This work develops an acquisitionalysis software application to investigate the spectral content of the heart rate variability signal derived from an electrocardiographic (EKG) waveform. The location and strength of the frequency content reveals general information concerning sympathetic and parasympathetic activity within the autonomic nervous system of the study subject. Current investigations into pediatric head trauma patients have revealed specific correlations between spectral content of the heart rate variability and overall patient recovery. The levels of serum catecholamines, specifically epinephrine and norepinephrine, are also investigated for a possible correlation with both trauma severity and spectral power of the heart rate variability signal. Two frequency regions are of particular interest in the power spectral density waveform, the low frequency band (0.01-0.15 Hz) and the high frequency band (0.15-0.50 Hz). The low frequency band is indicative of sympathetic nervous system activity (such as body temperature and arterial blood pressure regulation) as well as some parasympathetic nervous system activity. The high frequency band is indicative of parasympathetic activity (such as respiratory sinus arrhythmia) only. In fact, a prominent peak located at approximately 0.20 Hz (of a normal human adult) represents heart rate variability at the respiratory frequency. Clinical application of the acquisition and analysis techniques described herein has shown that elevated levels of low-frequency HRV power are indicative of improved chances for recovery from severe brain injury. In contrast, brain-dead pediatric head trauma patients were found to possess near-zero low-frequency power. Acute animal studies have shown that decreases in low-frequency HRV power and systemic arterial blood pressure with little change in high-frequency HRV power, may be a characteristic indicator of endotoxin-induced septic shock. The acquisitionalysis package described in this work may, therefore, prove beneficial to critical care medicine, and advance our understanding of cardiovascular neurophysiology.
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Department, Program, or Center
Mechanical Engineering (KGCOE)
DeLong, David James, "Spectral analysis of heart rate variability: Acquisitionalysis software development" (1992). Thesis. Rochester Institute of Technology. Accessed from
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