Poulsen T D, Klausen T, Richalet J P, Kanstrup I L, Fogh-Andersen N, Olsen N V
Department of Anaesthesia, Herlev Hospital, University of Copenhagen, Denmark.
Eur J Appl Physiol Occup Physiol. 1998 Apr;77(5):457-61. doi: 10.1007/s004210050360.
Exposure to acute hypoxia is associated with changes in body fluid homeostasis and plasma volume (PV). This study compared a dye dilution technique using Evans' blue (PV[Evans']) with a carbon monoxide (CO) rebreathing method (PV[CO]) for measurements of PV in ten normal subjects at sea level and again 24 h after rapid passive ascent to high altitude (4,350 m). Hypobaric hypoxia decreased arterial oxygen saturation to 79 (74-83)% (mean with 95% confidence intervals). The PV(Evans') remained unchanged from 3.49 (3.30-3.68) l at sea level to 3.46 (3.24-3.68) l at high altitude. In contrast PV(CO) decreased from 3.39 (3.17-3.61) l at sea level to 3.04 (2.75-3.33) l at high altitude (P < 0.05). Compared with sea level, this resulted in an increase of the mean bias between the two methods [from 0.11 (-0.05-0.27) l at sea level to 0.43 (0.26-0.60) l at high altitude] so that the ratio between PV(Evans') and PV(CO) increased from 1.04 (0.99-1.09) at sea level to 1.15 (1.06-1.24) at high altitude (P < 0.05). In conclusion, the two methods were not interchangeable as measures of hypoxia-induced changes in PV. The mechanism responsible for the bias remains unknown, but it is suggested that the results may reflect a redistribution of albumin caused by the combined effects in hypoxia of both an increased capillary permeability to albumin and a decrease in PV. As a result, the small perivascular compartment of albumin beyond the endothelium may increase without changes in the overall albumin distribution volume.
暴露于急性低氧环境与体液平衡和血浆容量（PV）的变化有关。本研究比较了使用伊文思蓝的染料稀释技术（PV[伊文思蓝法]）和一氧化碳（CO）再呼吸法（PV[CO法]）在海平面测量十名正常受试者的PV，并在快速被动上升到高海拔（4350米）24小时后再次测量。低压低氧使动脉血氧饱和度降至79（74 - 83）%（平均值及95%置信区间）。PV(伊文思蓝法)从海平面时的3.49（3.30 - 3.68）升在高海拔时保持不变，为3.46（3.24 - 3.68）升。相比之下，PV(CO法)从海平面时的3.39（3.17 - 3.61）升降至高海拔时的3.04（2.75 - 3.33）升（P < 0.05）。与海平面相比，这导致两种方法之间的平均偏差增加[从海平面时的0.11（-0.05 - 0.27）升增加到高海拔时的0.43（0.26 - 0.60）升]，使得PV(伊文思蓝法)与PV(CO法)的比值从海平面时的1.04（0.99 - 1.09）增加到高海拔时的1.15（1.06 - 1.24）（P < 0.05）。总之，作为测量低氧诱导的PV变化的方法，这两种方法不可互换。偏差产生的机制尚不清楚，但有人认为结果可能反映了低氧环境中毛细血管对白蛋白通透性增加和PV减少的联合作用导致白蛋白的重新分布。因此，内皮外的小血管周围白蛋白隔室可能增加，而白蛋白总体分布体积不变。
