Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe comparative effects of desflurane and isoflurane on lumbar cerebrospinal fluid pressure in patients undergoing craniotomy for supratentorial tumors.
We compared the effects of desflurane and isoflurane on cerebral perfusion pressure (CPP), lumbar cerebrospinal fluid pressure (LCSFP), and mean arterial blood pressure (MAP) in patients anesthetized with desflurane or isoflurane undergoing craniotomy for supratentorial mass lesions. Additionally, emergence from anesthesia was examined to determine if neurologic function could be assessed earlier after isoflurane or desflurane anesthesia. Thirty-six patients were randomized to receive either desflurane or isoflurane for maintenance of anesthesia at 1.2 minimum alveolar concentration (MAC). Patients were hyperventilated (PaCO(2), 30 +/- 2 mm Hg) after baseline LCSFP was obtained via the subarachnoid catheter. At a MAC of 1.2, mean LCSFP was not statistically different between the two study groups either before or after hyperventilation. Additionally, CPP was not significantly different between the two groups. Finally, patient's time to respond to commands was 50% shorter in the desflurane group (30 +/- 36 min) (mean +/- SD) when compared with the isoflurane group (72 +/- 126 min); however, this was not significant (P = 0.17). In patients undergoing craniotomy for supratentorial mass lesions, desflurane and isoflurane have similar effects on CPP and MAP. Additionally, desflurane in the setting of hyperventilation does not cause significant changes in LCSFP. ⋯ This is the largest study to date comparing the effects of desflurane and isoflurane on patients undergoing craniotomy for supratentorial mass lesion with evidence of midline shift or edema. Neither desflurane nor isoflurane significantly altered lumbar cerebrospinal fluid pressure when moderate hypocapnia was maintained.
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Anesthesia and analgesia · Apr 2004
Clinical TrialContinuous assessment of cerebral autoregulation in subarachnoid hemorrhage.
Cerebral vasospasm remains a leading cause of morbidity and mortality after subarachnoid hemorrhage (SAH). Cerebral ischemia may ensue when autoregulation fails to compensate for spasm. We examined how autoregulation is affected by vasospasm by using transcranial Doppler. The moving correlation coefficient between slow changes of arterial blood pressure and mean or systolic flow velocity (FV), termed "Mx" and "Sx," respectively, was used to characterize cerebral autoregulation. Vasospasm was declared when the mean FV increased to more than 120 cm/s and the Lindegaard ratio was more than 3. This occurred in 15 of 32 SAH patients. On the basis of the bilateral transcranial Doppler recordings of the middle cerebral artery in vasospastic patients, Mx and Sx were calculated for baseline and vasospasm. Mx increased during vasospasm (0.46 +/- 0.32; mean +/- SD) and was significantly higher (P = 0.021) than at baseline (0.21 +/- 0.24). Sx was also increased (0.22 +/- 0.26 vs 0.05 +/- 0.21 at baseline; P = 0.03). Mx correlated with mean FV (r = 0.577; P = 0.025) and the Lindegaard ratio (r = 0.672; P < 0.006). Mx (P = 0.006) and Sx (P = 0.044) were higher on the vasospastic side (Mx, 0.44 +/- 0.27; Sx, 0.24 +/- 0.23) when compared with the contralateral side (Mx, 0.34 +/- 0.29; Sx, 0.16 +/- 0.25). The increased Mx and Sx during cerebral vasospasm demonstrate impaired cerebral autoregulation. Mx and Sx provide additional information on changes in autoregulation in SAH patients. ⋯ The moving correlation coefficients between slow changes of arterial blood pressure and mean or systolic flow velocity, termed "Mx" and "Sx," respectively, characterize cerebral autoregulation but have not been applied to subarachnoid hemorrhage. A study in 15 patients revealed that Mx and Sx were significantly increased, indicating impaired autoregulation during vasospasm as compared with baseline, as well as on the side of vasospasm in comparison with the contralateral side.
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Anesthesia and analgesia · Apr 2004
ReviewA review of intrathecal and epidural analgesia after spinal surgery in children.
