Comparison of effect of different drug volumes of local anaesthetic for caudal analgesia on optic nerve sheath diameter in paediatric patients undergoing elective infra umbilical surgery.

Caudal block has become one of the most popular regional anaesthesia techniques for paediatric surgeries. It is administering of a local anaesthetic into the epidural space via the sacral hiatus to achieve anaesthesia of sacral and coccygeal nerve root. Depending on the site of surgery, different volumes are chosen for caudal block procedure.

 The optic nerve is a white matter tract of the brain that transmits cerebral spinal fluid and fluctuates in size based on changes in intracranial pressure. As optic nerve is capsulated by the distensible subarachnoid space, any change of intracranial pressure would theoretically reflect on this measurement. There is increasing evidence that optic nerve sheath diameter via a well correlated parameter with intracranial pressure and has high diagnostic precision for detecting altered intracranial pressure in children. Trans-orbital sonography is one of the non-invasive method to measure optic nerve sheath diameter.

 In this study, we will compare 0.5ml/kg and 1.0ml/kg drug volume of local anaesthetic for caudal analgesia on optic nerve sheath diameter in paediatric patients from 6 months to 60 months belonging to ASA I-II undergoing elective infra-umbilical.

 The methodology and procedure of the study will be explained to the patients’ parents and informed written consent will be taken from parents. A computer generated random number table will be used allocate patients in 2 groups (Group low volume and Group high volume).

 Patients will be taken to the OT, monitors will be attached and baseline vitals noted. After preoxygenation with 100% oxygen, induction with fentanyl, propofol and muscle relaxant and intubating with LMA will be done.

 Based on allocated drug volume 0.5ml/kg or 1.0ml/kg drug volume will be taken for caudal block. A baseline optic nerve sheath diameter will be measured before giving caudal block and measured again after 1 minute, 10 minutes and 30 minutes after giving caudal block. BP, HR, end tidal carbon dioxide, end tidal sevoflurane, oxygen saturation will also be noted simultaneously.