本文選題：生物電阻抗 + 無創(chuàng)監(jiān)測　； 參考：《第四軍醫(yī)大學》2007年博士論文

【摘要】： 顱內疾病如腦出血、腦梗塞及各種原因引起的腦水腫,嚴重威脅患者的生命安全,具有較高的致殘率和致死率,早診斷、早治療是改善預后、降低致殘致死率的關鍵。但是,目前還缺乏一種無創(chuàng)的輔助診斷技術與設備,用于對顱內血腫水腫進行早期、實時的監(jiān)測。 既往研究已表明,顱內血腫水腫時顱內組織的電阻抗將發(fā)生改變,顯示出應用生物電阻抗測量技術檢測顱內血腫水腫的研究價值和應用潛力。但由于顱骨的電阻率較高,在顱外只能無創(chuàng)檢測到微弱的電阻抗變化,增加了檢測的難度。 目前國外的研究大都在開顱狀態(tài)下進行動物實驗,沒有設計專門的電阻抗測量系統(tǒng);雖然國內有研究者設計了一套測量系統(tǒng),但是該系統(tǒng)采用兩電極法測量電阻抗,電極皮膚接觸阻抗對測量結果有較大影響。因此,在現(xiàn)有的研究基礎上,克服電極皮膚接觸阻抗的影響,提高測量系統(tǒng)的檢測精度,并將其應用于顱內血腫水腫的監(jiān)測,成為進一步研究的關鍵問題。 本論文以應用無創(chuàng)生物電阻抗技術檢測顱內血腫水腫為研究對象,在分析國內外研究現(xiàn)狀的基礎上,針對頭部無創(chuàng)生物電阻抗檢測技術中存在的關鍵問題,結合本課題組的實際情況與工作需要,主要進行了三方面的研究工作:通過仿真研究,提出了一種較為適用于頭部電阻抗測量的電極配置方案;基于四電極電阻抗測量方法,設計了一套電阻抗測量系統(tǒng);并應用該系統(tǒng),進行了初步的動物和人體實驗。具體包括: ○1 .對電極配置方案進行了軟件仿真研究。設計了兩種電極配置方案,方案一采用四電極法測量電阻抗,共有6個電極,將激勵電極配置在頭部正中線、兩個通道的測量電極分別對稱配置在激勵電極的左右兩側;方案二采用兩電極法測量電阻抗,共有4個電極,電極同時作為激勵和測量電極,將這些電極對稱配置在頭部的左右兩側。軟件仿真結果表明,方案一對測量區(qū)域內的電阻抗變化更為敏感;而且方案二采用兩電極法測量電阻抗,受到電極-皮膚接觸阻抗的影響較大,而方案一則采用四電極電阻抗測量法,可以減少電極皮膚接觸阻抗的影響,所以本研究采用電極配置方案一,應用四電極法測量頭部雙側的電阻抗。 在軟件仿真研究的基礎上,還提出了兩個數(shù)據分析指標,用于對顱內的電阻率擾動進行動態(tài)的分析和評估。 ○2 .針對目前已有設備采用兩電極法測量電阻抗、受到接觸阻抗影響較大這一問題,基于四電極電阻抗測量方法,設計了一套雙通道的、具有較高測量精度的多頻電阻抗測量系統(tǒng)。該系統(tǒng)具有以下的特性: 1)設計有兩個測量通道,可以測量頭部兩側的生物電阻抗; 2)采用直接數(shù)字頻率合成技術設計激勵信號源,采用正交數(shù)字解調技術解調生物電阻抗信息,提高了系統(tǒng)的測量精度; 3)激勵信號工作頻率可以在5~300kHz之間程控選擇,激勵電流強度可以在0~1mA之間程控選擇; 4)在全部的工作頻率范圍內,系統(tǒng)的共模抑制比可以達到80dB以上; 5)整個系統(tǒng)集成在一個機箱內,實現(xiàn)了系統(tǒng)的一體化、小型化,便于移動和進行床旁檢測,配合專門編寫的應用軟件,具備很強的實用性。 ○3 .使用設計的電阻抗測量系統(tǒng),進行了初步的動物實驗。實驗動物采用家兔,主要進行了兩種動物實驗: 1)腦出血動物模型實驗。使測量系統(tǒng)的兩個測量通道分別測量動物頭部左右兩側的、體表電極提取的電阻抗變化。采用自體血注入法制作腦出血動物模型,觀察注入血液前后,頭部兩側的電阻抗變化。結果表明,注入血液后,注血側的電阻抗上升了大約0.91%,而對側的電阻抗上升了大約0.45%。 