用心率变异性谱分析法研究振动性白指患者自主神经系统对冷刺激的反应
作者：罗 进 神原久孝 朱善宽
单位：罗 进.航天医学工程研究所，北京 100094
关键词：振动性白指；心率变异性;谱分析；自主神经系统；冷应激
航天医学与医学工程990102Autonomic Nervous Response to Cold Provocation in Vibration-Induced White Finger(VWF) Patients with HRV Analysis
LUO Jin
(Institute of Space Medico-Engineering,Beijing 100094，China)
SAKAKIBARA Hisataka ZHU Shankuan
, http://www.100md.com
(School of Medicine,Nagoya University,Nagoya 466,Japan)
Abstract：Objective To evaluate the autonomic nervous response of Vibration-induced white finger(VWF) patients to cold provocation test by power spectral analysis of heart rate variability(HRV).Methods The cold provocation test was conducted in 22 VWF patients and 19 healthy volunteers.ECG was recorded during the experiment,and converted to R-R interval signals after the experiment.The normalized LF[(0.02～0.15) Hz]component power，normalized HF[(0.15～0.40) Hz] component power and the ratio of LF to HF power(LF/HF ratio) were calculated.Results At the beginning of cold exposure,there were a significant decrease of HF% in both groups,and a significant increase of LF/HF ratio in VWF group as compared with pre-exposure value.The LF/HF ratio in VWF group during cold exposure was significantly higher than that in the control group.Conclusion Cold stimuli induced depression of parasympathetic nervous system in both groups，and the sympatho-vagal balance was maintained in the control group,but in VWF group it became sympathetic dominance during cold exposure.The sympathetic nervous system of VWF patients may be hyperreactive to cold stimuli.
, 百拇医药
Key words：vibration-induced white finger(VWF)；heart rate variability；power spectral analysis;autonomic nervous system；cold stress
摘要：目的 研究振动性白指患者的自主神经系统对冷刺激的反应。方法 22名振动性白指患者(VWF组)及19名正常对照(对照组)进行了局部冷水刺激实验，记录受试者的心电信号，实验后将记录的心电信号通过处理转化为R-R间期信号，然后对这些R-R间期信号进行功率谱分析，计算标准化的LF(0.02～0.15 Hz)功量(LF%)，标准化的HF(0.15～0.40Hz)功量(HF%)，以及LF/HF比率。结果 冷暴露开始后，VWF组及对照组的HF%与暴露前的水平相比都有显著下降，VWF组的LF/HF比率与暴露前的水平相比有显著增大，而且冷暴露中VWF组的LF/HF比率显著高于对照组的相应的LF/HF比率。结论 冷刺激导致VWF组和对照组的副交感神经活动减弱，但对照组还能保持交感与副交感的平衡，而VWF组却不能保持两者平衡，交感神经活动明显占优，冷刺激中VWF组LF/HF比率明显高于对照组的LF/HF比率说明振动性白指患者的交感神经系统对冷刺激可能存在过敏反应。
, 百拇医药
中图分类号：R135.4 文献标识码：A 文章编号：1002-0837(1999)01-0006-04
Workers using hand-held vibrating tools such as chain saws，rock drills，chipping hammers，and grinders may develop various disorders of hand-arm vibration syndrome.A typical symptom of hand-arm vibration syndrome is vibration-induced white finger(VWF)[1].VWF is due to temporary occlusion of digital blood flow from spasm of the digital arteries，usually provoked by exposure to cold.The characteristic vascular pathophysiology in VWF patients is an enhanced vasospastic response to cold[2,3].One possible reason for this enhanced vasospastic response to cold is that VWF patients have an increased response of the sympathetic nervous system to cold that leads to greater vasoconstriction and ultimately spasms[4].
, 百拇医药
In recent years，a newly developed noninvasive tool，the power spectral analysis of heart rate variability(HRV)，has been used to assess the rapid change in autonomic nervous activity in response to stimuli[5].Thus，in the present study，the response of the autonomic nervous system to cold provocation test(CPT) in VWF patients will be examined by using power spectral analysis of HRV.
methods
22 VWF patients(VWF group) and 19 healthy men (control group) with an average age of (59.3±3.6)a and (59.1±4.4)a，respectively,served as subjects.The 22 VWF patients all had experienced attacks of VWF.The vibrating tools that they had used included chain saw，rock drill,etc.None of the control subjects had ever been exposed to occupational vibration.There were no significant differences in the age，weight，or height between the VWF group and the control group(Tab.1).
