Modern operating rooms have standards for aiconditioning that state that the total air content within the OR be replaced once every 10 minutes with filtered sterile fresh air. To me, this makes scavenging a T-piece circuit for use in kids unnecessary. While you may get a faint whiff of sevo every now and then, the dilution is so rapid from the airconditioning that it becomes trivial.

Any thoughts?

The product information for Sevoflurane still recommends fresh gas flows of 2L/min or more. I realise this is based on research with rats that lack an enzyme that humans have, but has this recommendation been revised down anywhere in the world yet?

I commonly run sevo at under 1L/min FGF. Where do I stand medicolegally if the patient gets a renal problem (from any cause)?

Having done carotid endarterectomies for many years using isoflurane anesthesia, I have recently converted to remifentanil and propofol TCI. However, I will probably convert back soon.

My reasoning was that remi/propofol is more quickly titrated to BP than iso, and rapid wakening at the end should allow an earlier assessment of neurological function.

The titratability is fine, but the rapid wakening has not happened. My patient group is usually in their 60's, some ischemic heart disease, HT and LVH.

I induce with remi running at 1mcg/kg/min and propofol TCI 4-8mcg/mL then drop these to remi 0.15 mcg/kg/min and a propofol target of anywhere from 3-8, but usually 4-5mcg/mL. Surgery usually takes 2 to 2.5 hrs. During the clsing stages I turn remi down to 0.1mcg/kg/min and propofol down to 2-3mcg/mL

In the 6 patients I have used this technique, while being extremely stable intra-op, they have taken a long time to wake up. Much longer than with iso. Usually breathing after 5-10 minutes, but unresponsive for 15 or so minutes. Then rousable but not extubatable for a long time after, the longest being almost 2 hours! And even then, confused, agitated, uncooperative.

Needless to say, embarassing for me, surgeon pacing around waiting to test neuro function. None of us quite sure whether it is a cerebral event or just long emergence.

And this seems to be unique to CEA's. I also use this type of TIVA on my thoracic cases, with similar doses of drugs, and they are brightly awake within 5 minutes of turning off the remi/propofol.

Aany ideas why???

???

I have been a user of the Bispectral Index (BIS) monitor for about 6 months now, and find it a useful adjunct to gauging anesthetic depth.

I recently moved to a new hospital which did not have BIS monitoring, but did have Datex Entropy monitors, which for all intents and purposes looks and behaves like the BIS.

I am wondering if anyone else has had experience with both BIS and Entropy and how they compare in practice. I have found the following article that gives some comparison, but I am interested in "real-world" experiences.

QuoteTime-frequency balanced spectral entropy as a measure of anesthetic drug effect in central nervous system during sevoflurane, propofol, and thiopental anesthesia.
Vakkuri A, Yli-Hankala A, Talja P, Mustola S, Tolvanen-Laakso H, Sampson T, Viertio-Oja H.

Acta Anaesthesiol Scand. 2004 Feb;48(2):145-53. (PDF: 376KB)

Abstract

Time-frequency balanced spectral entropy of electroencephalogram (EEG) and frontal electromyogram (FEMG) is a novel measure of hypnosis during anesthesia. Two Entropy parameters are described: Response entropy (RE) is calculated from EEG and FEMG; and State Entropy (SE) is calculated mainly from EEG. This study was performed to validate their performance during transition from consciousness to unconsciousness under different anesthetic agents.

METHODS: Response entropy, SE [S/5 Entropy Module, M-ENTROPY (later in text: Entropy), Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland] and BIS (BIS XP, A-2000, Aspect Medical Systems, Newton, MA) data were collected from 70 patients; 30 anesthetized with propofol 2 mg kg-1, 20 with sevoflurane inhalation, and 20 with thiopental 5 mg kg-1. Loss and regaining of consciousness (LOC, ROC) was tested every 10 s, and sensitivity, specificity, and prediction probability (Pk) were calculated. Behavior of the indices was studied.

RESULTS: Sensitivity, specificity, and Pk values for consciousness were high and similar for all indices. During regaining of consciousness after propofol bolus, RE, SE, and BIS values recovered by 81 +/- 22%, 75 +/- 26%, and 59 +/- 18% (mean +/- SD), respectively, from the minimum relative to their baseline. After thiopental bolus, RE, SE, and BIS values recovered by 86+/-21%, 88 +/- 13%, and 63 +/- 14%, respectively. The relative rise was higher in RE and SE compared with BIS (P < 0.01). During deep levels of hypnosis, RE and SE decreased monotonously as a function of burst suppression ratio, while BIS showed biphasic behavior. On average, RE indicated emergence from anesthesia 11 s earlier than SE, and 12.4 s earlier than BIS.

CONCLUSIONS: All indices, RE, SE, and BIS, distinguished excellently between conscious and unconscious states during propofol, sevoflurane, and thiopental anesthesia. During burst suppression, Entropy parameters RE and SE, but not BIS, behave monotonously. During regaining of consciousness after a thiopental or propofol bolus, RE and SE values recovered significantly closer to their baseline values than did BIS. Response entropy indicates emergence from anesthesia earlier than SE or BIS