Visualization of Arterio-Venous Shunts by Cinefluorography in the Lungs of Normal Dogs.

Rahn, Hermann; Stroud, Robert C.; Tobin, Charles E.

doi:10.3181/00379727-80-19581

Cited by 44 publications

(17 citation statements)

References 1 publication

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“…The lack of correlation between the mean pulmonary artery pressure and the per cent of the cardiac output shunted weighs against the opening of potential anatomical pathways for shunting which, though normally present, are usually not patent; this is a mechanism proposed but not proven by animal experimentation (39)(40)(41)(42) and human autopsy studies (43,44). Furthermore, our data indicate that intracardiac shunts occasionally do occur but were relatively infrequent among our subjects.…”

Section: Discussionmentioning

confidence: 76%

Hypoxemia in pulmonary embolism, a clinical study

Wilson¹,

Pierce²,

Johnson³

et al. 1971

J. Clin. Invest.

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A B S T R A C T The cause of hypoxemia was studied in 21 patients with no previous heart or lung disease shortly after an episode of acute pulmonary embolism. The diagnosis was based on pulmonary angiography demonstrating distinct vascular filling defects or "cutoffs." It was found that virtually all of the hypoxemia in patients with previously normal heart and lungs could be accounted for on the basis of shunt-like effect. The magnitude of the shunting did not correlate with the percent of the pulmonary vascular bed occluded nor with the mean pulmonary artery pressure. The shunts tended to gradually recede over about a month after embolism. Patients without pulmonary infarction were able to inspire 80-111% of their predicted inspiratory capacities, and this maneuver temporarily diminished the observed shunt. Patients with pulmonary infarcts were able to inhale only to 60-69% of predicted inspiratory capacity, and this did not reverse shunting. These data suggest that the cause of right-to-left shunting in patients with pulmonary emboli is predominantly atelectasis.When the elevation of mean pulmonary artery pressure was compared to cardiac index per unit of unoccluded lung, it fell within the range of pulmonary hypertension predicted from published data obtained in patients with exercise in all except one case. This observation suggests that pulmonary vasoconstriction following embolism is not important in humans, although these data are applicable only during the time interval in which our patients were studied and in patients receiving heparin.

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Section: Discussionmentioning

confidence: 76%

Hypoxemia in pulmonary embolism, a clinical study

Wilson¹,

Pierce²,

Johnson³

et al. 1971

J. Clin. Invest.

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“…Besides recruiting unused vessels, arteriovenous shunts can be created allowing pathways for MPs, which are larger than capillaries, to pass relatively unhindered into the venous circulation. In fact, MPs that are >25 μm have been found in the pulmonary venous blood after injection possibly due to arteriovenous shunts in the lung [15, 16, 54-57]. …”

Section: Discussionmentioning

confidence: 99%

Threshold size for optimal passive pulmonary targeting and retention of rigid microparticles in rats

Kutscher

Chao

Deshmukh

et al. 2010

Journal of Controlled Release

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The relationship between microparticle (MP) size and lung targeting efficiency, intra-lung distribution and retention time was systematically studied after intravenous administration of rigid fluorescent polystyrene MPs of various sizes (2, 3, 6 and 10μm) to Sprague-Dawley rats. Total fluorescence was assessed and it was found that 2μm and 3μm MPs readily passed through the lung to the liver and spleen while 10μm MPs were completely entrapped in the lung for the one-week duration of the study. Approximately 84% of 6μm MPs that were initially entrapped in the lung were cleared over the next 2 days and 15% were cleared over the remaining 5 days. A Caliper IVIS® 100 small animal imaging system confirmed that 3μm MPs were not retained in the lung but that 6μm and 10μm MPs were widely distributed throughout the lung. Moreover, histologic examination showed MP entrapment in capillaries but not arterioles. These studies suggest that for rigid MPs the optimal size range required to achieve transient but highly efficiently targeting to pulmonary capillaries after IV injection is >6μm but <10μm in rats and that systemic administration of optimally sized MPs may be an efficient alternative to currently used inhalation-based delivery to the lung. KeywordsPassive pulmonary targeting; Rigid non-biodegradable microparticle; In vivo imaging

