Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1762617 (weakness)
 37,932 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In myasthenia gravis (MG) the status of respiratory function has a paramount importance and a careful evaluation is recommended. The weakness of respiratory muscles has been demonstrated in several studies. However, a reliable simple method for the evaluation of this muscular group was lacking until recently, when the usefulness of the maximum respiratory pressures, expiratory (MEP) and inspiratory (MIP), was demonstrated. We evaluated with this method a series of 23 patients with a diagnosis of MG (16 females and 7 males), with a mean age of 46 years (22-68 years), clinically stable and without symptomatic dyspnea. They were distributed in: grade I (5), grade II A (12), and grade II B (6). All of them were evaluated with flow-volume curves, pletysmography, gas transfer, MEP and MIP. The resulting values were then correlated with the expected ones, a reduction greater than one SD being considered as abnormal. The results showed that respiratory function was normal without a restrictive pattern. However, the force of respiratory muscles was reduced in the following proportions of patients in the different groups: grade I: MIP 40%, MEP 60%; in grades II A and II B both MEP and MIP were reduced in 84% of patients. When a statistical comparison with the expected values was carried out it was found that MEP and MIP, considered as a group, were reduced to 53% of the expected values (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Evaluation of respiratory muscle function (maximal respiratory pressures) in myasthenia gravis]. 210 Jan 31

Patients with congestive heart failure (CHF) suffer from respiratory muscle weakness which may contribute to dyspnea. Nasal continuous positive airway pressure (NCPAP) can improve left ventricular ejection fraction (LVEF) and reduce dyspnea in patients with CHF and Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) but its effects on respiratory muscle strength are not known. We therefore studied the effects of NCPAP on maximal inspiratory and expiratory pressures (MIP and MEP, respectively), LVEF, dyspnea, and fatigue in patients with chronic CHF and CSR-CSA over 3 mo. Eight patients were randomized to control and nine to nightly NCPAP. There were no significant changes in any of these factors in the control group during the study. In contrast, among the NCPAP group, MIP increased from 79.3 +/- 8.1 to 90.7 +/- 10.4 cm H2O (mean +/- SEM; p < 0.02), LVEF increased from 24.0 +/- 4.0 to 32.6 +/- 6.6% (p < 0.02) and symptoms of dyspnea and fatigue were alleviated. However, MEP did not change. In addition, the number of apneas and hypopneas decreased from 49 +/- 11 to 17 +/- 7 per hour of sleep (p < 0.001) and mean low Sao2 during sleep increased from 87.9 +/- 1.0 to 93.0 +/- 1.0% (p < 0.01). Our data indicate that nightly application of NCPAP in patients with CHF and CSR-CSA improves inspiratory muscle strength and LVEF, and relieves dyspnea and fatigue.
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PMID:CPAP improves inspiratory muscle strength in patients with heart failure and central sleep apnea. 854 29

Bronchiolitis obliterans organizing pneumonia (BOOP) preceding polymyositis is rare. In this report, a 51-year-old patient with fever, nonproductive cough, and dyspnea had bilateral basal interstitial infiltrates on chest roentgenogram. Open lung biopsy was consistent with BOOP. Prednisone therapy led to improvement, but 8 weeks later, fever, cough, and weakness of the arms and legs developed because the patient had not been compliant with the prednisone regimen. The creatine kinase (CK), the macrophage inflammatory protein (MIP-1), and the tumor necrosis factor (TNF-alpha) were elevated. Anti-Jo-1 antibody was not present. Quadriceps femoris muscle biopsy was compatible with polymyositis. After a second course of corticosteroid therapy, the patient became afebrile, the dyspnea resolved, the pulmonary infiltrates decreased, and the muscle strength improved. The serum CK, MIP-1, and TNF-alpha levels declined significantly. This is only the second reported case of BOOP preceding polymyositis. Patients with idiopathic BOOP should have follow-up for the possible development of connective tissue disorders including polymyositis.
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PMID:Bronchiolitis obliterans organizing pneumonia as the first manifestation of polymyositis. 904 78

