When given prophylactically, heparin decreases neurological impairment caused by severe cerebral arterial air embolism.

Moderate hemodilution (hematocrit approximately 30%) reduces neurologic injury after focal cerebral ischemia. In contrast, both clinical and experimental studies suggest that marked hemodilution (hematocrit < 30%) may exacerbate neurologic injury. We compared the effect of marked versus minimal hemodilution on cerebral infarct volume after focal cerebral ischemia in rabbits. Anesthetized New Zealand White rabbits underwent hemodilution by exchange of arterial blood with 6% high molecular weight hydroxyethyl starch. In the marked hemodilution group (n = 15) the target hemoglobin concentration was 6 g/100 mL. In the minimal hemodilution group (n = 15) the target hemoglobin concentration was 11 g/100 mL. After hemodilution, middle cerebral artery occlusion was achieved by embolizing an autologous blood clot via the internal carotid artery. Four hours after embolization, the animals were killed and their brains removed. Brains were sectioned, stained with 2,3,5-triphenyltetrazolium chloride, and infarct volumes determined via quantitative image analysis. Systemic physiologic variables were similar between groups, except for arterial hemoglobin concentration. The percentage of hemispheric infarct was significantly larger in the marked hemodilution group as compared to the minimal hemodilution group, 70% +/- 19% vs 51% +/- 23%, respectively (mean +/- SD); P = 0.02. Similarly, the percentage of infarct was greater in the hemodilution group as compared to the minimal hemodilution group in both cortex (73% +/- 18% vs 54% +/- 23%, respectively; P = 0.02) and subcortex (62% +/- 25% vs 44% +/- 23%, respectively; P = 0.04). These findings indicate that marked hemodilution exacerbates neurologic injury resulting from permanent focal ischemia. Although some degree of hemodilution may improve neurologic outcome, the advantage is lost at an extreme level of therapy.

Accurate assessment and replacement of blood loss and fluid-electrolyte deficit during craniosynostosis repair is difficult owing to patient size and the diversity of surgical technique. Forty-three patients undergoing primary craniosynostosis repair over a 10-year period were studied retrospectively to determine blood loss and fluid deficit and to assess blood transfusion practices during both intraoperative and postoperative periods. Blood loss was calculated on the basis of estimated red cell mass (ERCM) and fluid-electrolyte imbalance was investigated with blood samplings. Blood transfusion was considered appropriate if the postoperative or posttransfusion ERCM was within 12% of the preoperative value. Estimated fluid requirement (EFR) was used in 4 ml kg(-1) h(-1) except for neonates. Intraoperatively, 80% of all patients were appropriately managed with respect to blood transfusion and EFR. Postoperatively only 20% of the patients receiving transfusions were transfused appropriately. In 23.3% of these patients (10/43) unexpected respiratory distress developed immediately after their recovery from the anesthesia. With the measurement of estimated blood volume and allowable blood loss, appropriate transfusion could be achieved for the successful treatment of the primary craniosynostosis.

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Background: Dexmedetomidine, an α2-adrenergic agonist, can be used for sedation and as an adjuvant to anesthetics. This study aimed to evaluate the effects of preanesthetic administration of dexmedetomidine on the propofol and remifentanil requirement during general anesthesia and postoperative pain in patients undergoing laparoscopic cholecystectomy.Methods: Sixty patients were randomly assigned to group D or S (n = 30 each). Dexmedetomidine (0.5 µg/kg) and a comparable volume of saline were administered in groups D and S, respectively, over a 10 minutes period before induction. General anesthesia was induced and maintained with propofol and remifentanil; the bispectral index was maintained at 40-60. The intraoperative remifentanil and propofol dosages were recorded, and postoperative pain was assessed using a visual analog scale (VAS).Results: In groups S and D, propofol dosage was 8.52 ± 1.64 and 6.83 ± 1.55 mg/kg/h, respectively (P < 0.001), while remifentanil dosage was 7.18 ± 2.42 and 4.84 ± 1.44 µg/ kg/h, respectively (P < 0.001). VAS scores for postoperative pain were 6.50 (6-7) and 6.0 (6-7), respectively, at 30 minutes (P = 0.569), 5 (4-5) and 4 (3-5), respectively, at 12 hours (P = 0.039), and 2 (2-3) and 2 (1.25-2), respectively, at 24 hours (P = 0.044). The Friedman test revealed that VAS scores changed over time in both groups (P < 0.001).Conclusions: Preanesthetic single administration of a low dose of dexmedetomidine (0.5 µg/kg) can significantly decrease the remifentanil and propofol requirement during short surgeries and alleviate postoperative pain.