Powers D R, Brace R A
Department of Reproductive Medicine, University of California, San Diego, La Jolla 92093-0802.
Am J Obstet Gynecol. 1992 Dec;167(6):1698-709. doi: 10.1016/0002-9378(92)91764-2.
The purpose of this study was to compare the responses of the maternal ewe to intravenous volume expansion with either sufficient lactated Ringer's solution to elevate maternal venous pressure or sufficient hypotonic fluid to reduce blood osmolality.
Chronically catheterized pregnant sheep were intravenously infused over 4 hours with either commercial lactated Ringer's solution (5.55 +/- 0.50 L/hr, 255 mOsm/kg, mildly hypotonic) or diluted Ringer's solution (2.04 +/- 0.27 L/hr, 150 mOsm/kg, markedly hypotonic). Data were statistically analyzed with two- and three-factor analyses of variance and bivariate regression analysis.
During the mildly hypotonic infusion (n = 8) the maternal blood osmolality changes were -5.1 +/- 1.2, +2.7 +/- 1.0 and +6.8 +/- 1.1 mOsm/kg at 1 and 4 hours of infusion and 1 hour after the infusion. In four of the eight animals in this group profuse diarrhea developed. During the markedly hypotonic infusion (n = 11) the maternal blood osmolality changes were -9.9 +/- 1.1, -15.9 +/- 2.5, and -10.4 +/- 2.2 mOsm/kg at 1 and 4 hours of infusion and 1 hour after the infusion. Although urine osmolalities were significantly less than the osmolality of the infusate in both groups, only during the mildly hypotonic infusion was there a net loss of free water by the kidneys. The renal free water loss, the venous pressure increase, and the blood osmolality decrease were not significantly different whether diarrhea did or did not develop.
The infusion of large volumes of mildly hypotonic Ringer's solution to the pregnant ewe produces a paradoxic increase in maternal plasma osmolality as a result of the excretion of large volumes of free water by the kidneys, and if the venous pressure is increased more than about 6 mm Hg with this infusion, diarrhea develops in the animals.
本研究的目的是比较母羊对静脉扩容的反应，分别给予足量的乳酸林格氏液以升高母羊静脉压，或足量的低渗液以降低血液渗透压。
对长期插管的怀孕绵羊静脉输注4小时，分别给予市售乳酸林格氏液（5.55±0.50升/小时，255毫渗量/千克，轻度低渗）或稀释林格氏液（2.04±0.27升/小时，150毫渗量/千克，显著低渗）。数据采用双因素和三因素方差分析以及双变量回归分析进行统计学分析。
在轻度低渗输注期间（n = 8），输注1小时、4小时及输注后1小时，母羊血液渗透压变化分别为-5.1±1.2、+2.7±1.0和+6.8±1.1毫渗量/千克。该组8只动物中有4只出现大量腹泻。在显著低渗输注期间（n = 11），输注1小时、4小时及输注后1小时，母羊血液渗透压变化分别为-9.9±1.1、-15.9±2.5和-10.4±2.2毫渗量/千克。虽然两组的尿渗透压均显著低于输注液的渗透压，但仅在轻度低渗输注期间肾脏出现了自由水的净丢失。无论是否发生腹泻，肾脏自由水丢失、静脉压升高和血液渗透压降低均无显著差异。
向怀孕母羊输注大量轻度低渗的林格氏液会导致母羊血浆渗透压反常升高，这是由于肾脏排出大量自由水所致，并且如果输注时静脉压升高超过约6毫米汞柱，动物会出现腹泻。
