OBJECTIVES: normal circadian rhythm of autonomic nervous system function stands for the daily change of sympathetic and parasympathetic modulation, which can be measured by heart rate variability (HRV). Generally, patients in the intensive care unit (ICU) are prone to sleep-wake cycle dysregulation, therefore, it may have an influence on the circadian rhythm of autonomic nervous system. This study was designed to interpret possible dysregulation of autonomic nervous system in ICU patients by using HRV. METHODS: HRV was assessed every 3 hours in 21 ICU patients during a 7-minute period. The statistical differences of HRV features between the morning (AM 6 : 00–PM 12 : 00), and the afternoon (PM 12 : 00–PM 18 : 00) periods were evaluated in time domain and frequency domain. RESULTS: Patients showed significantly increased normalized power of low frequencey (nLF), absolute power of low frequencey (LF)/absolute power of high frequencey (HF) in the afternoon period as compared to the morning period. However, normalized power of high frequency (nHF) was significantly decreased in the afternoon period. There was no statistically significant difference between the morning period and the afternoon period in the time domain analysis. CONCLUSIONS: The increased sympathetic tone in the afternoon period supports possible dysregulation in the circadian rhythm of autonomic nervous system in ICU patients. Future studies can help to interpret the association between autonomic dysregulation and negative outcomes of ICU patients.
Autonomic Nervous System* ; Circadian Rhythm* ; Critical Care* ; Heart Rate* ; Heart* ; Humans ; Intensive Care Units*

We analyzed the manner and cause of death in 945 forensic autopsies from the Jungbu province (Central part of South Korea) conducted by the National Forensic Service Daejeon institute in 2020. Analysis of the manner of death revealed that 43.6% (412/945 cases) were natural deaths, 41.6% (393/945 cases) were unnatural deaths, and 14.8% (140/945 cases) deaths were unknown. Among the unnatural deaths, the major manner of death (40.7%, 160/393 cases) were by accidents, 29.5% (116/393 cases) were by suicide, 21.6% (85/393 cases) were undetermined, and 8.1% (32/393 cases) were by homicide. Among the unnatural deaths, the major cause of death (42.7%, 168/393 cases) were by trauma, 19.3% (76/393 cases) were by poisoning, and 16.5% (65/393 cases) were by asphyxia. Falling was the major cause of death by trauma (42.9%, 72/168 cases) and strangulation was the major cause of death by asphyxia (72.3%, 47/65 cases). Among natural deaths, heart disease was the major cause (43.7%, 180/412 cases), followed by vascular disease (18.9%, 78/412 cases). This study is the first statistical analysis of the manner and cause of deaths in the Jungbu province. A time-series statistical analysis of the manner and cause of deaths in this province might allow more advanced interpretations about both public safety and healthcare in the future.