Nur Erfan, Kim Yu-Sok, Truijen Jasper, van Beers Eduard J, Davis Shyrin C A T, Brandjes Dees P, Biemond Bart J, van Lieshout Johannes J
Department of Internal Medicine, Slotervaart Hospital, Amsterdam, The Netherlands.
Blood. 2009 Oct 15;114(16):3473-8. doi: 10.1182/blood-2009-05-223859. Epub 2009 Aug 21.
Sickle cell disease (SCD) is associated with a high incidence of ischemic stroke. SCD is characterized by hemolytic anemia, resulting in reduced nitric oxide-bioavailability, and by impaired cerebrovascular hemodynamics. Cerebrovascular CO2 responsiveness is nitric oxide dependent and has been related to an increased stroke risk in microvascular diseases. We questioned whether cerebrovascular CO2 responsiveness is impaired in SCD and related to hemolytic anemia. Transcranial Doppler-determined mean cerebral blood flow velocity (V(mean)), near-infrared spectroscopy-determined cerebral oxygenation, and end-tidal CO2 tension were monitored during normocapnia and hypercapnia in 23 patients and 16 control subjects. Cerebrovascular CO2 responsiveness was quantified as Delta% V(mean) and Deltamicromol/L cerebral oxyhemoglobin, deoxyhemoglobin, and total hemoglobin per mm Hg change in end-tidal CO2 tension. Both ways of measurements revealed lower cerebrovascular CO2 responsiveness in SCD patients versus controls (V(mean), 3.7, 3.1-4.7 vs 5.9, 4.6-6.7 Delta% V(mean) per mm Hg, P < .001; oxyhemoglobin, 0.36, 0.14-0.82 vs 0.78, 0.61-1.22 Deltamicromol/L per mm Hg, P = .025; deoxyhemoglobin, 0.35, 0.14-0.67 vs 0.58, 0.41-0.86 Deltamicromol/L per mm Hg, P = .033; total-hemoglobin, 0.13, 0.02-0.18 vs 0.23, 0.13-0.38 Deltamicromol/L per mm Hg, P = .038). Cerebrovascular CO2 responsiveness was not related to markers of hemolytic anemia. In SCD patients, impaired cerebrovascular CO2 responsiveness reflects reduced cerebrovascular reserve capacity, which may play a role in pathophysiology of stroke.
镰状细胞病（SCD）与缺血性中风的高发病率相关。SCD的特征为溶血性贫血，导致一氧化氮生物利用度降低，以及脑血管血流动力学受损。脑血管对二氧化碳的反应性依赖于一氧化氮，并且与微血管疾病中中风风险增加有关。我们质疑SCD患者的脑血管对二氧化碳的反应性是否受损以及是否与溶血性贫血相关。在23例患者和16名对照受试者的正常碳酸血症和高碳酸血症期间，监测经颅多普勒测定的平均脑血流速度（V（mean））、近红外光谱测定的脑氧合以及呼气末二氧化碳分压。脑血管对二氧化碳的反应性量化为每毫米汞柱呼气末二氧化碳分压变化时的Δ%V（mean）以及每毫米汞柱变化时的每升微摩尔数脑氧合血红蛋白、脱氧血红蛋白和总血红蛋白。两种测量方法均显示，与对照组相比，SCD患者的脑血管对二氧化碳的反应性较低（V（mean），每毫米汞柱3.7, 3.1 - 4.7 vs 5.9, 4.6 - 6.7 Δ%V（mean），P <.001；氧合血红蛋白，每毫米汞柱0.36, 0.14 - 0.82 vs 0.78, 0.61 - 1.22微摩尔/升，P =.025；脱氧血红蛋白，每毫米汞柱0.35, 0.14 - 0.67 vs 0.58, 0.41 - 0.86微摩尔/升，P =.033；总血红蛋白，每毫米汞柱0.13, 0.02 - 0.18 vs 0.23, 0.13 - 0.38微摩尔/升，P =.038）。脑血管对二氧化碳的反应性与溶血性贫血的标志物无关。在SCD患者中，脑血管对二氧化碳的反应性受损反映了脑血管储备能力降低，这可能在中风的病理生理学中起作用。
