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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We looked at the comparative recovery of asthma symptoms and changes in airflow obstruction after an acute exacerbation of asthma in 26 asthmatics, aged 18-69 years (mean = 43). In the 4 weeks following the acute episode, they recorded their respiratory symptoms and twice-daily peak expiratory flow rates (PEFR). In 14 subjects, lung volumes were also measured on days 1, 7 and 30. Mean initial FVC and FEV1 [+/- SEM (% predicted)] were 2.30 +/- 0.16 (61%) and 1.18 +/- 0.08 (39%). The rate of improvement of airflow obstruction initially paralleled that of asthma symptoms in subjects with mild or with a recent onset of asthma. On the first study day, diurnal variation of PEFR was minimal, increased rapidly during the first week of treatment and stabilized thereafter. Mean daily delta PEFR was significantly higher in the first than at the fourth week (P = 0.005). Recovery of asthma symptoms was associated with an overall reduction in FRC and RV but there was no significant correlation between FRC or RV and dyspnea score or PEFR. Perception of airflow obstruction was generally lower, improvement of symptoms slower and of smaller amplitude in those with long-standing asthma. In conclusion, during recovery from acute asthma: (1) diurnal variation of PEFR is initially minimal, increases rapidly after beginning steroids and stabilize in the two following weeks; (2) in patients with more than mild or long-standing asthma, and magnitude and range of perception of asthma symptoms is reduced and correlates less with PEFR; and (3) no significant correlation could be found between FRC or RV and dyspnea score or PEFR.
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PMID:Relationship between changes in diurnal variation of expiratory flows, lung volumes and respiratory symptoms after acute asthma. 177 75

We have compared the symptomatic benefit of air and oxygen at rest in hypoxemic patients with chronic obstructive airway disease (COAD) or interstitial lung disease (ILD). A total of 12 severely disabled patients with COAD (mean +/- SEM, PaO2, 50.3 +/- 3.7 mm Hg) and 10 with ILD (PaO2, 48.0 +/- 3.1 mm Hg) received 28% oxygen and air by Venturi face mask, each gas on two occasions, in a double-blind randomized fashion. SaO2 increased (p less than 0.01) in both groups during oxygen breathing: COAD, 85.1 +/- 2.3% versus 93.1 +/- 1.4%; ILD, 85.5 +/- 1.7% versus 94.7 +/- 0.9%. The patients with COAD stated that air helped their breathing on 15 of 24 occasions and that oxygen helped on 22 of 24 occasions (p less than 0.05). In the patients with ILD the values were 6 of 20 and 13 of 20 occasions, respectively (p less than 0.05). In both groups of patients the severity of breathlessness recorded on a 100-mm visual analog scale was significantly (p less than 0.05) lower during oxygen breathing: COAD, 29.6 +/- 4.5 versus 45.6 +/- 6.0; ILD, 30.2 +/- 5.1 versus 48.1 +/- 4.4. Ventilation measured by magnetometers was significantly lower during oxygen breathing in the patients with COAD (8.2 +/- 1.0 versus 9.3 +/- 1.1 L/min; p less than 0.05), but the difference between oxygen and air in patients with ILD was not statistically significant (9.3 +/- 1.3 versus 11.2 +/- 1.6 L/min; p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Symptomatic benefit of supplemental oxygen in hypoxemic patients with chronic lung disease. 202 42