2)腦水腫動物模型實驗。使測量系統(tǒng)的兩個測量通道分別測量動物頭部左右兩側的電阻抗變化,使用固定在顱骨上的顱釘,作為測量電極。采用光化學誘導法制作腦梗塞動物模型,觀察腦梗塞及隨后的腦水腫過程中的電阻抗變化�？梢杂^察到光照15分鐘后,電阻抗開始升高,光照30分鐘后停止,光照側的電阻抗上升了大約1.5%,之后電阻抗持續(xù)上升,90分鐘后光照側的電阻抗上升了大約4%,對側的電阻抗也呈現(xiàn)出上升的趨勢,上升幅度大約是光照側的一半。 通過腦出血和腦水腫模型實驗,表明顱內血腫水腫時,電阻抗呈現(xiàn)出上升的趨勢,這就提示了應用本測量系統(tǒng)、無創(chuàng)檢測顱內血腫水腫發(fā)展程度的可行性。 ○4 .使用設計的電阻抗測量系統(tǒng),進行了初步的健康人體頭部電阻抗測量實驗。實驗結果表明,該系統(tǒng)可以測量到健康人的頭部電阻抗的變化。由于健康人不存在顱內血腫水腫等病變,所以沒有直接觀察到由顱內血腫水腫引起的電阻抗變化;但是,該系統(tǒng)可以檢測到由人體的心臟跳動、深呼吸引起的微弱的頭部電阻抗變化,為將該系統(tǒng)應用于顱內血腫水腫病人的臨床檢測打下了基礎。 本論文的主要特色與創(chuàng)新之處包括: 對電極配置方案進行了仿真研究,提出了一種較為適合于頭部電阻抗測量的電極方案。 基于四電極電阻抗測量方法,針對檢測顱內血腫水腫的需要,研制了一套高性能、雙通道多頻電阻抗測量系統(tǒng)。并在設計過程中,提出了一種自動動態(tài)調整模擬放大倍數(shù)的方法,和校準電阻抗測量結果的方法。 在軟件仿真的基礎上,提出了2個反映電阻率擾動的數(shù)據分析指標:總體變化指數(shù)和對稱變化指數(shù)。經過初步的動物實驗證實,可以使用這兩個指標,依據相應的評判標準,對顱內血腫水腫的發(fā)展程度進行評估。 本論文在軟件仿真研究的基礎上,提出了一種較為適合于頭部電阻抗測量的電極配置方案和2個反映電阻率擾動的數(shù)據分析指標:總體變化指數(shù)和對稱變化指數(shù)。基于四電極電阻抗測量方法,針對檢測顱內血腫水腫的需要,研制了一套高性能、雙通道多頻電阻抗測量系統(tǒng)。初步的動物實驗表明,可以應用本測量系統(tǒng)無創(chuàng)、靈敏的檢測到顱內血腫水腫引起的電阻抗變化。在健康人體試驗中,使用本系統(tǒng)可以觀察到由人體的心臟跳動和深呼吸引起的電阻抗波動,表明無創(chuàng)生物電阻抗測量技術也可以應用于人體的頭部電阻抗測量。本論文的研究成果為應用無創(chuàng)生物電阻抗技術監(jiān)測顱內血腫水腫打下了堅實的基礎。
[Abstract]:Intracranial diseases such as cerebral hemorrhage , cerebral infarction and cerebral edema caused by various causes seriously threaten the life safety of patients , have higher disability rate and death rate , early diagnosis , early treatment is the key to improve prognosis and reduce disability mortality . However , there is still a lack of noninvasive auxiliary diagnosis technique and equipment for early and real - time monitoring of intracranial hematoma edema .





