Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2006
Randomized Controlled Trial Comparative StudyNitrous oxide and anesthetic requirement for loss of response to command during propofol anesthesia.
The blood concentration associated with loss of response (LOR) to command in 50% of subjects (CP50(LOR)) is an important measure of anesthetic potency. We therefore determined the CP50(LOR) in 40 healthy surgical patients, aged 18-60 yr old, receiving propofol alone or propofol with 67% nitrous oxide (N2O). Patients were randomized to receive 100% oxygen or 67% N2O in oxygen via facemask. ⋯ At testing for response to command, both the measured and target propofol concentrations were significantly larger and BIS values significantly smaller in the propofol-alone group compared with the propofol-N2O group. The CP50(LOR) of propofol in the propofol-alone group was 4.58 mug/mL (95% confidence interval [CI], 1.14-15.36) and 2.67 microg/mL (95% CI, 2.28-3.17) in the propofol-N2O group. The BIS value when 50% of patients responded to command was 60 (95% CI, 55-65) in the propofol-alone group and 75 (95% CI, 73-83) in the propofol-N2O group.
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Anesthesia and analgesia · Apr 2006
Randomized Controlled Trial Comparative StudyGelatin and hydroxyethyl starch, but not albumin, impair hemostasis after cardiac surgery.
We investigated the effect of postoperative administration of colloids on hemostasis in 45 patients after cardiac surgery. Patients were randomized to receive 15 mL kg(-1) of either 4% albumin, 4% succinylated gelatin, or 6% hydroxyethyl starch (molecular weight of 200 kDa/degree of substitution 0.5) as a short-term infusion. There was a comparable decrease in maximum clot firmness of thromboelastometry tracings in gelatin and hydroxyethyl starch groups immediately after completion of the infusion, whereas these values remained unchanged in the albumin group. ⋯ Fibrin formation (clot formation time, alpha-angle) and fibrinogen-dependent clot strength (maximum clot firmness and shear elastic modulus) were more disturbed in the hydroxyethyl starch group than in the gelatin group. We conclude that after cardiopulmonary bypass surgery, both gelatin and hydroxyethyl starch impair clot strength and fibrin buildup, which may predispose patients to increased blood loss. The greatest impairment in hemostasis was seen after hydroxyethyl starch administration, whereas albumin appeared to have the least effect on hemostatic variables.
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Anesthesia and analgesia · Apr 2006
Randomized Controlled Trial Comparative StudyThe effect of sevoflurane on cerebral autoregulation in young children as assessed by the transient hyperemic response.
The transient hyperemic response (THR) test is a simple, noninvasive technique to evaluate cerebral autoregulation using transcranial Doppler. It has not yet been used in studies involving children. In this study we evaluated this response in children undergoing general anesthesia using sevoflurane. ⋯ A THRR of more than 1.09 has previously been accepted as the lower limit of a positive response. The results in this study suggest that THR is affected by sevoflurane in a dose-dependent fashion but is maintained at up to 1.5 MAC. This suggests cerebral autoregulation is preserved in children anesthetized with up to 1.5 MAC sevoflurane.
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Anesthesia and analgesia · Apr 2006
Comparative StudyFibrinogen concentrate reverses dilutional coagulopathy induced in vitro by saline but not by hydroxyethyl starch 6%.
Severe bleeding often induces coagulopathy via loss, consumption, and dilution of clotting factors and platelets. The aims of our in vitro study were to characterize the influence of progressive hemodilution with either NaCl 0.9% or hydroxyethyl starch (HES) 6% on blood clot formation and to analyze the effect of substitution of fibrinogen and platelets on dilutional coagulopathy. Whole blood samples drawn from 8 volunteers were diluted from 20% to 80% of the sample volume with both diluents separately. ⋯ Platelets alone or in addition were not able to improve clot firmness to a clinically relevant extent. Dilutional coagulopathy induced by crystalloids can, in vitro, be effectively reversed by supplementation of fibrinogen. In contrast, HES molecules interfere with fibrin polymerization and, thus, administration of fibrinogen after dilution with HES 6% failed to significantly improve clot firmness.
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Anesthesia and analgesia · Apr 2006
Comparative StudyPostoperative delirium: the importance of pain and pain management.
Postoperative delirium is common in geriatric patients. Few studies have examined events in the postoperative period that may contribute to the occurrence of postoperative delirium. We hypothesized that postoperative delirium is related to postoperative pain and/or pain management strategy. ⋯ By multivariate logistic regression, age (odds ratio [OR], 2.5; 95% confidence interval [CI] 1.5 to 4.2), moderate (OR, 2.2; 95% CI 1.2 to 4.0) and severe (OR, 3.7; 95% CI 1.5 to 9.0) preoperative resting pain, and increase in level of pain from baseline to postoperative day one (OR, 1.1; 95% CI 1.01 to 1.2) were independently associated with a greater risk for the development of postoperative delirium. In contrast, patients who used oral opioid analgesics as their sole means of postoperative pain control were at decreased risk of developing delirium in comparison with those who used opioid analgesics via IV patient-controlled analgesia technique (OR, 0.4; 95% CI 0.2 to 0.7). These results validate our hypothesis that pain and pain management strategies are important factors related to the development of postoperative delirium in elderly patients.