, http://www.100md.com
Table 1 Characteristics of subjects group
age
weight(kg)
height(cm)
VWF(n=22)
59.3±3.6
60.3±6.2
161.4±4.9
control(n=19)
59.1±4.4
62.5±8.2
, http://www.100md.com
162.6±5.5
One experiment consisted of three periods,i.e.,pre-exposure，exposure，and recovery period.In pre-exposure period，subjects rest for about 30 min.In cold exposure period，the right hand of the subject was immersed to the wrist in 10 ℃ cold water for 10 min.In recovery period，subjects recovered for 10 min.During the above three periods，subjects lay supine quietly.ECG were continuously measured and recorded during the whole experiment by ambulatory ECG recorder SM-50(Fukuda Denshi).ECG signals were converted to R-R interval signals after experiment.The power spectrum was calculated on a series of 128 s.R-R intervals algorithm was maximum entropy method.The order of model was calculated by computer according to the Akaike criterion(software by Fukuda Denshi).One series was selected in pre-exposure period.Which ended 1 min before the cold exposure.4 consecutive series were selected 0.5 min after cold exposure period.Similarly，4 consecutive series were selected 1 min after the exposure during the recovery period.
, 百拇医药
In this study，the low-frequency component of the R-R interval power spectrum was 0.02～0.15 Hz,and the high-frequency component was 0.15～0.40 Hz.The normalized LF and HF component(LF% and HF%) were obtained by dividing the power of a given component by the total variance and multiplied by 100.The HF% reflects parasympathtic activity，and LF% reflect both the sympathetic and parasympathetic activities.The LF/HF ratio measures the sympatho-vagal balance[5].
, http://www.100md.com For statistical analysis,Wilcoxon non-parametric test was employed and P values below 0.05 were considered significant.
Results
Results of LF%，HF%，and LF/HF ratio of VWF group and control group before，during，and after cold exposure were shown in Fig.1～3.It can be seen that LF% in both group fluctuated around its pre-exposure value during and after cold exposure.There was a significant decrease of HF% after cold exposure in both group as compared with that before exposure.
, 百拇医药
Fig.1 LF% in VWF group and control group
Fig.2 HF% in VWF group and control group
+：P<0.05 compared with pre-exposure levels
Fig.3 LF/HF ratio in VWF group and control
+：P<0.05 compared with pre-exposure level；
*+：P<0.05 compared with control
, http://www.100md.com
Although LF/HF ratio in VWF group or control group were almost the same in pre-exposure period,the LF/HF ratio of VWF group increased rapidly after cold exposure and reached its peak value,then decreased gradually to its initial value in recovery period.But that of control group did not show significant changes during the whole cold exposure period.
Discussion
There have been several studies in using the HRV power spectral analysis to examine the autonomic nervous function of VWF patients.Heinonen et al found‘frequency related power' shifted among forestry workers exposed to hand-arm vibration by heart rate power spectral analysis[6].Murata et al separated the power spectrum of R-R interval into two components.One component was at the center frequency of about 0.3 Hz and the other was at about 0.1 Hz.The powers of these two components were used to evaluate the sympathetic and parasympathetic activities in workers exposed to hand-arm vibration[7].In the above studies，power spectral analysis was made on the R-R interval data during the resting state or deep breathing state.The response of autonomic nervous system to cold exposure has not been reported.
, 百拇医药
The HRV power spectral analysis was first used in the present study to examine the response of autonomic nervous system to cold provocation test in VWF patients.The results of HRV spectral analysis in this study showed that the response of autonomic nervous system to CPT was different between VWF group and control group.Before cold exposure，there were no significant differences in LF%，HF%，and LF/HF ratio between VWF group and control group.The decrease of HF% during cold exposure in both groups,indicated that the parasympathtic nervous system in VWF patients and controls was depressed.LF/HF ratio in control group did not have any significant change during cold exposure.However，in VWF group，it increased significantly.The above findings indicated that although cold exposure induced the depression of parasympathetic nervous system in both VWF patients and healthy controls，the sympatho-vagal balance in control group was maintained during cold exposure，while the balance in VWF group was not maintained and had shifted to relatively sympathetic dominance.The higher LF/HF ratio during cold exposure in VWF group compared to that in controls implied that the sympathetic nervous system of VWF patients may be hyperreactive to cold stimuli.