The purpose of this study was to determine the predictor variables for breathlessness and to investigate the criteria of reliability and responsiveness for measuring breathlessness during progressive, incremental exercise on the cycle ergometer. We studied a heterogeneous group of patients with stable asthma (mean +/- SEM age, 46 +/- 4 yr) for four visits at weekly intervals. Predictor variables were determined at the first visit. Nine independent physiologic variables were obtained at each minute during exercise; the Borg rating of breathlessness (range 0 to 10) was used as the dependent variable. The regression model relating the physiologic parameters to the Borg rating of breathlessness was highly significant (model F = 43.4; p = 0.0001). Backward elimination selected the strongest predictors of the Borg rating: peak inspiratory flow (VI); tidal volume (VT)/FVC; frequency of respiration (f); and peak inspiratory mouth pressures (Pm). These four variables explained 63% of the variance in the rating of dyspnea. Each of the four variables exhibited a linear relationship with the Borg rating. Test-retest reliability was assessed by comparing results at the first and second visits. Individual slopes (except for VT/FVC) and intercepts for the four predictor variables versus Borg ratings were highly reliable. The slope for work intensity (watts) and Borg ratings, but not the intercept, was highly reliable. Responsiveness was evaluated by randomly administering inhaled methacholine or inhaled metaproterenol, alternately, at the third and fourth visits to induce acute changes in lung function before exercise.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Measurement of breathlessness during exercise in asthmatics. Predictor variables, reliability, and responsiveness. 206 39

Acute bronchiolitis (AB) is a common lung disease in infants manifested clinically by dyspnea and wheezing. The purpose of this study was to measure simultaneous plasma levels of histamine and a stable prostaglandin F2 alpha metabolite [13,14-dihydro-15-keto-PGF2 alpha (PG metabolite)], by radioenzymatic and radioimmunoassays, respectively, during and after recovery from AB. Blood was obtained from 15 infants during AB and from 14 and 9 of these infants when re-evaluated 6 and 18 months later, respectively. Mean (+/- 1 SEM) pre- and posttherapy (inhaled isoetharine) histamine levels (pg/ml), 1,923 +/- 980 and 1,035 +/- 250 during AB, respectively, were markedly higher than those of the same nonwheezing subjects at 18 months, 360 +/- 125, but unexpectedly lower than those at 6 months, 9,210 +/- 5,242. Of the 14 infants evaluated at 6 months, 7 had elevated histamine levels along with histories of recurrent wheezing after AB. Similarly, pre- and posttherapy PG metabolite levels (pg/ml), 1,033 +/- 419 and 1,613 +/- 527, respectively, were significantly higher than those of the same children when asymptomatic at 6 (27 +/- 7) and 18 months (68 +/- 25). Pre- and posttherapy levels of histamine and PG metabolite were higher than those of normal and sick, nonwheezing infants. These data indicate that histamine and PG metabolite are detectable in plasma during AB and suggest a role for histamine and PGF2 alpha in the pathogenesis of airways inflammation in AB.
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PMID:Plasma elevations of histamine and a prostaglandin metabolite in acute bronchiolitis. 238

A low proportion of dietary calories as carbohydrate has been suggested for patients with chronic obstructive pulmonary disease, because oxidation of carbohydrate (CHO) compared to fat results in greater CO2 production (VCO2) and, at the same arterial PCO2 (PaCO2), higher alveolar and minute ventilation (VE) and increased dyspnea. We hypothesized that a low CHO-high fat diet, although reducing VCO2 and VE at rest, might result in only a small change in VCO2 and VE during exercise. Eight healthy volunteers were randomized to receive for 24 h either isocaloric diets containing 10% or 70% of total calories from CHO (remainder of nonprotein calories from fat). Measurements of VCO2, VE, and respiratory gas exchange ratio (R) were made at rest and during constant work rate cycle exercise below the anaerobic threshold. Five to seven days later, the alternate diet was given and the studies were repeated. At rest, mean VCO2 and R were significantly lower after the low CHO diet compared to the high CHO diet. Mean resting VE was less but not significantly (high CHO 9.6 [0.7] versus low CHO 8.7 [0.8] L/min, mean [SEM]). During exercise, mean VCO2 and R were significantly less after the low CHO diet, but mean VE was only slightly smaller and not significantly different between diets (high CHO 25.4 [1.1] versus low CHO 24.0 [1.0] L/min). The increase in VCO2 from rest to exercise was relatively independent of the substrate mix recently consumed, suggesting that the exercising muscles use stored muscle glycogen as substrate during short bouts of low-intensity exercise despite changes in substrate utilization by nonmuscle tissues at rest.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of altering the proportion of dietary fat and carbohydrate on exercise gas exchange in normal subjects. 249 33

