David W. Newell

BACKGROUND AND PURPOSE: Cerebral autoregulation can be evaluated by measuring relative blood flow changes in response to a steady-state change in the blood pressure (static method) or during the response to a rapid change in blood pressure (dynamic method). The purpose of this study was to compare the results of the two methods in humans with both intact and impaired autoregulatory capacity. METHODS: Using intraoperative transcranial Doppler sonography recordings from both middle cerebral arteries, we determined static and dynamic autoregulatory responses in 10 normal subjects undergoing elective surgical procedures. The changes in cerebrovascular resistance were estimated from the changes in cerebral blood flow velocity and arterial blood pressure in response to manipulations of blood pressure. Static autoregulation was determined by analyzing the response to a phenylephrine-induced rise in blood pressure, whereas rapid deflation of a blood pressure cuff around one thigh served as a stimulus for testing dynamic autoregulation. Both measurements were performed in patients with intact autoregulation during propofol anesthesia and again in the same patients after autoregulation had been impaired by administration of high-dose isoflurane. RESULTS: There was a significant reduction in autoregulatory capacity after the administration of high-dose isoflurane, which could be demonstrated using static (P < .0001) and dynamic (P < .0001) methods. The correlation between static or steady-state and dynamic autoregulation measurements was highly significant (r = .93, P < .0001). CONCLUSIONS: These data show that in normal human subjects measurement of dynamic autoregulation yields similar results as static testing of intact and pharmacologically impaired autoregulation.

Saccular intracranial aneurysms cause substantial morbidity and mortality. Recently, major changes have occurred in the way we think about and treat this disease. This review discusses the percutaneous endovascular treatment of intracranial aneurysms as compared with surgical intervention. The technological advances and supporting research contributing to this important change in practice patterns are reviewed.

INDICATIONS FOR SURGERY: An acute subdural hematoma (SDH) with a thickness greater than 10 mm or a midline shift greater than 5 mm on computed tomographic (CT) scan should be surgically evacuated, regardless of the patient's Glasgow Coma Scale (GCS) score. All patients with acute SDH in coma (GCS score less than 9) should undergo intracranial pressure (ICP) monitoring. A comatose patient (GCS score less than 9) with an SDH less than 10-mm thick and a midline shift less than 5 mm should undergo surgical evacuation of the lesion if the GCS score decreased between the time of injury and hospital admission by 2 or more points on the GCS and/or the patient presents with asymmetric or fixed and dilated pupils and/or the ICP exceeds 20 mm Hg. TIMING: In patients with acute SDH and indications for surgery, surgical evacuation should be performed as soon as possible. METHODS: If surgical evacuation of an acute SDH in a comatose patient (GCS < 9) is indicated, it should be performed using a craniotomy with or without bone flap removal and duraplasty.

We hypothesized that variation in extubating brain injured patients would affect the incidence of nosocomial pneumonia, length of stay, and hospital charges. In a prospective cohort of consecutive, intubated brain-injured patients, we evaluated daily: intubation status, spontaneous ventilatory parameters, gas exchange, neurologic status, and specific outcomes listed above. Of 136 patients, 99 (73%) were extubated within 48 h of meeting defined readiness criteria. The other 37 patients (27%) remained intubated for a median 3 d (range, 2 to 19). Patients with delayed extubation developed more pneumonias (38 versus 21%, p < 0.05) and had longer intensive care unit (median, 8.6 versus 3.8 d; p < 0.001) and hospital (median, 19.9 versus 13.2 d; p = 0.009) stays. Practice variation existed after stratifying for differences in Glasgow Coma Scale scores (10 versus 7, p < 0.001) at time of meeting readiness criteria, particularly for comatose patients. There was a similar reintubation rate. Median hospital charges were $29,057.00 higher for extubation delay patients (p < 0.001). This study does not support delaying extubating patients when impaired neurologic status is the only concern prolonging intubation. A randomized trial of extubation at the time brain-injured patients fulfill standard weaning criteria is justifiable.

OBJECTIVE: To review the use of transcranial Doppler ultrasonography (TCD) and transcranial color-coded sonography (TCCS) for diagnosis. METHODS: The authors searched the literature for evidence of 1) if TCD provides useful information in specific clinical settings; 2) if using this information improves clinical decision making, as reflected by improved patient outcomes; and 3) if TCD is preferable to other diagnostic tests in these clinical situations. RESULTS: TCD is of established value in the screening of children aged 2 to 16 years with sickle cell disease for stroke risk (Type A, Class I) and the detection and monitoring of angiographic vasospasm after spontaneous subarachnoid hemorrhage (Type A, Class I to II). TCD and TCCS provide important information and may have value for detection of intracranial steno-occlusive disease (Type B, Class II to III), vasomotor reactivity testing (Type B, Class II to III), detection of cerebral circulatory arrest/brain death (Type A, Class II), monitoring carotid endarterectomy (Type B, Class II to III), monitoring cerebral thrombolysis (Type B, Class II to III), and monitoring coronary artery bypass graft operations (Type B to C, Class II to III). Contrast-enhanced TCD/TCCS can also provide useful information in right-to-left cardiac/extracardiac shunts (Type A, Class II), intracranial occlusive disease (Type B, Class II to IV), and hemorrhagic cerebrovascular disease (Type B, Class II to IV), although other techniques may be preferable in these settings.