, 百拇医药
It has been reported that exposure to hand-arm vibration induces vasoconstriction and subsequent decrease in skin temperature and blood flow in the finger.These responses are mediated through the sympathetic nervous system.These responses can occur not only in the vibration exposed hand but also in the unexposed hands,even in the feet[8].Recent microneurographic techniques directly measuring skin sympathetic nerve activity from the median nerve and the tibial nerve have revealed that vibration evokes an increase in sympathetic activity in the nerves supplying the hands and feet,which is composed of vasoconstrictor impulses，and then induces vasoconstriction in the hands and feet[9].Increasing vibration intensity evokes greater skin sympathetic nerve activity and leads to larger reduction in blood flow[10].It was also found that acute exposure to vibration also increased plasma norepinephrine[11].Thus，it seems likely that long term exposure of hand-arm system to vibration could develop the hyperreactive of the sympathetic nervous system[11].
, 百拇医药
It was also found in the present study that in VWF group the level of HF% and LF/HF ratio gradually returned to their pre-exposure level after their rapid changes in 2～3 min of cold exposure.This may be due to the reason that immersion of one hand in 10℃ water may not sufficiently stimulate the sympathetic nervous system.Nakamoto[12] compared two kinds of cold exposure tests in his study: the immersion of one hand in 5℃ water for 10 min and 10℃ cold air exposure of the whole body for 30 min.He found that the level of plasma norepinephrine decreased after 5 min in the cold water immersion test but a high level was continuously maintained during cold air exposure.It was then suggested that cold air exposure of the whole body activated the sympathetic nervous system more greatly than one-hand immersion in cold water did.Thus，in our future study，the response of autonomic nervous system of VWF patients to cold air exposure should also be investigated.
, 百拇医药
[References]
[1] Griffin MJ.Handbook of human vibration[M].London:Academic Press,1990:553～593
[2] Yamada S，Suzuki H，Maeda K et al.Skin temperature of the finger and value of nail press test under various environmental conditions in persons affected by vibration hazards[J].J Sci Labor，1979,50:439～450
[3] Sakakibara H，Hashiguchi T，Furuta M et al.Circulatory disturbances of the foot in vibration syndrome[J].Int Arch Occup Environ Health,1991,63:145～148
, 百拇医药
[4] Olsen N，Fjeldborg P，Brochner-Mortensen J.Sympathetic and local vasoconstrictor response to cold in vibration induced white finger[J].Br J Ind Med,1985，42:272～275
[5] Ori Z，Monir G，Weiss J et al.Heart rate variability-Frequency domain analysis[J].Cardiology Clinics,1992，10:499～537
[6] Heinonen E，Farkkila M，Forsstrom J et al.Autonomic neuropath and vibration exposure in forestry workers[J].Br J Ind Med,1987，44:412～416
, 百拇医药
[7] Murata K，Araki S，Maeda K.Autonomic and peripheral nervous system dysfunction in workers exposed to hand-arm vibration: a study of R-R interval variability and distribution of nerve conduction velocities[J].Int Arch Occup Health,1991，63:205～211
[8] Egan CE，Espie BH,McGrann S et al.Acute effects of vibration on peripheral blood flow in healthy subjects[J].Occup Environ Med,1996，53:663～669
[9] Sakakibara H,Iwase S，Mano T et al.Skin sympathetic activity in the tibial nerve trigged by vibration applied to the hand[J].Int Arch Occup Environ Health,1990，62:455～458
, 百拇医药
[10] Mano T.Autonomic response to environmental stimuli in human body[J].Nagoya J Med Sci,1994，57 Suppl:59～75
[11] Harada N.Autonomic nervous function of hand-arm vibration syndrome patients[J].Nagoya J Med Sci,1994，57 Suppl:77～85
[12] Nakamoto M.Response of sympathetic nervous system to cold exposure in vibration syndrome subjects and age-matched healthy controls[J].Int Arch Occup Environ Health,1990，62:177～181
