Anesthesia and analgesia
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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.
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Anesthesia and analgesia · Apr 2006
Comparative StudyExcessive bleeding and transfusion in a prior cardiac surgery is associated with excessive bleeding and transfusion in the next surgery.
If there is a genetic predisposition to excessive bleeding, there should be an association in excessive blood loss between multiple cardiac surgeries. We retrospectively determined in 174 patients the association of excessive bleeding between 2 cardiac surgeries with cardiopulmonary bypass between January 19, 1990 and June 25, 2002. Excessive bleeding was defined by 2 criteria: (a) postoperating room chest tube blood loss over 24 h more than or equal to 750 mL (chest tube drainage [CTD] > or = 750) and (b) transfusion of any non-red blood cell (RBC) blood products. ⋯ The logistic regression models for CTD > or = 750 in the second surgery determined that CTD > or = 750 in the first surgery compared to CTD < 750 had an unadjusted odds ratio of 2.18 (P = 0.03) and an odds ratio of 2.42 (P = 0.03) when adjusted for age, sex, body surface area, preoperative anticoagulant use, cardiopulmonary bypass duration, and procedure type at second surgery. The logistic regression model for any non-RBC use in the second surgery determined that any non-RBC use in the first surgery compared with no non-RBC use had an unadjusted odds ratio of 2.32 (P = 0.02) and an odds ratio of 2.55 (P = 0.02) when adjusted for age, sex, body surface area, preoperative anticoagulant use, cardiopulmonary bypass duration, and procedure type at second surgery. We conclude that a history of excessive bleeding during the first operation is associated with more than two times increased risk for excessive bleeding in the second surgery.
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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
ReviewThe role of postoperative analgesia in delirium and cognitive decline in elderly patients: a systematic review.
Postoperative delirium and cognitive decline are adverse events that occur frequently in elderly patients. Preexisting patient factors, medications, and various intraoperative and postoperative causes have been implicated in the development of postoperative delirium and cognitive decline. Despite previous studies identifying postoperative pain as a risk factor, relatively few clinical studies have compared the effect of common postoperative pain management techniques (IV and epidural) or opioid analgesics on postoperative cognitive status. ⋯ Meperidine was consistently associated with an increased risk of delirium in elderly surgical patients, but the current evidence has not shown a significant difference in postoperative delirium or cognitive decline among other more frequently used postoperative opioids such as morphine, fentanyl, or hydromorphone. The available studies also suggest that IV or epidural techniques do not influence cognitive function differently. However, future investigations of sufficient study size and more standardized methods of defining outcomes are necessary to confirm the current findings.