Sepsis may be associated with disturbances in cerebral oxygen transport and cerebral haemodynamic function, thus rendering the brain particularly susceptible to hypoxia (Berg et al, 2011). The purpose of the present study was to assess the impact of isocapnic hypoxia on dynamic cerebral autoregulation in a human-experimental model of the systemic inflammatory response during the early stages of sepsis. A total of ten healthy volunteers were exposed to normoxia (FIO2 = 21%) and acute isocapnic inspiratory hypoxia (FIO2 = 12%) before and after a 4-hour lipopolysaccharide (LPS) infusion (2 ng kg-1). Middle cerebral artery blood follow velocity was assessed using transcranial Doppler ultrasound, and dynamic autoregulation was evaluated by transfer function analysis. Transfer function analysis revealed an increase in the phase difference between mean arterial blood pressure and middle cerebral artery blood flow velocity in the low frequency range (0.07-0.20 Hz) after LPS (Table). In contrast, there were no effects of isocapnic hypoxia on dynamic autoregulation. The observed increase in phase suggests that the dynamic cerebral autoregulation is enhanced after LPS infusion and resistant to any effects of acute hypoxia; this may protect the brain from ischemia and/or blood-brain barrier damage during the early stages of sepsis.
37th Congress of IUPS (Birmingham, UK) (2013) Proc 37th IUPS, PCC249
Poster Communications: Lipopolysaccharide infusion enhances dynamic cerebral autoregulation with no effects of acute isocapnic hypoxia in healthy volunteers
R. M. Berg1,2, R. R. Plovsing3, K. A. Evans4, C. B. Christiansen1, D. M. Bailey4, N. Holstein-Rathlou2, K. Møller1,5
1. Centre of Inflammation and Metabolism, Department of Infectious Diseases, University Hospital Rigshospitalet, Copenhagen Ï, Denmark. 2. Renal and Vascular Research Section, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark. 3. Intensive Care Unit 4131, University Hospital Rigshospitalet, Copenhagen Ï, Denmark. 4. Neurovascular Research Laboratory, Faculty of Health, Science and Sport, University of Glamorgan, Copenhagen Ï, United Kingdom. 5. Neurointensive Care Unit 2093, University Hospital Rigshospitalet, Copenhagen Ï, Denmark.
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