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PubMed1988

Diaphragm strength in patients with recent hemidiaphragm paralysis.

Eleven patients with unilateral diaphragm paralysis of recent onset were studied to investigate the effect of the paralysis on inspiratory muscle function. Nine of the patients had noticed a decrease in exercise tolerance, which was not explained by any other pathological condition. Hemidiaphragm dysfunction was confirmed by the demonstration of a greatly reduced or absent transdiaphragmatic pressure on stimulation of the phrenic nerve in the neck, by means of surface bipolar electrodes (unilateral twitch Pdi), compared with normal values on the contralateral side. Transdiaphragmatic pressure was 44.6% (9.4%) predicted during a maximal sniff and 30.3% (16.8%) predicted during a maximal static inspiration against a closed airway, confirming diaphragm weakness. Maximum static inspiratory mouth pressures were also low (61.7% (12.7%) predicted), consistent with a reduction in inspiratory muscle capacity. Phrenic nerve conduction time was prolonged on the affected side in nine patients, consistent with phrenic nerve dysfunction, whereas on the unaffected side it was normal. It is concluded that recent hemidiaphragm paralysis causes a reduction in transdiaphragmatic pressure that is associated with a reduction in maximum inspiratory mouth pressure. Phrenic nerve stimulation is a useful technique with which to confirm and quantify hemidiaphragm dysfunction. Measurement of phrenic nerve conduction time provides useful information about the underlying pathology.

Diaphragm↗
PubMedDate not supplied

Evaluation of major airway lesions using the flow-volume loop.

The flow-volume (FV) loop is another way of representing spirometric data from combinations of forced expiratory and forced inspiratory vital capacity breaths. The FV loop is of use in identifying, and often localizing, lesions of the larynx and the trachea (down to the carina). Three general patterns have been recognized. When the lesion behaves in a fixed fashion (as might occur with an artificial orifice), maximal expiratory and inspiratory flows are almost equally compromised. This results in a rectangular FV loop, irrespective of whether the lesion is located intrathoracically or extrathoracically. When the lesion behaves in a variable fashion, two distinct patterns are seen, depending on the location of the lesion (intrathoracic or extrathoracic). The variable lesion acts as a fixed lesion during one phase of forced respiration only. The extrathoracic variable lesion results in a predominant reduction in forced inspiratory flow, with little effect on expiratory flow, whereas the intrathoracic variable lesion produces a characteristic reduction in expiratory flow. These patterns reflect the transmural forces existing at the site of the lesion.

Adult↗
PubMed2006

Physical activity is independently related to aerobic capacity in cystic fibrosis.

It is unclear whether a relationship between physical activity (PA) and maximal oxygen uptake (V'(O2,max)) exists in cystic fibrosis (CF) and, if so, whether the relationship reflects a direct effect or is mediated by the effects of confounding variables, such as pulmonary or muscle function. The objective of the present study was to determine the relationship between PA and V'(O2,max) in CF while adjusting for possible influences of confounding factors. In total, 36 female and 35 male patients with CF from Germany and Switzerland (aged 12-40 yrs, forced expiratory volume in one second (FEV1) 25-107% predicted) were studied. A Wingate test was employed to measure muscle power. PA was monitored for 7 days and expressed in two ways: 1) average daily accelerometer count (ADAC) and 2) time spent in moderate-to-vigorous PA (MVPA). V'(O2,max) was determined during an incremental cycle exercise test to volitional fatigue. PA was positively related to V'(O2,max). In a multiple linear regression analysis, height, sex, FEV1, muscle power and ADAC (additionally explained variance 2.5%) or time spent in MVPA (additionally explained variance 3.7%) were identified as independent predictors of V'(O2,max). In conclusion, high levels of physical activity in addition to good muscular and pulmonary functions are associated with a high aerobic capacity in cystic fibrosis.

Adolescent↗
PubMed2006

Exercise performance improves in patients with COPD due to respiratory muscle endurance training.

