Journal of neurosurgical anesthesiology
-
J Neurosurg Anesthesiol · Apr 1997
Intact cerebral blood flow reactivity during remifentanil/nitrous oxide anesthesia.
Remifentanil hydrochloride is a new opioid rapidly metabolized by blood and tissue esterases. The swift degradation accounts for the elimination half-life (t1/2 beta) of < 10 min. An anesthetic agent allowing more rapid postoperative assessment of the neurosurgical patient would be beneficial. ⋯ Electroencephalographic monitoring showed a spectral edge frequency of 26 +/- 1 Hz before induction, 25 +/- 1 Hz during maintenance of the remifentanil/N2O anesthetic (0.32 +/- 0.15 microgram/kg/ min), 24 +/- 1 Hz during hypocapnic CBF determination, and 24 +/- 2 Hz during normocapnic CBF determination. At the completion of the procedure, the patients responded to commands within 3.6 +/- 2.5 min and were extubated 7.2 +/- 4.5 min after the remifentanil/N2O was discontinued. In conclusion, absolute CBF values during remifentanil/N2O are similar to previously reported CBF values during fentanyl/N2O and isoflurane/N2O anesthesia, and cerebrovascular reactivity to CO2 remains intact.
-
J Neurosurg Anesthesiol · Apr 1997
Comparative StudyFurosemide decreases cerebrospinal fluid formation during desflurane anesthesia in rabbits.
Previous studies suggest that desflurane may increase cerebrospinal fluid (CSF) formation rate (Vf) and volume, particularly during conditions of hypocapnia combined with elevated CSF pressure. The present study was designed to determine whether treatments routinely used in patients during anesthesia for neurological surgery would decrease Vf during desflurane anesthesia in rabbits. Three groups of six rabbits each were examined at four experimental conditions. ⋯ During the combination of desflurane, hypocapnia, and elevated CSF pressure, furosemide decreased Vf to 3.2 +/- 1.7 microliters.min-1, mannitol increased plasma osmolality and decreased plasma sodium concentration, and fentanyl decreased heart rate and increased plasma potassium concentration. Values for Ra and brain water content did not differ between groups. Of the four treatments examined, only furosemide decreased Vf during the combination of desflurane, hypocapnia, and elevated CSF pressure.
-
J Neurosurg Anesthesiol · Apr 1997
Comparative StudyPredictive accuracy of continuous propofol infusions in neurosurgical patients: comparison of pharmacokinetic models.
The performance of 10 pharmacokinetic models in predicting blood propofol concentrations was evaluated in patients during neurosurgical anesthesia. Eight patients-ASA category I or II, aged 49 +/- 18-years, weighing 71 +/- 20 kg, and scheduled for routine neurosurgery-were anesthetized with propofol and sufentanil using Ohmeda pumps controlled with a personal computer. Sufentanil was administered as a bolus of 0.3 microgram.kg-1, 5 min before induction of anesthesia, and infused at a constant rate of 0.5 microgram.kg-1.h-1 throughout the study. ⋯ The models of Gepts et al. (Anesth Analg 1987; 66:1256-1263, Anaesthesia 1988; 43(suppl):8-13), Tackley et al. (Br J Anaesth 1989;62:46-53), and Cockshott (Postgrad Med J 1985;61:55), derived from healthy patients receiving continuous propofol infusions, provided the best agreement between expected and measured propofol concentrations; they showed bias and inaccuracy lower than 17%. In conclusion, the accurate prediction of blood propofol concentrations from different continuous infusion rates in ASA I or II patients requires the selection of appropriate pharmacokinetic models derived from similar categories of patients and using a similar technique of propofol administration. However, in clinical practice, the selection of a specific set among the appropriate models is balanced by the interindividual variability in blood propofol concentrations adjusted to clinical effects.
-
J Neurosurg Anesthesiol · Apr 1997
Case ReportsCerebral oximetry during circulatory arrest for aneurysm surgery.
A patient underwent surgical clipping of a complex giant intracranial carotid aneurysm with the aid of extracorporeal circulation and complete hypothermic circulatory arrest. During the entire procedure, cerebrovascular oxygen saturation (ScO2) was spectroscopically measured. The patient experienced circulatory arrest for 34 min; for 15 of the 34 min ScO2 was < 34% (minimum 32%). The patient tolerated the procedure without new neurological deficit, thus demonstrating that the previously suggested "critical" level of 35% ScO2 is not absolute.
-
J Neurosurg Anesthesiol · Apr 1997
Jugular venous bulb oxygen saturation monitoring in arteriovenous malformation surgery.
We describe a case in which jugular venous bulb oxygen saturation (SjvO2) monitoring proved useful during the surgical resection of an intracranial arteriovenous malformation (AVM). Surgical resection of large intracranial AVMs may be followed by normal perfusion pressure breakthrough with brain swelling, hyperemia, and subsequent problems in achieving hemostasis. ⋯ In the case discussed, SjvO2 monitoring enabled assessment of the risk of postresection hyperemia preoperatively and permitted the degree and completeness of surgical AVM resection to be followed intraoperatively. During the normal perfusion pressure breakthrough bleeding which followed complete AVM resection, SjvO2 monitoring helped with safe management of the controlled hypotension that finally permitted hemostasis to be achieved.