Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Comparative Study Clinical TrialBispectral index values at sevoflurane concentrations of 1% and 1.5% in lower segment cesarean delivery.
Inadequate hypnosis in the absence of opioid analgesia may account for the increased incidence of awareness in cesarean delivery. An end-tidal concentration of 0.5 MAC isoflurane in 50% nitrous oxide (N(2)O) during cesarean delivery resulted in bispectral index (BIS) values >60, the threshold below which consciousness is unlikely. Our aim was to determine the BIS values achieved with the equivalent end-tidal concentration of sevoflurane and to determine if a larger concentration would consistently maintain BIS values <60. Twenty ASA physical status I-II parturients were randomized to receive an end-tidal concentration of either 1% sevoflurane or 1.5% sevoflurane delivered in 50% N(2)O throughout surgery. Thiopental 4 mg/kg was used for anesthetic induction. Morphine 0.1-0.15 mg/kg was administered only after delivery. Mean BIS values in the period between skin incision and neonatal delivery were 61 (95% confidence interval, 57-64) in the 1% sevoflurane group, versus 42 (95% confidence interval, 37-47) in the 1.5% sevoflurane group. BIS values were significantly different between groups at skin incision, uterine incision, delivery, and 10 min after delivery, but not thereafter. Indices of maternal and neonatal outcome were similar between groups. ⋯ Bispectral index (BIS) values <60 are consistent with a high probability of unconsciousness. An end-tidal concentration of 1.5% sevoflurane maintained BIS values <60 during cesarean delivery, whereas 1% did not. Adverse effects were not seen with the use of larger concentrations of sevoflurane.
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Clinical TrialPerioperative intravenous lidocaine has preventive effects on postoperative pain and morphine consumption after major abdominal surgery.
Sodium channel blockers are approved for IV administration in the treatment of neuropathic pain states. Preclinical studies have suggested antihyperalgesic effects on the peripheral and central nervous system. Our objective in this study was to determine the time course of the analgesic and antihyperalgesic mechanisms of perioperative lidocaine administration. Forty patients undergoing major abdominal surgery participated in this randomized and double-blinded study. Twenty patients received lidocaine 2% (bolus injection of 1.5 mg/kg in 10 min followed by an IV infusion of 1.5 mg. kg(-1). h(-1)), and 20 patients received saline placebo. The infusion started 30 min before skin incision and was stopped 1 h after the end of surgery. Lidocaine blood concentrations were measured. Postoperative pain ratings (numeric rating scale of 0-10) and morphine consumption (patient-controlled analgesia) were assessed up to 72 h after surgery. Mean lidocaine levels during surgery were 1.9 +/- 0.7 microg/mL. Patient-controlled analgesia with morphine produced good postoperative analgesia (numeric rating scale at rest,
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Anesthesia and analgesia · Apr 2004
Neither the accuracy nor the precision of thermal dilution cardiac output measurements is altered by acute tricuspid regurgitation in pigs.
Whether measurement of cardiac output using the thermal dilution technique (TDCO) is valid in the presence of tricuspid regurgitation (TR) is controversial. We assessed the accuracy and precision of the technique in pigs by comparison with data from an electromagnetic flowmeter on the aorta (EMCO). TR was created with sutures that immobilized the free-wall leaflets of the tricuspid valve, and cardiac output was adjusted with dobutamine to give values comparable to control measurements. TR reduced forward stroke volume from 17.2 to 12.6 mL/beat and caused the right atrium to dilate and pulse in synchrony with the right ventricle. Acute TR did not affect the linear regression relation between TDCO and EMCO and did not alter the correlation coefficient (r = 0.94 during both control and TR). These data demonstrate that acute TR does not affect the accuracy or precision of TDCO in pigs. ⋯ Cardiac output is a valuable measurement that guides the medical care of patients with heart and lung disease. This study demonstrates that the thermal dilution technique of determining cardiac output is valid when acute tricuspid valve regurgitation is present in pigs.
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Clinical TrialPostoperative epidural anesthesia preserves lymphocyte, but not monocyte, immune function after major spine surgery.
Extensive spine surgery is associated with postsurgical pain. Epidural pain therapy may reduce postoperative stress responses and thereby influence immune functions. In a randomized, controlled, double-blinded prospective trial, 54 patients received either conventional patient-controlled IV analgesia (PCIA; morphine 3 mg/15 min) or patient-controlled epidural analgesia (PCEA; 0.125% ropivacaine plus sufentanil 1 microg/mL at a base rate of 12 mL/h and bolus application of 5 mL/15 min). Circulating cytokines, C-reactive protein (CRP), cortisol, and cell-surface receptor expression of immune cells (cluster of differentiation [CD]14, human leukocyte antigen-DR, CD86, CD71, CD3, CD4, CD8, CD16, and CD19) were measured perioperatively to characterize immunological functions. PCEA, compared with PCIA, had no influence on altered levels of circulating cytokines (interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, and macrophage inhibitory factor) or indicators of the stress response (CRP and cortisol). Also, no significant difference was found in monocyte numbers or their human leukocyte antigen-DR, CD86, or CD71 expression. In contrast, the postoperative decrease in B lymphocytes and T-helper cells was significant in the PCEA group. Natural killer cells decreased significantly in patients receiving PCEA compared with PCIA. Therefore, postoperative epidural pain therapy has no influence on monocyte functions but reduces natural killer cells and preserves B-cell and T-helper cell populations. Epidural analgesia thus influences the specific rather than the innate immune system and potentially blunts the postsurgical lymphocyte depression, which is relevant for infectious resistance. ⋯ Epidural analgesia affects the immune system. Postoperative epidural analgesia, compared with conventional IV opioid therapy, preserves lymphocyte rather than monocyte functions. An improvement of postoperative immune function by epidural analgesia therefore may improve postoperative resistance to infectious complications or to chronic pain states.
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Clinical TrialThe supraclavicular block with a nerve stimulator: to decrease or not to decrease, that is the question.
Portable nerve stimulators for nerve blocks have been available for more than 40 yr. It is generally accepted that seeking a motor response at low outputs increases the chances of success. It is customary to start the procedure at a higher current with the goal of finding the nerve. After an adequate response is elicited, the current is decreased before the local anesthetic is injected. However, how low is low enough and, for that matter, how high is too high have not been adequately determined. Our experience seems to indicate that, in the supraclavicular block, the type of response obtained is as important as the output at which it is elicited, provided that this current is not higher than 1 mA. In this context, it is theoretically possible that our initial seeking current of 0.9 mA could be an adequate injection current if it is combined with an appropriate response. We designed this study to test the hypothesis that a response of the fingers in flexion or extension, elicited at 0.9 mA, could be followed immediately by the local anesthetic injection. We did not intend to compare 0.5 and 0.9 mA as minimum stimulating currents but rather as currents able to elicit an unmistakable motor twitch. Sixty patients were randomly assigned to one of two groups. Group 1 (n = 30) was injected with a motor twitch in the fingers that was still visible at 0.5 mA. Group 2 (n = 30) was injected after a similar response to that in Group 1 was elicited, but at the initial output of 0.9 mA, without any further decrease. The blocks were injected with 40 mL of local anesthetic solution. One patient was excluded from the study for failing to meet protocol criteria. The success rate in the remaining 59 patients was 100%; success was defined as complete sensory blockade at the median, ulnar, and radial nerve territories of the hand that was accomplished in