title: Effect of charcoal filter on the emergence from sevoflurane anesthesia in a semi-closed rebreathing circuit.
abstract: OBJECTIVE
  A charcoal filter attached within the anesthetic circuit has been shown to efficiently adsorb halothane or isoflurane, thus hastening anesthetic recovery in low or minimal flow system. This study was intended to demonstrate whether the charcoal filter enhances the recovery time from sevoflurane anesthesia using a semi-closed circuit system.
  
  
  METHODS
  Thirty healthy patients scheduled for elective surgery under sevoflurane anesthesia were randomly assigned to the charcoal filter or control group. Upon completion of surgery, the end-tidal concentration of sevoflurane was maintained at 2.0 vol%. A charcoal filter was attached to the expiratory limb of the breathing circuit of charcoal filter group subjects. After sevoflurane was discontinued, ventilation was controlled with the same minute volume as the intra-operative period at a fresh gas flow rate of 5 L·min⁻¹ with 100% O₂. The elimination kinetics of sevoflurane from end-tidal concentration, Bispectral index and times of eye opening and extubation were obtained.
  
  
  RESULTS
  The exponential time constant (τ) of alveolar sevoflurane concentration in the charcoal filter group was significantly shorter than that in the control group (1.7±0.5 vs. 2.5±1.1 min, p=0.008). The charcoal filter hastened rapid eye opening (11.1±3.8 vs. 14.8±3.0 min, p=0.007) and extubation (11.9±3.9 vs. 15.3±3.2 min, p=0.014), compared to the control group.
  
  
  CONCLUSIONS
  A charcoal filter enhances the recovery from sevoflurane anesthesia with a semi-closed rebreathing circuit.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, 250 Seongsan-ro, Seodaemun-gu, Seoul 120-752, Korea.
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Chang
authors.forename: Seung Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Yong Suk
authors.initials: YS
authors.lastname: Choi
authors.forename: Kyeong Tae
authors.initials: KT
authors.lastname: Min
mesh_terms: D000328:Adult; D000758:Anesthesia / Q000379:methods; D000762:Anesthesia Recovery Period; D000776:Anesthesiology / Q000295:instrumentation; D018685:Anesthetics, Inhalation / Q000737:chemistry / Q000494:pharmacology*; D002606:Charcoal / Q000737:chemistry*; D005374:Filtration / Q000379:methods*; D006801:Humans; D008738:Methyl Ethers / Q000737:chemistry / Q000494:pharmacology*; D008875:Middle Aged; D000077149:Sevoflurane; D013997:Time Factors
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D002606:Charcoal; D000077149:Sevoflurane