Longo Antonio, Geiser Martial H, Riva Charles E
Istituto di Oftalmologia, Università di Catania, Catania, Italy.
Invest Ophthalmol Vis Sci. 2004 Feb;45(2):546-51. doi: 10.1167/iovs.03-0757.
To evaluate the effect of posture change on subfoveal choroidal blood flow (ChBF) in normal volunteers.
The pulsatile, nonpulsatile, and mean ChBF were measured with laser Doppler flowmetry in 11 healthy volunteers with a mean age of 32 +/- 13 (SD) years. The posture of the subjects was changed from standing (90 degrees ), to supine (-8 degrees ), and back to standing, with a mechanically driven table. During the whole experimental procedure, ChBF and heart rate (HR) were continuously recorded. After 30 seconds in standing position, the subjects were tilted to supine during approximately 30 seconds. They remained in this position for approximately 2 minutes, after which they were tilted back to the standing position (recovery), where they remained for another approximately 2 minutes. Systemic brachial artery blood pressure (BP) was measured in the baseline, supine, and recovery positions. This procedure was repeated to measure the intraocular pressure (IOP) at the different postures.
Mean BP did not change significantly throughout the experimental procedure. As the body was tilted from standing to supine, HR decreased by 16% (P < 0.0004), IOP increased by 29% (P < 0.001), and mean ChBF increased by 11% (P < 0.01). The increase in ChBF was primarily due to an increase in the nonpulsatile component of the blood velocity.
Based on previously reported experimental data that indicate that the ocular perfusion pressure increases less than predicted by purely hydrostatic considerations when the body is tilted from the standing to the supine position, the observed increase in ChBF suggests a passive response of the choroidal circulation to the posture change.
评估姿势改变对正常志愿者黄斑下脉络膜血流（ChBF）的影响。
使用激光多普勒血流仪对11名平均年龄为32±13（标准差）岁的健康志愿者测量搏动性、非搏动性和平均ChBF。通过机械驱动台将受试者的姿势从站立（90度）变为仰卧（-8度），然后再变回站立。在整个实验过程中，持续记录ChBF和心率（HR）。在站立位30秒后，受试者在约30秒内倾斜至仰卧位。他们在该位置保持约2分钟，之后再倾斜回站立位（恢复），并在该位置再保持约2分钟。在基线、仰卧位和恢复位测量肱动脉系统血压（BP）。重复此过程以测量不同姿势下的眼压（IOP）。
在整个实验过程中，平均BP无显著变化。当身体从站立位倾斜至仰卧位时，HR下降16%（P<0.0004），IOP升高29%（P<0.001），平均ChBF升高11%（P<0.01）。ChBF的增加主要是由于血流速度的非搏动性成分增加。
基于先前报道的实验数据，即当身体从站立位倾斜至仰卧位时，眼灌注压的增加小于单纯流体静力因素预测的值，观察到的ChBF增加提示脉络膜循环对姿势改变的被动反应。
