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Results for “Bronchospirometry”

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At least 415 records · Page 23Linked to original sources
PubMed1982

Effects of arachidonic acid, PGF2 alpha, and a PGH2 analogue on airway diameters in dogs.

The effects of intravenous arachidonic acid, a prostaglandin H2 analogue [(15S)-hydroxyl-11 alpha, 9 alpha-(epoxymethano)prosta-5Z,13E-dienoic acid (PGH2-A)], and prostaglandin F2 alpha (PGF2 alpha) on lung mechanics and airway diameters were compared using tantalum bronchography in 20 paralyzed, artificially ventilated, pentobarbital-anesthetized dogs. These agents produced dose-related increases in lung resistance (RL) and decreases in dynamic compliance (Cdyn). Both RL and Cdyn changed maximally within 25 s after injection. RL, however, returned to base line within 2 min, whereas the decrease in Cdyn persisted much longer. Changes in the diameter of airways less than 2 mm produced small changes in RL and Cdyn. Larger changes in RL corresponded with changes in airways as large as 4 mm. Vagal reflexes or pulmonary edema were not important contributors to these effects. These data suggest that the changes in RL and Cdyn produced by intravascular injections of arachidonic acid, PGH2-A, and PGF2 alpha result from their direct effects on smooth muscle in airways as large as 4 mm.

Airway Resistance↗
PubMed1989

CO2 sensitivity changes during the menstrual cycle.

A study of the changes in CO2 sensitivity at rest was undertaken in 20 regularly menstruating females in an attempt to determine the influence of the menstrual cycle on this variable. A biphasic oral temperature graph was used to signify fertility and demarcate three phases of the cycle. A CO2-rebreathing test was conducted 3 times/wk for 6 wk to obtain CO2 sensitivity and CO2 threshold measures. An analysis of variance was used to compare the results collected in each phase of the cycle for each of the variables. A significant increase was found in the sensitivity to CO2 between the follicular and luteal phases, a significant decrease between the luteal and menstrual phases, and no significant difference between the follicular and menstrual phases. The change between follicular and luteal phases was attributed to the effect of progesterone, which is elevated during the luteal phase. No significant change was found in the CO2 threshold level.

Adolescent↗
PubMed1977

Continuous measurement of respiratory resistance in asthmatic children.

In 13 children (7-13 years old) with bronchial asthma in remission, respiratory system resistance was continuously measured by the forced oscillation method at 10 Hz, using on-line digital computer analysis. Corrections were made for mouth impedance which was determined from a prior Valsalva maneuver. Functional residual capacity was also periodically determined by the body plethysmographic technique in order to allow calculation of specific respiratory system conductance (SGRS). The total observation period of 45 min consisted of quiet breathing interrupted by vital capacity maneuvers. In a single-blind design, eight children were given 0.15 mg isoproterenol sulfate from a proprietary spray delivered in the beginning of an inspiratory vital capacity maneuver while five received a placebo (freon propellent alone). A significant increase in SGrs (+53%) was observed 75 sec after isoproterenol sulfate administration. SGrs peaked after 2 min (+ 61%) and remained elevated significantly for 10 min. No significant changes occurred in the placebo group. The immediate decrease in SGrs which was observed following control vital capacity maneuvers, was prevented by isoproterenol sulfate but not by the freon propellent. Our findings suggest that although peak bronchodilation does not occur before 2 min following isoproterenol sulfate inhalation, an effect, namely prevention of bronchoconstriction induced by a deep breath, is already detectable within seconds.

Adolescent↗
PubMed1978

Changes in volume of trapped gas in the lungs during provoked asthma followed by beta-2 receptor stimulation.

The volume of trapped gas (VTG) that could be mobilized by maximal breaths at the end of a nitrogen washout to 2% N2 was measured in 11 subjects with a history of asthma before and after provocation with specific allergens. The change after salbutamol was also measured. VTG was found to be more specific and sensitive for demonstrating early bronchospasm than changes in FEV1, VC or nitrogen washout. Salbutamol relieved all symptoms of bronchospasm.

Adult↗
PubMed1992

Analysis of respiratory impedance characteristics in chronic bronchitis.

Impedance measurements of the respiratory system were performed by means of the technique of forced oscillations to study the mechanical characteristics of the respiratory system in 33 patients with chronic bronchitis without spirometric evidence of airway obstruction (FEV1 greater than or equal to 70% predicted). In 23 patients (69.7%) impedance was found to be abnormal. Inhalation of a beta 2-adrenergic drug (terbutaline) resulted in acute reversibility of these findings. In the 10 patients (30.3%) with a normal baseline respiratory impedance, isocapnic hyperventilation with cold air resulted in impedance characteristics similar to the abnormalities spontaneously occurring in the other group. These changes were found to be completely reversible after the inhalation of terbutaline. On the basis of these findings we conclude that impedance measurements of the respiratory system by means of the technique of forced oscillations allow the determination of mechanical airway abnormalities in patients with chronic bronchitis.

Adult↗