Objective: To evaluate the autonomic nervous system function in chronic renal failure patients compared to normal control and to assess the effect of dialysis method and underlying diseases such as diabetes mellitus and hypertension, on autonomic nervous system function in chronic renal failure patients.

Method: We checked palm and sole skin temperature with digital thermometer, sympathetic skin responses and heart rate variability in chronic renal failure patients (77 persons) and normal control group (77 persons).

Results: The amplitude of sympathetic skin response (SSR) and heart rate variability (RRIV) of patients group showed statistically significant difference compared to control group (p＜0.05). The diabetic patient group with chronic renal failure showed prolonged latency of SSR in sole but significant differences were shown in amplitude and RRIV (p＜0.05). The hypertensive group with chronic renal failure showed prolonged latency of SSR in both palm and sole (p＜0.05) but the amplitude and RRIV of those didn,t show statistical difference (p＞0.05). CRF without diabetes mellitus and hypertension showed significant difference on amplitude of SSR and RRIV (p＜0.05) but autonomic nervous system function tests showed no difference (p＞0.05) between hemodialysis and peritoneal dialysis groups.

Conclusion: SSR test and RRIV could be valuable measure to evaluate autonomic nervous system functions in the patients with chronic renal failure.

Objective: To investigate the autonomic activities in spinal cord injured patients, and to compare their activities according to the level and completeness of spinal cord lesions.

Method: Thirty-five spinal cord injured patients and thirty healthy adults participated in this study. The ECG signals were recorded at the tilt angle of 0^o and 70^o for 5 minutes, and power spectral analysis of Heart Rate Variability (HRV) was done at each angle.

Results: The data reveals two major components such as a low-frequency (LF) component (0.05∼0.15 Hz) reflecting primarily sympathetic activities with orthostatic stress, and a high- frequency (HF) component (0.2∼0.3 Hz) reflecting parasympathetic activity. In supine position, all frequency components were not significantly different regardless the level and completeness of spinal cord lesion. At 70^o head-up tilt position, the LF power and heart rate didn't increase in complete tetraplegia but significantly increased in paraplegia and healthy adults (p＜0.05). However, the HF power didn't reveal any differences in four groups by decreasing significantly in all groups.

Conclusion: We concluded that there is an abnormal control of autonomic activities especially the sympathetic function in complete tetraiplegia, compared with paraplegia and healthy adults.

Objective: The aims of this study were to know the effects of long time bed immobilization on the heart rate variability and to know the correlation between the heart rate variability and other anthropometric parameters.

Method: The subjects of this study were 60 normal sedentary persons as control group and 22 patients who had been immobilized for a long time because of musculoskeletal problems without any systemic diseases. The heart rate variabilities were measured through the R-R interval variation at rest, deep breathing and valsalva maneuver. These values were compared between control and patient group and were analysed for correlation with age, weight, height, body mass index (BMI), amounts of smoking (pack years), spans of immobilization and physical activity scale (PAS).

Results: The mean heart rate variability of patients were 0.132⁑0.072, 0.216⁑0.109, and 0.289⁑0.171 in rest, deep breathing and valsalva maneuver respectively which were lower than the corresponding 0.176⁑0.085, 0.314⁑0.146, and 0.322⁑0.174 of normal control group. The heart rate variabilities were negatively correlated with age, BMI and amounts of smoking but positively correlated with the height. The physical activity scale of preimmobilization state was negatively correlated with resting heart rate variability but was positively correlated with heart rate variability during deep breathing and valsalva maneuvering state.

Conclusion: The long bed immobilization significantly decreased the heart rate variability and the heart rate variability could be used as a useful tool to measure the effects of immobilization on the heart.

Objective: To evaluate the effects of orthostatic stress with a head-up tilt on the autonomic nervous system and to determine how a cerebral stroke influences the cardiac autonomic function, using the power spectral analysis(PSA) of heart rate variability(HRV).

Method: We studied 11 stroke patients with a left hemiplegia and 14 patients with a right hemiplegia. Their hemispheric brain lesions were confirmed by the MRI. The ECG and respiration signals were recorded at the tilt angle of 0^o and 70^o for 5 minutes under the condition of frequency controlled respirtaion(0.25 Hz). Data were compared with the age- and sex-matched 12 healthy controls.

Result: In a control group, the normalized high frequency power showed a significant decrease during the head-up tilt(p＜0.05), whereas the normalized low frequency power showed a significant increase(p＜0.05). But for the left and right hemiplegia groups, there were no significant changes of normalized high and low frequency power under the orthostatic stress(p＞0.05). Compared with the right hemiplegia and control groups, the left hemiplegia group was associated more with a reduced low and high frequency power and showed no significant changes under the orthostatic stress.

Conclusion: PSA of HRV can identify the reduced cardiac autonomic activity in stroke patients, with a greater reduction in the left hemiplegia group than in the right hemiplegia group, which may cause a high risk of cardiac arrhythmias and sudden death.

The powers of the low-frequency(LF) and high-frequency(HF) components characterizing heart rate variability (HRV) appear to reflect, in their reciprocal relationship, changes in the state of the sympatho-vagal balance occurring during orthostatic stress with head-up tilt.

We studied 24 healthy volunteers (median age, 23.1 years) who were subjected after a rest period to a series of passive head-up tilt steps chosen from the following angles: 0⁰. 15⁰, 30⁰, 45⁰, 70⁰, and 90⁰ under the condition of frequency controlled respiration(0.25Hz) in order to get data of the Korean young adults.

During head-up tilt, heart rate and normalized low frequency power(LF_N : 0.05∼0.15 Hz) of HRV showed significant increase(p=0.000), but normalized high frequency power(HF_N : 0.2∼0.3 Hz) and total power showed progressive decrease(p=0.000, p＜0.01 respectively). Male showed significantly higher LF_N and lower HF_N than female at tilt table angle 0⁰(p＜0.01).

Power spectral analysis of HRV appears to be capable of providing a noninvasive quantitatibve evaluation of graded changes in the state of the sympatho-vagal balance.