Phillips E M, Butler T, Baylis P H
Department of Medicine, University of Newcastle upon Tyne, UK.
Clin Endocrinol (Oxf). 1994 Aug;41(2):207-12. doi: 10.1111/j.1365-2265.1994.tb02531.x.
Osmoregulation is normally studied using a 5% saline infusion. This may be deleterious in fluid overloaded patients. Twenty per cent mannitol is another osmotic stimulant. This study aimed to compare 20% mannitol infusion with 5% saline as an osmotic stimulant to thirst and vasopressin secretion in normal volunteers.
Eight healthy volunteers studied on 2 occasions in random order. Each study involved a 2-hour infusion period of either hypertonic (5%) saline (0.06 ml/kg/h) or hypertonic (20%) mannitol (0.07 ml/kg/h).
Plasma vasopressin (pVp), plasma sodium, plasma osmolality (pOsm), haematocrit (HCT), blood pressure, thirst, blood glucose and volume drunk at end of infusion.
Five per cent saline infusion stimulated significantly higher levels of pOsm, pVp and thirst than 20% mannitol. Plasma sodium rose significantly during 5% saline infusion and fell during 20% mannitol infusion. HCT fell and mean arterial pressure rose in both infusions but the changes were not clinically significant. Piecewise linear regression analysis defined the overall threshold for pVp release for the two solutions as 5% saline, 292 mosm/kg and 20% mannitol, 291 mosm/kg, and the post threshold slope as 5% saline, 0.46 pmol/l pVp per mosm and 20% mannitol, 0.30 pmol/l pVp per mosm. The threshold for thirst onset was 5% saline, 291 mosm/kg and 20% mannitol, 290 mosm/kg, and the post threshold slope, 5% saline, 0.58 cm thirst per mosm and 20% mannitol, 0.28 cm thirst per mosm. The differences between the calculated osmotic thresholds and slopes post threshold for the two infusions were not significant for the pVp versus pOsm relationship. The difference between the cumulative volume drunk following the two infusions did not reach statistical significance. Mannitol caused a significant diuresis.
Twenty per cent mannitol infusion is an effective osmotic stimulant to thirst and vasopressin release in normal individuals, but is less potent than 5% saline infusion.
通常使用5%盐水输注来研究渗透压调节。这对液体超负荷患者可能有害。20%甘露醇是另一种渗透刺激剂。本研究旨在比较20%甘露醇输注与5%盐水作为渗透刺激剂对正常志愿者口渴和血管加压素分泌的影响。
8名健康志愿者，分2次按随机顺序进行研究。每次研究包括2小时的高渗（5%）盐水（0.06 ml/kg/h）或高渗（20%）甘露醇（0.07 ml/kg/h）输注期。
输注结束时的血浆血管加压素（pVp）、血浆钠、血浆渗透压（pOsm）、血细胞比容（HCT）、血压、口渴程度、血糖以及饮水量。
与20%甘露醇相比，5%盐水输注刺激产生的pOsm、pVp和口渴程度显著更高。5%盐水输注期间血浆钠显著升高，20%甘露醇输注期间血浆钠下降。两种输注均使HCT下降且平均动脉压升高，但这些变化无临床意义。分段线性回归分析确定两种溶液pVp释放的总体阈值为：5%盐水，292 mosm/kg；20%甘露醇，291 mosm/kg；阈值后斜率为：5%盐水，每mosm 0.46 pmol/l pVp；20%甘露醇，每mosm 0.30 pmol/l pVp。口渴开始的阈值为：5%盐水，291 mosm/kg；20%甘露醇，290 mosm/kg；阈值后斜率为：5%盐水，每mosm 0.58 cm口渴增加量；20%甘露醇，每mosm 0.28 cm口渴增加量。两种输注的计算渗透压阈值与阈值后斜率之间，pVp与pOsm关系的差异不显著。两种输注后累积饮水量的差异未达到统计学意义。甘露醇导致显著利尿。
20%甘露醇输注是正常个体口渴和血管加压素释放的有效渗透刺激剂，但效力低于5%盐水输注。