Recieved date:April 13,1998, 百拇医药
单位：罗 进.航天医学工程研究所，北京 100094
关键词：振动性白指；心率变异性;谱分析；自主神经系统；冷应激
航天医学与医学工程990102Autonomic Nervous Response to Cold Provocation in Vibration-Induced White Finger(VWF) Patients with HRV Analysis
LUO Jin
(Institute of Space Medico-Engineering,Beijing 100094，China)
SAKAKIBARA Hisataka ZHU Shankuan
, http://www.100md.com
(School of Medicine,Nagoya University,Nagoya 466,Japan)
Abstract：Objective To evaluate the autonomic nervous response of Vibration-induced white finger(VWF) patients to cold provocation test by power spectral analysis of heart rate variability(HRV).Methods The cold provocation test was conducted in 22 VWF patients and 19 healthy volunteers.ECG was recorded during the experiment,and converted to R-R interval signals after the experiment.The normalized LF[(0.02～0.15) Hz]component power，normalized HF[(0.15～0.40) Hz] component power and the ratio of LF to HF power(LF/HF ratio) were calculated.Results At the beginning of cold exposure,there were a significant decrease of HF% in both groups,and a significant increase of LF/HF ratio in VWF group as compared with pre-exposure value.The LF/HF ratio in VWF group during cold exposure was significantly higher than that in the control group.Conclusion Cold stimuli induced depression of parasympathetic nervous system in both groups，and the sympatho-vagal balance was maintained in the control group,but in VWF group it became sympathetic dominance during cold exposure.The sympathetic nervous system of VWF patients may be hyperreactive to cold stimuli.
, 百拇医药
Key words：vibration-induced white finger(VWF)；heart rate variability；power spectral analysis;autonomic nervous system；cold stress
摘要：目的 研究振动性白指患者的自主神经系统对冷刺激的反应。方法 22名振动性白指患者(VWF组)及19名正常对照(对照组)进行了局部冷水刺激实验，记录受试者的心电信号，实验后将记录的心电信号通过处理转化为R-R间期信号，然后对这些R-R间期信号进行功率谱分析，计算标准化的LF(0.02～0.15 Hz)功量(LF%)，标准化的HF(0.15～0.40Hz)功量(HF%)，以及LF/HF比率。结果 冷暴露开始后，VWF组及对照组的HF%与暴露前的水平相比都有显著下降，VWF组的LF/HF比率与暴露前的水平相比有显著增大，而且冷暴露中VWF组的LF/HF比率显著高于对照组的相应的LF/HF比率。结论 冷刺激导致VWF组和对照组的副交感神经活动减弱，但对照组还能保持交感与副交感的平衡，而VWF组却不能保持两者平衡，交感神经活动明显占优，冷刺激中VWF组LF/HF比率明显高于对照组的LF/HF比率说明振动性白指患者的交感神经系统对冷刺激可能存在过敏反应。
, 百拇医药
中图分类号：R135.4 文献标识码：A 文章编号：1002-0837(1999)01-0006-04
Workers using hand-held vibrating tools such as chain saws，rock drills，chipping hammers，and grinders may develop various disorders of hand-arm vibration syndrome.A typical symptom of hand-arm vibration syndrome is vibration-induced white finger(VWF)[1].VWF is due to temporary occlusion of digital blood flow from spasm of the digital arteries，usually provoked by exposure to cold.The characteristic vascular pathophysiology in VWF patients is an enhanced vasospastic response to cold[2,3].One possible reason for this enhanced vasospastic response to cold is that VWF patients have an increased response of the sympathetic nervous system to cold that leads to greater vasoconstriction and ultimately spasms[4].
, 百拇医药
In recent years，a newly developed noninvasive tool，the power spectral analysis of heart rate variability(HRV)，has been used to assess the rapid change in autonomic nervous activity in response to stimuli[5].Thus，in the present study，the response of the autonomic nervous system to cold provocation test(CPT) in VWF patients will be examined by using power spectral analysis of HRV.
methods
22 VWF patients(VWF group) and 19 healthy men (control group) with an average age of (59.3±3.6)a and (59.1±4.4)a，respectively,served as subjects.The 22 VWF patients all had experienced attacks of VWF.The vibrating tools that they had used included chain saw，rock drill,etc.None of the control subjects had ever been exposed to occupational vibration.There were no significant differences in the age，weight，or height between the VWF group and the control group(Tab.1).
