PhD Scientific Days 2025

Health Sciences I.

Impact of Sedation on Circadian Rhythms in Mechanically Ventilated Children

Name of the presenter

Kriel Christopher

Institute/workplace of the presenter

Semmelweis Pediatrics Department Tuzolto Street

Authors

Christopher Kriel¹, Petra Pomlényi¹

1: Semmelweis Pediatrics Department Tuzolto Street

Text of the abstract

Introduction
Sleep and circadian rhythms are well-studied in adult ICUs, yet remain underexplored in pediatric ICUs (PICUs). Mechanically ventilated children often receive high doses of sedatives for comfort and ventilator synchrony, but these may disrupt circadian rhythms and impair recovery.

Aim
To examine the impact of commonly used sedatives on circadian rhythms in PICUs, using 6-sulfatoxymelatonin excretion and activity levels as markers.

Methodology
As part of an ongoing cohort study on sleep and circadian rhythms in PICUs, we analyzed data from 25 ventilated children: 18 had ≥2 days of melatonin data, and 24 had ≥2 days of actigraphy data post-extubation. Urine was collected every 6 hours and analyzed via ELISA for 6-sulfatoxymelatonin. Mixed-effect cosinor analysis was used to assess melatonin rhythmicity. Actigraphy was recorded with Empatica E4 devices and processed using the mean activity difference method to compute Daytime Activity Ratio (DARE). Sedation doses were extracted from medical records; children were classified into high/low dose groups by median splits for opioids and midazolam. Beta regression assessed sedation effects.

An extended DARE analysis included 51 children (32 ventilated, 19 controls), with beta regression controlling for age, PICU stay, and illness severity.

Results
High-dose midazolam (>6.9 mg/kg) was linked to significant melatonin acrophase delays (p = .044), especially in children intubated >4 days (p = .05). Opioids showed no significant effect. A trend toward delayed acrophase was seen in children under 3 compared to older peers (p = .058).

DARE analysis showed no significant differences between high and low sedation groups. However, in the larger cohort (N = 51), a trend toward reduced daytime activity was noted in ventilated children versus controls (β = –0.203, p = .067), suggesting possible circadian disruption.

Conclusion
Preliminary findings suggest high-dose midazolam may shift melatonin peaks to afternoon hours, disrupting circadian rhythm. Activity-based metrics also indicate reduced daytime activity post-ventilation, though not statistically significant. These findings merit further investigation.


chris.kriel2@gmail.com
Semmelweis University
Supervisor: Dr Klara Horvath