Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2004
Risk factors assessment of the difficult airway: an italian survey of 1956 patients.
Over the last decade, there has been a heightened awareness and an increase in the amount of literature being published on recognition and prediction of the difficult airway. During the preoperative evaluation of the airway, a thorough history and physical specifically related to the airway should be performed. Various measurements of anatomic features and noninvasive clinical tests can be performed to enhance this assessment. ⋯ A Mallampati Class 3 correlated with a C-L Grade 2 (0.94), whereas a Mallampati Class 4 correlated with a C-L Grade 3 (0.85) and a C-L Grade 4 (0.80). Operator evaluation, performed by a simplified tracheal intubation difficulty scale, showed a linear correlation of 0.96 compared with the C-L groups. Although there is a correlation between oropharyngeal volume and difficult intubation, the Mallampati score by itself is insufficient for predicting difficult endotracheal intubation.
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Anesthesia and analgesia · Dec 2004
Comparative StudyA comparison of changes in cardiac preload variables during graded hypovolemia and hypervolemia in mechanically ventilated dogs.
We developed an online monitoring system to measure systolic blood pressure variation (SPV) and its down (dDown) and up components, along with pulse pressure variation (dPP). Using the system, we compared different cardiac preload indicators-such as stroke volume variation (SVV) and corrected flow time (FTc)-along with central venous pressure and pulmonary artery occlusion pressure in mechanically-ventilated dogs during normovolemia, graded hypovolemia (-200 and -350 mL), and hypervolemia (+200 and +350 mL). We simultaneously measured these preload indicators along with global hemodynamic variables and investigated their validity and limitations to access preload changes. ⋯ The results of this study indicate that SPV, dDown, dPP, and SVV are useful indicators of hypovolemia, but not of hypervolemia. Conversely, hypovolemia could not be detected reliably by FTc, but it does reflect blood volume changes during hypervolemia. Although SPV, dDown, and dPP measurements require no additional invasion and cost beyond arterial cannulation, their limits must be kept in mind for the monitoring of blood volume status in mechanically-ventilated patients.
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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
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
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.