BACKGROUND: Impaired exercise tolerance is frequently observed in patients with COPD. Respiratory muscle endurance training (RMET) by means of normocapnic hyperpnea can be used to improve respiratory muscle function and probably exercise capacity. RMET is not applied on a large scale because complicated equipment is needed to maintain carbon dioxide homeostasis during hyperpnea, which can also be done by enlarging the dead space of the ventilatory system by breathing through a tube. Therefore, tube breathing might be a new, inexpensive method for home-based RMET. The aim of this study was to assess whether home-based RMET by means of tube breathing improves endurance exercise performance in patients with COPD. METHODS: We randomized 36 patients with moderate-to-severe COPD to RMET by paced tube breathing (n = 18) or sham training (control, n = 18). Both groups trained twice daily for 15 min, 7 days per week, for 5 weeks. RESULTS: Patients receiving RMET showed significant improvements in endurance exercise capacity (constant-load exercise on cycle ergometry; 18 min vs 28 min, p < 0.001), in perception of dyspnea (Borg score; 8.4 vs 5.4, p < 0.001), and respiratory muscle endurance capacity (sustainable inspiratory pressure; 25 cm H(2)O vs 31 cm H(2)O, p = 0.005). Quality of life (chronic respiratory disease questionnaire) also improved (78.7 to 86.6, p = 0.001). The control group showed no significant changes. CONCLUSION: Home-based RMET by means of tube breathing leads to a significant improvement of endurance exercise capacity, a reduction in perception of dyspnea, and an improvement in quality of life in patients with moderate-to-severe COPD.

Aged↗
PubMed1988

Bracing arms increases the capacity for sustained hyperpnea.

Patients with severe chronic obstructive pulmonary disease (COPD) frequently lean forward, bracing their arms. We wondered whether the resulting shoulder girdle support improves the function of the ventilatory pump. We tested this possibility in 4 normal men by measuring the maximal ventilation that they could voluntarily sustain for 4 min while seated with their elbows braced firmly on a table and while seated with their elbows held just above the table. Bracing the arms increased ventilatory capacity significantly in all subjects, but the magnitude of the change was small (8%). We attribute the change to improved function of the accessory muscles that expand the rib cage. We speculate that this effect assumes greater importance in patients with COPD, whose diaphragms are flattened and ineffective, because such patients depend more on the inspiratory muscles of the rib cage.

Adult↗
PubMed1981

[Efficacy of gas exchange in the lung of children (author's transl)].

Determination of the CO transfer through lungs is the most direct method of determination of lung function. In children more convenient for practical use is the "steady state" than the "single breath" method. Besides classical coefficient of transfer (TLCO) interpretation of results may be widened by coefficients of the CO fractional uptake - global (FUCO) and partials, informing about exchange of gases in airways (FUCO) and in alveolies (FUaCO) the predicted values of the above coefficients should be calculated, accordingly to the opinion of authors, in relation with tidal volume (TV) or with total lung capacity (TLC), but FUCO and FUaCO with frequency of breathing (f). Cited examples of clinical results prove practical usefulness of application the "steady state" method in children.

Adolescent↗
PubMed1996

Nutritional status and mortality in chronic obstructive pulmonary disease.

The role of nutritional status in the prognosis of subjects with severe chronic obstructive pulmonary disease was studied in a cohort of Canadian men and women followed for 3 to 5 yr. A total of 348 subjects who were recruited for a study of negative pressure ventilation were evaluated for lung function and body weight, and a subset who entered hospital for the study (n=184) had baseline measures of diffusing capacity, maximal inspiratory and expiratory mouth pressure (PImax and PEmax), and blood gases. Predictors of survival were analyzed using Cox regression models. In the total cohort, low body mass index (BMI) and use of home oxygen were independently associated with reduced survival. In the hospitalized group, predictors of respiratory mortality were elevated PaCO2 and low BMI, PImax, and diffusing capacity. PaO2 (measured on oxygen therapy), FEV1, PEmax, age, smoking behavior, and gender were not associated with survival. The predictors of total mortality were similar, except that BMI was no longer significant. In conclusion, low body weight, a potentially modifiable factor, was associated with respiratory mortality, but whether it has a casual effect or is a marker of declining health can only be resolved through an intervention trial.

