TY - JOUR

T1 - Lipopolysaccharide infusion enhances dynamic cerebral autoregulation without affecting cerebral oxygen vasoreactivity in healthy volunteers

AU - Berg, Ronan M G

AU - Plovsing, Ronni R

AU - Evans, Kevin A

AU - Christiansen, Claus B

AU - Bailey, Damian M

AU - Holstein-Rathlou, Niels-Henrik

AU - Møller, Kirsten

PY - 2013/10/16

Y1 - 2013/10/16

N2 - INTRODUCTION: Sepsis may be associated with disturbances in cerebral oxygen transport and cerebral haemodynamic function, thus rendering the brain particularly susceptible to hypoxia. The purpose of this study was to assess the impact of isocapnic hypoxia and hyperoxia on dynamic cerebral autoregulation in a human-experimental model of the systemic inflammatory response during the early stages of sepsis.METHODS: A total of ten healthy volunteers were exposed to acute isocapnic inspiratory hyperoxia (FIO₂ = 40%) and 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.RESULTS: 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 (P<0.01). In contrast, there were no effects of either isocapnic hyperoxia or hypoxia on dynamic autoregulation, and the cerebral oxygen vasoreactivity to both hyperoxia and hypoxia was unaffected by LPS.CONCLUSIONS: The observed increase in phase suggests that dynamic cerebral autoregulation is enhanced after LPS infusion and resistant to any effects of acute hypoxia; this may protect the brain from ischaemia and/or blood-brain barrier damage during the early stages of sepsis.

AB - INTRODUCTION: Sepsis may be associated with disturbances in cerebral oxygen transport and cerebral haemodynamic function, thus rendering the brain particularly susceptible to hypoxia. The purpose of this study was to assess the impact of isocapnic hypoxia and hyperoxia on dynamic cerebral autoregulation in a human-experimental model of the systemic inflammatory response during the early stages of sepsis.METHODS: A total of ten healthy volunteers were exposed to acute isocapnic inspiratory hyperoxia (FIO₂ = 40%) and 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.RESULTS: 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 (P<0.01). In contrast, there were no effects of either isocapnic hyperoxia or hypoxia on dynamic autoregulation, and the cerebral oxygen vasoreactivity to both hyperoxia and hypoxia was unaffected by LPS.CONCLUSIONS: The observed increase in phase suggests that dynamic cerebral autoregulation is enhanced after LPS infusion and resistant to any effects of acute hypoxia; this may protect the brain from ischaemia and/or blood-brain barrier damage during the early stages of sepsis.

KW - Blood Flow Velocity

KW - Cerebral Cortex/diagnostic imaging

KW - Healthy Volunteers

KW - Hemodynamics

KW - Homeostasis/drug effects

KW - Humans

KW - Hypoxia/physiopathology

KW - Infusions, Intravenous

KW - Lipopolysaccharides/administration & dosage

KW - Male

KW - Middle Cerebral Artery/diagnostic imaging

KW - Oxygen/blood

KW - Sepsis/physiopathology

KW - Ultrasonography, Doppler, Transcranial

KW - Young Adult

U2 - 10.1186/cc13062

DO - 10.1186/cc13062

M3 - Journal article

C2 - 24131656

VL - 17

SP - R238

JO - Critical Care

JF - Critical Care

SN - 1364-8535

IS - 5

ER -