Anesthesia and analgesia
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Anesthesia and analgesia · May 2016
The Sensitivity and Specificity of Pulmonary Carbon Dioxide Elimination for Noninvasive Assessment of Fluid Responsiveness.
We sought to determine whether the response of pulmonary elimination of CO2 (VCO2) to a sudden increase in positive end-expiratory pressure (PEEP) could predict fluid responsiveness and serve as a noninvasive surrogate for cardiac index (CI). ⋯ PEEP-induced changes in VCO2 predicted fluid responsiveness with accuracy in patients undergoing cardiac surgery.
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Anesthesia and analgesia · May 2016
Central Nervous System-Toxic Lidocaine Concentrations Unmask L-Type Ca2+ Current-Mediated Action Potentials in Rat Thalamocortical Neurons: An In Vitro Mechanism of Action Study.
High systemic lidocaine concentrations exert well-known toxic effects on the central nervous system (CNS), including seizures, coma, and death. The underlying mechanisms are still largely obscure, and the actions of lidocaine on supraspinal neurons have received comparatively little study. We recently found that lidocaine at clinically neurotoxic concentrations increases excitability mediated by Na-independent, high-threshold (HT) action potential spikes in rat thalamocortical neurons. Our goal in this study was to characterize these spikes and test the hypothesis that they are generated by HT Ca currents, previously implicated in neurotoxicity. We also sought to identify and isolate the specific underlying subtype of Ca current. ⋯ At clinically CNS-toxic concentrations, lidocaine unmasked in thalamocortical neurons evoked HT action potentials mediated by the L-type Ca current while substantially suppressing Na-dependent excitability. On the basis of the known role of an increase in intracellular Ca in the pathogenesis of local anesthetic neurotoxicity, this novel action represents a plausible contributing candidate mechanism for lidocaine's CNS toxicity in vivo.
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Anesthesia and analgesia · May 2016
Analysis of Transpulmonary Thermodilution Data Confirms the Influence of Renal Replacement Therapy on Thermodilution Hemodynamic Measurements.
Transpulmonary thermodilution (TPTD) is used frequently in the intensive care unit to determine cardiac index (CI), intrathoracic blood volume index (ITBVI), and extravascular lung volume index (EVLWI). Renal replacement therapy (RRT) influences TPTD results, but the underlying mechanisms are not completely understood. We hypothesized that RRT blood flow induces errors in TPTD measurements. ⋯ Analysis of TPTD data shows that thermodilution curve forms are modified with RRT, resulting in an erroneous calculation of thermodilution-derived hemodynamic parameters.
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Anesthesia and analgesia · May 2016
Controlled Clinical TrialEstimated Maximal Safe Dosages of Tumescent Lidocaine.
Tumescent lidocaine anesthesia consists of subcutaneous injection of relatively large volumes (up to 4 L or more) of dilute lidocaine (≤1 g/L) and epinephrine (≤1 mg/L). Although tumescent lidocaine anesthesia is used for an increasing variety of surgical procedures, the maximum safe dosage is unknown. Our primary aim in this study was to measure serum lidocaine concentrations after subcutaneous administration of tumescent lidocaine with and without liposuction. Our hypotheses were that even with large doses (i.e., >30 mg/kg), serum lidocaine concentrations would be below levels associated with mild toxicity and that the concentration-time profile would be lower after liposuction than without liposuction. ⋯ Preliminary estimates for maximum safe dosages of tumescent lidocaine are 28 mg/kg without liposuction and 45 mg/kg with liposuction. As a result of delayed systemic absorption, these dosages yield serum lidocaine concentrations below levels associated with mild toxicity and are a nonsignificant risk of harm to patients.
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Anesthesia and analgesia · May 2016
Observational StudyFeasibility of Report Cards for Measuring Anesthesiologist Quality for Cardiac Surgery.
In creating the Merit-Based Incentive Payment System, Congress has mandated pay-for-performance (P4P) for all physicians, including anesthesiologists. There are currently no National Quality Forum-endorsed risk-adjusted outcome metrics for anesthesiologists to use as the basis for P4P. ⋯ The impact of anesthesiologists on the total variability in cardiac surgical outcomes was probably about one-fourth as large as the surgeons' contribution. None of the anesthesiologists caring for cardiac surgical patients in New York State over a 3+ year period were identified as performance outliers. The use of a performance metric based on death or major complications for P4P may not be feasible for cardiac anesthesiologists.