Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2006
Case ReportsInfusion pump delivers over-dosage of propofol as a result of missing syringe support.
We describe the malfunction of a common drug infusion pump. The syringe saddle was missing and allowed the syringe barrel to contact the pump case, which decreased the outward displacement of the syringe clamp. Then, the infusion pump falsely detected a smaller syringe size and consequently delivered an increased infusion rate and overdose of propofol to the patient. More commonly, an incorrectly mounted syringe may increase the outward displacement of the syringe clamp so that the infusion pump falsely detects a larger syringe size, with resultant less than expected infusion rate.
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Anesthesia and analgesia · Apr 2006
The delivery of drugs to patients by continuous intravenous infusion: modeling predicts potential dose fluctuations depending on flow rates and infusion system dead volume.
IV drug infusion has the potential for dosing errors, which arise from complex interactions between carrier flows and the infusion set dead volume. We computed the steady-state mass of drug stored in the infusion set dead volume, using phenylephrine as a model compound. The mass of drug in the dead volume increases with stock drug concentration and desired dose but decreases with carrier flow rate. ⋯ This time is longest for large stock-drug concentrations, larger dead volumes, and slower final carrier rates. These computations illustrate that (a) the dead volume may contain a large mass of drug available for inadvertent bolus, (b) cessation of carrier flow can profoundly reduce drug delivery, and (c) after a change in carrier flow or drug dosing, a significant lag is possible before drug delivery achieves steady state. Although computed for phenylephrine, the concepts are generic and valid for any drug administered by IV infusion.
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Anesthesia and analgesia · Apr 2006
Randomized Controlled Trial Comparative StudyParavertebral blocks provide superior same-day recovery over general anesthesia for patients undergoing inguinal hernia repair.
Inguinal herniorrhaphy is commonly performed on an outpatient basis under nerve blocks or local or general anesthesia (GA). Our hypothesis is that use of paravertebral blocks (PVB) as the sole anesthetic technique will result in shorter time to achieve home readiness and improved same-day recovery over a 'fast-track' GA. Fifty patients were randomly assigned to receive either PVB or GA under standardized protocols (PVB = 0.75% ropivacaine, followed by propofol sedation; GA = dolasetron 12.5 mg, propofol induction, rocuronium, endotracheal intubation; desflurane; bupivacaine 0.25% for field block). ⋯ Time-to-home readiness and discharge times were shorter for patients in the PVB group (156 +/- 60 and 253 +/- 37 minutes) compared with those in the GA group (203 +/- 91 and 218 +/- 93 minutes) (P < 0.001). Adverse events (e.g., nausea, vomiting, sore throat) and pain requiring treatment in the first 24 hours occurred less frequently in patients who had received PVB than in those who had received GA. In outpatients undergoing inguinal herniorrhaphy, PVB resulted in faster time to home readiness and was associated with fewer adverse events and better analgesia before discharge than GA.
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Anesthesia and analgesia · Apr 2006
Randomized Controlled Trial Comparative StudyNitrous oxide induces paradoxical electroencephalographic changes after tracheal intubation during isoflurane and sevoflurane anesthesia.
In this randomized, double-blind, controlled study, we tested the hypothesis that nitrous oxide (N2O) affects bispectral index (BIS) and 95% spectral edge frequency (SEF95) in response to tracheal intubation during anesthesia with isoflurane and sevoflurane. In protocol 1, we randomly allocated 90 ASA physical status I patients to 6 groups (n = 15 each). Anesthesia was induced with isoflurane or sevoflurane with 0%, 33%, or 66% N2O. ⋯ In patients receiving 66% N2O-isoflurane or 66% N2O-sevoflurane, both BIS and SEF95 were significantly decreased after tracheal intubation and significantly lower than in those patients receiving only isoflurane or sevoflurane, respectively (P < 0.01 for both). In protocol 2, 3 microg/kg of IV fentanyl completely abolished the decrease of BIS and SEF95 after tracheal intubation during anesthesia with 66% N2O-isoflurane and 66% N2O-sevoflurane (n = 10). We conclude that 66% N2O induced a paradoxical decrease of BIS in response to tracheal intubation during anesthesia with isoflurane and sevoflurane.