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Angelo L. Maset, Anthony Marmarou, John D. Ward, Sung Choi, Harry A. Lutz, Danny Brooks, Richard J. Moulton, Antonio DeSalles, J. Paul Muizelaar, Hope Turner, and Harold F. Young

been explored in only a limited number of studies. 8, 24 This study describes the temporal course of the pressure-volume index (PVI) and ICP in adult patients with severe head injury. The objective was to characterize the biomechanical profile of the head-injured patient immediately upon stabilization in the neuroscience intensive care unit (ICU) and to follow the course of ICP and PVI during the 5 days postinjury. Having established this relationship, the concept that early detection of reduced neuraxis compliance can identify those patients at risk for

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Pressure-volume index as a function of cerebral perfusion pressure

Part 2: The effects of low cerebral perfusion pressure and autoregulation

W. John Gray and Michael J. Rosner

P revious studies of the relationship of cerebral perfusion pressure (CPP) changes to “brain stiffness, ” whether measured by compliance, elastance, volume pressure response, or pressure-volume index (PVI), have suggested that at normal levels of intracranial pressure (ICP), “brain stiffness” does not change significantly when CPP is changed within the 50- to 160-mm Hg range. 1, 10, 18 Recent work by us in cats has shown that deep barbiturate anesthesia nearly obliterates the relationship between PVI and CPP, but under light anesthesia cats showed a

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Pressure-volume index as a function of cerebral perfusion pressure

Part 1: The effects of cerebral perfusion pressure changes and anesthesia

W. John Gray and Michael J. Rosner

against the volume change, the slope of this line being the pressure-volume index (PVI); 39, 40 this is the calculated volume (in milliliters) required to raise the CSF pressure by a factor of 10. The PVI can also be calculated from the CSF pressure response to the addition of a bolus of known volume. 28 Because of the instantaneous rise in CSF pressure after a bolus injection, it is thought that the PVI is largely a reflection of the vascular component of the intracranial compartment. 24, 39 Within the vascular compartment, cerebral blood flow (CBF) remains

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Hideo Takizawa, Thea Gabra-Sanders, and J. Douglas Miller

difficult when they are collapsed by mass lesions or brain swelling, and ICP monitoring may have to be conducted from the brain surface. This is a serious problem because estimation of the volume-pressure relationship is impossible in just those patients in whom such information is most urgently required. It would be beneficial to know whether, or under what circumstances, bolus injection into the subarachnoid space yielded the same results as at the lateral ventricle. This series of experiments was planned to determine the variations in pressure-volume index (PVI) at

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Kenneth Shapiro and Anthony Marmarou

often fatal, rises in pressure represents a critical shortcoming. To circumvent this deficiency, techniques using bolus manipulation of fluid 10 and, more recently, pulse wave analysis 1 have been developed. These techniques can be used to assess neural axis compliance in order to identify patients at risk of sudden increases of ICP. One of these techniques, the pressure-volume index (PVI), which utilizes bolus manipulation of cerebrospinal fluid (CSF), has been developed in this laboratory. The application of PVI testing to the care of head-injured children will be

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Intracranial volume-pressure relationship in man

Part 1: Calculation of the pressure-volume index

Joseph Th. J. Tans and Dick C. J. Poortvliet

I ntracranial volume-pressure relationship can be studied using the volume-pressure response (VPR), defined by Miller and co-workers 8, 9 as the pressure change following 1-ml bolus additions or reductions of ventricular volume. The VPR is limited in that it provides information about only a small part of the volume-pressure curve, 15 and in that comparison of different VPR values is difficult without adding the baseline pressures at which they were evaluated. The pressure-volume index (PVI), defined by Marmarou, et al. , 6, 7 as the volume necessary to

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Kenneth Shapiro, Arno Fried, and Anthony Marmarou

testing was conducted using the bolus manipulation technique described by Marmarou, et al. , 12, 13 to derive the pressure-volume index (PVI) as a descriptor of neural axis volume-buffering capacity and the resistance to the absorption of cerebrospinal fluid (CSF). Earlier studies from this laboratory described normative values for these parameters in a group of normal subjects differing in age and body size. 24 Also described were techniques for estimating the expected normal PVI in children of different sizes which served as a comparison to gauge the effects of a

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Claudia S. Robertson, Raj K. Narayan, Charles F. Contant, Robert G. Grossman, Ziya L. Gokaslan, Rajesh Pahwa, Pedro Caram Jr., Robert S. Bray Jr., and Arthur M. Sherwood

approximately 13 ml. Fig. 2. Power shifts within the 4- to 15-Hz frequency range of the power density spectrum generated by the discrete Fourier transform (DFT) were found to occur with changes in intracranial compliance. To describe these frequency shifts, the power-weighted average frequency (or high-frequency centroid (HFC)) within the 4- to 15-Hz band is calculated. An HFC of 6.5 to 7.0 Hz indicates a normal intracranial compliance, while an HFC of 9.0 Hz occurs with reduction in pressure-volume index to approximately 13 ml. Statistical Analysis The

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A laboratory model of shunt-dependent hydrocephalus

Development and biomechanical characterization

Arno Fried, Kenneth Shapiro, Futoshi Takei, and Ira Kohn

through the ventricular cannula. The pressure-volume index (PVI) was calculated from the response of CSF pressure to bolus injection using the equation: PVI = ΔV/log (P p /P o ), in which P o is the intracranial pressure (ICP) prior to injection, P p is the peak ICP recorded immediately after the injection, and ΔV is the volume injected. 17, 18 The resistance to the absorption of CSF (R o ) was calculated by a bolus injection technique 18 and the constant CSF infusion technique. 14 After bolus injection, R o was calculated using the equation: R o = P o /PVI × log

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Shizuo Hatashita and Julian T. Hoff

was measured using a needle system similar to that used for the measurement of tissue pressure, with the needle inserted into the cisterna magna. The pressure-volume relationship of the intracranial space was determined using the pressure-volume index technique of Marmarou and colleagues. 13 A bolus of saline (0.20 to 0.23 ml) was injected into the cisterna magna at a rate of 0.051 to 0.057 ml/sec. The pressure-volume index (PVI) was calculated from the peak pressure generated by bolus injection (P p ), using the equation: PVI = V/log(P p /P o ), where V is the