Intracranial physiology and biomechanics

1982 ◽  
Vol 57 (4) ◽  
pp. 500-510 ◽  
Author(s):  
Eugeny I. Paltsev ◽  
Edward B. Sirovsky
Keyword(s):  
Brain Function ◽  
Quantitative Data ◽  
Fluid Pressure ◽  
Fluid Injection ◽  
Intracranial Volume ◽  
Clinical Tests ◽  
Content Type ◽  
Minimal Error ◽  
Active Compliance ◽  
Ventricular Fluid Pressure

✓ The intracranial pressure-volume (PV) relationship was examined postoperatively after removal of brain tumors in two groups of patients (13 in all). Changes of ventricular fluid pressure were analyzed by a method involving fluid injection into the lateral ventricle. A technique has been developed which provides quantitative data on the PV relationship with minimal error. The results confirm the exponential nature of the PV relationships. Various parameters characterizing the intracranial volume compliance, the cerebrospinal fluid pressure, and their interrelationship were investigated. It was found that 1) intracranial PV dependence is accurately defined by three parameters; 2) in patients who are not critically ill, ΔP/ΔV at P = Pmean does not vary statistically, and may be used as one of the important parameters to determine the regulation of the intracranial PV relationships. Examples are presented of the use of the data from the PV test for the control of the intracranial PV relationship. Examples are also given of the computation of volume redistribution in the cranium, both spontaneous and evoked by clinical tests. Analysis of the results allows the conclusion that the intracranial volume compliance concerned is an active compliance, which is controlled by the systems maintaining brain function.

Intracranial volume-pressure relationship in man

1982 ◽  
Vol 56 (4) ◽  
pp. 524-528 ◽  
Author(s):  
Joseph Th. J. Tans ◽  
Dick C. J. Poortvliet
Keyword(s):  
Best Approximation ◽  
Continuous Monitoring ◽  
Fluid Pressure ◽  
Constant Term ◽  
Volume Index ◽  
Intracranial Volume ◽  
Content Type ◽  
The Best Approximation ◽  
Ventricular Fluid Pressure ◽  
Fine Print

✓ The pressure-volume index (PVI) was determined in 40 patients who underwent continuous monitoring of ventricular fluid pressure. The PVI value was calculated using different mathematical models. From the differences between these values, it is concluded that a monoexponential relationship with a constant term provides the best approximation of the PVI.

Intracranial volume-pressure relationship in man

1983 ◽  
Vol 59 (5) ◽  
pp. 810-816 ◽  
Author(s):  
Joseph Th. J. Tans ◽  
Dick C. J. Poortvliet
Keyword(s):  
Continuous Monitoring ◽  
Fluid Pressure ◽  
Pressure Rise ◽  
Intracranial Volume ◽  
Content Type ◽  
Intensive Monitoring ◽  
Therapeutic Consequences ◽  
Ventricular Fluid Pressure ◽  
The Relationship ◽  
Fine Print

✓ Pressure-volume indices (PVI's) were determined for a heterogeneous group of 40 patients who underwent continuous monitoring of ventricular fluid pressure (VFP). The main purpose was to investigate the relationship between VFP and PVI and to establish the significance of the measured PVI values. Determinations of PVI appear to be useful only when baseline VFP is under 20 mm Hg, maximum VFP is under 30 mm Hg, A-waves are absent, and B-waves do not occur numerously. The authors advocate starting with 1-ml bolus infusions, and then, when the resulting pressure rise exceeds 4 mm Hg, additional bolus infusions can be omitted. Results indicate that 13 ml and 10 ml are the key values for the PVI. A PVI of less than 13 ml indicates the need for either reduction of VFP and improvement of compliance or intensive monitoring of both the VFP and the volume-pressure relationship; if the PVI is below 10 ml, anti-hypertensive treatment is almost always necessary. Values of PVI's between 13 and 18 ml, although pathological, usually have no therapeutic consequences.