, http://www.100md.com
Table 1 Characteristics of subjects group
age
weight(kg)
height(cm)
VWF(n=22)
59.3±3.6
60.3±6.2
161.4±4.9
control(n=19)
59.1±4.4
62.5±8.2
, http://www.100md.com
162.6±5.5
One experiment consisted of three periods,i.e.,pre-exposure，exposure，and recovery period.In pre-exposure period，subjects rest for about 30 min.In cold exposure period，the right hand of the subject was immersed to the wrist in 10 ℃ cold water for 10 min.In recovery period，subjects recovered for 10 min.During the above three periods，subjects lay supine quietly.ECG were continuously measured and recorded during the whole experiment by ambulatory ECG recorder SM-50(Fukuda Denshi).ECG signals were converted to R-R interval signals after experiment.The power spectrum was calculated on a series of 128 s.R-R intervals algorithm was maximum entropy method.The order of model was calculated by computer according to the Akaike criterion(software by Fukuda Denshi).One series was selected in pre-exposure period.Which ended 1 min before the cold exposure.4 consecutive series were selected 0.5 min after cold exposure period.Similarly，4 consecutive series were selected 1 min after the exposure during the recovery period.
, 百拇医药
In this study，the low-frequency component of the R-R interval power spectrum was 0.02～0.15 Hz,and the high-frequency component was 0.15～0.40 Hz.The normalized LF and HF component(LF% and HF%) were obtained by dividing the power of a given component by the total variance and multiplied by 100.The HF% reflects parasympathtic activity，and LF% reflect both the sympathetic and parasympathetic activities.The LF/HF ratio measures the sympatho-vagal balance[5].
, http://www.100md.com For statistical analysis,Wilcoxon non-parametric test was employed and P values below 0.05 were considered significant.
Results
Results of LF%，HF%，and LF/HF ratio of VWF group and control group before，during，and after cold exposure were shown in Fig.1～3.It can be seen that LF% in both group fluctuated around its pre-exposure value during and after cold exposure.There was a significant decrease of HF% after cold exposure in both group as compared with that before exposure.
, 百拇医药
Fig.1 LF% in VWF group and control group
Fig.2 HF% in VWF group and control group
+：P<0.05 compared with pre-exposure levels
Fig.3 LF/HF ratio in VWF group and control
+：P<0.05 compared with pre-exposure level；
*+：P<0.05 compared with control
, http://www.100md.com
Although LF/HF ratio in VWF group or control group were almost the same in pre-exposure period,the LF/HF ratio of VWF group increased rapidly after cold exposure and reached its peak value,then decreased gradually to its initial value in recovery period.But that of control group did not show significant changes during the whole cold exposure period.
Discussion
There have been several studies in using the HRV power spectral analysis to examine the autonomic nervous function of VWF patients.Heinonen et al found‘frequency related power' shifted among forestry workers exposed to hand-arm vibration by heart rate power spectral analysis[6].Murata et al separated the power spectrum of R-R interval into two components.One component was at the center frequency of about 0.3 Hz and the other was at about 0.1 Hz.The powers of these two components were used to evaluate the sympathetic and parasympathetic activities in workers exposed to hand-arm vibration[7].In the above studies，power spectral analysis was made on the R-R interval data during the resting state or deep breathing state.The response of autonomic nervous system to cold exposure has not been reported.
, 百拇医药
The HRV power spectral analysis was first used in the present study to examine the response of autonomic nervous system to cold provocation test in VWF patients.The results of HRV spectral analysis in this study showed that the response of autonomic nervous system to CPT was different between VWF group and control group.Before cold exposure，there were no significant differences in LF%，HF%，and LF/HF ratio between VWF group and control group.The decrease of HF% during cold exposure in both groups,indicated that the parasympathtic nervous system in VWF patients and controls was depressed.LF/HF ratio in control group did not have any significant change during cold exposure.However，in VWF group，it increased significantly.The above findings indicated that although cold exposure induced the depression of parasympathetic nervous system in both VWF patients and healthy controls，the sympatho-vagal balance in control group was maintained during cold exposure，while the balance in VWF group was not maintained and had shifted to relatively sympathetic dominance.The higher LF/HF ratio during cold exposure in VWF group compared to that in controls implied that the sympathetic nervous system of VWF patients may be hyperreactive to cold stimuli.
