Bednarczyk E M, Rutherford W F, Leisure G P, Munger M A, Panacek E A, Miraldi F D, Green J A
Case Western Reserve University School of Medicine, Division of Cardiology, University Hospitals of Cleveland, OH 44106.
DICP. 1990 May;24(5):456-60. doi: 10.1177/106002809002400501.
The use of positron emission tomography (PET) has been well documented as a relatively noninvasive method of measuring cerebral blood flow (CBF), both globally and regionally. The utility of readily detecting alterations in CBF is apparent, particularly when applied to the evaluation of therapeutic interventions thought to influence CBF. We report the effects of hypocapnia, an experimental condition of known cerebral vasoconstriction, in ten normal volunteers. Subjects had brain blood flow evaluated utilizing H215O as the positron emitter before and after approximately five minutes of hyperventilation. Baseline CBF was measured as a mean +/- SD of 61.2 +/- 16.3 mL/min/100 g of tissue. Mean baseline arterial blood gas values were PaO2 107.4 +/- 14 mm Hg, PaCO2 37.7 +/- 0.89 mm Hg, and pH 7.39 (calculated from mean [H+]). Post hyperventilation, global CBF was measured as 31.1 +/- 10.8 mL/min/100 g. Mean arterial blood gas values were PaO2 141.7 +/- 21 mm Hg, PaCO2 19.7 +/- 5 mm Hg, and pH 7.63 (calculated from mean [H+]). CBF decreased by a mean of 49.5 +/- 11 percent. Data analysis using the Student's t-test showed a significant change over baseline in PaCO2 (p less than 0.001) and CBF (p less than 0.001), in the hyperventilated state. Correlations were noted between the decrease in CBF and change in PaCO2 (r = 0.81) as well as between hyperventilation PaCO2 and the change in CBF (r = 0.97). We conclude that, as measured by PET, CBF decreases significantly during a state of artificial hyperventilation to a degree consistent with results seen using other methods. PET appears to be a valuable tool in the assessment of interventions that could influence CBF.
正电子发射断层扫描（PET）作为一种测量全脑和局部脑血流量（CBF）的相对非侵入性方法，其应用已有充分记录。易于检测CBF变化的实用性显而易见，特别是当应用于评估被认为会影响CBF的治疗干预措施时。我们报告了低碳酸血症（一种已知的脑血管收缩实验条件）对十名正常志愿者的影响。在受试者进行约五分钟的过度通气前后，利用H215O作为正电子发射体对其脑血流量进行评估。基线CBF测量值为平均61.2±16.3 mL/分钟/100克组织。基线动脉血气平均值为：动脉血氧分压（PaO2）107.4±14毫米汞柱，动脉血二氧化碳分压（PaCO2）37.7±0.89毫米汞柱，pH值7.39（根据平均[H+]计算）。过度通气后，全脑CBF测量值为31.1±10.8 mL/分钟/100克。动脉血气平均值为：PaO2 141.7±21毫米汞柱，PaCO2 19.7±5毫米汞柱，pH值7.63（根据平均[H+]计算）。CBF平均下降了49.5±11%。使用学生t检验进行数据分析显示，在过度通气状态下，PaCO2（p<0.001）和CBF（p<0.001）与基线相比有显著变化。观察到CBF下降与PaCO2变化之间存在相关性（r = 0.81），以及过度通气时的PaCO2与CBF变化之间存在相关性（r = 0.97）。我们得出结论，通过PET测量，在人工过度通气状态下CBF显著下降，下降程度与使用其他方法得到的结果一致。PET似乎是评估可能影响CBF的干预措施的一种有价值的工具。