The symptom of breathlessness is an important outcome measure in the management of patients with chronic obstructive pulmonary disease (COPD). Clinical ratings of dyspnea and routine lung function are weakly related to each other. However, in the clinical setting breathlessness in COPD is encountered under conditions of increased respiratory effort, impeded respiratory muscle action, or functional weakness. Thus, the present study was carried out to determine whether and to what extent clinical ratings of dyspnea and respiratory muscle dysfunction relate to each other. In 21 patients with COPD two methods were used to rate dyspnea: a modified Medical Research Council Scale (MRC) and the Baseline Dyspnea Index (BDI), which is a multidimensional instrument for measuring dyspnea based on three components: magnitude of task, magnitude of effort, and functional impairment. A baseline focal score was obtained as the sum of the three components. Measures were: pulmonary volumes; arterial blood gases; maximal voluntary ventilation (MVV); maximal inspiratory and expiratory pressures (MIP and MEP, respectively); and breathing patterns ventilation (VE), tidal volume (VT), and respiratory frequency (Rf). In 15 patients pleural pressure was also measured during both quiet breathing (Pplsw) and maximal inspiratory sniff maneuver at FRC (Pplsn). BDI and MRC ratings related to each other and showed comparable weak associations with standard parameters (FEV1, PaCO2, VT), MIP, and MEP. In contrast, MVV closely and similarly related to both ratings. Pplsw (%Pplsn), a measure of respiratory effort, and Pplsw (%Pplsn)/VT(%VC), an index of neuroventilatory dissociation, related significantly to both the BDI (r2 = -0.77 and r2 = -0.75, respectively) and the MRC (r2 = 0.81 and r2 = 0.74, respectively). Using MVV, Pplsw (%Pplsn), and Pplsw (%Pplsn)/VT(%VC) in a stepwise multiple regression as independent variables with BDI rating as dependent variable, MVV explained an additional 14.5% of the variance of the BDI over the 67.8% predicted by Pplsw (%Pplsn). Our results demonstrate that the level of chronic exertional dyspnea in COPD increases as the ventilatory muscle derangement increases. The level of the relationships among dyspnea ratings and MVV and respiratory effort helps to explain some of the mechanisms of chronic dyspnea of COPD. These measures should be considered for therapeutic intervention to reduce dyspnea.
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PMID:Chronic exertional dyspnea and respiratory muscle function in patients with chronic obstructive pulmonary disease. 927 Sep 88

Respiratory muscle weakness may be the sole cause of dyspnea or may aggravate dyspnea due to another respiratory disease, and is often difficult to recognise clinically. The assessment of respiratory muscles should follow a graded approach using tests of increasing complexity. Clinical examination should look for dyspnea, orthopnea, morning headache, daytime somnolence, fatigability, tachypnea, abdominal, or rib cage paradox, and amyotrophy. Imaging is useful in diagnosing diaphragmatic paralysis using chest radiograph, fluoroscopy or ultrasound. In cases of moderate to severe respiratory muscle weakness, lung volumes show reduced vital capacity and total lung capacity. Measuring the change in vital capacity from sitting to supine position is useful since it shows a 25-50% fall in cases of diaphragmatic paralysis. The specific and classical tests of respiratory muscle strength are maximum inspiratory and expiratory pressures (MIP and MEP) sustained during one second against near complete occlusion. Sniff nasal inspiratory pressure (SNIP) is a new and easier test of inspiratory muscle strength. Normal values obtained with these simple tests rule out clinically significant respiratory muscle weakness. In case of doubt, more complex and invasive tests can be used such as transdiaphragmatic pressure and magnetic stimulation of the phrenic nerves.
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PMID:[Evaluation of respiratory muscles]. 975 85

