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.
Right ventricular infarction has many clinical features. Although hypoxemia is a common presenting symptom with multiple causes in the setting of myocardial infarction, the authors present a case resulting from an acute right-to-left shunt secondary to a previously dormant patent foramen ovale. A 74-year-old male presented to the hospital after feeling unwell for the previous 2 days. Initial evaluation revealed marked hypoxemia without respiratory distress. Electrocardiographic findings and cardiac seromarkers revealed a completed inferior myocardial infarction. The patient's hypoxemia was refractory to 100% oxygen, indicating a right-to-left shunt. A transesophageal echocardiogram confirmed clinical suspicions for a right-to-left shunt through a patent foramen ovale. Despite sporadic reports in the literature, this still is a poorly recognized clinical condition. The authors review a case report that will enable the general intemist to consider a right-to-left shunt in the setting of hypoxemia in myocardial infarction.
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.
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.
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