Forty-seven consecutive patients aged 1-38 years underwent operation for hypertrophic obstructive cardiomyopathy (HOCM) between 1972 and 1986. Isolated myectomy-myotomy was performed in 43 patients, three patients underwent myectomy and concomitant aortic valve repair, and one patient underwent concomitant mitral valve replacement. The peak systolic pressure gradient from the left ventricle to the aorta decreased from 70 +/- 33 mm Hg (mean +/- SEM) preoperatively to 10 +/- 15 mm Hg immediately after repair (p less than 0.001). Moderate or severe mitral insufficiency was identified in 16 patients preoperatively and was corrected by myectomy alone in 15. There was no operative mortality; two late deaths occurred during follow-up (median, 5 years; maximum, 16 years) for estimated 5- and 10-year survivals of 97 +/- 2% and 88 +/- 10%, respectively. Reoperation was required for aortic valve replacement (n = 2), remyectomy (n = 2), and permanent pacemaker implantation (n = 3). Preoperative symptoms were relieved in 24 of 29 (83%) patients with dyspnea, in 18 of 19 (95%) with angina, and in six of 10 (60%) with syncope. These results support myectomy-myotomy for symptomatic children and young adults with HOCM. Also, it appears that late survival after myectomy-myotomy in these young patients may be improved over that observed in historical controls treated with medications alone; operation should be considered for asymptomatic children and adults less than 40 years of age with large (greater than 80 mm Hg) left ventricular outflow gradients.
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PMID:Results of operation for hypertrophic obstructive cardiomyopathy in children and adults less than 40 years of age. 276 26

The results of surgical treatment of post-infarction left ventricular aneurysms in 49 patients with congestive heart failure preoperatively were analyzed. Average patient age was 55 years. Preoperative total ejection fraction averaged 30.5 +/- 1.5% (mean +/- SEM), contractile segment ejection fraction was 42.5 +/- 1.1% and end-diastolic volume of aneurysm was 81.4 +/- 10.4 ml. Seventy eight percent of patients underwent coronary artery bypass grafting concomitantly with aneurysmectomy. Mean follow-up after operation was 41.5 +/- 3.5 months. Hospital mortality was 8.2%, the 5 year survival rate was 70 +/- 7% and the 5 year complication free rate was 52 +/- 8%. Mean functional class of dyspnea improved significantly from 2.9 +/- 0.1 preoperatively to 1.6 +/- 0.1 at late follow-up (p less than 0.001). Likewise, isotopic ejection fraction at rest increased from 13.7 +/- 1.3% preoperatively to 30.9 +/- 3.0% postoperatively (p less than 0.0001). Logistic regression analysis isolated two factors which influenced postoperative survival independently: contractile segment ejection fraction (p = 0.045) and myocardial score of left anterior descending coronary artery (p = 0.035). Combining these two risk factors, it was possible to identify a low risk group of patients with a 5 year survival probability of 93 +/- 6%, contrasting with a high risk group of patients having a 5 year survival of 57 +/- 9% (p less than 0.02). Thus, resection of left ventricular aneurysms complicated by congestive heart failure provides improvement in left ventricular function and clinical status.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Left ventricular aneurysm complicated by congestive heart failure: an analysis of long-term results and risk factors of surgical treatment. 278 22

