Early fluid and protein shifts in men during water immersion

Abstract

High precision blood and plasma densitometry was used to measure transvascular fluid shifts during water immersion to the neck. Six men (28-49 years) undertook 30 min of standing immersion in water at 35.0 +/- 0.2 degrees C; immersion was preceded by 30 min control standing in air at 28 +/- 1 degrees C. Blood was sampled from an antecubital catheter for determination of blood density (BD), plasma density (PD), haematocrit (Ht), total plasma protein concentration (PPC), and plasma albumin concentration (PAC). Compared to control, significant decreases (p less than 0.01) in all these measures were observed after 20 min immersion. At 30 min, plasma volume had increased by 11.0 +/- 2.8%; the average density of the fluid shifted from extravascular fluid into the vascular compartment was 1006.3 g.l-1; albumin moved with the fluid and its albumin concentration was about one-third of the plasma protein concentration during early immersion. These calculations are based on the assumption that the F-cell ratio remained unchanged. No changes in erythrocyte water content during immersion were found. Thus, immersion-induced haemodilution is probably accompanied by protein (mainly albumin) augmentation which accompanies the intravascular fluid shift.

The measurement of blood density and its meaning

“…The application of this effect as a "double density dilution" was demonstrated first in a thesis by Moser (44). Later, descriptions were also published (7,9,12,14,15). If, for example, some fluid is entering (or leaving) the circulation there are two mixing equations: the first describes the mixing of the entering fluid with blood, the second the mixing with plasma.…”

“…This procedure has also been used to study the circadian variations of orthostatic stability (50,57). Further orthostatic and pressure-dependent reactions can be demonstrated by observing the effects on blood density of blood volume changes (11), of water immersion (12), and of lower body positive pressure (14). Continuous measurements of arterial blood density appears to be important for the interpretation of respiratory changes of the blood density (46).…”

Effect of graded water immersion on vital capacity and plasma volume in patients with cervical spinal cord injury

“…13 The shift of volume has been estimated at 700 ml to the chest during immersion in healthy individuals. 1,2 This increase includes both blood and mobilized interstitial fluid to the central blood volume, 15 which can be estimated by hematocrit change. 16 Xiphoid and neck references are also useful in discriminating the effects of abdominal hydrostatic compression from thoracoabdominal hydrostatic compression on pulmonary volumes.…”

“…1 This reduction has been primarily attributed to the restrictive effect of increased central blood volume. 1,2 Paradoxically, an increase in VC has been observed in immersed tetraplegic individuals.…”

“…1 This reduction has been primarily attributed to the restrictive effect of increased central blood volume. 1,2 Paradoxically, an increase in VC has been observed in immersed tetraplegic individuals. 3,4 Another study showed that cardiac output increases in tetraplegic subjects during head-out immersion, but it did not investigate the effect on pulmonary function.…”