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
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.
-
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.
-
Subarachnoid hemorrhage (SAH) causes a stress response with increased concentrations of plasma catecholamines and serious cardiac arrhythmias. Increased QT dispersion has been shown to predispose to cardiac arrhythmias. In SAH patients, QT dispersion has not been studied previously. ⋯ There was a positive correlation with QT dispersion and the plasma concentration of DHPG, a metabolite of norepinephrine (P < .05). All patients had episodes of cardiac arrhythmia during the 18-hour recording period. In conclusion, increased QT dispersion is a common finding after SAH and may be a result of high plasma concentrations of catecholamines in these patients.
-
J Neurosurg Anesthesiol · Jul 1999
Case ReportsAcute left ventricular dysfunction and subarachnoid hemorrhage.
Severe left ventricular (LV) dysfunction associated with acute subarachnoid hemorrhage (SAH) due to cerebral aneurysm rupture. ⋯ Severe left ventricular dysfunction may occur in acute SAH and may necessitate delay of aneurysm surgery.