A clinical comparison of subdural screw pressure measurements with ventricular pressure

1983 ◽  
Vol 58 (1) ◽  
pp. 45-50 ◽  
Author(s):  
A. David Mendelow ◽  
John O. Rowan ◽  
Lilian Murray ◽  
Audrey E. Kerr
Keyword(s):  
Head Injury ◽  
Intracranial Pressure ◽  
Severe Head Injury ◽  
Fluid Pressure ◽  
Ventricular Catheter ◽  
Pressure Measurements ◽  
Content Type ◽  
Single Lumen ◽  
Ventricular Fluid Pressure ◽  
Fine Print

✓ Simultaneous recordings of intracranial pressure (ICP) from a single-lumen subdural screw and a ventricular catheter were compared in 10 patients with severe head injury. Forty-one percent of the readings corresponded within the same 10 mm Hg ranges, while 13% of the screw pressure measurements were higher and 46% were lower than the associated ventricular catheter measurements. In 10 other patients, also with severe head injury, pressure measurements obtained with the Leeds-type screw were similarly compared with ventricular fluid pressure. Fifty-eight percent of the dual pressure readings corresponded, while 15% of the screw measurements were higher and 27% were lower than the ventricular fluid pressure, within 10-mm Hg ranges. It is concluded that subdural screws may give unreliable results, particularly by underestimating the occurrence of high ICP.

Effects of intravenous nitroglycerin on the intracranial pressure and volume pressure response

1983 ◽  
Vol 58 (4) ◽  
pp. 562-565 ◽  
Author(s):  
Ghaleb A. Ghani ◽  
Yung Fong Sung ◽  
Michael S. Weinstein ◽  
George T. Tindall ◽  
Alan S. Fleischer
Keyword(s):  
Blood Pressure ◽  
Intracranial Pressure ◽  
Fluid Pressure ◽  
Pressure Response ◽  
Mean Blood Pressure ◽  
Intravenous Nitroglycerin ◽  
Content Type ◽  
Ventricular Fluid Pressure ◽  
The Mean ◽  
Fine Print

✓ Ventricular fluid pressure (VFP) and volume-pressure response were measured during nitroglycerin (NTG) infusion in nine patients anesthetized with N2O and fentanyl. The patients' ventilation was controlled, and PaCO2 was kept at 32 ± 4 mm Hg. When an infusion of 0.01% NTG was given intravenously to decrease the mean blood pressure to 95.1%, 84.7%, and 78.2% of control, the VFP increased from control levels of 9.94 ± 2.14 mm Hg to 12.89 ± 2.25, 15.6 ± 2.85, and 14.43 ± 3.45 mm Hg, respectively. The volume-pressure response showed a significant increase when blood pressure decreased to 84.7% and 78.2% of control. These results suggest that intravenous NTG caused an increase in the intracranial pressure and a decrease in the intracranial compliance.

Disposable system for intraventricular pressure measurement and CSF drainage

1972 ◽  
Vol 36 (6) ◽  
pp. 798-801 ◽  
Author(s):  
Harvey M. Shapiro ◽  
S. R. Wyte ◽  
A. B. Harris ◽  
A. Galindo
Keyword(s):  
Pressure Transducer ◽  
Fluid Pressure ◽  
Drainage System ◽  
Intraventricular Pressure ◽  
Content Type ◽  
Csf Drainage ◽  
Continuous Record ◽  
Adjustable Mechanism ◽  
Standard Pressure ◽  
Ventricular Fluid Pressure

✓ A simple disposable system for controlled cerebrospinal fluid drainage and monitoring of ventricular fluid pressure is described. The unit is connected between the patient's external ventriculostomy and a standard pressure transducer. This drainage system is easily assembled, incorporates an adjustable mechanism for releasing pressure, provides a continuous record of ventricular fluid pressure, and permits hourly measurement of CSF drainage. The pressure recording is continued even when the ventricular fluid pressure falls below a predetermined maximal value.

Intracranial pressure in conscious rabbits after intraventricular reserpine

1974 ◽  
Vol 40 (6) ◽  
pp. 743-746 ◽  
Author(s):  
Lars Edvinsson ◽  
Kai C. Nielsen ◽  
Christer Owman ◽  
Kurt A. West
Keyword(s):  
Cerebral Blood Volume ◽  
Fluid Pressure ◽  
Sympathetic Nerves ◽  
Intraventricular Injection ◽  
Content Type ◽  
Left Lateral Ventricle ◽  
Fluid Production ◽  
Ventricular Fluid Pressure ◽  
Conscious Rabbits ◽  
Central Depressant

✓ Ventricular fluid pressure was measured continuously for 50 hours in conscious rabbits via a cannula implanted into the left lateral ventricle. Intraventricular injection of 25 µg reserpine (in a volume of 10 µl) resulted in increased pressure compared to that in non-injected controls during the first 7 to 10 hours. This was interpreted as depletion of noradrenaline in intracranial sympathetic nerves leading to increased cerebral blood volume and increased cerebrospinal fluid production. During the remainder of the experiment, the ventricular fluid pressure was reduced, probably due to a predominance of the central depressant effects of reserpine.

