title: Influence of isoflurane on the diastolic pressure-flow relationship and critical occlusion pressure during arterial CABG surgery: a randomized controlled trial.
abstract: The effects of isoflurane on the determinants of blood flow during Coronary Artery Bypass Graft (CABG) surgery are not completely understood. This study characterized the influence of isoflurane on the diastolic Pressure-Flow (P-F) relationship and Critical Occlusion Pressure (COP) during CABG surgery. Twenty patients undergoing CABG surgery were studied. Patients were assigned to an isoflurane or control group. Hemodynamic and flow measurements during CABG surgery were performed twice (15 minutes after the discontinuation of extracorporeal circulation (T15) and again 15 minutes later (T30)). The zero flow pressure intercept (a measure of COP) was extrapolated from a linear regression analysis of the instantaneous diastolic P-F relationship. In the isoflurane group, the application of isoflurane significantly increased the slope of the diastolic P-F relationship by 215% indicating a mean reduction of Coronary Vascular Resistance (CVR) by 46%. Simultaneously, the Mean Diastolic Aortic Pressure (MDAP) decreased by 19% mainly due to a decrease in the systemic vascular resistance index by 21%. The COP, cardiac index, heart rate, Left Ventricular End-Diastolic Pressure (LVEDP) and Coronary Sinus Pressure (CSP) did not change significantly. In the control group, the parameters remained unchanged. In both groups, COP significantly exceeded the CSP and LVEDP at both time points. We conclude that short-term application of isoflurane at a sedative concentration markedly increases the slope of the instantaneous diastolic P-F relationship during CABG surgery implying a distinct decrease with CVR in patients undergoing CABG surgery.
authors.affiliation: Department of Anesthesiology, University Medical Center Goettingen , Germany.
authors.forename: José
authors.initials: J
authors.lastname: Hinz
authors.affiliation: Department of Anesthesiology, University Medical Center Goettingen , Germany.
authors.forename: Ashham
authors.initials: A
authors.lastname: Mansur
authors.affiliation: Department of Anesthesiology, University Medical Center Goettingen , Goettingen , Germany.
authors.forename: Gerd G
authors.initials: GG
authors.lastname: Hanekop
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University of Oldenburg , Oldenburg , Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Weyland
authors.affiliation: Department of Cardiothoracic Surgery, Transplantation & Mechanical Support, Royal Brompton & Harefield Hospital , London , United Kingdom.
authors.forename: Aron F
authors.initials: AF
authors.lastname: Popov
authors.affiliation: Department of Cardiothoracic, Transplant and Vascular Surgery, Hannover Medical School , Hannover , Germany.
authors.forename: Jan D
authors.initials: JD
authors.lastname: Schmitto
authors.affiliation: Department of Anesthesiology, Erasmus University/Rotterdam , Rotterdam , Netherlands.
authors.forename: Frank F G
authors.identifier: 0000-0001-5693-3721
authors.initials: FF
authors.lastname: Grüne
authors.affiliation: Department of Anesthesiology, University Medical Center Goettingen , Göttingen , Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bauer
authors.affiliation: Department of Anesthesiology, University Medical Center Goettingen , Goettingen , Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kazmaier
keywords: Cardiac anesthesia; Cardiac surgery; Cardio; Cardioprotective effects; Coronary blood flow; Critical care medicine; Hemodynamic monitoring; Inhalational anesthetic agent