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Neil A. Martin, Curtis Doberstein, Cynthia Zane, Michael J. Caron, Kathleen Thomas and Donald P. Becker

individualized. Three patients were treated with hypervolemia, which was augmented by the administration of nimodipine in one case and dopamine-induced hypertension in two cases. Transcranial Doppler Ultrasound Recordings were made of mean blood flow velocity in the intracranial internal carotid artery (ICA) and middle cerebral artery (MCA) using a 2-MHz probe. These vessels were insonated through the temporal window as previously described by Aaslid, et al. 1 All measurements were performed using a TCD apparatus. * Systemic blood pressure, hematocrit, PaCO 2 , and

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Neil A. Martin, Ravish V. Patwardhan, Michael J. Alexander, Cynthia Zane Africk, Jae Hong Lee, Ehud Shalmon, David A. Hovda and Donald P. Becker

were used to confirm that the three hemodynamic phases, based on CO 2 -corrected CBF 15 , V MCA , and HI, were separate and distinct. These tests were also used to assess any statistically significant differences in AVDO 2 , CMRO 2 , PI, ICP, and CPP values between phases. Results Patterns of CBF and Blood Flow Velocity After Head Injury The daily mean values (± SEM) of the key parameters derived from CBF and TCD studies are illustrated graphically in Fig. 1 upper left and right . For comparison, previous studies have described the normal adult

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Jae Hong Lee, Neil A. Martin, George Alsina, David L. McArthur, Ken Zaucha, David A. Hovda and Donald P. Becker

. Transcranial Doppler Ultrasonography Recordings were made of the mean blood flow velocity in the MCA, EC—ICA, and basilar artery using a 2-MHz probe. These vessels were insonated through temporal (MCA), submandibular (EC—ICA), and suboccipital/foraminal (basilar artery [BA]) windows according to the general principles first described by Aaslid, et al. 3 All measurements were performed with the aid of a commercially available TCD apparatus (Neuroguard Cerebrovascular Diagnostic System; Nicolet Biomedical, Inc., Madison, WI). Mean velocity recordings from this instrument

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Paul Vespa, Mayumi Prins, Elizabeth Ronne-Engstrom, Michael Caron, Ehud Shalmon, David A. Hovda, Neil A. Martin and Donald P. Becker

. Ann NY Acad Sci 59 : 290 – 298 , 1995 Bullock R, Zauner A, Myseros JS, et al: Evidence for prolonged release of excitatory amino acids in severe human head trauma. Relationship to clinical events. Ann NY Acad Sci 59: 290–298, 1995 11. Chan KH , Miller JD , Dearden NM , et al : The effect of changes in cerebral perfusion pressure upon middle cerebral artery blood flow velocity and jugular bulb venous oxygen saturation after severe brain injury. J Neurosurg 77 : 55 – 61 , 1992 Chan KH, Miller JD, Dearden

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Jae Hong Lee, Daniel F. Kelly, Matthias Oertel, David L. McArthur, Thomas C. Glenn, Paul Vespa, W. John Boscardin and Neil A. Martin

). 45, 46 Efforts were made to avoid changes in ventilator settings or vasopressor or sedative doses immediately before testing. Mannitol use was also avoided during this time. Physiological Parameters and TCD Ultrasonography Recordings were made of the mean blood flow velocity of the right and left MCA and extracranial ICA by using a 2-MHz probe. These vessels were insonated through the temporal (MCA) and submandibular (extracranial ICA) windows according to the principles described by Aaslid, et al. 3 Continuous monitoring of bilateral MCA flow velocities

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Matthias Oertel, Daniel F. Kelly, Jae Hong Lee, David L. McArthur, Thomas C. Glenn, Paul Vespa, W. John Boscardin, David A. Hovda and Neil A. Martin

Object. Hyperventilation therapy, blood pressure augmentation, and metabolic suppression therapy are often used to reduce intracranial pressure (ICP) and improve cerebral perfusion pressure (CPP) in intubated head-injured patients. In this study, as part of routine vasoreactivity testing, these three therapies were assessed in their effectiveness in reducing ICP.

Methods. Thirty-three patients with a mean age of 33 ± 13 years and a median Glasgow Coma Scale (GCS) score of 7 underwent a total of 70 vasoreactivity testing sessions from postinjury Days 0 to 13. After an initial 133Xe cerebral blood flow (CBF) assessment, transcranial Doppler ultrasonography recordings of the middle cerebral arteries were obtained to assess blood flow velocity changes resulting from transient hyperventilation (57 studies in 27 patients), phenylephrine-induced hypertension (55 studies in 26 patients), and propofol-induced metabolic suppression (43 studies in 21 patients). Changes in ICP, mean arterial blood pressure (MABP), CPP, PaCO2, and jugular venous oxygen saturation (SjvO2) were recorded. With hyperventilation therapy, patients experienced a mean decrease in PaCO2 from 35 ± 5 to 27 ± 5 mm Hg and in ICP from 20 ± 11 to 13 ± 8 mm Hg (p < 0.001). In no patient who underwent hyperventilation therapy did SjvO2 fall below 55%. With induced hypertension, MABP in patients increased by 14 ± 5 mm Hg and ICP increased from 16 ± 9 to 19 ± 9 mm Hg (p = 0.001). With the aid of metabolic suppression, MABP remained stable and ICP decreased from 20 ± 10 to 16 ± 11 mm Hg (p < 0.001). A decrease in ICP of more than 20% below the baseline value was observed in 77.2, 5.5, and 48.8% of hyperventilation, induced-hypertension, and metabolic suppression tests, respectively (p < 0.001 for all comparisons). Predictors of an effective reduction in ICP included a high PaCO2 for hyperventilation, a high study GCS score for induced hypertension, and a high PaCO2 and a high CBF for metabolic suppression.

Conclusions Of the three modalities tested to reduce ICP, hyperventilation therapy was the most consistently effective, metabolic suppression therapy was variably effective, and induced hypertension was generally ineffective and in some instances significantly raised ICP. The results of this study suggest that hyperventilation may be used more aggressively to control ICP in head-injured patients, provided it is performed in conjunction with monitoring of SjvO2.

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effectiveness in reducing ICP. Methods. Thirty-three patients with a mean age of 33 ± 13 years and a median Glasgow Coma Scale (GCS) score of 7 underwent a total of 70 vasoreactivity testing sessions from postinjury Days 0 to 13. After an initial 133 Xe cerebral blood flow (CBF) assessment, transcranial Doppler ultrasonography recordings of the middle cerebral arteries were obtained to assess blood flow velocity changes resulting from transient hyperventilation (57 studies in 27 patients), phenylephrine-induced hypertension (55 studies in 26 patients), and propofol

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Matthias Oertel, W. John Boscardin, Walter D. Obrist, Thomas C. Glenn, David L. McArthur, Tooraj Gravori, Jae Hong Lee and Neil A. Martin

The interindividual variation in the extracranial ICA diameter is broad. 22 To account for this in the diagnosis of vasospasm, Jakobsen, et al., 34 introduced an SI (SI = V MCA /ISI, where ISI is the initial slope index of the clearance curve obtained using the 133 Xe technique). Because slope measurements cannot be used to obtain an adequate measurement of CBF, 60 a modified SI was developed by Lee and associates 44 (SI = V MCA /CBF 15 ). It should be noted that the SI is derived by two independent techniques of measuring blood flow velocity and blood flow