Adult↗
PubMed1996

Bronchodilatation and the inspiratory flow volume curve.

The inspiratory flow volume curve is included in the spirometric tracing provided by most pulmonary function laboratories and is useful in assessing upper airway abnormalities. We analyzed the changes in peak inspiratory flow (PIF), forced inspiratory flow at 50% (FIF50), and forced inspiratory vital capacity (FIVC) that occur with bronchodilator challenge testing (3 puffs of a beta-agonist by metered-dose inhaler without a spacer device) in 145 consecutive patients. Fifty-five patients responded to bronchodilators with either a 12% or 200-mL change in FEV1 or FVC. All of these subjects produced forced expiratory maneuvers that fulfilled American Thoracic Society criteria or acceptability. The FIVC was the only inspiratory parameter that consistently showed a similar correlation to the bronchodilator responsiveness demonstrated by the FEV1 or FVC. With the reduction in air trapping, a 12% or 200-mL change in the FIVC is additional confirmatory evidence of bronchodilator responsiveness.

Adrenergic beta-Agonists↗
PubMed2005

Relationship of inspiratory flow rate and volume on digit tip skin and ulnar artery vasoconstrictor responses in healthy adults.

Reflex vasoconstrictive responses are commonly used to assess sympathetic nerve function of the extremities. A regularly used reflex trigger is deep and rapid inspiration. However, little is known about the relationship between respiratory effort and the magnitude of the resultant vasoconstrictor response. This study investigates the association of inspiratory flow rate and volume to the level of vasoconstrictor reflexes in the 4th digit tip skin and the ulnar artery in 12 healthy volunteers (age range 21-65, mean 38.1 years). The effects of Peak Inspiratory Flow (PIF) and Forced Inspiratory Vital Capacity (FIVC) on blood flow were measured at three levels of respiratory effort: low (PIF < 1.0 l/min; FIVC < 1.0 l), medium (PIF = 1.0-1.5 l/min; FIVC = 1.0-1.5 l), and high (PIF > 1.5 l/min; FIVC > 1.5 l) at two separate occasions. Ulnar vasoconstrictor responses showed good correlation with all levels of respiratory effort. Skin digit tip responses showed good correlation at medium and high levels but not at low respiratory effort. Repeatability of both tests was good. Correlation of inspiratory flow rate to vasoconstriction was consistently better than with inspiratory volume. Both digit tip and ulnar vasoconstrictor responses were maximal with greatest respiratory effort.

Adult↗
PubMed1997

Respiratory muscle strength and endurance in individuals with tetraplegia.

The purpose of this study was to assess the strength and endurance capacity of the respiratory muscles in individuals with tetraplegia and to compare these properties to those in able-bodied subjects. In addition, the relationship between respiratory muscle properties and respiratory function, ie, ventilation and gas exchange, was examined. Fifteen individuals with tetraplegia (TP) and 15 able-bodied controls (AB) participated in this study. Respiratory muscle strength was assessed by measuring static inspiratory (Pi-max) and expiratory (Pe-max) mouth pressure, whereas inspiratory endurance capacity (Pendu) was determined using an incremental ventilatory threshold loading test. Results were significantly lower in TP compared to AB: Pi-max (5.9 vs 8.4 kPa), Pre-max (5.6 vs 12.3 kPa), Pendu (2.7 vs 6.9 kPa), vital capacity (3.1 vs 5.5 l) and rest oxygen uptake (0.21 vs 0.29 ml/min) and significant correlations were found between the respiratory muscle properties and the respiratory function. Of note is the fact that the ratio Pendu/Pi-max was significantly lower in TP (0.49) compared to AB (0.82). This implies that the capacity to generate pressure during the endurance test was not fully used in TP, probably due to an early onset of muscle fatigue and an altered force-length relationship of the diaphragm muscle. Results of this study demonstrate a limited ability in individuals with tetraplegia to ventilate.

Adult↗
PubMed1998

Differences between remaining ability and loss of capacity in maximum aerobic impairment.