Frequently, patients with COPD with similar spirometric impairment have marked differences in dyspnea and exercise limitation. As the classic "blue bloater" with attenuated respiratory drive is described as being less dyspneic than his "pink puffer" counterpart, we wondered whether the variability in dyspnea and exercise tolerance in a group of patients with COPD with relatively similar degrees of air-flow obstruction might be partly explained by the variability in resting respiratory drives (unstimulated P0.1 and hypoxic and hypercapnic P0.1 responses). Therefore, we measured unstimulated mouth occlusion pressure (P0.1), hypoxic response (-delta P0.1/delta SaO2), hypercapnic response (delta P0.1/delta PCO2), 6-min walk distance, VO2max, steady-state exercise VE/VO2, exercise SaO2, and dyspnea using an oxygen cost diagram in 15 subjects with severe COPD (mean FEV1% 35.2 +/- 1.9 SEM). No correlations between spirometric impairment and either dyspnea or exercise performance were seen. Unstimulated P0.1 correlated inversely with spirometric impairment but did not correlate with dyspnea, VO2max or 6-min walk distance. Both hypoxic and hypercapnic responses were significantly correlated with greater exercise ventilation (VE/VO2), less exercise O2 desaturation, and a greater VO2max, but not with dyspnea or 6-min walk distance. The results of this study do not support the concept that depressed respiratory drives are associated with less dyspnea or greater exercise capability in COPD.
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PMID:Relationship of respiratory drives to dyspnea and exercise performance in chronic obstructive pulmonary disease. 311 45

Many patients with chronic obstructive pulmonary disease (COPD) receiving supplemental oxygen state that this treatment makes them less short of breath at rest. We postulated that this phenomenon may be related to improved arterial oxygenation, reduced ventilation, or stimulation of nasal receptors caused by the flow of gas. Eight patients who reported this phenomenon were studied in a quiet room. Each patient received zero flow, 2, or 4 L/min of air or oxygen through nasal cannula for 5 min at each level in random order in a single blind manner. At the end of each period, arterial blood gas composition was measured, and breathlessness was assessed with a visual analog scale. The scale was calibrated to read from zero (not at all breathless) to 100 (extremely short of breath). The entire protocol was repeated after application of topical lidocaine to the nasal passages. Results were assessed by analysis of variance. We found no significant effect of inspired oxygen concentration, gas flow, arterial oxygen tension, or arterial carbon dioxide tension on breathlessness. There was, however, a significant increase in breathlessness after nasal anesthesia from 44 +/- 3 SEM to 52 +/- 4 SEM (p less than 0.005). We suggest that the reduction of breathlessness in these patients by nasal oxygen is a placebo effect caused by wearing the nasal cannulas and is unrelated to gas flow or the increased arterial oxygen tension.
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PMID:The effect of nasal flow on breathlessness in patients with chronic obstructive pulmonary disease. 314 98

Pulmonary functions at rest and cardiorespiratory responses to low speed treadmill walking were investigated in 24 patients (P), (mean age, 38 years; range, 20 to 56 yr) with multiple sclerosis and compared with a control group (C). The following parameters were significantly (p less than 0.01) different in P from those in C. At rest in P, the residual volume to TLC ratio was 21% greater, respiratory muscle strength index was 28% lower, and heart rate (HR) was 11 beats/min-1 higher. During treadmill walking at a given speed, HR, minute ventilation (VE), and O2 consumption (VO2) were all elevated (37 to 119%). In addition, the energy cost of walking, per unit distance, above resting, was 2 to 3 times greater, with mean +/- SEM values for P of 0.299 +/- 0.019 and C of 0.147 +/- 0.006 at 2 km/h and 0.275 +/- 0.042 and 0.110 +/- 0.005 (for P and C, respectively) ml O2 kg-1 m-1 at 4 km/h; the HR and VE/VO2, also when referred to a given VO2, were higher. We conclude that a high energy cost of walking may be an important contributing factor to breathlessness and leg fatigue in patients with multiple sclerosis. Poor conditioning, altered cardiovascular control, and respiratory muscle weakness may play additional roles.
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PMID:Energy cost of walking and exertional dyspnea in multiple sclerosis. 377 62


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