title: High risk of intraoperative awareness during cardiopulmonary bypass with isoflurane administration via diffusion membrane oxygenators.
abstract: In cardiac surgery with the aid of extracorporeal circulation (ECC), inhalation anaesthetics can be administered via the oxygenator. Until the recent advent of a new type of diffusion membrane oxygenator, we routinely added the inhalation agent, isoflurane, to the gas flow of a microporous capillary membrane-type oxygenator. Applying this procedure to the diffusion-type oxygenators, the depth of anaesthesia appeared to be affected, which manifested itself through unusually high intraoperative perfusion pressures. This observation led to a prospective randomized study comprising 60 patients and two models of a microporous capillary membrane oxygenator, as well as two models of a diffusion membrane oxygenator. Simultaneous isoflurane concentration measurements at both the gas inlet and outlet ports of the oxygenators showed that, whereas in the microporous capillary-type oxygenators the isoflurane administered was reduced by about 50% during the passage of gas through the device, there was only a minimal transfer of isoflurane in the diffusion-type membrane oxygenators.
authors.affiliation: Clinic for Cardiothoracic Surgery, University of Regensburg, Germany. alois.philipp@klinik.uni-regensburg.de
authors.forename: Alois
authors.initials: A
authors.lastname: Philipp
authors.forename: Christoph
authors.initials: C
authors.lastname: Wiesenack
authors.forename: Renate
authors.initials: R
authors.lastname: Behr
authors.forename: Franz X
authors.initials: FX
authors.lastname: Schmid
authors.forename: Dietrich E
authors.initials: DE
authors.lastname: Birnbaum
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D001364:Awareness; D002315:Cardiopulmonary Bypass; D004058:Diffusion; D015199:Extracorporeal Membrane Oxygenation / Q000009:adverse effects* / Q000295:instrumentation; D006801:Humans; D007432:Intraoperative Period; D007530:Isoflurane / Q000008:administration & dosage*; D010107:Oxygenators, Membrane / Q000009:adverse effects*; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D018685:Anesthetics, Inhalation; D007530:Isoflurane