Effects of a step increase in left atrial pressure on effective diffusivity in intact sheep

N. A. Pou, J. W. Klaesner, R. E. Parker, C. Finney, R. J. Roselli

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Abstract

The optical measurement of filtration coefficient (K,) requires a step increase in left atrial pressure (tPLA) in a zone 3 lung. Multiple Indicator Dilution (MID) curves were used in 6 sheep to determine any changes in lung permeability and surface area which would effect optical Kfc measurements in intact sheep. One week prior to experiment, catheters were surgically placed in the carotid artery, jugular vein, pulmonary artery and left atrium. A Foley balloon was inserted in the left atrium for elevation of lung venous pressure. To establish zone 3 condition, venous pressure was elevated to 5-10 cmH20 one day prior to the experiment. All sheep were allowed to breathe spontaneously during the experiment. MID curves were collected for !4C-urea (which is sensitive to permeability and surface area) and "C- butanediol (which has been shown to be sensitive to surface area) at baseline, 10 mins and 2 H after a tPLA of 15.5 ± 6.6 cmH20. These curves were analyzed using the Effective Diffusivity (v'DS) model. Pulmonary vascular resistance did not change while microvascular pressure doubled. Cardiac output dropped from 3.9±4.4 L/tnin to 3.3±0.5 L/min 10 min after tPLA and 3.1±0.5 L/min after 2H tPLA. No change in ureaVt)S, butanediol V'DS, or the ratio of urea to butanediol was observed. The MID data do not suggest any changes resulting from the step increase in t PLA needed for optical measurement Kfc in the intact animal. It is, however, important to know changes in cardiac output.

Original languageEnglish
Pages (from-to)A351
JournalFASEB Journal
Volume10
Issue number3
StatePublished - Dec 1 1996

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