, 百拇医药
It has been reported that exposure to hand-arm vibration induces vasoconstriction and subsequent decrease in skin temperature and blood flow in the finger.These responses are mediated through the sympathetic nervous system.These responses can occur not only in the vibration exposed hand but also in the unexposed hands,even in the feet[8].Recent microneurographic techniques directly measuring skin sympathetic nerve activity from the median nerve and the tibial nerve have revealed that vibration evokes an increase in sympathetic activity in the nerves supplying the hands and feet,which is composed of vasoconstrictor impulses，and then induces vasoconstriction in the hands and feet[9].Increasing vibration intensity evokes greater skin sympathetic nerve activity and leads to larger reduction in blood flow[10].It was also found that acute exposure to vibration also increased plasma norepinephrine[11].Thus，it seems likely that long term exposure of hand-arm system to vibration could develop the hyperreactive of the sympathetic nervous system[11].
, 百拇医药
It was also found in the present study that in VWF group the level of HF% and LF/HF ratio gradually returned to their pre-exposure level after their rapid changes in 2～3 min of cold exposure.This may be due to the reason that immersion of one hand in 10℃ water may not sufficiently stimulate the sympathetic nervous system.Nakamoto[12] compared two kinds of cold exposure tests in his study: the immersion of one hand in 5℃ water for 10 min and 10℃ cold air exposure of the whole body for 30 min.He found that the level of plasma norepinephrine decreased after 5 min in the cold water immersion test but a high level was continuously maintained during cold air exposure.It was then suggested that cold air exposure of the whole body activated the sympathetic nervous system more greatly than one-hand immersion in cold water did.Thus，in our future study，the response of autonomic nervous system of VWF patients to cold air exposure should also be investigated.
, 百拇医药
[References]
[1] Griffin MJ.Handbook of human vibration[M].London:Academic Press,1990:553～593
[2] Yamada S，Suzuki H，Maeda K et al.Skin temperature of the finger and value of nail press test under various environmental conditions in persons affected by vibration hazards[J].J Sci Labor，1979,50:439～450
[3] Sakakibara H，Hashiguchi T，Furuta M et al.Circulatory disturbances of the foot in vibration syndrome[J].Int Arch Occup Environ Health,1991,63:145～148
, 百拇医药
[4] Olsen N，Fjeldborg P，Brochner-Mortensen J.Sympathetic and local vasoconstrictor response to cold in vibration induced white finger[J].Br J Ind Med,1985，42:272～275
[5] Ori Z，Monir G，Weiss J et al.Heart rate variability-Frequency domain analysis[J].Cardiology Clinics,1992，10:499～537
[6] Heinonen E，Farkkila M，Forsstrom J et al.Autonomic neuropath and vibration exposure in forestry workers[J].Br J Ind Med,1987，44:412～416
, 百拇医药
[7] Murata K，Araki S，Maeda K.Autonomic and peripheral nervous system dysfunction in workers exposed to hand-arm vibration: a study of R-R interval variability and distribution of nerve conduction velocities[J].Int Arch Occup Health,1991，63:205～211
[8] Egan CE，Espie BH,McGrann S et al.Acute effects of vibration on peripheral blood flow in healthy subjects[J].Occup Environ Med,1996，53:663～669
[9] Sakakibara H,Iwase S，Mano T et al.Skin sympathetic activity in the tibial nerve trigged by vibration applied to the hand[J].Int Arch Occup Environ Health,1990，62:455～458
, 百拇医药
[10] Mano T.Autonomic response to environmental stimuli in human body[J].Nagoya J Med Sci,1994，57 Suppl:59～75
[11] Harada N.Autonomic nervous function of hand-arm vibration syndrome patients[J].Nagoya J Med Sci,1994，57 Suppl:77～85
[12] Nakamoto M.Response of sympathetic nervous system to cold exposure in vibration syndrome subjects and age-matched healthy controls[J].Int Arch Occup Environ Health,1990，62:177～181
Recieved date:April 13,1998, 百拇医药