Key result
Delirium in ICU patients was not associated with altered autonomic function, with no difference in HFnu (75±7 vs 68±23) or LF:HF ratio (-0.7±1.0 vs -0.1±1.1) compared to those without delirium.
Why the study?
Does ICU delirium alter sympathovagal balance as assessed by heart rate variability?
Observational (n=25)
Does ICU delirium alter sympathovagal balance as assessed by heart rate variability?
Autonomic function, as measured by heart rate variability, does not appear to be altered in patients with ICU delirium.
Delirium shows no HRV link in ICU; hypothesis-generating for autonomic mechanisms and requires prospective confirmation.
Sympathovagal balance, assessed with heart rate variability (HRV), may be altered in intensive care unit (ICU) delirium. HRV was measured in the frequency domain [low frequencies (LF)=0.04-0.15 Hz and high frequencies (HF)=0.15-0.40 Hz] with HF in normalized units (HFnu) to evaluate parasympathetic tone and LF:HF ratio for sympathovagal balance. The authors assessed 726 ICU patients and excluded patients with conditions affecting HRV. No difference could be found between patients with (N=13) and without (N=12) delirium by comparing the mean (±standard deviation) of the HFnu (75±7 versus 68±23) and the LF:HF ratio (-0.7±1.0 versus -0.1±1.1). This study suggests that autonomic function is not altered in ICU delirium.
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Zaal et al. (2014) conducted an observational in ICU delirium (n=25). Delirium vs. No delirium was evaluated on Heart rate variability (HFnu and LF:HF ratio). Delirium in ICU patients was not associated with altered autonomic function, with no difference in HFnu (75±7 vs 68±23) or LF:HF ratio (-0.7±1.0 vs -0.1±1.1) compared to those without delirium.
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