Experience with an intracranial pressure transducer readjustable in vivo

1974 ◽  
Vol 40 (2) ◽  
pp. 272-276 ◽  
Author(s):  
Wolfgang Gobiet ◽  
Wolfgang Joachim Bock ◽  
Jürgen Liesegang ◽  
Wilhelm Grote
Keyword(s):  
Intracranial Pressure ◽  
Pressure Transducer ◽  
Fluid Pressure ◽  
Zero Point ◽  
Epidural Pressure ◽  
Content Type ◽  
Ventricular Fluid Pressure ◽  
Term Monitoring

✓ A new implantable miniature intracranial pressure transducer is described whose main advantage is the possibility of zero point calibration in vivo. Comparative studies verify that epidural pressure corresponds well with ventricular fluid pressure. During long-term monitoring of 30 patients the transducer proved both safe and reliable.

Knowledge needs in the non-profit sector: an evidence-based model of organizational practices

2016 ◽  
Vol 20 (1) ◽  
pp. 23-48 ◽  
Author(s):  
Dinesh Rathi ◽  
Lisa M. Given ◽  
Eric Forcier
Keyword(s):  
Quantitative Data ◽  
Qualitative Data ◽  
Free Text ◽  
Evidence Based ◽  
Theory Approach ◽  
Organizational Practices ◽  
Content Type ◽  
Non Profit ◽  
Types Of Knowledge ◽  
Survey Responses

Purpose – This paper aims to present findings from a study of non-profit organizations (NPOs), including a model of knowledge needs that can be applied by practitioners and scholars to further develop the NPO sector. Design/methodology/approach – A survey was conducted with NPOs operating in Canada and Australia. An analysis of survey responses identified the different types of knowledge essential for each organization. Respondents identified the importance of three pre-determined themes (quantitative data) related to knowledge needs, as well as a fourth option, which was a free text box (qualitative data). The quantitative and qualitative data were analyzed using descriptive statistical analyses and a grounded theory approach, respectively. Findings – Analysis of the quantitative data indicates that NPOs ' needs are comparable in both countries. Analysis of qualitative data identified five major categories and multiple sub-categories representing the types of knowledge needs of NPOs. Major categories are knowledge about management and organizational practices, knowledge about resources, community knowledge, sectoral knowledge and situated knowledge. The paper discusses the results using semantic proximity and presents an emergent, evidence-based knowledge management (KM)-NPO model. Originality/value – The findings contribute to the growing body of literature in the KM domain, and in the understudied research domain related to the knowledge needs and experiences of NPOs. NPOs will find the identified categories and sub-categories useful to undertake KM initiatives within their individual organizations. The study is also unique, as it includes data from two countries, Canada and Australia.

Building holistic and agile collection development and assessment

2015 ◽  
Vol 16 (1) ◽  
pp. 62-85 ◽  
Author(s):  
Cheri Jeanette Duncan ◽  
Genya Morgan O'Gara
Keyword(s):  
Quantitative Data ◽  
Holistic Approach ◽  
Assessment Model ◽  
Data Sets ◽  
Collection Development ◽  
Content Type ◽  
Qualitative And Quantitative ◽  
Institutional Goals ◽  
Scholarly Output ◽  
Use Of Data

Purpose – The purpose of this paper is to examine the development of a flexible collections assessment rubric comprised of a suite of tools for more consistently and effectively evaluating and expressing a holistic value of library collections to a variety of constituents, from administrators to faculty and students, with particular emphasis to the use of data already being collected at libraries to “take the temperature” of how responsive collections are in supporting institutional goals. Design/methodology/approach – Using a literature review, internal and external conversations, several collections pilot projects, and a variety of other investigative mechanisms, this paper explores methods for creating a more flexible, holistic collection development and assessment model using both qualitative and quantitative data. Findings – The products of scholarship that academic libraries include in their collections are expanding exponentially and range from journals and monographs in all formats, to databases, data sets, digital text and images, streaming media, visualizations and animations. Content is also being shared in new ways and on a variety of platforms. Yet the framework for evaluating this new landscape of scholarly output is in its infancy. So, how do libraries develop and assess collections in a consistent, holistic, yet agile, manner? Libraries must employ a variety of mechanisms to ensure this goal, while remaining flexible in adapting to the shifting collections environment. Originality/value – In so much as the authors are aware, this is the first paper to examine an agile, holistic approach to collections using both qualitative and quantitative data.

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