Effect of sildenafil and acclimatization on cerebral oxygenation at altitude
Effect of sildenafil and acclimatization on cerebral oxygenation at altitude
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DOI：
10.1042/cs20050036
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发表时间：
2005-09-01
期刊：
影响因子：
6
通讯作者：
Imray, CHE
中科院分区：
文献类型：
--
作者：
Chan, CWM;Hoar, H;Imray, CHE
‘磷酸二酯酶-5抑制剂可减少低压缺氧下的缺氧性肺血管收缩，但尚不清楚是否会影响脑血流量或氧合。本研究旨在评价西地那非对急性高原暴露和习服后脑血流动力学的影响。10名受试者在快速上升到3480米后的第1天和第3天，在服用西地那非(50 Mg)前和之后连续2小时进行研究。心率(HR)在习服前1h上升(76.3+/-1.0次/min，基线为72.5+/-1.5次/min；P&t；0.05)，2小时恢复到基线(71.3+/-1.1次/min；P>；0.05)。平均血压(BP)从基线的96.0+/-2.0毫米汞下降到1小时的91.7+/-2.5(P<；0.001)和2小时的89.8+/-1.8毫米汞柱(P<；0.0001)，而动脉血氧饱和度(SaO(2))(动脉血氧饱和度)从基线的83.9+/-0.5%上升到1 h和85.0+/-0.5%(P<；0.0001)的85.3+/-0.4%(P<；0.0001)。MCAV[大脑中动脉血流速度]和PETCO2(呼气末二氧化碳分压)无明显变化，但RSO(2)(局部脑氧饱和度)在1h(62.7±-0.8%；P<；0.05)和2 h(65.3+/-0.9%；P<；0.0001)较基线(59.3±-1.3%)逐渐升高。驯化3d后，静息RSO(2)和RMCA(MCA阻力)增加，氧输送下降。西地那非治疗后心率和平均血压变化与用药第1天相似，SaO(2)无明显变化。然而，RSO(2)增加了[基线的61.7%+/-0.9%至1小时的65.0+/-1.0%(P<；0.0001)和2小时的64.0+/-0.9%(P<；0.001)]，尽管MCAV从基线的65.3+/-1.8厘米/S下降到1小时的61.3+/-1.5厘米/S(P<；0.01)和60.9+/-1.7厘米/S(P<；0.001)。0.0001)和PETCO2[基线时为+/-0.05kPa2小时为+/-0.04kPa(P<；0.01)]。这些观察结果表明，西地那非改善了高原地区的脑氧合。虽然习服前的早期变化可能主要源于肺脏，但后来的观察可能是一种直接的脑影响，值得进一步研究。
`Phosphodiesterase-5 inhibitors decrease hypoxic pulmonary vasoconstriction under hypobaric hypoxia, but are not known to affect cerebral blood flow or oxygenation. The present study was designed to evaluate the effect of sildenafil on cerebral haemodynamics during acute exposure to altitude and after acclimatization. Ten subjects were studied 1 and 3 days after rapid ascent to 3480 m before and for two consecutive hours after taking sildenafil (50 mg). Before acclimatization, HR (heart rate) rose at 1 h (76.3 +/- 1.0 beats/min compared with 72.5 +/- 1.5 beats/min at baseline; P < 0.05) and had returned to baseline at 2 h (71.3 +/- 1.1 beats/min; P > 0.05). Mean BP (blood pressure) fell from 96.0 +/- 2.0 mmHg at baseline to 91.7 +/- 2.5 (P < 0.001) at 1 h and 89.8 +/- 1.8 mmHg (P < 0.0001) at 2 h, whereas Sao(2) (arterial oxygen saturation) increased from 83.9 +/- 0.5 % at baseline to 85.3 +/- 0.4 % (P < 0.0001) at 1 h and 85.0 +/- 0.5 % (P < 0.01) at 2 h. MCAV [MCA (middle cerebral artery) velocity] and PETCO2 (end-tidal partial pressure Of CO2) were unchanged, but rSo(2) (regional cerebral oxygen saturation) rose progressively at 1 h (62.7 +/- 0.8 %; P < 0.05) and 2 h (65.3 +/- 0.9 %; P < 0.0001) compared with baseline (59.3 +/- 1.3 %). After 3 days of acclimatization, resting rSo(2) and RMCA (MCA resistance) increased and oxygen delivery fell. Changes in HR and mean BP after sildenafil were similar to day 1, but Sao(2) did not change. However, rSo(2) increased [61.7 +/- 0.9 % at baseline to 65.0 +/- 1.0 % (P < 0.0001) at 1 h and 64.0 +/- 0.9 % (P < 0.001) at 2h], despite a reduction in MCAV [65.3 +/- 1.8 cm/s at baseline to 61.3 +/- 1.5 cm/s (P < 0.01) at 1 h and 60.9 +/- 1.7 cm/s (P < 0.0001) at 2 h] and PETCO2 [4.1 +/- 0.05 kPa at baseline to 4.0 +/- 0.04 kPa at 2 h (P < 0.01)]. These observations suggest that sildenafil improves cerebral oxygenation at altitude. Whereas the early changes before acclimatization may be largely pulmonary in origin, the later observations may be a direct cerebral effect which warrants further study.