Impact of valsalva maneuver duration on brain function in patients undergoing high-intensity focused ultrasound liver ablation: a randomized controlled trial.

Summary

In a three-arm RCT of 153 patients undergoing HIFU under general anesthesia, Valsalva episodes >5.2 minutes markedly increased EEG burst suppression (66.7%) versus short VM (30.8%) or control (2.0%). Long VM also increased emergence agitation and worsened QoR-15, while delirium differences were not statistically significant. Findings support limiting VM duration per episode to ≤5.2 minutes to mitigate neurophysiologic stress.

Key Findings

• Burst suppression rates increased from 2.0% (control) to 30.8% (≤5.2 min VM) and 66.7% (>5.2 min VM); p<0.001.
• Long VM reduced alpha/beta power and increased permutation entropy versus control, indicating cortical depression.
• Emergence agitation was highest with long VM (64.7%) and QoR-15 scores were lowest; delirium differences were not significant.

Clinical Implications

Limit Valsalva episodes to ≤5.2 minutes when feasible; anticipate agitation after prolonged VM and consider EEG-guided titration to avoid burst suppression. Coordinate with proceduralists to segment VM requests and allow recovery periods.

Limitations

• Single procedural context (HIFU for liver cancer) may limit generalizability
• Delirium differences were underpowered (low event rates); EEG used 4-channel monitoring

Future Directions

Validate VM time thresholds across surgeries; integrate continuous EEG-guided protocols; study hemodynamic-cerebral coupling during VM to refine safe practice windows.