ABSTRACT
The Spectral Entropy proposed to monitor the depth of anesthesia includes the State Entropy (SE) computed from the EEG (0.8-32 Hz frequency band), and the Response Entropy (RE) computed from EEG and facial muscles activity (0.5-47 Hz frequency band). We report an unexpected Entropy response to saline spraying at the end of posterior fossa surgery. Six patients undergoing scheduled functional surgery of the posterior fossa were included in this report. They were anesthetized with propofol and remifentanil using TCI and received an intubation dose of rocuronium. At the end of surgery, saline spraying, performed for hemostatic purpose and wreckage elimination, resulted in a sustained increase in RE and SE without hemodynamic modification in four patients, while no change was observed in the two other ones. In one of the responding patients, 0.1 mg kg(-1) rocuronium attenuated the Entropy response. In the two non responders, repetition of spraying or rocuronium administration did not change Entropy value. Recovery from anesthesia was comparable in all patients and none of them complained from awareness. We conclude that Entropy can increase during posterior fossa surgery in non-paralyzed patients. This response probably reflects an increase in facial muscle activity rather than a change in depth of anesthesia, as far as it can be attenuated by a small dose of rocuronium. While this hypothesis requires further investigation, these observations suggest that saline spraying may confound interpretation of Entropy during posterior fossa surgery.
Subject(s)
Brain/surgery , Electroencephalography/drug effects , Sodium Chloride/administration & dosage , Administration, Topical , Adult , Androstanols , Anesthetics, Intravenous , Blood Pressure/drug effects , Brain/drug effects , Entropy , Facial Muscles/drug effects , Heart Rate/drug effects , Hemostatic Techniques , Humans , Monitoring, Intraoperative/methods , Neuromuscular Nondepolarizing Agents , Piperidines , Propofol , Remifentanil , Rocuronium , VolatilizationABSTRACT
In this work, the renal function of ten patients has been studied during an anesthesia with halothane (5 patients) or enflurane (5 patients), a new volatile anesthetic agent. Before and during the anesthesia, the patients were perfused with Lactate Ringer solution. Blood and urine samples were regularly collected to allow the measures of the various parameters of the renal function. Halothane decreases the glomerular filtration rate, the renal plasmatic flow; the filtrated fraction remains stable. Enflurane decreases the glomerular filtration rate but increases the renal plasmatic flow; besides the filtrated fraction decreases. As far as water and electrolytes are concerned, halothane mainly decreases the urine output, the osmolar clearance and the fractional excretion of sodium. This suggests that it chiefly acts on the proximal tube of the nephron. Enflurane mainly decreases the urine output and the free water clearance. This suggests an effect on the distal tube of the nephron.
