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C S Garrard

Publications and source records attributed to C S Garrard.

41 records · Page 3Linked to original sources
PubMedDate not supplied

Analysis of aerosol deposition in the healthy human lung.

Wide variation in the pattern of deposition of inhaled aerosols has previously been described in both healthy and diseased humans. To investigate the factors responsible for such variation, the authors studied a group of 13 healthy nonsmoking subjects. One two occasions each subject inhaled a monodisperse 8.1 mm (mass median aerodynamic diameter) Fe2O3 aerosol labelled with 99mTc using a standardized breathing pattern. Pulmonary function was defined by tests of forced expiratory airflow. Total activity in the right lung at 0 hr and at 24 hr (24-hr percent retention) was measured using a gamma camera. Numerical indices of deposition pattern were derived in several ways from the initial gamma camera image of the right lung by comparing the ratio of activity within a mid- and peripheral lung region of interest, by analyzing the profile of radioactivity within a horizontal band across the right lung from the midline to the lung edge, and by analysis of a distribution histogram of activity within the whole lung (skew and kurtosis). The 24-hr percent retention of aerosol showed considerable intrasubject variability unlike the deposition indices. The various deposition indices were found to correlate with the 24-hr percent retention, FEV1.0, FEV1.0/FVC%, and MMFR at varying levels of significance. Results indicate that the pattern of aerosol deposition in healthy humans is influenced by mild degrees of obstruction to airflow, as reflected by tests of forced expiratory airflow, increasing airways obstruction being associated with more central deposition of the inhaled aerosol. Deposition indices derived from the initial pattern of aerosol distribution within the lung may prove to be more reliable and sensitive than measurements of 24-hr percent retention in defining aerosol deposition pattern.

Adult↗
PubMedDate not supplied

The effects of expiratory positive airway pressure on functional residual capacity in normal subjects.

Functional residual capacity (FRC) was determined by constant volume, whole body plethysmography in seven normal subjects under resting conditions and following the addition of increasing levels of expiratory positive airway pressure (EPAP). There was a significant increase in FRC in six of the seven subjects studied. Grouped data showed a progressive increase in FRC with increasing EPAP (p less than 0.01). The highest level of EPAP (15 cm H2O) was associated with a 20% increase in FRC. We have been able to confirm that EPAP provides a simple and effective method of increasing FRC which could be applied to the treatment of conditions characterized by temporary and reversible reduction in lung volume.

Adult↗
PubMedDate not supplied

Ventilatory support in asthma.

Mechanical ventilation in acute asthma is associated with significant morbidity and mortality, and maximal medical therapy should prevent it being used inappropriately. We review current standards of medical therapy in acute asthma, the indications for mechanical ventilation and its management.

Acute Disease↗