Related Experiment Video
Updated: Aug 6, 2025
Paired Cisterna Magna Nanoinjection and Laser Speckle Contrast Imaging Assay to Study Cerebral Blood Flow Regulation In Vivo
Published on: July 8, 2025
Effect of paediatric caudal injection volume on optic nerve sheath diameter and regional cerebral oximetry: A
Aybike Onur Gönen1, Güner Kaya, Ayşe Çiğdem Tütüncü
1From the Department of Anaesthesiology and Intensive Care (AOG, GK, AÇT, PK) and Department of Paediatric Surgery, Cerrahpasa Medical Faculty, Istanbul University - Cerrahpasa, Fatih/İstanbul, Türkiye (RÖ, SE).
Background:
Caudal injections commonly used for neuraxial anaesthesia in children can displace cerebrospinal fluid cranially causing safety concerns in terms of raised intracranial pressure. Optic nerve sheath diameter (ONSD) is a noninvasive surrogate for the measurement of intracranial pressure. Regional cerebral oximetry (CrSO 2 ) can monitor brain oxygenation, which may decrease by a reduction in cerebral flow due to increased intracranial pressure.
Objectives:
Comparing how caudal injection volumes of 0.8 and 1.25 ml kg -1 influence ONSD and CrSO 2 within the first 30 min after injection.
Design:
Prospective, randomised and parallel group trial.
Setting:
Operating room.
Patients:
Fifty-eight elective paediatric surgical patients between ages 1 and 7 years old, ASA class I or II, without previous intracranial or ocular pathology and surgery appropriate for single - shot caudal anaesthesia.
Intervention:
Single-shot caudal anaesthesia with 0.8 ml kg -1 (group L, n = 29) and 1.25 ml kg -1 (group H, n = 29) of 2 mg kg -1 bupivacaine solution.
Main Outcome Measures:
Optic nerve sheath diameter measured with ultrasonography and regional cerebral oximetry measured by near - infrared spectroscopy before (NIRS), immediately after, 10, 20 and 30 min after the block.
Results:
Mean ONSD values increased from a baseline of 4.4 ± 0.2 mm to a maximum of 4.5 ± 0.2 mm 20 min after injection in group L and from a baseline of 4.5 ± 0.3 mm to a maximum of 4.8 ± 0.3 mm 10 min after injection in group H. Eight of 29 patients in group H and none in group L had an ONSD increase by more than 10%. Both groups had a reduction of less than 2.5% in CrSO 2 .
Conclusion:
Caudal injection with 1.25 ml kg -1 increased ONSD, an indirect measurement of ICP, more than 0.8 ml kg -1 and neither volume caused a clinically important reduction in CrSO 2 .
Trial Registration:
ClinicalTrials.gov Identifier: NCT04491032.