In the evaluation of exercise intolerance of patients with respiratory diseases the American Medical Association (AMA) and the American Thoracic Society (ATS) have proposed similar classification for rating aerobic impairment using maximum oxygen uptake (VO2max) normalized for total body weight (ml min-1 kg-1). However, subjects with the same VO2max weight-corrected values may have considerably different losses of aerobic performance (VO2max expressed as % predicted). We have proposed a new, specific method for rating loss of aerobic capacity (VO2max, % predicted) and we have compared the two classifications in a prospective study involving 75 silicotic claimants. Logistic regression analysis showed that the disagreement between rating systems (higher dysfunction by the AMA/ATS classification) was associated with age > 50 years (P < 0.005) and overweight (P = 0.04). Interestingly, clinical (dyspnea score) and spirometric (FEV1) normality were only associated with the VO2max, % predicted, normal values (P < 0.01); therefore, in older and obese subjects the AMA/ATS classification tended to overestimate the aerobic dysfunction. We conclude that in the evaluation of aerobic impairment in patients with respiratory diseases, the loss of aerobic capacity (VO2max, % predicted) should be used instead of the traditional method (remaining aerobic ability, VO2max, in ml min-1 kg-1).

Disability Evaluation↗
PubMed1992

Demand vs. capacity in the healthy pulmonary system.

This review examines the lung and chest wall adaptation to exercise in health in persons of widely varying degrees of fitness. First we examine the regulation of breathing and gas exchange in the sedentary young adult who shows a near perfect regulation of alveolar gases, ventilation to perfusion distribution, diffusion equilibrium in the lung during all levels of exercise. This individual's respiratory muscles are also ideally recruited both tonically and phasically so as to meet multi-faceted postural, locomotory and respiratory demands. The topic of plasticity in the pulmonary system is discussed with specific reference to the effects of physical training and athleticism. The key point made here is that both homeostasis of gas transport and mechanical efficiency, with which the pulmonary system meets the demands of muscular exercise will depend upon the ability to maintain a significant margin between demand vs. structural capacity. Pulmonary diffusion capacity and at least some aspects of respiratory muscle function seem to be "overbuilt" in the young untrained adult. This margin of safety no longer prevails as the athlete becomes fitter. The cause is to be found in the relative lack of adaptability of the lung and chest wall to the training stimulus. Examples of demand coming very close or exceeding the capacity of the pulmonary system include the highly trained young endurance athlete and the aged athlete. Examples of "failure" or near failure in the pulmonary system's response to exercise include: a) exercise induced arterial hypoxemia via diffusion limitation; b) diaphragmatic fatigue in endurance exercise; c) expiratory flow limitation at VO2max.; d) achieving the capacity of inspiratory muscles for pressure generation at VO2max. and e) oxygen cost of breathing which is in excess of 15% of VO2max. in those athletes who experience the most mechanical limitation.

Adaptation, Physiological↗
PubMed1998

[Chronic obstructive pulmonary disease patients undergoing home oxygen therapy: a study of clinical parameters, nutritional status and ambulatory capacity].

AIM OF THE STUDY: The aim of the study was to document the nutritional status and the calorie demands of patients suffering from severe chronic airflow obstruction (BPCO) who were on continuous domiciliary oxygen therapy (OCD) and to correlate this information with the clinical picture, the severity of the respiratory disease and the daily distance walked, this to be measured in a prospective manner. PATIENTS AND METHODS: Fifty clinically stable patients with chronic airflow obstruction on continuous oxygen therapy for 33 months (range 4-106) in whom the following measures were made at home: pulmonary function, maximal static inspiratory and expiratory pressure (PIMAX and PEMAX), strength of hand, grip, the mean distance walked daily (wearing a pedometer for one week), body mass index (IMC), and the body composition by electrical bio-impedence and calorie requirements. RESULTS: Thirty four per cent of patients presented with an excessive body mass (IMC > 27 kg/m2), 42 per cent had normal nutrition (IMC 20-27 kg/m2) and 24 per cent were malnourished (IMC < 20 kg/m2). Malnourished patients had, in a statistically significant manner, airflow obstruction of greater severity and a lower oxygen saturation and a PEMAX as well as a lower daily distance compared to over weight subjects. However, their net calorie requirements were markedly higher (39 +/- 5 Kcal/kg/j) compared to patients having normal weight (29 +/- 11 kcal/kg/j) or excess weight (25 +/- 8 kcal/kg/j). From the clinical standpoint no malnourished patient fulfilled the clinical criteria of chronic bronchitis. By contrast 61 per cent of subjects with normal nutrition and 94 per cent of subjects with excessive weight were chronic bronchitics. CONCLUSION: In the group of patients with severe airflow obstruction on domiciliary oxygen, 25 per cent were malnourished and this was in spite of netly increased calorie consumption which is superior to their theoretical need. This suggests that the solution of increasing supplements to their dietary requirements would be a difficult to realise. These subjects presented also with a more marked ventilatory handicap and a clinical picture characterised by the absence of the classical signs of chronic bronchitis.

