Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2004
Case ReportsThe anterior jugular venous system: variability and clinical impact.
The anterior jugular venous system, with its interconnections to the subclavian and deep jugular veins, provides a collateral venous network across the midline of the neck area, which is especially important in unilateral occlusion of an innominate vein. We illustrate the variability of this system and its clinical impact on catheterization by three cases of landmark-guided central venous cannulation. Case 1: Cannulation of the left internal jugular vein with a central venous catheter and of the left innominate vein (LIV) with a pulmonary artery catheter resulted in correctly positioned catheter tips. ⋯ We describe the normal anatomy of the anterior jugular venous system and its role as a major collateral. Correct placement of central venous catheters may be possible via the anterior jugular venous system. Conversely, central venous catheters malpositioned in the anterior jugular vein can increase the risk for complications and should be removed.
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Anesthesia and analgesia · Dec 2004
The effect of dilution on plasma coagulation kinetics determined by thrombelastography is dependent on antithrombin activity and mode of activation.
Hemodilution-associated hypercoagulability has been the focus of several investigations because significant morbidity and mortality have been associated with perioperative thrombophilia. Because most investigations implicate imbalances in procoagulant/anticoagulant activity as the etiology of hemodilution-associated hypercoagulability, we determined the effects of dilution on coagulation kinetics and clot strength with thrombelastography (TEG(R)). Control plasma (+/-celite activation) and antithrombin (AT)-deficient (<10% activity) plasma were diluted 0%, 10%, 20%, and 30% with saline. ⋯ Celite activation eliminated dilution-associated changes in R values in control plasma but resulted in linear decreases (R(2) = 0.88-0.96, P < 0.0001) in alpha, A, and G in response to dilution. Thus, our data indirectly support the concept that decreases in AT activity cause dilution-mediated hypercoagulability in plasma. Finally, celite activation permits quantification of dilution with TEG.
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Anesthesia and analgesia · Dec 2004
Is intrathecal magnesium sulfate safe and protective against ischemic spinal cord injury in rabbits?
We performed three sets of experiments to investigate the safety of intrathecal magnesium and to determine its optimal dose for protection, if any, against ischemic spinal cord injury in rabbits. First, we examined neurotoxicity of 0.3, 1, 2, or 3 mg/kg of magnesium sulfate (n = 6 each). Significant sensory dysfunction was observed in the 3-mg/kg group 7 days after administration. ⋯ Third, we evaluated the effects of 0.3 mg/kg or 1 mg/kg of magnesium sulfate or saline (n = 6 each) administered before ischemia on hindlimb motor function and histopathology after spinal cord ischemia (15 min). Magnesium did not improve neurologic or histopathologic outcome 96 h after reperfusion. The results indicate that intrathecal magnesium has a risk of neurotoxicity and shows no evidence of protective effects against ischemic spinal cord injury.
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Anesthesia and analgesia · Dec 2004
Apoptosis is not enhanced in primary mixed neuronal/glial cultures protected by isoflurane against N-methyl-D-aspartate excitotoxicity.
Volatile anesthetics reduce acute excitotoxic cell death in primary neuronal/glial cultures. We hypothesized that cells protected by isoflurane against N-methyl-d-aspartate (NMDA)-induced necrosis would instead become apoptotic. Primary mixed neuronal/glial cultures prepared from fetal rat brain were exposed to dissolved isoflurane (0 mM, 0.4 mM [1.8 minimum alveolar anesthetic concentration], or 1.6 mM [7 minimum alveolar anesthetic concentration]) and NMDA (0 or 100 microM) at 37 degrees C for 30 min. ⋯ At 48 h, no evidence was found to indicate that cells protected by isoflurane had become apoptotic or apoptotic-like. However, cells protected by dizocilpine against necrosis showed evidence of caspase-3-mediated apoptosis. These in vitro data do not support the hypothesis that isoflurane protection against acute excitotoxic necrosis results in apoptosis.
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Anesthesia and analgesia · Dec 2004
The volume kinetics of acetated Ringer's solution during laparoscopic cholecystectomy.
We studied the distribution and elimination of an IV infusion of 20 mL/kg of acetated Ringer's solution (approximately 1500 mL) over 60 min in 12 women undergoing laparoscopic cholecystectomy. A plasma dilution of 4.2% developed during the induction of general anesthesia, even though fluid was withheld. The additional plasma dilution induced by the subsequent volume expansion was slightly larger than expected from previous volunteer experiments and averaged 18%. ⋯ These data represent a half-life of the fluid in the patients that is 17 times longer (median, 4.5 h) than the half-life of the plasma dilution (16 min), indicating a strong tendency to the formation of peripheral edema. A nomogram based on the kinetic variables suggests that infusion rates should be relatively rapid early on during surgery but slower later. This strategy creates a constant plasma dilution at any desired level without causing undue peripheral accumulation of fluid.