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Critical Care |

Circadian Rhythms of Melatonin in Intensive Care Unit Patients: Relationships With Delirium

Shirley Jones*, MD; Rhonda Wardlow, AAS; Heath White, DO; Angela Hochhalter, PhD; Alan Stevens, PhD; Chanhee Jo, PhD; Phyllis Zee, MD; David Earnest, PhD; Alejandro Arroliga, MD
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Scott and White Healthcare/Texas A&M Health Science Center, Temple, TX


Chest. 2012;142(4_MeetingAbstracts):369A. doi:10.1378/chest.1382991
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Abstract

SESSION TYPE: Neuro Critical Care

PRESENTED ON: Tuesday, October 23, 2012 at 04:30 PM - 05:45 PM

PURPOSE: Delirium is a frequent complication in intensive care unit (ICU) patients and alterations in circadian rhythms may have a role. Melatonin is a marker of circadian rhythmicity and peaks around 4:00 am. Evidence suggests that ICU patients have irregular circadian rhythms but no studies address a link between circadian rhythms and ICU delirium.

METHODS: We performed a prospective observational study of 45 subjects admitted to the ICU with an expected stay of >48 hours. Excluded subjects had history of dementia, mental retardation, alcohol intoxication or withdrawal, infectious encephalopathy, stroke, active psychosis, suspicion of seizures, end stage renal or liver disease. Demographics, urinary samples for 6-sulphatoxymelatonin every three hours and delirium assessments twice daily were collected. Circadian rhythms of melatonin were determined using a Lomb-Scargle Fourier Transform analysis. A least-square fitting of the data was applied with a sinusoidal parametric function. Through regression analysis, the period was extracted. Peak melatonin levels between 2-6 am were accepted as normal.

RESULTS: 80% of subjects experienced delirium at least once (Ever delirium) versus 20% who did not (Never delirium). A single peak of melatonin occurred in 35/36 Ever delirium subjects and in 6/9 Never delirium subjects. While more Ever delirious subjects had peaks outside the normal time, (63% vs. 50%) in the first 24 hours, the opposite was true in the second 24 hours (58% vs. 100%). Over 48 hours, more subjects had peak melatonin levels outside of the normal time regardless of delirium. Peak melatonin between 2-6 am did not correlate with delirium (p= 0.45). In subjects with 48 hours of data, a greater range in period was observed in Ever delirious subjects (17.8 hours to 31.8 hours) compared to Never delirious (24.2 hours to 27.9 hours) but the small sample size limits its interpretation.

CONCLUSIONS: The timing of peak melatonin level does not correlate with ICU delirium.

CLINICAL IMPLICATIONS: ICU delirium does not appear to be related to alterations in the circadian rhythm of melatonin.

DISCLOSURE: The following authors have nothing to disclose: Shirley Jones, Rhonda Wardlow, Heath White, Angela Hochhalter, Alan Stevens, Chanhee Jo, Phyllis Zee, David Earnest, Alejandro Arroliga

No Product/Research Disclosure Information

Scott and White Healthcare/Texas A&M Health Science Center, Temple, TX

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