Anesthesiology
-
Multicenter Study
What sample sizes are required for pooling surgical case durations among facilities to decrease the incidence of procedures with little historical data?
Better predictions of each case's duration would reduce operating room labor costs and patient waiting times. A barrier to using historical case duration data to predict the duration of future cases is the absence for some cases of previous data for the same scheduled procedure from the same facility. The authors examined sample size requirements for pooling case duration data from several facilities to create a 90% chance of having case duration data for almost all procedures. ⋯ The lack of historical case duration data for scheduled procedures is an important cause of inaccuracy in predicting case durations. However, millions of cases probably would be required to provide historical case duration data for almost all procedures.
-
Randomized Controlled Trial Clinical Trial
The influence of hyperoxic ventilation during sodium nitroprusside-induced hypotension on skeletal muscle tissue oxygen tension.
Increasing inspired oxygen concentrations might provide a simple and effective intervention to increase oxygen tension in tissues during controlled hypotension. To test this hypothesis, the influence of hyperoxic ventilation (100% O2) on skeletal muscle oxygen partial pressure (Ptio2) in patients receiving sodium nitroprusside-induced controlled hypotension was studied. ⋯ Hyperoxic ventilation improved skeletal muscle tissue oxygenation during sodium nitroprusside-induced hypotension. This improved local tissue oxygenation seems to be most likely due to an increase in convective oxygen transport and the attenuation of hyperoxemia-induced arteriolar vasoconstriction by sodium nitroprusside.
-
It has been generally considered that supraspinal morphine activates the serotonergic descending inhibitory system and releases serotonin (5-hydroxytryptamine [5-HT]) in the spinal cord, producing antinociception through activation of 5-HT receptors. The involvement of a spinal gamma-aminobutyric acid-mediated (GABAergic) system is also suggested in supraspinal morphine antinociception. It has been reported that spinal GABAergic system contributes to 5-HT3 receptor-mediated antinociception. In this study, the authors investigated the contribution of spinal 5-HT3 receptor and the GABAergic system in the intracerebroventricular morphine-induced antinociception. ⋯ Intracerebroventricular morphine evokes spinal GABA release via the activation of 5-HT3 receptors in the spinal cord, resulting in antinociceptive effect.
-
Clinical Trial
Pharmacokinetics of bupivacaine during postoperative epidural infusion: enantioselectivity and role of protein binding.
Changing plasma protein concentrations may affect the protein binding and pharmacokinetics of drugs in the postoperative period. This study examined the effect of postoperative increases (in response to surgery) in plasma alpha1-acid-glycoprotein (AAG) concentrations on the plasma concentrations of the enantiomers of bupivacaine during continuous epidural infusion of racemic bupivacaine for postoperative pain relief. ⋯ The study confirmed that the pharmacokinetics of bupivacaine are enantioselective. During postoperative epidural infusion, changing plasma AAG concentrations affect the protein binding of both enantiomers of bupivacaine. Consequently, total plasma concentrations of the enantiomers increase with time, whereas unbound concentrations reach a plateau.