Richard H. Lyons

Hemodynamics in Labile Hypertension A Follow-Up Study

A preliminary follow-up study has been carried out in 68 labile hypertensive patients followed for an average of 50.4 months. The high cardiac output pattern found initially tended to revert toward a normal cardiac output and higher total peripheral resistance. This suggests that the high cardiac output pattern is an early hemodynamic abnormality. No difference between those groups could be shown on the basis of complications at the time of this study.

The measurement of venous pressure by the direct method

Abstract The observations reported in this paper have dealt with some of the factors influencing the measurement of venous pressure by the direct method. They indicate that errors may be introduced (a) by certain variations in the technique, including: 1. (1) the level of the site of venipuncture, and 2. (2) the degree of abduction of the arm; and (b) by certain variations in the state of the patient, including his position, relaxation, and type of respiration. Modifications of current techniques are suggested which tend to minimize these errors. Moreover, the evidence from anatomical material and from roentgenologic measurements indicates that the methods now used for establishing the level of the auricle may, in persons with deep chests, tend to place the assumed level of the auricle at a falsely high position. This, in turn, leads to a falsely low venous pressure reading. To minimize this error a new method of establishing the reference point is suggested, a method which relates this point to the posterior rather than the anterior surface of the chest. Anatomical evidence indicates that in adults in the supine position the level of the auricle is approximately 100 mm. anterior to the skin of the back. When this level is used as the reference point, variations in chest diameter are not reflected in the venous pressure readings. The range of venous pressures in normal people in the supine position, using a reference point 100 mm. anterior to the skin of the back, is from 50 to 150 mm. of water.

A Study of Reflex Venomotor Reactions in Man

By the use of simple clamps, a segment of a forearm vein was temporarily isolated from the circulation so that change in pressure within the segment measured change in venous tone. Reflex venoconstriction was elicited by appropriate stimuli. These reactions could be blocked by interruption of the sympathetic pathway to the vein under study. The magnitude of the responses obtained supports the concept that neurogenic venomotor reactions may be quantitatively significant in circulatory adjustments.

The effect of salt loading and salt depletion on renal function and electrolyte excretion in man.

Glomerular filtration rate (GFR), renal plasma flow (RPF), and electrolyte excretion were studied in 17 patients subjected to salt depletion and loading. Salt depletion led to maximal renal salt conservation with the average GFR and RPF slightly decreased. Salt loading produced increased excretion of sodium and chloride with the average GFR and RPF slightly increased. Since the decreased electrolyte excretion with salt depletion and increased electrolyte excretion with salt loading were essentially independent of the direction of change in GFR and RPF, it is inferred that tubular absorptive activity is a more significant factor in achieving electrolyte balance than are GFR changes.

DIGITAL HEMODYNAMICS IN THE NORMOTENSIVE AND HYPERTENSIVE STATES. I. DIGITAL MEAN ARTERIAL AND VENOUS PRESSURES, BLOOD FLOW, AND VASCULAR RESISTANCE.

Rheoplethysmographic studies were conducted to evaluate the digital hemodynamics of the hypertensive state. It is concluded that digital blood flow is similar in normal and hypertensive subjects; digital mean arterial pressures and calculated vascular resistances were significantly elevated in the hypertensive as compared to the normal subject; there is a small but definite increase in digital venous pressure in the hypertensive state; and the digital vasculature and in particular the arteriovenous shunts are otherwise similar in both the normal and the hypertensive subject.

Digital Hemodynamics in the Normotensive and Hypertensive States II. Venomotor Tone

By use of the technic of rheoplethysmography, it has been demonstrated that the small veins and venules participate in the over-all increase in peripheral resistance in hypertension.An arbitrary grading of the degree of venomotor tone in hypertension has been established.