Previous studies have shown that the electrical impedance of the intracranial tissues will change when the intracranial hematoma is edema , showing the research value and application potential of using bioelectrical impedance measurement technique to detect the edema of intracranial hematoma . However , because of the high resistivity of the skull , only slight changes in electrical impedance can be detected outside the skull , and the difficulty of detection is increased .





At present , most of the researches abroad are carried out in animal experiments under the open - cranial state , and no special electrical impedance measurement system is designed ; however , the system adopts two - electrode method to measure the electrical impedance , and the contact impedance of the electrode skin has a great influence on the measurement result .





Based on the analysis of the present situation of non - invasive bioelectrical impedance technology , the paper presents a kind of electrode configuration scheme which is suitable for the measurement of head electrical impedance . Based on the research of simulation , a kind of electrode configuration scheme is proposed , which is suitable for the measurement of head electrical impedance . Based on the four - electrode electrical impedance measurement method , a set of electrical impedance measurement system is designed , and the system is applied to carry out preliminary animal and human experiments .





1 . Two kinds of electrode configuration schemes are designed . Two kinds of electrode configuration schemes are designed . A four - electrode method is adopted to measure the electrical impedance . The two electrodes are symmetrically arranged on the left and right sides of the excitation electrode .





On the basis of software simulation research , two data analysis indexes are proposed for dynamic analysis and evaluation of the resistivity disturbance of intracranial .





02 . According to the four - electrode electrical impedance measurement method , a multi - frequency electric impedance measurement system with high measurement accuracy is designed aiming at the problem that the current device adopts two - electrode method to measure the electrical impedance , and a multi - frequency electric impedance measurement system with high measurement accuracy is designed based on the four - electrode electrical impedance measurement method .





1 ) two measuring channels are designed , and the bioelectrical impedance on two sides of the head can be measured ;





2 ) designing an excitation signal source by adopting a direct digital frequency synthesis technology , demodulating the bioelectrical impedance information by adopting an orthogonal digital demodulation technique , and improving the measurement accuracy of the system ;





3 ) the operating frequency of the excitation signal can be selected by programming between 5 and 300 kHz , and the excitation current intensity can be selected by programming between 0 and 1 mA ;





4 ) the common mode rejection ratio of the system can reach more than 80 dB in all operating frequency ranges ;





5 ) the whole system is integrated in one chassis , the integration of the system is realized , the miniaturization is realized , the mobile terminal is convenient to move and the bedside detection is carried out , the special writing application software is matched , and the system has strong practicability .





03 . A preliminary animal experiment was conducted using the designed electrical impedance measurement system . The experimental animals used rabbits , mainly two animal experiments :





1 ) Animal model of cerebral hemorrhage . Two measuring channels of the measuring system were used to measure the changes of electrical impedance of the body surface electrodes on the left and right sides of the animal ' s head . The changes of electrical impedance at both sides of the head were made by using autologous blood injection method . The results showed that the electrical impedance at the side of the head increased by about 0.91 % before and after the injection of blood , while the electrical impedance on the opposite side increased by about 0.45 % .





2 ) Animal model of cerebral edema . Two measuring channels of the measuring system were used to measure the changes of electrical impedance on the left and right sides of the animal ' s head . The electrical impedance of the cerebral infarction and the subsequent cerebral edema was observed . After 15 minutes of illumination , the electrical impedance of the illumination side increased by about 1.5 % . After 30 minutes of illumination , the electrical impedance of the light side increased by about 4 % . The electrical impedance on the opposite side also increased , and the rise was about half of the light side .





Through the experiment of cerebral hemorrhage and cerebral edema model , indicating that intracranial hematoma edema , the electrical impedance presents a rising trend , which suggests the feasibility of applying the measurement system and non - invasive detection of edema development degree of intracranial hematoma .





04 . The experimental results show that the system can measure the changes of the electrical impedance of the head of the healthy person . The results show that the system can measure the changes of the electrical impedance caused by the edema of the intracranial hematoma . However , the system can detect the changes of the electrical impedance of the head caused by the beating of the heart and deep breath of the human body , and the system can be used for the clinical detection of the patients with intracranial hematoma edema .





The main features and innovations of this thesis include :





The electrode configuration scheme is simulated and studied , and a kind of electrode scheme is proposed which is suitable for the measurement of the electrical impedance of the head .





Based on the four - electrode electrical impedance measurement method , a high - performance and dual - channel multi - frequency impedance measurement system is developed for the purpose of detecting the edema of intracranial hematoma . In the design process , a method for automatically dynamically adjusting the analog amplification factor and the method of calibrating the electrical impedance measurement result are presented .





On the basis of software simulation , two data analysis indexes reflecting the resistivity disturbance are presented : the general change index and the symmetry change index . After the preliminary animal experiment , the two indexes can be used , and the degree of development of intracranial hematoma edema can be evaluated according to the corresponding evaluation criteria .





Based on the research of software simulation , this paper presents an electrode configuration scheme and two data analysis indexes which reflect resistivity disturbance : general change index and symmetry change index . Based on the four - electrode electrical impedance measurement method , a set of high - performance and dual - channel multi - frequency electrical impedance measurement system is developed for detecting the edema of intracranial hematoma .

【學位授予單位】：第四軍醫(yī)大學
【學位級別】：博士
【學位授予年份】：2007
【分類號】：R35;R651.15

【引證文獻】

相關碩士學位論文 前2條

1 吳劍威;電阻抗測量技術對兔腦急性血液循環(huán)障礙性疾病監(jiān)測初步實驗研究[D];第四軍醫(yī)大學;2010年

2 趙璐璐;顱腦阻抗特性三維建模及磁感應成像仿真研究[D];沈陽工業(yè)大學;2013年

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本文編號：1821910