Biomedical subjects

Andrew Hoffman

Publications and source records attributed to Andrew Hoffman.

3 recordsLinked to original sources

PubMed2004

Energetic cost of breathing, body composition, and pulmonary function in horses with recurrent airway obstruction.

This study was conducted to determine whether horses with naturally occurring, severe chronic recurrent airway obstruction (RAO) 1). have a greater resting energy expenditure (REE) than control horses, 2). suffer body mass depletion, and 3). have significantly decreased REE after bronchodilation and, therefore, also 4). whether increased work of breathing contributes to the cachexia seen in some horses with RAO. Six RAO horses and six control horses underwent indirect calorimetric measures of REE and pulmonary function testing using the esophageal balloon-pneumotachograph method before and after treatment with ipratropium bromide, a parasympatholytic bronchodilator agent, at 4-h intervals for a 24-h period. Body condition scoring was performed, and an estimate of fat mass was determined via B-mode ultrasonography. O(2) and CO(2) fractions, respiratory airflow, respiratory rate, and pleural pressure changes were recorded, and O(2) consumption, CO(2) production, REE, pulmonary resistance, dynamic elastance, and tidal volume were calculated. In addition, we performed lung function testing and calorimetry both before and after sedation in two control horses. RAO horses had significantly lower body condition scores (2.8 +/- 1.0 vs. 6.4 +/- 1.2) and significantly greater O(2) consumption than controls (4.93 +/- 1.30 vs. 2.93 +/- 0.70 ml.kg(-1).min(-1)). After bronchodilation, there was no significant difference in O(2) consumption between RAO horses and controls, although there remained evidence of residual airway obstruction. There was a strong correlation between O(2) consumption and indexes of airway obstruction. Xylazine sedation was not associated with changes in pulmonary function but did result in markedly decreased REE in controls.

Adrenergic alpha-Agonists↗

PubMed2003

Physiologic responses of sheep to two different methods of papain exposure.

Human emphysema is a progressive, destructive lung disease that produces morphologic and functional heterogeneity throughout its course. Consequently, the mature form of the disease is described by a broad range of anatomic, radiological, and physiologic patterns. This report describes the development and characterization of a sheep model of emphysema that represents many of the essential features of both homogeneous and heterogeneous emphysema. Emphysema was produced by two different techniques of papain exposure: (1) aerosol (75 IU/kg) given weekly for 4 treatments (HM) or (2) aerosol (75 IU/kg) weekly for 3 treatments following subsegmental intrabronchial instillations, 75 IU (in 10 saline) per lobe in 6 lobes (HT). Dexamethasone (0.06 mg/kg iv) was administered prior intrabronchial instillations only. On computed tomography, the HM group had homogeneous emphysema, the HT group gross nonuniformity of disease and bullae formation. Both groups demonstrated a significant (p < 0.05) increase in residual volume (HM, +38%; HT, +30%). There was a significant increase (p = 0.002) in total lung capacity per kilogram for the HM group. Emphysema had no effect on active or passive chest wall compliances. Diffusion capacity was significantly (p < 0.05) reduced in both groups. Both elastic (p = 0.066) and resistive (p = 0.025) components of impedance were increased in the HT, and airway resistance increased significantly in the HM groups. The HM model demonstrated gas trapping, a characteristic feature of emphysema, but failed to replicate the alterations in lung dynamics observed in the human form of this disease. The HT model demonstrated less static hyperinflation but significant frequency dependence and hence appeared to better represent the dynamic characteristics of human emphysema.

Administration, Inhalation↗

PubMed2002

Bronchoscopic lung volume reduction using tissue engineering principles.

Bronchoscopic lung volume reduction (BLVR), a minimally invasive procedure based on tissue engineering principles, was performed in six sheep with papain-induced experimental emphysema (EMPH). Physiologic measurements, at baseline, after generation of EMPH, and at 3 and 9 weeks after BLVR, included lung volumes, diffusing capacity (DL(CO)), pressure-volume relationships for the lung and chest wall, pleural pressures generated during active respiratory muscle contraction, lung resistance and dynamic elastance. The animal model displayed hyperinflation (change in total lung capacity +8%; change in residual volume +66%), reduced DL(CO) (-21%), and elevated airway resistance (+76%) that resembled advanced human EMPH. BLVR was well tolerated without complications, and it reduced lung volumes (change in total lung capacity -16%; change in residual volume -55%) in a pattern that resulted in significant improvements in vital capacity (10%). At autopsy, well-organized, peripheral scars associated with tissue contraction were observed at 33 of the 36 (91%) treated sites. There was no evidence of infection, abscess, or granuloma formation, or allergic reaction. Scar tissue, generated by BLVR, replaced hyperinflated lung, reduced overall lung volume, and improved respiratory function safely and consistently. The BLVR technology employed in this study addresses the limitations identified in our prior attempt at BLVR therapy and appears safe and effective enough to justify a trial in humans.

Airway Resistance↗