Adult↗
PubMed1987

Effect of chronic airways obstruction on measurement of the single-breath carbon-monoxide-diffusing capacity.

We have examined the effect of chronic airways obstruction on the measurement of the single-breath carbon-monoxide-diffusing capacity (DLCLSB). We reviewed the results of 136 consecutive pulmonary function tests (comprising standard spirometry, helium dilution lung volumes and DLCOSB) obtained in patients who had an FEV1/FVC less than 70%. We calculated DLCOSB using two different values for alveolar volume (VA). In the first method (HeDL), VA was measured by single-breath dilution of helium during the test. In the second method (RbDL), VA was measured as the sum of the inspiratory vital capacity, performed during the test, and the residual volume, determined separately by helium rebreathing. The mean HeDL/RbDL, reflecting disparity between computations of DLCOSB in individual subjects was 0.85 +/- 0.13 in patients with moderate obstruction (40 less than or equal to FEV1/FVC% less than 60) and was 0.80 +/- 0.14 in those with severe obstruction (FEV1/FVC% less than 40). The mean HeDL/RbDL was lowest (0.73 +/- 0.12) in those with severe elevation of RV/TLC (RV/TLC% greater than 60). HeDL/RbDL correlated best with RV/TLC (r = -0.71, p less than 0.001). Unexplained variance in HeDL/RbDL was not significantly reduced by including the relationship between HeDL/RbDL and pulmonary function indices commonly used to measure airways resistance. These data suggest (1) the difference between HeDL and RbDL in patients with moderate and severe chronic airways obstruction is greater than previously reported; (2) the disparity between HeDL and RbDL stems from slow space ventilation rather than from increased resistance to air flow, and (3) HeDL underestimates gas transfer in poorly ventilated lung compartments.

Aged↗
PubMed1992

Early prediction of successful weaning during pressure support ventilation in chronic obstructive pulmonary disease patients.

OBJECTIVE: The aim of this study was to examine variables for early prediction of successful weaning in chronic obstructive pulmonary disease (COPD) patients during pressure support ventilation weaning. DESIGN: Thirteen COPD patients were prospectively studied to compare the respiratory pattern (inspiratory time, expiratory time, total breath cycle duration, tidal volume, respiratory rate, minute ventilation), the respiratory drive (airway occlusion pressure at 0.1 sec, tidal volume/inspiratory time), and blood gases after 30 mins of pressure support weaning. SETTING: The study was performed in the 20-bed General Critical Care Unit of the Rome "La Sapienza" University Hospital. PATIENTS: We evaluated 13 consecutive COPD patients fulfilling the standard weaning criteria (including clinical status, blood gases, forced vital capacity, maximum inspiratory pressure, and spontaneous respiratory rate after a 30-min T-piece trial) in which we compared respiratory pattern, respiratory drive, and blood gases after 30 mins of pressure support weaning. MEASUREMENTS AND MAIN RESULTS: After 30 mins of pressure support ventilation weaning (pressure support level 20 cm H2O), we measured respiratory pattern (airway pressure and airflow tracing), airway occlusion pressure at 0.1 sec (occluding the inspiratory line during expiration with a rubber balloon), tidal volume/inspiratory time, maximal inspiratory pressure, and blood gases. According to the result of the weaning trial, the patients were divided into two groups (not weaned and weaned), and the statistical difference between the evaluated variables was analyzed in weaned and not weaned groups. We did not observe a significant difference in breathing pattern data and arterial blood gases between weaned and not weaned patients. By contrast, airway occlusion pressure at 0.1 sec and maximum inspiratory pressure measured after 30 mins of weaning trial appeared significantly (p less than .001) different in patients in whom the weaning trial succeeded or failed. Considering maximum inspiratory pressure, we could not separate weaned from not weaned patients, while all patients showing values of airway occlusion pressure at 0.1 sec less than 4.5 cm H2O were easily weaned. CONCLUSIONS: This study confirms that conventional weaning criteria are often inadequate in predicting successful weaning of COPD patients, while airway occlusion pressure at 0.1 sec during the first phase of pressure support ventilation weaning can represent a good weaning predictor.

