title: Reduction of cerebral mean blood flow velocity and oxygenation after high-volume (1.5 ml kg⁻¹) caudal block in infants.
abstract: BACKGROUND
  We have recently described a bi-directional bulk flow of cerebrospinal fluid (CSF) (coined 'the CSF rebound mechanism') after the use of high-volume caudal block in infants, which may explain the secondary longitudinal spread of the block. If important the initial cephalad transfer of CSF should be of such a magnitude that it would cause a transient reduction in cerebral blood flow (CBF) and cerebral oxygenation. The primary aim of this observational study was to delineate the magnitude of the reduction of CBF velocity (CBFV) associated with high-volume caudal block in infants.
  
  
  METHODS
  Ultrasound Doppler measurements of CBFV in the middle cerebral artery and also haemodynamic parameters and cerebral regional oxygenation (C(R)SO2) were followed during 5 min after the initial caudal injection (1.5 ml kg(-1), ropivacaine 0.2%) in 12 infants <3 months of age.
  
  
  RESULTS
  The caudal injection was associated with immediate and major reductions in CBFV indicating a concomitant reduction in CBF. A significant reduction of cerebral regional oxygenation C(R)SO2 was also observed. Systemic haemodynamic parameters were unchanged during the observation period.
  
  
  CONCLUSIONS
  High-volume caudal block causes a biphasic change in CBFV and was also found to affect cerebral oxygenation. Our findings lend further support to 'the CSF rebound mechanism' for secondary spread of high-volume caudal block.
authors: Department of Paediatric Anaesthesia, Intensive Care & ECMO and marit.lundblad@karolinska.se marit.lundblad@telia.com.
authors: M
authors: M
authors: Lundblad
authors: Department of Paediatric Anaesthesia, Intensive Care & ECMO and.
authors: J
authors: J
authors: Forestier
authors: Department of Anaesthesiology & Intensive Care, AKH/Medical University of Vienna, Vienna, Austria.
authors: D
authors: D
authors: Marhofer
authors: Department of Women's and Children's Health, Childhood Cancer Research Unit, Karolinska Institutet, Stockholm, Sweden.
authors: S
authors: S
authors: Eksborg
authors: Department of Paediatric Cardiology, Astrid Lindgrens Children's Hospital/Karolinska University Hospital, Stockholm, Sweden.
authors: P
authors: P
authors: Winberg
authors: Department of Paediatric Anaesthesia, Intensive Care & ECMO and Department of Physiology & Pharmacology, Section of Anaesthesiology & Intensive Care and.
authors: P A
authors: PA
authors: Lönnqvist
mesh_terms: D000577:Amides / Q000009:adverse effects; D000763:Anesthesia, Caudal / Q000009:adverse effects*; D000779:Anesthetics, Local / Q000009:adverse effects*; D001783:Blood Flow Velocity / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D002555:Cerebrospinal Fluid / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000502:physiology; D006552:Hernia, Inguinal / Q000601:surgery; D059685:Herniorrhaphy; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D000077212:Ropivacaine; D019265:Spectroscopy, Near-Infrared; D016683:Supine Position; D018616:Ultrasonography, Doppler, Duplex; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D010100:Oxygen
keywords: ICP (intracranial pressure) increase; anaesthesia, paediatric; anaesthetic techniques, regional, caudal; measurement techniques, ultrasound