Anesthesia and analgesia
-
Anesthesia and analgesia · Sep 2006
Randomized Controlled TrialIs depth of anesthesia, as assessed by the Bispectral Index, related to postoperative cognitive dysfunction and recovery?
We randomized 74 patients to either a lower Bispectral Index (BIS) regimen (median BIS, 38.9) or a higher BIS regimen (mean BIS, 50.7) during the surgical procedure. Preoperatively and 4-6 wk after surgery, the patients' cognitive status was assessed with a cognitive test battery consisting of processing speed index, working memory index, and verbal memory index. ⋯ No difference was observed in the other two test battery components. Somewhat deeper levels of anesthesia were therefore associated with better cognitive function 4-6 wk postoperatively, particularly with respect to the ability to process information.
-
Anesthesia and analgesia · Sep 2006
Clinical TrialImaging pain modulation by subanesthetic S-(+)-ketamine.
Little is known about the effects of low-dose S-(+)-ketamine on the cerebral processing of pain. We investigated the effects of subanesthetic IV S-(+)-ketamine doses on the perception of experimental painful heat stimuli. Healthy volunteers were evaluated with functional magnetic resonance imaging (fMRI) while receiving the painful stimuli in conjunction with placebo and increasing doses (0.05, 0.1, 0.15 mg x kg(-1) x h(-1)) of ketamine infusion. ⋯ During placebo administration, a typical pain activation network (thalamus, insula, cingulate, and prefrontal cortex) was found, whereas decreased pain perception with ketamine was associated with a dose-dependent reduction of pain-induced cerebral activations. Analysis of the dose-dependent ketamine effects on pain processing showed a decreasing activation of the secondary somatosensory cortex (S2), insula and anterior cingulate cortex. This part of the anterior cingulate cortex (midcingulate cortex) has been linked with the affective pain component that underlines the potency of ketamine in modulating affective pain processing.
-
Anesthesia and analgesia · Sep 2006
Clinical TrialChanges in electroencephalographic bicoherence during sevoflurane anesthesia combined with intravenous fentanyl.
With the introduction of bispectral index (BIS) as a measure of a patient's sedation during general anesthesia, attention has been directed toward bispectral analysis of electroencephalography (EEG). In the present study we evaluated the relationship between EEG bicoherence and sevoflurane concentration. Sixteen ASA physical status I-II patients scheduled for elective abdominal surgery were enrolled in the study. ⋯ The BIS value decreased as the sevoflurane concentration increased and leveled off at 1.4% and higher concentrations of sevoflurane. The SEF 95 also decreased as the sevoflurane concentration increased up to 2.3%. Thus the distribution pattern of the two bicoherence peaks is likely to be better than BIS of the anesthetic effect of sevoflurane during surgery.
-
We evaluated empirically the extent to which the use of a cognitive aid during a high-fidelity simulation of a malignant hyperthermia (MH) event facilitated the correct and prompt treatment of MH. We reviewed the management of 48 simulated adult MH scenarios; 24 involving CA 1 and 24 involving CA 2 residents. In the CA 1 group, 19 of the 24 teams (79%) used a cognitive aid, but only 8 of the 19 teams used it frequently or extensively. ⋯ The teams that performed the best in treating MH used a cognitive aid extensively throughout the simulation. Although the effect was less pronounced in the more experienced CA 2 cohort, there was still a strong correlation between performance and cognitive aid use. We were able to show a strong correlation between the use of a cognitive aid and the correct treatment of MH.
-
Anesthesia and analgesia · Sep 2006
Change in expiratory flow detects partial endotracheal tube obstruction in pressure-controlled ventilation.
Only extreme degrees of endotracheal tube (ETT) narrowing can be detected with monitoring of tidal volume (V(T)) during pressure-controlled ventilation (PCV). To assess the degree of ETT obstruction in PCV and to compare it to V(T) monitoring, we produced 3 levels of partial ETT obstruction in 11 healthy anesthetized piglets using ETTs of 4 different inner diameters (IDs 9.0, 8.0, 7.0, and 6.0 mm). An expiratory flow over volume ((e)-V) curve was plotted and the time constant (tau(e)) at 15% of expiration time (T(e)) was calculated. ⋯ V(T) monitoring failed to detect ETT narrowing. By contrast, V(ex fract,15) decreased and tau(e) increased significantly with increasing ETT narrowing (for IDs 9.0, 8.0, 7.0, and 6.0, mean V(ex fract,15) was 195, 180, 146, and 134 mL respectively and mean tau(e) was 380, 491, 635, 794 ms for IDs 9.0, 8.0, 7.0, and 6.0 respectively). We conclude that when the elastic recoil that drives (e) is appropriately considered, analysis of (e) and V(ex fract,15) detects partial ETT obstruction during PCV.