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Biomedical subjects

B D Butler

Publications and source records attributed to B D Butler.

27 records · Page 2Linked to original sources
PubMed1986

Effect of bronchial blood flow on pulmonary artery wedge pressure with pulmonary embolism.

Discrepancies between pulmonary artery wedge pressure (WP) and left atrial pressure (LAP) occur with pulmonary embolism. Theoretically, this discrepancy could be affected by the bronchial circulation or by the type of embolus. To test this in dogs, we determined the effects of embolism induced by glass beads and by air upon the WP with intact vs. ligated bronchial blood flow to the left lower lobe. For those animals receiving pulmonary air infusions, the pulmonary artery pressure, WP, and pulmonary vascular resistance showed significant (p less than .05) elevations with no change in LAP. There were no changes in these values when the bronchial blood flow was interrupted. When glass beads (120 mu) were injected into the left lower lobe, the pulmonary artery pressure and pulmonary vascular resistance rose as in the air emboli groups (p less than .05); however, WP remained at control values and approximated LAP. Obstructing the bronchial blood flow did not change this response. We conclude that the discrepancy between WP and LAP depends upon the type of embolus and is not affected by bronchial blood flow.

Animals↗
PubMed1985

Phospholipids identified on the pericardium and their ability to impart boundary lubrication.

Phospholipids have been identified by thin-layer chromatography in appreciable quantities in pericardial fluid taken from 12 dogs and found to include sphingomyelin and phosphatidylcholines, -ethanolamines, -inositols and -serines--the cholines predominating. The extracts, the synthetic surfactants and a mixture of synthetics simulating the extracts were all found to be good lubricants when tested by a standard method. The phosphatidylcholines were capable of reducing friction between two otherwise hydrophilic surfaces by as much as 100- to 200-fold when deposited as an oriented monolayer. A goniometer was used to measure an average contact angle of 33 degrees for a drop of saline placed upon the internal wall of the pericardium, indicating an appreciably hydrophobic surface anticipated if surfactant were directly adsorbed. The results are consistent with the classical theory of "boundary" lubrication (17) as modified (21) to reflect the almost ideal molecular structure of the identified surfactants for adsorption, film cohesion and interaction of fatty-acid chains during sliding. This model is proposed as an alternative to hydrodynamic lubrication in the pericardium and one compatible with several practical aspects such as pericardial rub and the maintenance of normal heart action after pericardectomy.

Animals↗
PubMed1985

Surfactants identified in lung lymph and their ability to act as abhesives.

Phospholipid has been extracted from pulmonary lymph collected from 10 dogs. Thin-layer chromatography was used to identify phosphatidylcholine (PC) 55.6 +/- 2.9%, sphingomyelin 21.3 +/- 1.7%, phosphatidylethanolamine 11.2 +/- 4.9%, and lysophosphatidylcholine 5.9 +/- 0.8%. All extracts proved highly surface active, reducing the surface tension of saline to 27.7 +/- 0.7 dyn/cm upon 80% film compression and increasing the maximum contact angle on glass (theta) from 7 +/- 1 to 47.4 +/- 1.4 degrees. The hydrophobic properties induced on glass were further demonstrated by the ability to cause saline to withdraw and expose a dry surface. A standard adhesion test was used to measure the "tack" produced by the major proteins in lymph. However, when the surface energy of the hydrophilic glass surfaces was reduced by a monolayer of lymph phospholipid extract or an equivalent mixture of synthetic surfactants, the adhesive force was reduced by 79 +/- 4% for albumin and 55 +/- 4% for globulin. As a 0.1% liposomal suspension, PC gave 55% release with albumin. Reversible bonding of the lumen of lymph vessels by the "tacky" proteins present is discussed as a possible factor contributing to the large changes in flow resistance known to occur in the pulmonary lymphatic system.

Adhesives↗
PubMed1985

Transpulmonary passage of venous air emboli.

Twenty-seven paralyzed anesthetized dogs were embolized with venous air to determine the effectiveness of the pulmonary vasculature for bubble filtration or trapping. Air doses ranged from 0.05 to 0.40 ml X kg-1 X min-1 in 0.05-ml increments with ultrasonic Doppler monitors placed over arterial vessels to detect any microbubbles that crossed the lungs. Pulmonary vascular filtration of the venous air infusions was complete for the lower air doses ranging from 0.05 to 0.30 ml X kg-1 X min-1. When the air doses were increased to 0.35 ml X kg-1 X min-1, the filtration threshold was exceeded with arterial spillover of bubbles occurring in 50% of the animals and reaching 71% for 0.40 ml X kg-1 X min-1. Significant elevations were observed in pulmonary arterial pressure and pulmonary vascular resistance. Systemic blood pressure and cardiac output decreased, whereas left ventricular end-diastolic pressure remained unchanged. The results indicate that the filtration of venous bubbles by the pulmonary vasculature was complete when the air infusion rates were kept below a threshold value of 0.30 ml X kg-1 X min-1.

Animals↗
PubMed1979

The lung as a filter for microbubbles.

A new ultrasonic Doppler device has been used noninvasively over the femoral artery of anesthetized dogs to prove that it can detect carefully calibrated microbubbles of 14--189 micrometers diam when these are infused directly into the aorta. The same evaluated technique has then been employed to detect any bubbles escaping into the arterial system when gas was infused into the venous system either as microbubbles or as a bolus. Results from 18 dogs showed that, under normal conditions, the lungs are a superb filter for bubbles and that any cutoff diameter is less than 22 micrometers. However, bubbles escaped entrapment when the lungs were severely overloaded with gas (20 ml) or were pretreated with a pulmonary vasodilator (aminophylline). The dog preparation and arterial Doppler device appear to be ideal for future studies to determine what other factors might compromise the capability of the lungs to filter microbubbles. Physiological parameters showed dramatic changes when bubbles were detected as escaping into the arterial system by comparison with their effect when retained within the lungs. Changes in respiration profile indicated that they may offer a useful index of the degree of venous embolization and, hence, a warning of impending overload leading to arterial embolization.

Air↗
PubMed1978

The kangaroo rat as a model for type I decompression sickness.

This study involved 720 exposures of 70 kangaroo rats trapped in West Texas and showed that decompression-induced tail biting in this animal provides a good animal model for marginal limb bends in man. That this phenomenon can be reversed by recompression and pathological examination of the tail both indicated that a similar mechanism is probably involved in kangaroo rats and humans. Quantitatively, the most susceptible 20% of kangaroo rats can reproduce the no-stop decompression limits for man for exposure times ranging from 5 min to 8 h, for both air and helium-oxygen. Even the average minimum no-tail-biting depth of 46.2 fsw (2.40 ATA) for this species is much closer to the minimum bends depth of man than to the equivalent depth for other animals of its size, and is as good as the goats'. Its size and habits make the kangaroo rat much more convenient than other animals to use as a model for marginal decompression sickness, and particularly attractive economically for testing long helium-oxygen schedules and other means of decompression sickness prevention.

Animals↗
PubMedDate not supplied

Biophysical aspects of gas bubbles in blood.

The widespread use of bubble oxygenators during cardiopulmonary bypass has raised questions concerning the production and introduction of gaseous microemboli (GME) into patients. An understanding of the complications associated with GME requires awareness of the biophysical and biochemical responses that occur between bubbles and blood. The production of GME as well as their interactions with each other and with blood products are examined. These interactions can influence the data collected from Doppler ultrasound devices and the development of organ dysfunction.

Cardiopulmonary Bypass↗