Aged↗
PubMedDate not supplied

[Usefulness of volumetric studies in the evaluation of respiratory efficiency in nervous system diseases].

In nervous system diseases impairing the efficiency of respiratory muscles the authors determined vital capacity, minute ventilation and respiratory capacity. On the basis of volumetric investigations the authors tried to find an optimal schedule for administration of drugs in myasthenia and determine the usefulness of volumetric and gasometric measurements for the evaluation of respiratory efficiency in neurological diseases.

Body Weight↗
PubMed2006

Surrogates of mortality in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) remains a leading cause of disability and death in the United States. The identification and amelioration of systemic manifestations of COPD may improve long-term outcomes, including survival. These systemic manifestations often correlate with increased risk of mortality and may be considered surrogates of disease severity. Several potential clinical surrogates are evaluated, including airflow obstruction, dyspnea, malnutrition, hypoxemia, exercise capacity, lung hyperinflation, and anemia. The evidence in support of the impact of various COPD treatment modalities on systemic manifestations of COPD is also reviewed. Finally, the usefulness of measuring body mass index, degree of airflow obstruction, dyspnea, and exercise capacity in combination (the BODE index), as a measure of disease severity and mortality risk in COPD, is examined and found to be a simple-to-use tool for predicting COPD-related hospitalization and mortality.

Anemia, Hypochromic↗
PubMed1996

[Functional results of surgical lung volume reduction in severe pulmonary edema].

BASIC PROBLEM AND OBJECTIVE OF THE STUDY: Lung volume reduction (LVR) is a new surgical approach designed to relieve shortness of breath and improve exercise tolerance in patients with severe lung emphysema. The aim of this study was to analyse changes of lung function, gas exchange, exercise tolerance and degree of dyspnoea one and 3 months after LVR. PATIENTS AND METHODS: Seventeen patients (15 men and two women; mean age 53 [38-68] years) with severe emphysema (six with alpha 1-PI deficiency) underwent unilateral (n = 14) or bilateral (n = 3) LVR surgery. One week before and one and 3 months after surgery pulmonary function tests, arterial blood gas analysis at rest breathing room air, 6-minute walking distance and dyspnoea score (Medical Research Council Scale) were determined. RESULTS: There was a significant increase in forced expiratory vital capacity after one second (FEV1, P < 0.001), and a significant decrease in total lung capacity (TLC, P < 0.0001) and residual volume (RV, P < 0.0001). The mean increase in FEV1 was 39% and in PaO2 9%. The mean decrease in TLC was 20%, in RV 26% (P < 0.001; both comparisons), and in paCO2 4% (not significant). The mean 6-minute walking distance increased by 96% from 229 to 405 meters (P < 0.0001). The mean dyspnoea score on a five point scale (0-4 points) decreased by 52% from 3.4 to 1.6. With the exception of the improved inspiratory vital capacity the postoperative results at one and 3 months after LVR did not differ significantly. All patients were alive 3 months postoperatively. CONCLUSIONS: In patients with severe emphysema surgical LVR shows significantly improved pulmonary function, gas exchange, dyspnoea and walking distance as assessed one and three months postoperatively. The early mortality seems to be low.

Acute Disease↗