F. J. Dagher

Transcapillary Refilling After Hemorrhage in Normal Man: Basal Rates and Volumes; Effect of Norepinephrine

REPARTITION of the body water, with compensatory refilling of the vascular tree, is an important homeostatic mechanism following hemorrhage. It was recognized in the 19th century and ascribed to an increased flow of lymph from the thoracic duct. Disputing this, Starling,35 in a series of classic experiments published in 1896, showed that the passage of water across the capillary wall depended on the oncotic pressure exerted by the plasma proteins, as well as on hydrostatic pressure changes. The physiologic effects of hemorrhage and of shock have been studied extensively since Starlings time. Most of the data have come from animal experiments, and though the processes of hemodilution following

Hemorrhage in normal man. The effects of angiotensin.

Summary o 1. The effect of angiotensin has been studied in normal man, as it bears on the resting plasma volume and on changes in the plasma volume during transcapillary refill following experimental hemorrhage. 2. In 1 of 5 normal subjects given the drug there was a severe reaction; for this reason, further experiments were deemed inadvisable. The data on the other 4 were consistent, and for this reason are reported though the numbers are small. 3. Angiotensin caused a reduction in plasma volume averaging 5.3 per cent of the resting value, when given as an infusion 4 hours after the hemorrhage and during the maximum transcapillary refill phase. The net refill over 24 and 48 hours is unchanged by angiotensin and is the same as that observed after norepinephrine. 4. This effect of angiotensin is similar to that exhibited by norepinephrine but is less marked. Norepinephrine reduces the plasma volume 15 to 20 per cent during refill; angiotensin gives a reduction of about 5 per cent. In addition, the effect is reversed during the second 2 hours of angiotensin infusion, with a gradual restoration of the transcapillary refill curve to its normal configuration. 5. Angiotensin further reduces the sodium: potassium ratio in the urine, in some cases below that value produced by hemorrhage alone. In 2 of our cases this alteration was long lasting. 6. Clinical use of angiotensin should be undertaken with these data in mind.

DIURNAL VARIATION IN BLOOD VOLUME OF MAN.

Summary Isotope dilution with I 131 iodinated human serum albumin was used to measure the blood volume of 12 ambulatory, normally active, healthy young adults during the course of a day. Volumes increased and hematocrit decreased significantly on the average with changes most marked by evening.

EQUILIBRIUM BEHAVIOR OF TAGGED ERYTHROCYTES IN EXPERIMENTAL "IRREVERSIBLE SHOCK".

Summary o 1. Equilibrium behavior of erythrocytes tagged with Evans blue dye and radiochromate in the normal and shocked animal was studied. 2. There was no alteration in the disappearance curve of Evans blue dye. 3. There seemed to be a slope of decreasing erythrocyte activity in the shocked animals. This slope was not such as to produce a statistically significant decrement at either 50 or 90 minutes. In Shoemakers work, steep slopes of strong significance were reported in two thirds of the animals. 4. In no animal did we observe an “inflection point” with a secondary plateau to suggest the clear delineation of a “slowly circulating” red cell volume. 5. The red cell volume measured at the conclusion of the experiment correlated almost perfectly with that observed at the start, as corrected for volume loss by sampling. We therefore did not discover any evidence for a “noncirculating” red cell mass in these animals. 6. On the basis of these data, we cannot confirm the concept that irreversible shock in the dog results in a significant sequestration of erythrocytes from that mass normally exchangeable with infused tagged cells.