Anesthesiology
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Efficacy of acute normovolemic hemodilution assessed as a function of fraction of blood volume lost.
It has been recommended that intraoperative acute normovolemic hemodilution (ANH) be considered for patients expected to experience surgical blood loss of 20% or more of their blood volume. Previous mathematical analyses have not evaluated the potential efficacy of ANH in terms of fraction of blood volume lost. Since decrease of oxygen-carrying capacity is a function of erythrocyte loss relative to blood volume, the purpose of this analysis was to provide an assessment of ANH applicable to all blood volumes and to determine whether this recommendation is appropriate. ⋯ This analysis suggests that surgical blood loss should be 0.50 or more for ANH to begin to "save" erythrocytes and 0.70 or more of the patient's blood volume for ANH to save 1 unit erythrocytes, for the usual surgical patient with an initial hematocrit of 0.32-0.36 and a transfusion "trigger" hematocrit (the value at which transfusion is initiated) of 0.18-0.21.
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Randomized Controlled Trial Clinical Trial
Preoperative anxiolysis and postoperative recovery in women undergoing abdominal hysterectomy.
Every year, millions of patients receive sedatives for reduction of anxiety before surgery, but there is little objective data on the effect of this treatment on postoperative outcomes. To address this issue, the effects of benzodiazepine administration were evaluated in women undergoing abdominal surgery. ⋯ Benzodiazepines administered before surgery have minimal beneficial effects on the postoperative clinical course of women undergoing abdominal hysterectomy.
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Recent studies have determined that an initial rectal acetaminophen dose of approximately 40 mg/kg is needed in children to achieve target antipyretic serum concentrations. The timing and amount of subsequent doses after a 40-mg/kg dose has not been clarified for this route of administration. Based on the authors' previous pharmacokinetic data, they examined whether a 40-mg/kg loading dose followed by 20-mg/kg doses at 6-h intervals maintain serum concentrations within the target range of 10-20 microg/ml, without evidence of accumulation. ⋯ A rectal acetaminophen loading dose of 40 mg/kg followed by 20-mg/kg doses every 6 h results in serum concentrations centered at the target range of 10-20 microg/ml. There was large interindividual variability in pharmacokinetic characteristics. There was no evidence of accumulation during the 24-h sampling period.
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Anesthesiologists routinely increase the delivered anesthetic concentration before surgical stimulation in anticipation of increased anesthetic requirement to achieve certain goals (e.g., amnesia, unconsciousness, and immobility). Electroencephalographic monitoring is one method of determining indirectly anesthetic effect on the brain. The present study investigated the effect of surgical stimuli on the concentration-response relation of desflurane-induced electroencephalographic changes. ⋯ During surgery, higher concentrations of the volatile anesthetic are required to achieve a desired level of cortical electrical activity and, presumably, anesthesia.
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Parameters determining carbon monoxide (CO) concentrations produced by anesthetic breakdown have not been adequately studied in clinical situations. The authors hypothesized that these data will identify modifiable risk factors. ⋯ Anesthetic identity, fresh gas flow rates, absorbent quantity, and water content are the most important factors determining patient exposures. Minute ventilation and carbon dioxide production by the patient are relatively unimportant.