Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2010
Correlations between activated clotting time values and heparin concentration measurements in young infants undergoing cardiopulmonary bypass.
Monitoring heparin concentration along with the activated clotting time (ACT) may provide a more accurate guide for the administration of heparin to infants during cardiopulmonary bypass (CPB). However, standard laboratory assays of heparin concentration (antifactor Xa heparin concentration) require plasma instead of whole blood, and results are not immediately available to clinicians. Alternatively, measurements of whole blood heparin concentration may be performed at the bedside using an automated protamine titration device, the Hepcon instrument (Hepcon Hemostasis Management System Plus; Medtronics, Minneapolis, MN). The purpose of this investigation was to compare ACT measurements from 3 commercially available instruments and bedside measurements of whole blood heparin concentration using the Hepcon instrument with laboratory measurements of antifactor Xa plasma heparin concentration in infants younger than 6 months of age undergoing CPB. ⋯ In infants younger than 6 months old undergoing CPB, caution is warranted when using ACT values as the sole indication of adequate heparin anticoagulation. In general, ACT prolongation correlates poorly with plasma heparin concentration. Only i-STAT ACT values showed a moderate correlation when measured immediately before the termination of CPB. Alternatively, bedside measurements of whole blood heparin concentration measured by the Hepcon instrument agreed well with antifactor Xa laboratory measurements. Our data support the clinical utility of bedside measurements of heparin concentration to provide timely, convenient, and accurate measurements of heparin concentration in these infants.
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Anesthesia and analgesia · Jul 2010
The effective concentration of epsilon-aminocaproic Acid for inhibition of fibrinolysis in neonatal plasma in vitro.
Pediatric patients, particularly neonates, are at high risk for bleeding complications after cardiovascular surgery because of their immature hemostatic system, small size, and the complex operations they require. Activation of intravascular fibrinolysis is one of the principle effects of cardiopulmonary bypass that causes poor postoperative hemostasis. This complication has long been recognized and treated with antifibrinolytic medications, including the lysine analog epsilon aminocaproic acid (EACA). The therapeutic plasma concentration of EACA has been scientifically determined for the adult population, but the current recommended dosage for neonates has been empirically derived from adult studies. Therefore, we investigated the appropriate concentration of EACA for neonates undergoing bypass. ⋯ Our data establish the minimal effective concentration of EACA necessary to completely prevent fibrinolysis in neonatal blood in vitro. This concentration is significantly less than that targeted by current dosing schemes, indicating that neonates are possibly being exposed to greater levels of EACA than is clinically necessary.
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Anesthesia and analgesia · Jul 2010
Blockade of the sinuvertebral nerve for the diagnosis of lumbar diskogenic pain: an exploratory study.
In this exploratory study we evaluated sensitivity and target specificity of sinuvertebral nerve block (SVNB) for the diagnosis of lumbar diskogenic pain. Diskography has been the diagnostic gold standard. Fifteen patients with positive diskography underwent SVNB via interlaminar approach to the posterior aspect of the disk. ⋯ The sensitivity was 73.3% (95% CI: 50.9%-95.7%). The target specificity was 40% (15.2%-64.8%). The results indicate that SVNB cannot yet replace diskography but encourage future studies to improve its target specificity.
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Anesthesia and analgesia · Jul 2010
Ropivacaine-induced peripheral nerve injection injury in the rodent model.
Intraneural administration of local anesthetics has been associated with nerve damage. We undertook the present study to investigate histological changes induced by ropivacaine injection into rat sciatic nerve. ⋯ This study demonstrates that, in the rat model, ropivacaine is associated with marked histological abnormality, including edema of the perineurium and axonal destruction with wallerian degeneration, when injected into or extraneurally placed onto a nerve. Extrafascicular injection and extraneural placement were associated with similar, although milder, histological damage than intrafascicular injection. Further work is needed to investigate the functional implications, if any, of the histological abnormalities observed in this study.