In view of the overall experience regarding regional anesthetic techniques to control postoperative pain in infants and children, it is feasible that a similar efficacy and safety profile can be obtained when using such techniques after major orthopedic procedures such as anterior or posterior spinal fusion. I reviewed previous reports regarding the use of neuraxial techniques to provide analgesia after spine surgery in the pediatric population. ⋯ Variations of the analgesic technique include 1). the dose of the medications used; 2). the route of delivery (intrathecal or epidural); 3). the mode of delivery (single dose, intermittent bolus dosing, and continuous infusion); 4). the number of epidural catheters used (one versus two); 5). the medications infused (opioids, local anesthetics, or both); 6). the opioid used (morphine, fentanyl, hydromorphone); and 7). the analgesic regimen of the control group (intermittent "as needed" morphine or patient-controlled analgesia). Although limited data are available to document the analgesic superiority of these techniques over parenteral opioids, clinical data offer evidence of other benefits, including decreased intraoperative blood loss and quicker return of gastrointestinal function.
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Anesthesia and analgesia · Apr 2004
Intrathecal clonidine and bupivacaine have synergistic analgesia for acute thermally or inflammatory-induced pain in rats.
We investigated the interaction between spinally administered bupivacaine and clonidine using an animal model of acute and inflammatory pain. Rats implanted with lumbar intrathecal catheters were injected intrathecally with saline (control), bupivacaine (1 to 100 microg), or clonidine (0.1 to 3 microg) and tested for their responses to thermal stimulation to the tail (tail flick test) and subcutaneous formalin injection into the hindpaw (formalin test). The effects of the combination of bupivacaine and clonidine on both stimuli were tested by isobolographic analysis. General behavior and motor function were examined as side effects. The 50% effective doses of bupivacaine and clonidine were significantly smaller when combined compared with each single drug in both the tail flick test (2.82 and 0.11 microg versus 7.1 and 0.29 microg, respectively) and phase 1 (0.24 and 0.009 microg versus 5.7 and 0.15 microg) and phase 2 (0.31 and 0.012 microg versus 3.2 and 0.16 microg) of the formalin test. Side effects were decreased by the combination. These results suggest a favorable combination of intrathecal bupivacaine and clonidine in the management of acute and inflammatory pain. ⋯ The analgesic interaction between intrathecally administered bupivacaine and clonidine was examined during acute thermal and inflammatory-induced pain in rats. The analgesia produced by the combination of these two drugs was synergistic in both acute thermal and inflammatory induced pain, with a decrease in behavioral side effects.
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Anesthesia and analgesia · Apr 2004
The effect of erythropoietin on allogeneic blood requirement in patients undergoing elective liver resection: a model simulation.
We investigated whether recombinant human erythropoietin (rHuEPO) administration would reduce red blood cell (RBC) transfusion requirements in patients undergoing elective liver resection. We retrospectively investigated 200 patients undergoing elective liver resection. Factors likely to predict perioperative RBC transfusion were studied using a logistic regression analysis. A mathematical model was used to simulate RBC transfusion requirements if (a). transfusion thresholds had been predefined at a hemoglobin concentration of 7-8 g/dL, (b). preoperative hemoglobin concentrations had been increased to 15 g/dL by rHuEPO administration in patients with preoperative hemoglobin concentration in the range 10-13 g/dL, and (c). both interventions had been used. A cost/benefit evaluation of rHuEPO administration formed part of this simulation. RBC transfusion was correlated with major and median liver resection, total liver vascular exclusion, and a combined nonhepatic abdominal surgery but was not correlated with a preoperative hemoglobin concentration in the range 10-13 g/dL. Adherence to a small transfusion threshold or rHuEPO administration alone would have resulted in a slight reduction in transfusion requirements and transfusion rates for the whole population. However, the two interventions in combination would have significantly reduced both variables. One-hundred-eighteen patients undergoing median and major liver resection received 92% of RBC transfused. Sixty-six of these 118 patients had preoperative hemoglobin concentrations in the range 10-13 g/dL and could have received rHuEPO before surgery. rHuEPO alone would have avoided the transfusion of 63 RBC packs of 203 in this subgroup and 12 transfused patients of 31 (P = 0.02). rHuEPO administration to these 66 patients would have cost 186000 Euro. The 63 RBC saved would have cost 10,710 Euro. ⋯ A mathematical model simulation suggests that the routine preoperative administration of erythropoietin to patients scheduled for major and median liver resection presenting with a preoperative hemoglobin concentration in the range 10-13 g/dL could reduce blood transfusion requirements. However, the cost/benefit ratio warrants consideration.