Objective:

To evaluate the effect of injection speed on optic nerve sheath diameter (ONSD) changes during caudal block in children.

Key Findings:

• At 10 minutes post-injection, ONSD was significantly higher in the high-speed group (4.73 ± 0.43 mm) compared to the low-speed group (4.52 ± 0.35 mm, P = 0.027).
• At 20 minutes post-injection, ONSD was significantly higher in the low-speed group (4.73 ± 0.57 mm) compared to the high-speed group (4.49 ± 0.42 mm, P = 0.010).
• Both groups showed significant increases in ONSD from baseline onward (P < 0.05), without returning to baseline by 40 minutes.
• A significant time-by-group interaction (P < 0.001) indicated different temporal patterns of ONSD changes between groups.
• No significant differences in mean arterial pressure, heart rate, or end-tidal carbon dioxide were observed at any time point (P > 0.05).

Interpretation:

Limitations:

• The study only included children aged 1–3 years, limiting generalizability to other age groups.
• The sample size may not be sufficient to detect rare adverse events.

Conclusion: