Chest wall distortion and regional lung volume distribution in erect humans.

Using 133Xe measured the regional distribution of FRC and of boluses administered at FRC in seated subjects during relaxation, lateral compression of the lower rib cage, and contraction of the inspiratory muscles so that mouth pressure was 50 cmH2O subatmospheric. Lateral compression increased apex-to-base differences of volume and bolus distribution, suggesting an increase of the apex-to-base gradient of pleural surface pressure. Changes in rib cage shape were measured with magnetometers and were qualitatively similar to those associated with increases in apex-to-base difference of pleural surface pressure in animals. Inspiratory effort decreased apex-to-base difference in volume and induced a similar trend in bolus distribution. Though changes in the rib cage shape were directionally similar, they were much smaller than those associated with decreased pleural surface pressure gradients in animals, and the changes in regional volume we observed were more likely due to forces generated by diaphragmatic contraction. These results were compatible with the apex-to-base gradient of pleural pressure being strongly influenced by shape adaptation between lung and chest wall.     

Pressure-volume curve of lung and lobes in kittens

In the neonatal period, the incomplete aeration of the lung parenchyma and the presence of some pulmonary fluid could determine inequalities in the mechanical behavior of lung regions, favoring unevenness of ventilation distribution. We studied the pressure-volume (PV) curve of excised lungs of kittens in the 1st wk of life 1) by changing the volume a known amount and measuring the corresponding changes in transpulmonary pressure (PL) and 2) by ventilating them at a fixed PL at a rate of 20 cycles/min. An expiratory load equal to the value of PL at the resting volume of the respiratory system was added to avoid the collapse of the lung. A lobar bronchus was then tied, and the measurements were repeated. The difference in PV curves before and after ligature therefore represented the PV curve of the lobe. This was done for all the lobes (upper and middle right, lower right, lower left, upper left) in a random order. A total of 20 lungs and 61 lobes have been studied. Individual lobes were not different in terms of dry-to-wet weight ratio, compliance per unit weight, or per maximal volume and shape of the PV curve, indicating a similar mechanical behavior. Dynamic lung compliance averaged 76% +/- 15 SD of the static value, suggesting some degree of asynchronous behavior of lung regions or viscoelastic properties of the tissue.     

Changes in L-ornithine decarboxylase activity in regenerating lung lobes

Growth of regenerating lung lobes is preceded by an increase of the activity of L-ornithine decarboxylase (ODC). Mechanical factors play a role in determining both the growth rate and enhancement of activity of ODC in regenerating lung lobes. Hormonal regulation also appears of importance as shown by the increased ODC activity in a transplanted lobe.     

Alveolar liquid clearance in multiple nonperfused canine lung lobes

Grimme, John D., Susan M. Lane, and Michael B. Maron.Alveolar liquid clearance in multiple nonperfused canine lung lobes. J. Appl. Physiol. 82(1):348-353, 1997.We evaluated the ability of canine isolatednonperfused lung lobes to absorb fluid from their air spaces bysimultaneously measuring alveolar liquid clearance (ALC) in three lobesremoved from the same dog. Autologous plasma was instilled in the airspaces of each lobe, and the increase in plasma protein concentrationresulting from fluid reabsorption was used to calculate ALC. ALC after4 h was 16.5 ± 0.6% (SE) of the instilled fluid volume underbaseline conditions and was 30.2 ± 1.3% after terbutaline(10⁵ M) administration.These values were similar to those previously reported for intact dogs.Propranolol (10⁴ M) andouabain (10³ M) reduced ALCin terbutaline-stimulated lobes to 20.4 ± 0.8 and 3.9 ± 1.4%,respectively. There was no significant difference in ALC among thethree lobes under either baseline conditions or after terbutalineadministration. These data indicate that the sodium and water transportmechanisms of the canine alveolar epithelium remain viable during 4 hof nonperfusion and that there are no intrinsic differences in thetransport properties of individual lung lobes. The ability to studyseveral lobes simultaneously without the need for perfusion will allowfor the design of experiments in which multiple interventions can bestudied by using lung lobes from the same animal.

     

Changes in lung volume parameters regarding the received dose in the lobes of the lungs after locoregional radiotherapy of breast cancer

AimThe purpose of this study was to evaluate ΔLVP¹ and correlate them with MLD² and V20³ in the lobes of the lung.BackgroundRadiation-induced lung injury after breast irradiation is controversial. The incidence of such an injury could have negative consequences on breast cancer patients.Materials and MethodsTwenty-three women treated with Breast-conserving surgery, chemotherapy, and locoregional RT⁴ underwent body plethysmography pre-RT and 3 and 6 months post-RT. Statistical analysis was used to evaluate ΔLVP over time and relate them with MLD, V20, age, and concurrent hormonal therapy.ResultsLVP decreased after 3 months and then showed a slight improvement by returning partially to their pre-RT values after 6 months. The mean ΔLVP was −0.64% for one Gy increase of MLD and −0.34% for one percent increase of V20 after 3 months. After 6 months, only ΔVC⁵ showed 0.45% reduction with MLD in the upper lobe. Finally, there was no significant correlation between ΔLVP with respect to age and concurrent hormonal therapy.ConclusionsThe results of this study showed that lung volume changes were not a cause for concern in breast cancer patients. There are three reasons to support this conclusion. Lung volume changes and percentage reductions in LVP for each Gy increase of MLD and each percentage increase of V20 in each lobe were small; patients were asymptomatic during the follow-up period; and LVP showed partial improvements after 6 months.