Noninvasive Monitoring of Cerebrovascular Reactivity with Near Infrared Spectroscopy in Head-Injured Patients
ABSTRACT Monitoring of cerebrovascular pressure reactivity (PRx) has diagnostic and prognostic value in head-injured patients, but requires invasive monitoring of intracranial pressure (ICP). Near infrared spectroscopy (NIRS) is a noninvasive method that is suitable for continuous detection of cerebral blood volume changes. We compared a NIRS-based index of cerebrovascular reactivity, called total hemoglobin reactivity (THx), against standard measurements of PRx in a prospective observational study. Forty patients with closed-head injury were monitored daily with arterial blood pressure (ABP), ICP, and a NIRS-based total hemoglobin index. PRx and THx were calculated as the moving correlation coefficients using 5-min time windows between 10-sec averaged values of ICP and ABP, and total hemoglobin index and ABP, respectively. A total of 120 recordings were performed between the median first (IQR 0.75-2) and fourth (IQR 2-6) day after head injury, giving a total duration of 1760 hours. PRx and THx demonstrated a significant association across averaged individual recordings (r = 0.49, p < 0.0001), and across patients (r = 0.56, p = 0.0002). Assessment of optimal cerebral perfusion pressure (CPP) and ABP using THx was possible in about 50% of recordings, and showed a significant agreement with the optimal CPP and ABP assessed with PRx. THx may be of diagnostic value to optimize therapy oriented toward restoration and continuity of cerebrovascular reactivity, especially in patients for whom direct ICP monitoring is not feasible.
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ABSTRACT: This paper focuses on the design and development of a CD-based learning environment which was based on the Nine Events of Instructions presented by Gagne (Gagne, Briggs, & Wagner, 1992). The learning module was then used as an instructional strategy to teach an animation course in the second year of the Film and Animation (FA) degree in the Faculty of Creative Multimedia (FCM). While this course has been traditionally given in a lecture-based environment, an attempt was made to move towards a more multimedia-mediated environment using the CD to provide a student-centred approach in learning the principles of animation. The aim of the study was to ascertain the attitudes and reactions of the students in this learning environment. Data were collected through a survey and questionnaire. A pre-test and post-test exercise was also administered to the students. Statistical analyses performed on the data showed that the students' attitudes and reactions were positive towards this student-centred environment and student learning was enhanced.
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ABSTRACT: Postural change during anesthesia has a complex effect on the systemic and cerebral circulations which can potentially decrease cerebral blood flow and oxygenation. Cerebral oximetry is emerging as a monitor of cerebral perfusion with widespread application in many types of surgery. The technology is based on the differential absorption of oxygenated and deoxygenated hemoglobin to near-infrared light. However, the dynamic coupling that exists between cerebral arterial, venous and cerebrospinal fluid volumes may influence oximetric readings during postural change. Interpretation of cerebral oxygen saturation measurement must account for these changes in cerebral physiology if monitoring is to predict neurological outcome.09/2013; 3(3). DOI:10.1007/s40140-013-0020-y
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ABSTRACT: The review touches upon the current physiopathological concepts relating to the field of intracranial pressure (ICP) monitoring and offers an up-to-date overview of the ICP monitoring technologies and of the signal-analysis techniques relevant to clinical practice. Improved ICP probes, antibiotic-impregnated ventricular catheters and multimodality, computerized systems allow ICP monitoring and individualized optimization of brain physiology. Noninvasive technologies for ICP and cerebral perfusion pressure assessment are being tested in the clinical arena. Computerized morphological analysis of the ICP pulse-waveform can provide an indicator of global cerebral perfusion. Current recommendations for the management of traumatic brain injury indicate ICP monitoring in patients who remain comatose after resuscitation if the admission computed tomography scan reveals intracranial abnormalities such as haematomas, contusions and cerebral oedema. The most reliable methods of ICP monitoring are ventricular catheters and intraparenchymal systems. A growing number of these devices are being safely placed by neurointensivists. The consensus is to treat ICP exceeding the 20 mmHg threshold, and to target cerebral perfusion pressure between 50 and 70 mmHg. Recent evidence suggests that such thresholds should be optimized based on multimodality monitoring and individual brain physiology. Noninvasive ICP estimation using transcranial Doppler can have a role as a screening tool in patients with low to intermediate risk of developing intracranial hypertension. However, the technology remains insufficiently accurate and too cumbersome for continuous ICP monitoring.Current opinion in anaesthesiology 02/2011; 24(2):117-23. DOI:10.1097/ACO.0b013e32834458c5 · 2.53 Impact Factor