Biomedical subjects

F Fryder-Doffey

Publications and source records attributed to F Fryder-Doffey.

4 recordsLinked to original sources

PubMed1994

Cardiopulmonary adaptations to pneumonectomy in dogs. III. Ventilatory power requirements and muscle structure.

Static and dynamic mechanical characteristics of the respiratory system were measured in five adult foxhounds 6-15 mo after right pneumonectomy (R-PNX) and in five matched foxhounds that underwent right thoracotomy without pneumonectomy (Sham). In R-PNX dogs, elastic recoil was lower than that in the left lung of Sham dogs. On exercise, absolute ventilatory power requirements of the lung and its components were measured, i.e., power requirements to overcome elastic and viscous resistances of the lung as well as power requirements during inspiration and expiration. All components were higher for a given minute ventilation in R-PNX dogs than in both lungs of Sham dogs. Ventilatory power requirements after R-PNX were also higher than in three adult foxhounds after left PNX studied previously by the same techniques. After R-PNX, the mass of the right costal diaphragm and total mass of inspiratory muscles were greater than in Sham dogs. There were no significant differences in ultrastructural features of the costal diaphragm. The unilateral increase in muscle mass is likely the result of chronic elevation and stretch of the right costal diaphragm after R-PNX.

Air Pressure↗

PubMed1994

Compensatory lung growth occurs in adult dogs after right pneumonectomy.

We investigated the structural changes in the left lung of five adult male foxhounds 5 mo (n = 2) or 16 mo (n = 3) after right pneumonectomy (approximately 54% of lung resected) and five sex- and age-matched foxhounds 15-16 mo after right thoracotomy without pneumonectomy. Lungs were fixed by intratracheal instillation of glutaraldehyde and analyzed by standard morphometric techniques. After right pneumonectomy, volume of the left lung increased by 72%. Volumes of all septal structures increased significantly and were more pronounced at 5 than at 16 mo after pneumonectomy. At 16 mo, the relative increases in volume with respect to the control left lung were as follows: epithelium 73%, interstitium 100%, endothelium 55%, and capillary blood volume 43%. Surface areas of alveoli and capillary increased significantly by 52% and 34%, respectively. At 5 mo after pneumonectomy, harmonic mean thickness of the tissue-plasma barrier was significantly greater but at 16 mo it was not different from controls. There was a significant increase in diffusing capacity for oxygen (33% above controls) at 16 mo after pneumonectomy. These data suggest that, in contrast to previous findings after left pneumonectomy, compensatory lung growth does occur in adult dogs after resection of > 50% of lung.

Animals↗

PubMed1993

Morphometric model for pulmonary diffusing capacity. I. Membrane diffusing capacity.

The pulmonary diffusing capacity is related to the quantitative design characteristics of the pulmonary gas exchanger. The current model for estimating DLO2 from morphometric data breaks the diffusion path for O2 into four steps, three of which represent the membrane part of DLO2. A critique of this model on the basis of newer evidence leads to a modification of the model where the path from the alveolar surface to the erythrocyte membrane is considered as a single step. The structural determinant of this model for DMO2 is the ratio of effective diffusion surface to effective total barrier thickness. The effective surface is formulated as a fraction of the alveolar surface area, the most robust measure of lung design, whereas the effective barrier thickness is the harmonic mean distance--or mean proximity--between alveolar surface and erythrocyte surface. The methods for obtaining the morphometric measurements are discussed. The results show that the new morphometric estimates of DMO2 are 33% lower than those obtained with the old model, resulting in a reduction of the estimates of DLO2 by 10-20%.

Animals↗

PubMed1993

Structural changes underlying compensatory increase of diffusing capacity after left pneumonectomy in adult dogs.

To determine if the functional compensation in diffusing capacity of the remaining lung following pneumonectomy is due to structural growth, we performed morphometric analysis of the right lung in three adult foxhounds approximately 2 yr after left pneumonectomy (removal of 42% of lung) and compared the results to those in normal adult dogs previously studied by the same techniques. Diffusing capacity was calculated by an established morphometric model and compared to physiologic estimates at peak exercise in the same dogs after pneumonectomy. The major structural changes after left pneumonectomy are hyperinflation of the right lung, alveolar enlargement, and thinning of the alveolar-capillary tissue barrier. These changes confer significant functional compensation for gas exchange by reducing the overall resistance to O2 diffusion. The magnitude of compensation in diffusing capacity estimated either morphometrically or physiologically is similar. In spite of morphometric and physiologic evidence of functional compensation, there is no evidence of significant growth of structural components. After pneumonectomy, morphometric estimates of diffusing capacity are on average 23% higher than physiologic estimates in the same dogs at peak exercise. We conclude that the previously reported large differences between morphometric and physiologic estimates of diffusing capacity reflects the presence of large physiologic reserves available for recruitment.

Animals↗