Lung transplantation recipients have reduced exercise capacity despite normal resting pulmonary and hemodynamic function. The limiting factor may be contractile dysfunction of skeletal muscle. To test this postulate, we measured limb and respiratory muscle function in nine clinically stable lung allograft recipients (six men and three women, aged 30 to 65 yr, at 5 to 102 mo after transplantation) with reduced exercise capacity. Respiratory muscle strength was tested by measuring maximal inspiratory and expiratory pressure (MIP and MEP, respectively). Ankle dorsiflexor muscle strength was measured during maximal voluntary contraction (MVC). In a subset of six recipients, we also measured contractile properties and fatigue characteristics of the tibialis anterior muscle, using electrical stimulation of the motor point. Data were compared with values from age- and sex-matched control subjects. MIP values of transplant recipients did not differ from control values; however, MEP was blunted by 30% relative to control (p < 0.05), and MVC was decreased by 39% (p < 0.05). The force-frequency relationships and fatigue characteristics of the tibialis anterior were not different between the patient and control groups. We conclude that stable lung allograft recipients experience expiratory and lower limb weakness that may contribute to exercise intolerance.
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PMID:Respiratory and limb muscle function in lung allograft recipients. 1050 8

The effect of Cushing's syndrome on respiratory muscle strength is unknown. Therefore, we studied 10 consecutive patients with severe Cushing's syndrome. The respiratory muscles were assessed using maximal inspiratory and expiratory mouth pressures (MIP, MEP), maximal sniff transdiaphragmatic pressures (max sniff Pdi), and maximal sniff esophageal pressures (max sniff Pes). Maximal quadricep strength was also assessed. The patients demonstrated an overall mean MIP 92 cm H(2)O, SD 19 (mean 105% of predicted; SD, 23%), mean MEP 134 cm H(2)O, SD 35 (mean 99% of predicted; SD, 25%), mean max sniff Pdi 107 cm H(2)O, SD 12 (mean 78% of predicted; SD, 10%) and mean max sniff Pes of 92 cm H(2)O, SD 11 (mean 92% of predicted; SD, 11%). Quadriceps muscle strength was reduced in all 10 patients: mean 26 kg, SD 9 (mean 49% of predicted strength, SD 21%). Respiratory muscle weakness was not found, despite the presence of severe quadriceps impairment. We conclude that major weakness of the respiratory muscles is not usual in Cushing's syndrome.
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PMID:Respiratory muscle strength in Cushing's syndrome. 1055 53

Although ventilatory failure is the most common cause of death in amyotrophic lateral sclerosis (ALS) and measurement of respiratory muscle strength (RMS) has been shown to have prognostic value, no single test of strength can predict the presence of hypercapnia reliably. RMS was measured in 81 ALS patients to evaluate the relationship between tests of RMS and the presence of ventilatory failure, defined as a carbon dioxide tension > or = 6 kPa. We studied the predictive value of vital capacity (VC), static inspiratory and expiratory mouth pressures (MIP, MEP), maximal sniff oesophageal (sniff P(oes)), transdiaphragmatic (sniff P(di)) and nasal (SNP) pressure, cough gastric (cough P(gas)) pressure and transdiaphragmatic pressure after bilateral cervical magnetic phrenic nerve stimulation (CMS P(di)) to identify the risk of ventilatory failure in the whole group and in subgroups of patients with and without significant bulbar involvement. For patients without significant bulbar involvement, sniff P(di) had greatest predictive power [odds ratio (OR) 57] with specificity, sensitivity and positive and negative predictive values (PPV, NPV) of 87, 90, 74 and 95%, respectively Of the less invasive tests, per cent predicted SNP had greater overall predictive power (OR 25, specificity 85%, sensitivity 81%) than per cent predicted VC (9, 89%, 53%) and per cent predicted MIP (6, 83%, 55%). No test had significant predictive power for the presence of hypercapnia when used to measure RMS in a subgroup of patients with significant bulbar weakness. Thirty-five patients underwent polysomnography. CMS P(di), sniff P(di) and per cent predicted SNP were significantly correlated with the apnoea/hypopnoea index (AHI) (P = 0.035, 0.042 and 0.026, respectively). The correlations between AHI and per cent predicted MIP and VC were less strong (both non-significant). In ALS patients without significant bulbar involvement, novel tests of RMS have greater predictive power than conventional tests to predict hypercapnia. In particular, the non-invasive SNP is more sensitive than VC and MIP, suggesting that it could usefully be included in tests of respiratory muscle strength in ALS and will be helpful in assessing the risk of ventilatory failure. In patients with significant bulbar involvement, tests of respiratory muscle strength do not predict hypercapnia. Sleep-disordered breathing is correlated with RMS and the novel tests of RMS having the strongest relationship with the degree of sleep disturbance.
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PMID:Respiratory muscle strength and ventilatory failure in amyotrophic lateral sclerosis. 1157 Dec 18

