Search PubMed⌕ Search

Biomedical subjects

G Batra

Publications and source records attributed to G Batra.

8 recordsLinked to original sources
PubMed1982

Changes in collateral ventilation with increased vascular pressure and edema formation.

To test the hypothesis that development of hemodynamic edema results in decreased collateral ventilation, we rapidly volume-expanded anesthetized dogs with volumes equivalent to 10 (n = 5) and 15% (n = 5) of body weight. We measured collateral resistance (Rcoll), pulmonary arterial pressure, and left ventricular end-diastolic pressure before, during, and for 1-2 h after the infusion. Lungs were subsequently processed for microscopic examination and measurement of extravascular lung water content. During the infusion, Rcoll increased modestly independent of the fluid-infusion rate or the rate of increase in vascular pressures. After the infusion, Rcoll continued to increase to maximum levels 2-33 times base line even though pressures decreased dramatically. At the end of the experiment, Rcoll returned to base line in one dog and was 3-15 times base line in the other dogs. These changes bore no relationship to the severity of edema formation. Until alveolar flooding occurs, accumulation of lung interstitial fluid and changes in collateral ventilation appear to be coincident events rather than causally related variables.

Airway Resistance↗
PubMed1981

Effects on body position and cholinergic blockade on mechanics of collateral ventilation.

We studied the effects of position and cholinergic blockade on the mechanics of collateral ventilation in anesthetized paralyzed dogs. Resistance to collateral flow (Rcoll) is higher when an obstructed segment is dependent than when it is nondependent. Decreases of Rcoll in response to the local infusion of low oxygen mixtures are greater in dependent regions. We conclude that 1) changes in position affect Rcoll directly through local changes in lung volume related to the gradient of pleural pressure; 2) responses of collateral channels to local concentrations of CO2 and O2 are determined by ventilation perfusion relationships, which vary at different heights in the lung; and 3) resting cholinergic tone in the anesthetized dog varies at different heights in the lung.

Airway Resistance↗
PubMed1980

A morphologic study of the influx of neutrophils into dog lung alveoli after lavage with sterile saline.

The appearance of neutrophils in the alveoli of the lung is a common result of pulmonary infection, although the route of neutrophil migration across the alveolar wall has not been demonstrated in normal animals. Recently, however, several methods of stimulating the influx of neutrophils into alveoli have been developed. In the present study, the lung wash model was used to attract large numbers of neutrophils into the airways in order to identify the site of influx of alveolar neutrophils. The combined use of scanning and transmission electron microscopy has made it possible to visualize the migration of neutrophils from the capillaries, through the interstitial spaces, and through the epithelium at the junctions between Type I and Type II cells.

Animals↗
PubMed1979

Size of the pool of alveolar neutrophils in normal rabbit lungs.

Morphometric methods and two unique characteristics of neutrophils enabled us to measure the size of the pool of neutrophils in alveoli of rabbit lungs. Rabbit lungs contained an estimated 6.11 x 10(4) alveolar neutrophils/g wet wt of lungs, and 9.57 x 10(5) alveolar neutrophils/rabbit. Lung lavage was successful in removing an average of 42.2% of the neutrophils in the air containing spaces of the lungs. An average of 2.5 +/- 3.5 (SD)% of the cells in the lung washes were neutrophils, but an average of 10.23 +/- 5.0 (SD)% of the cells that were free in the alveolus were neutrophils. Studies of the interaction of alveolar macrophages and neutrophils in vitro showed that neither cell phagocytoses or destroys the other in significant quantities; however, alveolar macrophages containing neutrophils have been observed.

Animals↗
PubMed1978

Collateral ventilation in man.

To determine whether collateral ventilation (defined as the ventilation of alveolar structures through passages or channels that bypass the normal airways) changes with age or emphysema, we compared the mechanics of collateral ventilation in seven young normal subjects, three old normal subjects and five patients with emphysema. In supine normal subjects at the end of a quiet expiration, resistance to airflow was greater through collateral channels than through bronchi and bronchioles. In emphysema, airways resistance could exceed collateral resistance, causing air to flow preferentially through collateral pathways. We conclude that high collateral resistance minimizes collateral airflow in supine normal subjects. When peripheral airways become obstructed or obliterated in emphysema, collateral channels may provide for more even distribution of ventilation.

Adult↗
PubMed1977

Effect of transpulmonary and vascular pressures on rate of pulmonary edema formation.

The effect of transpulmonary pressure (Ptp) on rate of extravascular fluid accumulation in isolated canine left lower lobes perfused at constant vascular pressures was investigated. Changes in rate of extravascular fluid accumulation were estimated by changes in rate of slow weight gain. Mean inflow pressure (Ppa) was constant at 34 cmH2O. Mean outflow pressure (Ppv) was constant at either 27.2 cmH2O or 13.6 cmH2O. When increasing Ptp is associated with a derecruitment of vascular beds as the lung changes from predominantly zone III toward zone II, or zone I, there is a decrease in rate of weight gain. When increasing Ptp is not associated with a derecruitment of vascular beds, it is impossible on the basis of these experiments to predict the change in rate of weight gain.

Animals↗
PubMed1976

Airway responses to methacholine in allergic and nonallergic subjects.

After inhalation challenge with methacholine, bronchoconstrictor responses were produced in allergic subjects with asthma and hay fever as well as nonallergic subjects. Our results indicate that allergic persons possess a greater pulmonary responsiveness to inhalation of this parasympathomimetic agent than nonallergic subjects; however, patterns of response were different in the 2 types of allergic subjects, those with asthma and those with hay fever. Whereas both types of allergic subjects responded with changes in specific airway conductance when nonallergic subjects did not, only asthmatic subjects differed from nonallergic subjects when comparisons of spirometry were made. These data suggest that there is hypersensitivity of both central and peripheral airways in asthmatics and in the larger central airways of nonasthmatic allergic subjects.

Adult↗