title: Dynamic cerebral autoregulation to induced blood pressure changes in human experimental and clinical sepsis.
abstract: Previous studies have demonstrated that dynamic cerebral autoregulation to spontaneous fluctuations in blood pressure is enhanced following lipopolysaccharide (LPS) infusion, a human experimental model of early sepsis, whereas by contrast it is impaired in patients with severe sepsis or septic shock. In this study, we hypothesized that this pattern of response would be identical during induced changes in blood pressure. Dynamic cerebral autoregulation was assessed in nine healthy volunteers and six septic patients. The healthy volunteers underwent a 4-h intravenous infusion of LPS (total dose: 2 ng kg-1). Mean arterial blood pressure (MAP, arterial transducer) and middle cerebral artery blood flow velocity (MCAv, transcranial Doppler ultrasound) were recorded continuously during thigh-cuff deflation-induced changes in MAP for the determination of a modified rate of regulation (RoR). This was performed before and after LPS infusion in healthy volunteers, and within 72 h following clinical diagnosis of sepsis in patients. In healthy volunteers, thigh-cuff deflation caused a MAP reduction of 16 (13-20) % at baseline and 18 (16-20) % after LPS, while the MAP reduction was 12 (11-13) % in patients (P<0·05 versus volunteers at baseline; P<0·01 versus volunteers after LPS). The corresponding RoR values increased from 0·46 (0·31-0·49) s-1at baseline to 0·58 (0·36-0·74) s-1after LPS (P<0·05) in healthy volunteers, whereas they were similar to values observed in patients [0·43 (0·36-0·52) s-1; P = 0·91 versus baseline; P = 0·14 versus LPS]. While our findings support the concept that dynamic cerebral autoregulation is enhanced during the very early stages of sepsis, they remain inconclusive with regard to more advanced stages of disease, because thigh-cuff deflation failed to induce sufficient MAP reductions in patients.
authors.affiliation: Department of Clinical Physiology, Nuclear Medicine & PET, University Hospital Rigshospitalet, Copenhagen Ø, Denmark. ronan@dadlnet.dk.|Centre of Inflammation and Metabolism, Department of Infectious Diseases M7641, University Hospital Rigshospitalet, Copenhagen Ø, Denmark. ronan@dadlnet.dk.
authors.forename: Ronan M G
authors.initials: RM
authors.lastname: Berg
authors.affiliation: Department of Intensive Care, University Hospital Rigshospitalet, Copenhagen Ø, Denmark.|Department of Anaesthesia, Køge Hospital, Køge, Denmark.
authors.forename: Ronni R
authors.initials: RR
authors.lastname: Plovsing
authors.affiliation: Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Wales, UK.
authors.forename: Damian M
authors.initials: DM
authors.lastname: Bailey
authors.affiliation: Renal and Vascular Research Section, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen Ø, Denmark.
authors.forename: Niels-Henrik
authors.initials: NH
authors.lastname: Holstein-Rathlou
authors.affiliation: Centre of Inflammation and Metabolism, Department of Infectious Diseases M7641, University Hospital Rigshospitalet, Copenhagen Ø, Denmark.|Neurointensive Care Unit 2093, Department of Neuroanaesthesiology, University Hospital Rigshospitalet, Copenhagen Ø, Denmark.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Møller
mesh_terms: D000328:Adult; D000368:Aged; D062186:Arterial Pressure; D001783:Blood Flow Velocity; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D006706:Homeostasis; D006801:Humans; D008070:Lipopolysaccharides; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018805:Sepsis / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial; D055815:Young Adult
chemical_list: D008070:Lipopolysaccharides
keywords: cerebral blood flow; endotoxin; lipopolysaccharide; rate of regulation; sepsis-associated encephalopathy