The restrictive defect was quantified (Forced vital capacity, FVC) and their postural dependence and the respiratory muscle weakness (Maximal inspiratory and expiratory pressures, MIP and MEP) in 29 patients (12 to 46 years) with spinal injury from cervical (C) 4 to thoracic (T) 7 (30 days to 48 months post injury period). The FVC in C (seated) was 2200 +/- 560 ml (47.2%), and in T was 2940 +/- 750 ml (66.6%), p < 0.008. The postural dependence of the FVC was higher in C with an increase of 25% and only of 10% in the T (p < 0.03). This postural dependence was a function of the FVC according to the regression equation: FVC % (supine) = 24.73+ 0.7341* FVC % seated (r 0.8771, p < 0.001). The MIP in C was 61.59 (53.82%) +/- 17.26 cm H2O and in T was 87.25 (77.85%) +/- 24.27 cmH2O (p < 0.05). The MEP in C was 48.53 (24.97%) +/- 18.09 cm H2O, and in T was 58.75 (30.74%) +/- 27.67 cmH2O (p NS). No correlation was found between FVC and maximal statics respiratory pressures. In conclusion, the C showed more significant restrictive defect and a great postural dependence of the FVC. In both, the expiratory muscle weakness was more severe than the inspiratory group. Inspiratory muscle weakness was higher in C.
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PMID:[Functional respiratory evaluation in patients with high traumatic spinal injury]. 1172 18

The intracellular Ca(2+) concentration ([Ca(2+)](i)) in skeletal muscles must be rapidly regulated during the excitation-contraction-relaxation process. However, the signalling components involved in such rapid Ca(2+) movement are not fully understood. Here we report that mice deficient in the newly identified PtdInsP (phosphatidylinositol phosphate) phosphatase MIP/MTMR14 (muscle-specific inositol phosphatase) show muscle weakness and fatigue. Muscles isolated from MIP/MTMR14(-/-) mice produced less contractile force, had markedly prolonged relaxation and showed exacerbated fatigue relative to normal muscles. Further analyses revealed that MIP/MTMR14 deficiency resulted in spontaneous Ca(2+) leakage from the internal store - the sarcoplasmic reticulum. This was attributed to decreased metabolism (dephosphorylation) and the subsequent accumulation of MIP/MTMR14 substrates, especially PtdIns(3,5)P(2) and PtdIns (3,4)P(2). Furthermore, we found that PtdIns(3,5)P(2) and PtdIns(3,4)P(2) bound to, and directly activated, the Ca(2+) release channel (ryanodine receptor 1, RyR1) of the sarcoplasmic reticulum. These studies provide the first evidence that finely controlled PtdInsP levels in muscle cells are essential for maintaining Ca(2+) homeostasis and muscle performance.
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PMID:Deficiency of MIP/MTMR14 phosphatase induces a muscle disorder by disrupting Ca(2+) homeostasis. 1946 20


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