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Biomedical subjects

M Plit

Publications and source records attributed to M Plit.

15 recordsLinked to original sources
PubMed1994

Effects of inspired air conditions on catecholamine response to exercise in asthma.

The influence of different inspired air conditions on exercise-induced bronchoconstriction (EIB) is well appreciated. However, the mechanism by which this influence is exerted is uncertain. To determine if varied inspired air conditions during exercise could affect the catecholamine response to physical exercise, we had 13 asthmatic and 6 healthy children (aged 10-18 years) undergo two bouts of cycle ergometry tests under different air conditions. One test was done while breathing cold dry (CD) air (temperature, -20.2 degrees C; relative humidity, 0%) and the other while breathing warm humid (WH) air (temperature, 34.3 degrees C; relative humidity, 100%). Forced expiratory volume in 1 second (FEV1) and plasma catecholamine concentrations were recorded before and after exercise. Marked EIB (48 +/- 5% SEM fall in FEV1 from baseline) developed in all asthmatics after the CD exercise, but no EIB was noted after the WH exercise. Normal controls had no EIB under either test conditions. Plasma levels of catecholamines at rest, and the changes that occurred during and after exercise, were comparable within as well as between the groups in both tests. Catecholamines did not rise in asthmatics following development of EIB. These data demonstrate that inspired air conditions do not influence the sympathoadrenal response to exercise, at least as reflected in plasma catecholamine levels. In fact, this response did not differ between asthmatics and normals, irrespective of the development of EIB. These results are consistent with previous reports about impaired catecholamine response of asthmatics to bronchoconstriction.

Adolescent↗
PubMed1993

Exercise, regardless of induced bronchoconstriction or inspired air conditions, does not alter airway reactivity.

The effects of exercise on asthmatic airway caliber are well recognized. Only a few studies, however, evaluated the effects of prior exercise on asthmatic airway reactivity. Eight asthmatic children (ages 10 to 16 years; mean, 12) performed histamine inhalation tests on three occasions assigned in random order: (1) control; (2) 40 to 60 min after exercise (6 min ergometer cycling) done while breathing cold dry (CD) air (temperature = -13 degrees C, relative humidity = 0 percent); and (3) 40 to 60 min after exercise done while breathing warm humid (WH) air (temperature = 33 degrees C, relative humidity = 100 percent). While there was a marked exercise-induced bronchoconstriction (EIB) in the CD test with a postexercise fall in FEV1 of 39.2 +/- 8 percent (mean +/- SEM), there was no EIB in the WH test (4.6 +/- 2 percent). There was no difference, however, in the geometric mean histamine concentration required to produce a 20 percent fall in FEV1 (PC20) among the CD, WH, and control tests (0.52 mg/ml, 0.60 mg/ml, and 0.55 mg/ml, respectively). Airway reactivity in asthmatic children is not influenced by a prior exercise challenge, independent of the conditions of the inspired air during the exercise. Moreover, exercise per se, regardless of development of EIB, does not change the reactivity.

Adolescent↗
PubMed1990

Growth hormone response to exercise in asthmatic and normal children.

Maximal growth hormone (GH) increments following exercise were compared in asthmatic (n = 14) and normal (n = 8) children. Exercise, which consisted of 6 min ergometer cycling while breathing cold dry (CD) air, induced asthma in all asthmatic patients but not in normal subjects. Baseline plasma GH levels were similar in both groups. Following exercise, however, asthmatic patients had significantly higher mean GH increments than normal subjects (14.8 vs 4.9 ng/ml, P less than 0.025). To evaluate the possible role of bronchoconstriction in the GH response all subjects exercised again, this time while breathing warm humid (WH) air. Despite the absence of exercise-induced asthma (EIA) while breathing WH air, asthmatic patients still had significantly higher mean GH increments than normal subjects (9.2 vs 2.3 ng/ml, P less than 0.05). We conclude that some asthmatic children show excessive GH secretion after exercise regardless of inspired air conditions or the development of EIA.

Adolescent↗
PubMed1989

Temperature and humidity modify airway response to inhaled histamine in normal subjects.

The airway response to inhaled histamine is known to be influenced by various stimuli (e.g., infection, ozone). Temperature (T) has been shown to affect it in vitro. We studied whether T and humidity (H) modify airway response to inhaled histamine in normal subjects. Twelve normal subjects 21 to 46 yr of age (mean age, 29 yr) performed two similar histamine inhalation tests, the only difference being the conditions of the inspired air. One test was done while breathing cold dry air (mean T +/- SEM, -17.3 +/- 1.8 degrees C; relative H, 0%), and the other while breathing warm humid air (mean T +/- SEM, 33.9 +/- 0.5 degrees C; relative H, 100%). Whereas the geometric mean histamine concentration required to produce a 15% fall in FEV1 in the warm humid tests was 22.7 mg/ml, it was 11.9 mg/ml in the cold dry test (p less than 0.01). It is concluded that the T and H of inspired air modify the airway response to inhaled histamine in normal subjects.

