Plasma Volume, Body Weight, and Acute Mountain Sickness

Acetazolamide and chronic hypoxia: effects on haemorheology and pulmonary haemodynamics

“…As previously shown in humans, acetazolamide treatment slightly decreased Hct in both preventive and curative groups [3]. As confirmed by our study, exposure to chronic hypoxia results in a fall in plasma volume [21] and an increase in total blood volume secondary to an increase in volume of RBCs [22]. As acetazolamide has diuretic effects, it is expected to further reduce plasma volume in hypoxia, which could offset the decrease in Hct induced by acetazolamide through its stimulatory effects on ventilation and blood oxygenation that may cause a reduction of renal erythropoietin release [3,4].…”

“…Therefore, one may suggest that the decrease in Hct in hypoxic rats treated by acetazolamide was not fully explained by the decrease in erythropoiesis (as suggested by the decrease in percentage of reticulocytes), and was also probably the resulting effect of the plasma volume rise, which could be interpreted as a physiological adaptation for maintaining blood volume at the normal value. The hypoxia-induced decrease in plasma volume was probably attributed to the well-known blunting effect of hypoxia on the renin-aldosterone system [21] and other complex mechanisms, such as peripheral arterial chemoreception [23,24]. The mechanism by which acetazolamide could oppose this blunting effect remains to be established.…”

Plasma volume in acute hypoxia: comparison of a carbon monoxide rebreathing method and dye dilution with Evans' blue

“…By the use of a radio-labelled erythrocyte methodology, Sawka et al (1996) have recently reported a decrease in plasma volume by appoximately 11% after arrival at 4,300 m. Our data obtained with the CO rebreathing method are in support of such a magnitude of plasma loss during early exposure to hypoxaemia. With more sustained hypoxaemia, the decrease in albumin distribution volume that has been observed (Surks et al 1966;Hannon et al 1969;Frayser et al 1975;Jain et al 1980Jain et al , 1981Richalet et al 1983;Singh et al 1986), could be secondary to acclimatisation processes producing a gradual return to Values are means with 95% con®dence intervals; *P < 0.05 compared with sea level Fig. 2 The ratio between the volume of distribution of albumin (PV Evans' ) and the plasma volume measured by a carbon monoxide (CO) rebreathing method (PV CO ) at sea level and at high altitude.…”

“…Using the same method, reductions in plasma volume of 8% and 11% have been found after 3 days and 12 days, respectively, in ten men transported to an altitude of 3,500 m (Singh et al 1986). With the use of Evans' blue, an increased plasma volume (15%) has been found in one person with moderate acute mountain sickness after 7 days at 4,950 m, whereas a reduction of 7% has been found in eight subjects who had only minor symptoms (Richalet et al 1983). In contrast, no changes in plasma volume (distribution volume of 125 I-labelled albumin in twelve subjects) have been detected 24 h after a rapid, passive ascent to 4,350 m (Hansen et al 1994).…”

“…Determination of plasma volume in hypoxic environments has been the subject of many studies (Surks et al 1966;Hannon et al 1969;Frayser et al 1975;Jain et al 1980Jain et al , 1981Richalet et al 1983;Singh et al 1986;Hansen et al 1994). In all of these, the distribution volume of radio-labelled albumin or Evans' blue has been used as a marker of the plasma volume.…”