pressure (P = .042), quadriceps muscle strength (P = .02), lung function (P = .035), increased brain natriuretic peptide (P = .02), smoking history (P = .01), and pulmonary hypertension incidence (P = .03). Multivariate logistic regression analysis found a lower LVEF, increased smoking history, and lower systolic blood pressure as significant independent predictors for inspiratory muscle weakness. The combination of lower LVEF, lower systolic blood pressure, and smoking history predicted inspiratory muscle weakness. Patients with suspected inspiratory muscle weakness should be examined and, if inspiratory muscle weakness exists, then inspiratory muscle training should be provided. Reducing inspiratory muscle weakness has the potential to improve many of the deleterious effects of chronic heart failure.

Inspiratory muscle strength and walking capacity in patients with COPD

ABSTRACT Purpose: It has been suggested that patients with inspiratory muscle weakness could benefit from specific inspiratory muscle training (IMT). We aimed to examine the frequency of patients with inspiratory muscle weakness in a Danish hospital-based outpatient pulmonary rehabilitation program, and to evaluate the association between inspiratory muscle strength and peripheral muscle strength and walking capacity. Methods: Maximal Inspiratory Pressure (MIP) was assessed in 97 patients with COPD (39 men, 58 women, mean age years 70 ± 9, forced expiratory volume in 1 s ((FEV1) = 35 ± 10% pred.). The impact of MIP on knee-extension strength, walking distance, and symptom burden was evaluated using multiple linear regression analyses. Results: The MIP of the patients with COPD was 63 (95% CI 59; 67) cmH2O and it was significantly reduced compared to gender and age-matched reference values 76 (95% CI 73; 79) cmH2O (p < 0.001). Seven patients (7.2%) were under the lower limit of normal. MIP was negatively correlated with increasing age, female gender, decreasing knee-extension strength and lower FEV1% pred. Walking distance was associated with knee-extension strength and it was not associated with MIP. Conclusion: Maximal inspiratory pressure was reduced in patients with COPD but only a few patients had a weak MIP. Whilst MIP was associated with leg muscle strength, it was not associated with walking distance or symptoms.

Preoperative expiratory and inspiratory muscle weakness to predict postoperative outcomes in patients undergoing elective cardiac surgery.

Few studies have evaluated preoperative respiratory muscle strength as a risk factor for postoperative morbidity and mortality. The objective of this study was to evaluate the association of preoperative inspiratory muscle weakness (IMW) and preoperative expiratory muscle weakness (EMW) with duration of mechanical ventilation, length of stay in the intensive care unit (ICU), incidence of postoperative pulmonary complications (PPCs), and mortality in patients undergoing elective cardiac surgery. This was a prospective observational study. Patients admitted for elective cardiac surgery were recruited. Maximal inspiratory and expiratory pressure were measured before surgery. A multivariate regression model was used to adjust for possible confounding variables and test the association of IMW and EMW with the duration of mechanical ventilation, length of stay in the ICU, PPCs, and hospital mortality. Two hundred and fifty-five patients were included in this study. The presence of IMW was associated with an increase in the duration of mechanical ventilation (P = .012). The presence of EMW was associated with a reduction in the incidence of PPCs (P = .005). IMW had no significant association with length of stay in the ICU, PPCs, or hospital mortality. EMW had no significant association with the duration of mechanical ventilation, length of stay in the ICU, or hospital mortality. In patients undergoing elective cardiac surgery, preoperative IMW is associated with the duration of mechanical ventilation while preoperative EMW is associated with a decrease in PPCs.

An Unusual Cause of Dysphagia

An Unusual Cause of Dysphagia

Alteration of Inspiratory Muscle Strength is Related to Change in Deep Breathing Heart Rate Variability in Patients Submitted to Open-Heart Surgery

Aim: Despite the reduction of respiratory muscle strength and cardiac autonomic modulation after open-heart surgery has been demonstrated, the association between changes in both variables has not been investigated. This study aimed to determine the correlation between change in inspiratory muscle strength and change in deep breathing heart rate variability in patients submitted to open-heart surgery.Material and Methods: An observational cross-sectional study was conducted among 32 participants aged between 35 and 60 years who were undergoing coronary artery bypass graft and cardiac valve surgery. Inspiratory muscle strength was assessed by measuring maximal inspiratory pressure using a respiratory pressure meter (RPM 01, Micro Medical Ltd., United Kingdom). Deep breathing heart rate variability was collected using a Polar heart rate monitor (Polar Electro Ltd., Finland) during a slow and deep breathing control. Evaluations were performed on the day of admission and discharge.Results: There was statistically significant reduction in maximal inspiratory pressure and deep breathing heart rate variability indices in discharge period (p&amp;lt;0.05). The difference of expiratory/inspiratory ratio and inspiratory-expiratory differences was significantly correlated with the change in maximal inspiratory pressure in both absolute (r=-0.864, p=0.003 and r=-0.841, p=0.004, respectively) and percentages of predicted values (r=-0.868, p=0.003 and r=-0.834, p=0.005, respectively).Conclusion: Inspiratory muscle weakness was related to impair cardiac vagal modulation in patients who had undergone open-heart surgery. The present study could provide rehabilitation targets to improve inspiratory muscle strength and cardiac vagal tone.

Ventilación espontánea en ventilación mecánica invasiva: un pulmón dual

Introducción: El uso de la ventilación mecánica invasiva (VMI) convencionalmente con modos controlados y uso de sedantes conlleva a un aumento de complicaciones y eventos indeseados como la disfunción diafragmática al inhibir la ventilación espontanea. Este artículo revisara la viabilidad de la ventilación espontanea en VMI partiendo de la actividad muscular inspiratoria como mecanismo fisiológico para la ventilación pulmonar, los cambios al ser remplazado por un mecanismo donde la ventilación es generada por la VMI, la interacción entre los dos mecanismos “pulmón dual” y sus efectos a nivel pulmonar. La evidencia disponible se encuentra en SDRA con ventajas y desventajas, se propone estrategias de evaluación, monitoria, regulación del impulso y esfuerzo inspiratorio que facilite la ventilación espontanea durante la VMI. Método: Se realizó una revisión documental en 4 fases: 1. Búsqueda de información, 2. Selección de publicaciones, 3. Procesamiento y análisis de la información seleccionada, 4. Redacción del documento. Conclusión: La ventilación espontánea en VMI es viable al reducir la incidencia de la debilidad muscular y podría disminuir la estancia en UCI. En estudios en SDRA el “pulmón dual” presenta más ventajas que desventajas y se reconoce su utilidad en SDRA leve o moderado. Hacen falta estudios en situaciones clínicas menos complejas y más comunes en UCI o pulmones sanos donde podría encontrarse más ventajas. Se sugiere realizar la evaluación del momento clínico y fisiopatológico, monitorear la VMI, monitorear y regular el impulso respiratorio y el esfuerzo muscular enfocándose en los principios de protección pulmonar y diafragmática.