Administration, Inhalation↗
PubMed1986

A comparison between right atrial and pulmonary arterial oxygen tensions.

Oxygen tensions of 50 simultaneously withdrawn blood samples from the right atrial orifice of a triple-lumen pulmonary artery catheter and from the pulmonary artery lumen were compared. Mixed venous oxygen tensions ranged from 21 mmHg to 44.9 mmHg. The correlation coefficient was 0.96 (t = 2.09; P = 0.01). The benefits and drawbacks of intermittent right atrial oxygen tension monitoring are discussed.

Cardiac Catheterization↗
PubMed1986

Respiratory heat loss in exercise-induced asthma. Measurement and clinical application.

The theoretical considerations of conditioning inspired air and the application of the respiratory heat loss (RHL) formula are discussed. An on-line method for measuring RHL is described together with the apparatus for generating frigid dry and warm humid air. Exercise-induced asthma (EIA) was studied using these methods. Thirteen asthmatic and 6 normal children and adolescents participated in the study. Each subject undertook two submaximal exercise tests consisting of 6 minutes' ergometric cycling against a fixed load. One test was done while breathing cold dry air (mean temperature -22 degrees C and 0% relative humidity) and the other while breathing warm humid air (mean temperature 36 degrees C and 100% relative humidity). All the other exercise parameters (e.g. heart rate, minute ventilation, oxygen uptake) were carefully matched between the two tests. In the cold dry air tests with a mean RHL of 1,43 kcal/min, all asthmatic subjects developed EIA with a mean fall in forced expiratory volume in the 1st second (FEV1) of 48% from baseline. In the warm humid air tests with negligible RHL (0,02 kcal/min) none of the asthmatics developed EIA (mean fall in FEV1 5%). The difference between the two tests was highly significant (P less than 0,001). Neither air condition caused bronchospasm in the normal subjects. A dose-response relationship was obtained between the degree of RHL and corresponding fall in FEV1.

Adolescent↗
PubMed1984

Assessment of a new combination inhaler containing salbutamol and beclomethasone dipropionate in the management of asthmatic patients.

Fifteen patients with chronic asthma completed a double-blind cross-over trial during which they were treated with the same daily doses of salbutamol and beclomethasone dipropionate (BDP) from either a combination inhaler or two separate inhalers. Lung function was measured at the end of each treatment period and each patient kept a diary card throughout. Daily assessments of patients' symptoms and additional medication requirements were similar during both treatment periods. Peak expiratory flow rate (PEFR) recordings taken four times a day showed little diurnal variation during both periods. Mean PEFRs for the groups during a period of 2 weeks were similar for both treatments at all times. Overall daily mean PEFRs showed a trend in favour of the combination inhaler. There was a suggestion of greater variability in airway obstruction during the period when the separate inhalers were used, as assessed by the number of occasions that the PEFR was outside the range (overall daily mean +/- 15%). Lung function measurements at the end of each period showed a trend in favour of the combination inhaler which was clinically significant in terms of the forced expiratory volume in the 1st second and forced vital capacity. The combination inhaler provides an alternative in the management of asthma which is at least as effective as treatment with salbutamol and BDP from two separate inhalers.

Adolescent↗
PubMed1984

A guide to the rational use of dopamine, dobutamine and isoprenaline in patients who need inotropic support.

Which inotropic agent to use to the patient's greatest advantage is a common problem in hospital practice. Sympathetic nervous system physiology is outlined to explain the actions of dopamine, dobutamine and isoprenaline. The following suggestions are made: Where a low-dosage inotropic effect is required, dopamine should probably be used because of the unique benefit of increased renal blood flow. Where there are no tachyarrhythmias, dopamine should be the drug of choice. In dosages greater than 5 - 10 micrograms/kg/min, dopamine should be combined with nitroprusside. If further inotropic activity is required, the effect of dopamine can be increased with the concomitant use of isoprenaline. In the presence of tachyarrhythmias dobutamine may be of benefit.

Autonomic Nervous System↗
PubMed1984

Vitamin B12 levels in the prolonged use of sodium nitroprusside.

Long-term (greater than 48 h) sodium nitroprusside (SNP) infusion significantly reduced cobalamin (vitamin B12) levels in 23 patients treated in a CCU after myocardial infarction. There was no evidence of vitamin B12 deficiency or SNP toxicity. Low vitamin B12 levels should not limit the use of SNP, because prolonged infusion of SNP at maximum doses of 2.5 micrograms/kg X min did not adversely affect hemodynamic stability.

Blood Pressure↗