Journal of neurosurgical anesthesiology
-
J Neurosurg Anesthesiol · Oct 1999
Cerebral oxygenation in patients after severe head injury: monitoring and effects of arterial hyperoxia on cerebral blood flow, metabolism and intracranial pressure.
Early impaired cerebral blood flow (CBF) after severe head injury (SHI) leads to poor brain tissue oxygen delivery and lactate accumulation. The purpose of this investigation was to elucidate the relationship between CBF, local dialysate lactate (lact(md)) and dialysate glucose (gluc(md)), and brain tissue oxygen levels (PtiO2) under arterial normoxia. The effect of increased brain tissue oxygenation due to high fractions of inspired oxygen (FiO2) on lact(md) and CBF was explored. ⋯ The PtiO2 response to 100% FiO2 (oxygen reactivity) was inversely correlated with outcome (P < .01). Monitoring PtiO2 after SHI provides valuable information about cerebral oxygenation and substrate delivery. Increasing arterial oxygen tension (PaO2) effectively increased PtiO2, and brain lact(md) was reduced by the same maneuver.
-
J Neurosurg Anesthesiol · Oct 1999
Monitoring brain PO2, PCO2, and pH during graded levels of hypoxemia in rabbits.
Brain ischemia and hypoxia are of concern when they occur following traumatic brain injury because they frequently result in potentially preventable secondary brain damage. In this study, we examined the ability of an implantable catheter (Paratrend 7; Diametrics Medical, St. Paul, MN) to continuously measure brain tissue pH, PCO2, and PO2 during graded levels of hypoxia. ⋯ As expected, there was a good correlation between the changes in pH, PCO2, and PO2 in brain tissue and sagittal sinus blood. Brain tissue PO2 was numerically lower than sagittal sinus blood at all inspired levels of oxygen. These data suggest that the Paratrend 7 may be useful in monitoring brain tissue oxygen tension in patients at risk for regional cerebral ischemia and hypoxia.
-
J Neurosurg Anesthesiol · Oct 1999
ReviewRecovery from anesthesia and postoperative extubation of neurosurgical patients: a review.
The most feared complications after intracranial surgery are development of an intracranial hematoma and major cerebral edema. Both may result in cerebral hypoperfusion and brain injury. Arterial hypertension via catecholamine release or sympathetic stimulation and hypercapnia may be predisposing factors. ⋯ It is, however, often possible to perform a brief awakening of the patient without extubation to allow early neurological evaluation, followed by delayed emergence and extubation. Close hemodynamic and respiratory monitoring are mandatory in all cases. The availability of ultrashort intravenous anesthetic agents and adrenergic blocking agents has added to the flexibility in the immediate emergence period after intracranial surgery.
-
A decrease of 1-2 degrees C core temperature provides protection against cerebral ischemia. However, shivering usually prevents reduction in core temperature in unanesthetized patients. Therefore, it was tested whether facial and airway heating increases the shivering threshold and enables core cooling in unanesthetized patients. ⋯ Subsequently, in all subjects, within seconds after the application of facial focal warming, motor activity was suppressed almost completely, and within minutes core temperatures significantly decreased. Preliminary studies described here indicate that focal facial warming applied during active whole body cooling to initiate mild hypothermia might minimize the need to pharmacologically suppress involuntary motor activity. Such a procedure might be useful for initiating as soon as possible (such as during emergency transport), cerebral mild hypothermia in order to maximize protection and thus improve outcome in neurologically injured patients (head trauma, stroke).
-
J Neurosurg Anesthesiol · Oct 1999
Effects of morphine on cerebral blood flow autoregulation CO2-reactivity in experimental subarachnoid hemorrhage.
Previous reports show that naloxone improves ischemic deficits and clinical conditions in patients after subarachnoid hemorrhage (SAH). These observations have raised concern about the routine use of morphine in the treatment of severe headache after SAH. The present study was carried out to investigate the effects of morphine on cerebral vasoreactivity after experimental SAH. ⋯ However, the mean slope of the linear regression lines of CBF/MABP was 0.49 +/- 0.32 ml/100g/min/mm Hg in the morphine group, which was significantly lower than 1.24 +/- 0.59 ml/100g/min/mm Hg in the controls (p < 0.05). Also the mean CO2-reactivity was significantly lower, 0.64 +/- 0.53 %/0.1kPa, in the morphine group, compared to 2.36 +/- 0.87 %/0.1kPa in the controls (p < 0.001). The results show that in rats with SAH, morphine partially restores CBF autoregulation but attenuates CO2-reactivity.