Autonomic Modulation After Spinal Anesthesia With Depth of Anesthesia and Vital Signs.

Study Overview
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Brief Summary
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Spinal anaesthesia has the advantage that produced nerve block by the injection of local anaesthetic into cerebrospinal fluid (CSF). However, the greatest challenge in spinal anaesthesia is to control the spread of local anaesthetic through the CSF to provide a block which is adequate for the proposed surgery without unnecessary extensive spread, and increased risk of complications.

Detailed Description
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The activity of the autonomic nervous system is of fundamental importance in the regulation of vital bodily functions. Unbalance of autonomic nerve system results in considerably disordered vital function. Clinically, this is of great significance, because if an anesthetic agent produces cause the sympathetic system to block, the effects can be serious in individual cases, particularly on the cardiovascular system. If complications are to be avoided, it is essential to assess the degree of block correctly. Clinical monitoring has a variety of applications, a particularly useful one being measurement of the sympathetic system during regional anesthesia, for which quantification of the blocking effect is a clinical necessity and the degree of block needs to be ascertained without delay. The autonomic nervous system (ANS) plays an important role in the regulation of hemodynamics during anesthesia. Analysis of beat-to-beat fluctuations of heart rate and blood pressure is a promising new approach to the clinical diagnosis and management of alterations in cardiovascular regulation. Continuous Wavelet Transform (CWT), which could overcome the limitation of the steady-state assumption in the classical spectral analysis, is believed as a reliable and robust method to access cardiorespiratory dynamics of the ANS and the investigators will applied during spinal anesthesia to evaluate the detail changes.

Official Title
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Department of Anaesthesiology, Taipei Veterans General Hospita, Taipei, Taiwan

Conditions
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Participants Scheduled for Surgery Under Spinal Anesthesia Without Impairment of Renal, Hepatic, Cardiac or Respiratory Function

Intervention / Treatment
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* Other: observation study about the autonomic response after spinal anesthesia


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1. patients scheduled for operation with spinal anesthesia Exclusion Criteria: recently treat with a sedative, beta-blocker, parasympatholytic, or opioid agent emergency surgery hypovolemia and hypothermia, arrhythmia, diabetes, or impairment of renal, hepatic, coagulation, cardiac, or respiratory function

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| hyperbaric bupivacaine<br>The dosage of hyperbaric bupivacaine decided by the clinical anesthesiologist. This study is an observational study. | Other: observation study about the autonomic response after spinal anesthesia<br>* ECG waveforms were continuously recorded using a multichannel polygraphic system (Embla N7000, Natus, Pleasanton, CA). The data were saved at a rate of 1024 Hz directly to a memory card within the device for offline analysis of heart rate variability (HRV) and PPG. All data included in the analysis were obtained from continuous artifact-free ECG recordings for analysis of the immediate effects of spinal anesthesia.<br>|
| plain bupivacaine<br>The dosage of plain bupivacaine decided by the clinical anesthesiologist. This study is an observational study. | Other: observation study about the autonomic response after spinal anesthesia<br>* ECG waveforms were continuously recorded using a multichannel polygraphic system (Embla N7000, Natus, Pleasanton, CA). The data were saved at a rate of 1024 Hz directly to a memory card within the device for offline analysis of heart rate variability (HRV) and PPG. All data included in the analysis were obtained from continuous artifact-free ECG recordings for analysis of the immediate effects of spinal anesthesia.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| record and compare changes in ANS function( HRV and PPGA) after spinal anesthesia in different group | Electrocardiography and pulse photoplethysmography signals were recorded after spinal anesthesia. The spectrogram of beat-to-beat R-to-R intervals was derived by continuous wavelet transform (CWT), and the immediate power of high frequency (HFi) and low frequency (LFi) bands was extracted at 1-second intervals. The derived parameters, HF, LF, and pulse photoplethysmography amplitude, were normalized by their maximum and minimum values. Mixed-model regression and repeated-measures analysis of variance were used to explore the time-dependent effect. | maximum for 4 hours |