Anesthesiology
-
Comparative Study Clinical Trial Controlled Clinical Trial
Comparison of plasma compartment versus two methods for effect compartment--controlled target-controlled infusion for propofol.
Target-controlled infusion (TCI) systems can control the concentration in the plasma or at the site of drug effect. A TCI system that targets the effect site should be able to accurately predict the time course of drug effect. The authors tested this by comparing the performance of three control algorithms: plasmacontrol TCI versus two algorithms for effect-site control TCI. ⋯ Effect compartment-controlled TCI can be safely applied in clinical practice. A biophase model combining the Marsh kinetics and a time to peak effect of 1.6 min accurately predicted the time course of propofol drug effect.
-
In doses typically administered during conscious sedation, remifentanil may be associated with ventilatory depression. However, the time course of ventilatory depression after an initial dose of remifentanil has not been determined previously. ⋯ After administration of 0.5 microg/kg remifentanil, there was a decrease in slope and downward shift of the carbon dioxide ventilatory response curve. This reached its nadir approximately 2.5 min after injection, consistent with the computed onset half-time of 2.9 min. The onset of respiratory depression appears to be somewhat slower than previously reported for the onset of remifentanil-induced electroencephalographic slowing. Recovery of ventilatory drive after a small dose essentially was complete within 15 min.
-
Subarachnoid hemorrhage can lead to cerebral ischemia and irreversible brain injury. The purpose of this study was to determine whether subarachnoid hemorrhage produces changes in brain tissue oxygen pressure, carbon dioxide pressure, or pH during surgery for cerebral aneurysm clipping. ⋯ These results show that subarachnoid hemorrhage can significantly decrease brain tissue oxygen pressure and pH related to the severity of the bleed. Increasing the desflurane concentration to 9% increased brain tissue oxygen pressure in all patients and brain tissue pH in patients with subarachnoid hemorrhage with baseline acidosis.
-
Dynamic intraesophageal pressure (Pes) is used to estimate intrapleural pressure (Ppl) to calculate lung compliance and resistance. This study investigated the nonhuman primate Ppl-Pes tissue barrier frequency response and the dynamic response requirements of Pes manometers. ⋯ In monkeys, the Ppl-Pes tissue barrier has a frequency response suitable for Ppl estimation during low-frequency mechanical ventilation, and Pes manometers should have a minimum uniform frequency response up to 8.5 Hz. However, the Ppl-Pes tissue barrier adversely affects the accurate estimation of dynamic Ppl at high frequencies, with varied airway pressure amplitudes and offsets, such as the Ppl encountered during high-frequency oscillatory ventilation.
-
Females have worse outcome than do males after coronary artery bypass grafting; however, gender effects on length of stay (LOS) outcomes, such as duration of intubation or intensive care unit (ICU) LOS, have not been evaluated previously. The authors hypothesized that adjustment for pertinent preoperative covariates would eliminate any significant effect of gender on duration of intubation, LOS in the ICU after extubation, total ICU LOS, postoperative (exclusive of ICU) LOS, or total postoperative LOS. ⋯ Even in the context of accelerated recovery programs, these analyses show that female sex has powerful associations with increased LOS intervals for coronary artery bypass grafting surgery, even after adjustment for preoperative covariates. These effects could result from differences in the ways in which men and women respond to coronary artery disease, anesthesia, and coronary artery bypass grafting surgery, or to bias on the part of healthcare workers.