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EEG response to a high volume (1.5 mL/kg) caudal block in infants less than 3 months
  1. Paul Castillo1,
  2. Sampsa Vanhatalo2,
  3. Marit Lundblad1,
  4. Mats Blennow3 and
  5. P A Lonnqvist1
  1. 1 Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
  2. 2 Neurosciences, Helsinki University Central Hospital, Helsinki, Finland
  3. 3 Women and Child Health, Karolinska Institute, Stockholm, Sweden
  1. Correspondence to Dr Paul Castillo, Department of Physiology and Pharmacology, Karolinska Institute, Stockholm 17177, Sweden; paul.castillo{at}


Introduction The substantial compression of the dural sac and the subsequent cranial shift of cerebrospinal fluid caused by a high-volume caudal block has been shown to significantly but transiently reduce cerebral blood flow. The aim of the present study was to determine whether this reduction in cerebral perfusion is significant enough to alter brain function, as assessed by electroencephalography (EEG).

Methods Following ethics approval and parental informed consent, 11 infants (0–3 months) scheduled to undergo inguinal hernia repair were included in the study. EEG electrodes (using nine electrodes according to the 10–20 standard) were applied following anesthesia induction. Following a 5 min baseline period, a caudal block was performed (1.5 mL/kg), whereafter the EEG, hemodynamic, and cerebral near-infrared spectroscopy responses were followed during a 20 min observation period that was divided into four 5 min segments. Special attention was given to alterations in delta power activity since this may indicate cerebral ischemia.

Results All 11 infants displayed transient EEG changes, mainly represented by increased relative delta power, during the initial 5–10 min postinjection. The observed changes had returned close to baseline values 15 min postinjection. Heart rate and blood pressure remained stable throughout the study.

Conclusion A high-volume caudal block appears to increase intracranial pressure, thereby reducing cerebral blood flow, to the extent that it transiently will affect cerebral function as assessed by EEG (increased delta power activity) in approximately 90% of small infants.

Trial registration number ACTRN12620000420943.

  • Anesthesia, Conduction
  • Drug-Related Side Effects and Adverse Reactions
  • Pediatrics

Data availability statement

Data are available on reasonable request.

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  • Contributors PC: iInclusion of patients, data acquisition, data analyses including statistics, manuscript writing. SV: data analysis, manuscript writing. ML: study supervision, manuscript input. MB: study design. PAL: study idea, study design, study supervision, manuscript writing, guarantor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.