title: Impact of the anesthetic conserving device on respiratory parameters and work of breathing in critically ill patients under light sedation with sevoflurane.
abstract: BACKGROUND
  Sevoflurane sedation in the intensive care unit is possible with a special heat and moisture exchanger called the Anesthetic Conserving Device (ACD) (AnaConDa; Sedana Medical AB, Uppsala, Sweden). The ACD, however, may corrupt ventilatory mechanics when used during the weaning process of intensive care unit patients. The authors compared the ventilatory effects of light-sedation with sevoflurane administered with the ACD and those of classic management, consisting of a heated humidifier and intravenous sedation, in intensive care unit patients receiving pressure-support ventilation.
  
  
  METHODS
  Fifteen intensive care unit patients without chronic pulmonary disease were included. A target Richmond Agitation Sedation Scale level of -1/-2 was obtained with intravenous remifentanil (baseline 1-condition). Two successive interventions were tested: replacement of the heated humidifier by the ACD without sedation change (ACD-condition) and sevoflurane with the ACD with an identical target level (ACD-sevoflurane-condition). Patients finally returned to baseline (baseline 2-condition). Work of breathing, ventilatory patterns, blood gases, and tolerance were recorded. A steady state of 30 min was achieved for each experimental condition.
  
  
  RESULTS
  ACD alone worsened ventilatory parameters, with significant increases in work of breathing (from 1.7 ± 1.1 to 2.3 ± 1.2 J/l), minute ventilation, P0,1, intrinsic positive end-expiratory pressure (from 1.3 ± 2.6 to 4.7 ± 4.2 cm H2O), inspiratory pressure swings, and decreased patient comfort. Sevoflurane normalized work of breathing (from 2.3 ± 1.2 to 1.8 ± 1 J/l), intrinsic positive end-expiratory pressure (from 4.7 ± 4.2 to 1.8 ± 2 cm H2O), inspiratory pressure swings, other ventilatory parameters, and patient tolerance.
  
  
  CONCLUSIONS
  ACD increases work of breathing and worsens ventilatory parameters. Sevoflurane use via the ACD (for a light-sedation target) normalizes respiratory parameters. In this patient's population, light-sedation with sevoflurane and the ACD may be possible during the weaning process.
authors.affiliation: From the Department of PeriOperative Medicine, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France (R.C., N.A.B.S., J.-E.B.); Department of PeriOperative Medicine, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France, and R2D2, EA-7281, Medical School, Universite d'Auvergne, Clermont-Ferrand, France (S.P., E.F., J.-M.C.); Anesthesiology and Critical Care Medicine, Department B, Saint Eloi Hospital, University Hospital of Montpellier, Montpellier, France (S.J.); and Biostatistics Unit, Department of Clinical Research and Innovation, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France (B.P.).
authors.forename: Russell
authors.initials: R
authors.lastname: Chabanne
authors.forename: Sebastien
authors.initials: S
authors.lastname: Perbet
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Futier
authors.forename: Nordine Ait
authors.initials: NA
authors.lastname: Ben Said
authors.forename: Samir
authors.initials: S
authors.lastname: Jaber
authors.forename: Jean-Etienne
authors.initials: JE
authors.lastname: Bazin
authors.forename: Bruno
authors.initials: B
authors.lastname: Pereira
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Constantin
mesh_terms: D000328:Adult; D000368:Aged; D016638:Critical Illness / Q000628:therapy*; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage*; D008875:Middle Aged; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000295:instrumentation* / Q000379:methods; D015656:Respiratory Mechanics / Q000187:drug effects* / Q000502:physiology; D000077149:Sevoflurane; D014939:Work of Breathing / Q000187:drug effects* / Q000502:physiology
chemical_list: D006993:Hypnotics and Sedatives; D008738:Methyl Ethers; D000077149:Sevoflurane