Pittet J F, Forster A, Suter P M
Department of Anesthesiology, University Hospital of Geneva, Switzerland.
Chest. 1990 Feb;97(2):420-4. doi: 10.1378/chest.97.2.420.
Attenuation of ventilator-synchronous pressure fluctuations of intracranial pressure has been demonstrated during high frequency ventilation in animal and human studies, but the consequences of this effect on cerebral blood flow have not been investigated in man. We compared the effects of high frequency jet ventilation and intermittent positive pressure ventilation on CBF in 24 patients investigated three hours after completion of open-heart surgery. The patients were investigated during three consecutive periods with standard sedation (morphine, pancuronium): a. IPPV; b. HFJV; c. IPPV. Partial pressure of arterial CO2 (PaCO2: 4.5-5.5 kPa) and rectal temperature (35.5 to 37.5 degrees C) were maintained constant during the study. The CBF was measured by intravenous 133Xe washout technique. The following variables were derived from the cerebral clearance of 133Xe: the rapid compartment flow, the initial slope index, ie, a combination of the rapid and the slow compartment flows, and the ratio of fast compartment flow over total CBF (FF). Compared to IPPV, HFJV applied to result in the same mean airway pressure did not produce any change in pulmonary gas exchange, mean systemic arterial pressure, and cardiac index. Similarly, CBF was not significantly altered by HFJV. However, important variations of CBF values were observed in three patients, although the classic main determinants of CBF (PaCO2, cerebral perfusion pressure, Paw, temperature) remained unchanged. Our results suggest that in patients with normal systemic hemodynamics, the effects of HFJV and IPPV on CBF are comparable at identical levels of mean airway pressure.
在动物和人体研究中已证实，高频通气期间颅内压的呼吸机同步压力波动会减弱，但这种效应在人体中对脑血流量的影响尚未得到研究。我们比较了高频喷射通气和间歇正压通气对24例心脏直视手术后三小时接受检查的患者脑血流量的影响。在连续三个阶段对患者进行标准镇静（吗啡、泮库溴铵）状态下的检查：a. 间歇正压通气；b. 高频喷射通气；c. 间歇正压通气。研究期间，动脉二氧化碳分压（PaCO2：4.5 - 5.5 kPa）和直肠温度（35.5至37.5摄氏度）保持恒定。通过静脉注射133Xe洗脱技术测量脑血流量。从133Xe的脑清除率得出以下变量：快速区室流量、初始斜率指数，即快速区室流量和慢速区室流量的组合，以及快速区室流量与总脑血流量的比值（FF）。与间歇正压通气相比，施加相同平均气道压力的高频喷射通气在肺气体交换、平均体循环动脉压和心脏指数方面未产生任何变化。同样，高频喷射通气也未显著改变脑血流量。然而，尽管脑血流量的经典主要决定因素（PaCO2、脑灌注压、气道压、温度）保持不变，但在三名患者中观察到了脑血流量值的重要变化。我们的结果表明，在全身血流动力学正常的患者中，在相同平均气道压力水平下，高频喷射通气和间歇正压通气对脑血流量的影响相当。
