Biomedical subjects

S Enjeti

Publications and source records attributed to S Enjeti.

5 recordsLinked to original sources

PubMed1983

Hemodynamic mechanisms in anaphylaxis.

Intravenous administration of ascaris suum antigen (1 mg) as well as histamine (5 mg) was associated with rapid and marked reductions in cardiac output (QT) and systemic arterial pressure (Pa) in anesthetized mechanically ventilated dogs. When venous return was maintained constant by an external pump reservoir system, both antigen and histamine caused rapid reductions in the reservoir blood volume consistent with peripheral pooling. In addition, interruption of the splanchnic arterial inflow by occlusion of the descending thoracic aorta restored the cardiac output to control during histamine shock, whereas QT during antigen shock was unaffected by aortic occlusion, even though the circulatory failure was of similar magnitude. Therefore, we conclude that differences in responses of antigen and histamine shock to aortic occlusion indicate that mechanisms leading to peripheral pooling of blood are different with the two agents. In addition, stability of left atrial pressure following the administration of either agent, when the venous return is maintained constant, suggests that intrinsic myocardial dysfunction is not a major initiating mechanism in the two shock states studied.

Anaphylaxis↗

PubMed1982

Effects of positive end expiratory pressure on shunt flow in atelectasis.

We studied the effects of positive end expiratory pressure (PEEP) on vascular pressure flow relationships in atelectatic lobes in the closed-chest pigs and compared our results to measurements we previously obtained in sublobar atelectasis. Regional hemodynamic responses to lung inflation were significantly different between lobes and sublobar regions. PEEP caused marked increase in the fraction of cardiac output perfusing the atelectatic lobe from 16.5 +/- 2.0% (SE) to 32.5 +/- 2.0% at similar pulmonary vascular transmural pressures. In contrast, similar levels of PEEP failed to redistribute blood flow to the atelectatic sublobar regions. We propose that distortion of the sublobar region with inflation of the surrounding lung may be responsible for the failure of redistribution of pulmonary blood flow with application of PEEP.

Animals↗

PubMed1982

Mechanical factors and the regulation of perfusion through atelectatic lung in pigs.

The role of mechanical interdependence in the perfusion of atelectatic lung was studied in two ways: a) regional hemodynamics were compared before (control) and after the development of lobar and sublobar atelectasis, and b) the effect of thoracotomy on regional hemodynamics was assessed. With lobar atelectasis mean lobar blood flow and vascular conductance decreased to 60% of control. Sublobar atelectasis caused mean sublobar blood flow and vascular conductance to decrease to 6% of control. Opening the chest after production of lobar atelectasis caused blood flow to fall to 50% of control. When sublobar atelectasis was produced in the open chest, sublobar blood flow decreased to 25% of control measurements made prior to thoracotomy. We conclude that with a closed chest, sublobar vascular distortion mediated by mechanical interdependence may be an important mechanism responsible for the differences in hemodynamic responses to atelectasis between lobes and sublobar regions.

Animals↗

PubMed1979

Sublobar atelectasis and regional pulmonary blood flow.

We studied the effects of sublobar atelectasis on regional blood flow in anesthetized paralyzed pigs. Following the washout of nitrogen from the lung with oxygen, a sublobar airway was obstructed and a peripheral segment of lung allowed to collapse. Blood flow to the atelectatic region fell from a control of 140.0 +/- 20.5 to 16.6 +/- 2.9 ml/(min . g). Basilar regions that became atelectatic spontaneously during the course of the studies had similar decreases in blood flow. Inflation of the surrounding lung by the application of positive end-expiratory pressure failed to increase blood flow and vascular conductance within the atelectatic regions. These results indicate that mechanical and hypoxic effects on vessels perfusing sublobar atelectatic regions limit the effects of interdependence from the surrounding lung. Furthermore, with inflation of the surrounding lung, increases in pulmonary shunting of blood are small.

Animals↗

PubMed1978

Pulmonary function in young smokers: male-female differences.

To delineate the pattern of pulmonary function abnormalities and associated pathophysiologic mechanisms in young smokers, 205 volunteers between the ages of 18 and 25 were studied with a variety of pulmonary function tests. Differences between male and female smokers were observed. Pulmonary function abnormalities consistent with small airway dysfunction were noted in male smokers, but not in female smokers. Decreased forced expiratory flows at high lung volumes suggesting large airway dysfunction were noted in both male and female smokers. Decreases in diffusing capacity for CO consistent with abnormalities of the pulmonary vascular system were seen in smokers of both sexes, but were more prominent in females. Because men develop chronic obstruction pulmonary disease more frequently than do women even when adjustments for smoking are made, and because women develop primary pulmonary hypertension more frequently than do men, these chronic diseases may reflect distinct pathophysiologic response of the 2 sexes to agents such as cigarettes.

Adolescent↗