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Thử nghiệm tĩnh tự điều trong quá trình an thần midazolam / fentanyl và propofol gây mê ở bệnh nhân headinjured nhận được chăm sóc đặc biệt. (Top tracing) trung bình áp lực động mạch (ABP) mmHg. (Trung tracing) áp lực nội sọ (ICP mmHg). (Dưới tracing) vận tốc máu (FV) cm / s. | Page 119 Figure 8.3 A Testing static autoregulation during midazolam fentanyl sedation and propofol anaesthesia in a head-injured patient receiving intensive care. Top tracing Mean arterial pressure ABP in mmHg. Middle tracing Intracranial pressure ICP in mmHg . Bottom tracing Blood velocity FV in cm s. There is no change in FV despite the increase in ABP as a result of 0.01 phenylephrine infusion during propofol anaesthesia right trace autoregulation intact. The increase in ABP during midazolam-fentanyl sedation is accompanied by a similar increase in FV and ICP indicating impaired autoregulation. B The recovery in blood velocity FV cm s after thigh cuff deflation is steeper in patients with intact left dynamic autoregulation dROR . In contrast the FV remains depressed after cuff deflation in those with impaired autoregulation during desflurane anaesthesia right trace . basis of the continuous blood pressure record and compares its predictions with the measured response.55 The dRoR describes the rate of restoration of FV s with respect to the drop in MBP in other words the rate of change in cerebral vascular resistance or the fast process . The normal dRoR is 20 s i.e. process is complete within approximately 5 s .56 The time for autoregulation to normalize FV during normocapnia occurs well within the period of hypotension achieved with cuff deflation before the MAP returns to baseline 10-20 s .56 57 Collection of autoregulation data in the first 10 s avoids the influence of CO2-rich blood from the legs following thigh cuff deflation. Hypercapnia increases CBF by vasodilatation of cerebral blood vessels and reduces autoregulatory capacity.23 Transient Hyperaemic Response Test This test is performed by compressing the common carotid artery for a period of 5-8 s and observing the change in FV in the ipsilateral circle of Willis. When the carotid artery is compressed FV decreases and the distal cerebrovascular bed dilates in response to the drop in perfusion .