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“…There seems to be good evidence that in the resting basal state not all pulmonary capillaries are functional at any given moment (16). A fair amount of evidence has also accumulated that pulmonary arteriovenous anastomoses exist in mammalian (16)(17)(18)(19) 3. As a result of the increased pulmonary blood flow there may occur increased pressure distention of the pulmonary vascular bed (20); this may conceivably be followed by a progressive decrease in intrinsic or neurogenically controlled vascular "tone" as a compensatory phenomenon.…”

Section: Discussionmentioning

confidence: 99%

Response of Pulmonary Artery Pressure and Total Pulmonary Resistance of Untrained, Convalescent Man to Prolonged Mild Steady State Exercise1

Sancetta¹,

Rakita²

1957

J. Clin. Invest.

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Although many published studies relevant to the effects of exercise on the gross pulmonary hemodynamics of patients with heart disease are available in the literature, few data are to be found which deal with normal man (1-6). There have been conflicting claims that there is no increase, no significant increase, a consistent increase, or an occasional decrease in the pulmonary artery pressure of normal man as the result of exercise loads eventuating in oxygen uptakes up to 400 ml. per M.2 per min. (2) and pulmonary blood flows two to three times the resting basal levels (1, 5). Moreover, comparison among the published data is difficult because of variations in the exercise posture, the duration of exercise, the work loads employed, and the timing of blood and pressure sampling, which often are varied in different subjects within the same body of data.Slonim, Ravin, Balchum, and Dressler (6) alone have systematically studied the continuous pulmonary artery pressure variations in 5 normal subjects in the recumbent position over a 7-minute period of exercise, employing an almost uniform work rate between 784 and 840 foot-pounds per minute. These authors noted immediate increases in pulmonary systolic, diastolic and mean pressures, which usually reached a peak between the first and third minutes of exercise with an overall tendency to a slight secondary decline by the sixth minute. A steady state was not achieved.The present report is intended to extend these findings employing a mild and uniform external work load of 850 foot-pounds per minute sustained over a period of 39 minutes. This mild amount of work was selected in order that steady state be attained in a reasonably uniform period of time, 1 Supported by a grant from United Appeal, Lorain County, Ohio. that it be maintained as long as possible, and that some lower limit of valid, measurable change be established for comparison in subjects with heart disease physically unable to exercise at higher work loads and achieve the steady state (7). MATERIALS AND METHODSStudies were conducted on 12 subj ects with normal cardio-respiratory systems who had convalesced from various illnesses (bronchopneumonia, active peptic ulcer, eczematoid dermatitis), or had been admitted for investigation of minor complaints. None were anemic or febrile. All had been ambulatory for several days before the studies were conducted. On the day prior to the experiment the subjects were exercised in the supine position at a standard work rate of 850-foot pounds per minute for a period of 39 minutes. In all but three instances the steady state, as determined by repetitive determinations of the oxygen consumption (8), was attained within 10 to 12 minutes of exercise; in the remaining three, it was attained at the 12 to 14-minute period. The following morning, at an ambient temperature of 23 degrees C., cardiac catheterization was performed in the post-absorptive state with mild sedation (Pentobarbital Sodium, 0.1 Gm.), employing standard No. 7F Cournand catheters. The supine position was...

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Visualization of Arterio-Venous Shunts by Cinefluorography in the Lungs of Normal Dogs.

Cited by 44 publications

References 1 publication

Hypoxemia in pulmonary embolism, a clinical study

Hypoxemia in pulmonary embolism, a clinical study

Threshold size for optimal passive pulmonary targeting and retention of rigid microparticles in rats

Response of Pulmonary Artery Pressure and Total Pulmonary Resistance of Untrained, Convalescent Man to Prolonged Mild Steady State Exercise1

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