title: Monitoring with EEG entropy decreases propofol requirement and maintains cardiovascular stability during induction of anaesthesia in elderly patients.
abstract: OBJECTIVE
  Electroencephalographic entropy is used to measure the degree of brain hypnosis and anaesthesia depth. Two parameters are displayed in the monitor, state entropy (SE) and response entropy (RE). Ageing leads to reduction in liver mass as well as hepatic blood flow, which decreases clearance of propofol and increases the risk of cardiovascular adverse effects. The aim of this study is to demonstrate the effect of electroencephalographic entropy on propofol requirement and haemodynamic parameters during induction of anaesthesia in elderly patients.
  
  
  METHODS
  We studied 72 elderly patients. Standard monitoring was performed for all patients together with entropy monitor. Patients were allocated randomly either to the control group, which were given the recommended induction dose of propofol, or to the entropy group which was induced with propofol based on entropy reading where the end-point was SE 50 and SE-RE difference less than 10. Propofol induction doses and haemodynamic changes were recorded. Anaesthesia was maintained using sevoflurane and O2 air mixture.
  
  
  RESULTS
  After induction of anaesthesia, the systolic, diastolic, mean arterial pressure, RE and SE were significantly lower in the control group (P value < 0.05). Total dose of propofol and the dose kg-1 were significantly reduced by 37.1% and 31.8%, respectively, in the entropy group (P value < 0.01).
  
  
  CONCLUSIONS
  The use of electroencephalographic entropy during induction of anaesthesia in elderly patients reduces propofol requirements and maintains cardiovascular stability.
authors.affiliation: King Khaled Eye Specialist Hospital, Department of Anesthesia, Riyadh, Kingdom of Saudi Arabia. waleed_riad@yahoo.com
authors.forename: W
authors.initials: W
authors.lastname: Riad
authors.forename: M
authors.initials: M
authors.lastname: Schreiber
authors.forename: A B
authors.initials: AB
authors.lastname: Saeed
mesh_terms: D000368:Aged; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D019277:Entropy; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology; D016343:Monitoring, Intraoperative / Q000379:methods*; D008991:Monitoring, Physiologic; D013508:Ophthalmologic Surgical Procedures; D015742:Propofol / Q000494:pharmacology*; D011446:Prospective Studies; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D000077149:Sevoflurane; D015742:Propofol