Annales françaises d'anesthèsie et de rèanimation
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The occurrence of a fat embolism syndrome (FES) can be explained by two hypothetic mechanisms. In the mechanical hypothesis, bone marrow enters into the cardiovascular system during an intramedullary peak pressure. This peak could occur during either long bone fracture and/or intramedullary nailing or cemented or noncemented arthroplasty. ⋯ Aprotinin and heparin are beneficial in counteracting blood cell aggregation. A prophylactic use of vena cava filters has been advocated. Prevention or early treatment of hypovolaemia and hypoxaemia are essential.
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Ann Fr Anesth Reanim · Jan 1997
Review Comparative Study[Techniques for measuring intracranial hypertension].
A wide variety of monitoring devices have been used for intracranial pressure measurement. The aim of this article is to present the most common devices and to assess their accuracy, stability and complications, with reference to current literature. ⋯ However new techniques with distal measurement (fiberoptic or strain gauge) seem to be accurate, but have a higher cost. Some practical problems, such as the zero pressure reference level and the side of measurement, are also discussed.
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Ann Fr Anesth Reanim · Jan 1997
Review[Evaluation of ischemic repercussions of intracranial hypertension].
The main risk involved in severe intracranial hypertension is, the occurrence of cerebral ischaemia, either locally during herniation or globally as a consequence of reduced cerebral perfusion pressure (CPP). Neurological features of ischaemia occur at a late stage. A continuous monitoring of brain function with EEG or evoked potential techniques, while largely used in the operating room have not been so far fully evaluated in the intensive care setting. ⋯ ICP and CPP monitoring remains the basis for intensive care surveillance during the phase of intracranial hypertension, with alarming settled at admitted critical values (ICP = 30 mmHg; CPP = 70 mmHg). As ischaemic threshold for cerebral blood flow may be different in patients and in normal experimental animals, the reliability of these critical values of ICP and CPP is uncertain. Therefore, transcranial Doppler, jugular metabolic monitoring and, as recently available, cortical tissue PO2 monitoring are mandatory for early detection and assessment of ischaemia.
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A main indication for intracranial pressure monitoring is severe head trauma, where it acts as a diagnostic, prognostic and therapeutic guide. Others indications for intracranial pressure monitoring are patients with CSF circulation disturbances, whatever the cause, and various pathologies inducing intracranial hypertension, such as encephalopathies. Intracranial pressure monitoring must be associated with the measurement of mean arterial pressure, arterial and jugular venous oxygen saturation and blood flow velocity in major intracranial arteries with transcranial Doppler sonography.
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Intracranial pressure waves include fast waves (pulse and respiration) and slow waves. Only the latter are considered here. Since the definition of three wave types in the pioneering works of Janny (1950) and Lundberg (1960), their study of frequential characteristics shows they are included in a spectrum where three contiguous frequency bands are individualised: the B wave band (BW) between 8 x 10(-3) Hz and 50 x 10(-3) Hz; the Infra B band (IB) below 8 x 10(-3) Hz; and the Ultra B band (UB) beyond 50 x 10(-3) Hz to 200 x 10(-3) Hz. ⋯ They are linked with slow peripheral arterial pressure waves, with biological rhythms and with biomechanics and vasomotricity in the craniospinal enclosure. They are pathological for the slowest (IB), particularly if they are plateau waves, but the physiologic-pathologic boundary is not yet established for each type of slow waves. They can cause severe consequences if they result in major cerebral perfusion pressure changes, and if they induce or worsen herniations.