張雪峰，呂 赤，張 成

沈陽(yáng)軍區(qū)總醫(yī)院普通外科，遼寧 沈陽(yáng) 110016

無(wú)論平時(shí)還是戰(zhàn)時(shí)，創(chuàng)傷及失血性休克(hemorrhagic shock，HS)都是外科的常見病理狀態(tài)和重要的研究領(lǐng)域。機(jī)體在遭受創(chuàng)傷后，常合并出現(xiàn)HS，創(chuàng)傷和HS可引起炎性介質(zhì)(如細(xì)胞因子和花生四烯酸等)合成增加、白細(xì)胞粘附分子表達(dá)上調(diào)及多形核粒細(xì)胞在損傷組織內(nèi)聚集，引起復(fù)雜的應(yīng)激免疫級(jí)聯(lián)反應(yīng)，進(jìn)而出現(xiàn)一系列的病理生理改變，嚴(yán)重時(shí)可導(dǎo)致多器官功能障礙[1]。為進(jìn)一步闡明致病機(jī)制并尋找搶救治療的突破口，需要選擇一種合適的創(chuàng)傷合并HS動(dòng)物模型作為研究平臺(tái)。盡管一些學(xué)者認(rèn)為動(dòng)物實(shí)驗(yàn)研究的結(jié)果很難應(yīng)用于臨床實(shí)踐，但畢竟動(dòng)物實(shí)驗(yàn)研究可獲得某一特定條件下的臨床信息，而且臨床上許多治療理念的更新和方法的改進(jìn)都源于動(dòng)物實(shí)驗(yàn)的研究成果。因此，本文對(duì)創(chuàng)傷合并HS的實(shí)驗(yàn)動(dòng)物模型研究進(jìn)展從致病機(jī)制和麻醉與否兩方面介紹如下。

1 根據(jù)致病機(jī)制分類

1.1 頭部創(chuàng)傷合并HS模型 嚴(yán)重的頭部創(chuàng)傷常伴隨出現(xiàn)低血壓和腦缺血，這是嚴(yán)重頭部創(chuàng)傷后出現(xiàn)繼發(fā)性腦損害和死亡的主要原因。頭部創(chuàng)傷主要引起兩種類型的腦水腫，即細(xì)胞毒性腦水腫和血管源性腦水腫[2]。細(xì)胞毒性腦水腫是由于細(xì)胞膜Na/K通道的通透性增加，腦實(shí)質(zhì)細(xì)胞腫脹所致；血管源性腦水腫是由于血腦屏障破壞后，血管通透性增加，富含蛋白質(zhì)的液體在細(xì)胞外間隙集聚所致。高處墜落傷、液體沖擊傷、控制性腦皮質(zhì)撞擊傷等多種創(chuàng)傷性顱腦損傷模型均表現(xiàn)為腦水腫[2,3]。在HS合并頭部創(chuàng)傷的動(dòng)物模型中，液體沖擊傷和控制性腦皮質(zhì)撞擊傷模型應(yīng)用最為廣泛[4-6]。為闡明HS與頭部創(chuàng)傷的相互作用關(guān)系，動(dòng)物實(shí)驗(yàn)研究多側(cè)重于探討采用何種復(fù)蘇策略可以減輕繼發(fā)性腦損傷的問(wèn)題，包括應(yīng)用何種液體進(jìn)行復(fù)蘇、應(yīng)用多大量液體進(jìn)行復(fù)蘇及復(fù)蘇多長(zhǎng)時(shí)間等問(wèn)題。血紅蛋白替代物HBOC(hemoglobin-based oxygen carrier)溶液已用于HS合并頭部創(chuàng)傷動(dòng)物模型的研究。結(jié)果顯示，HBOC在豬的HS復(fù)合模型中是非常有效的低容量復(fù)蘇試劑[7-9]。大多數(shù)使用HBOC作為復(fù)蘇液體進(jìn)行HS合并頭部創(chuàng)傷研究的實(shí)驗(yàn)是利用大鼠和豬實(shí)施的[10,11]。也有實(shí)驗(yàn)使用賀斯(一種擇期手術(shù)時(shí)治療低血容量的血漿容量擴(kuò)增劑)和精氨酸血管加壓劑研究其對(duì)豬HS合并液體沖擊性顱腦損傷的影響[12-14]。Bourguignon等[15]利用豬HS合并頂骨凍傷模型研究了早期和延遲液體復(fù)蘇對(duì)預(yù)后的影響。

1.2 胸部創(chuàng)傷合并HS 胸部鈍器傷是導(dǎo)致肺炎、急性肺損傷和急性呼吸窘迫綜合征的獨(dú)立危險(xiǎn)因素，因此，近年來(lái)大部分胸部鈍器傷動(dòng)物模型都被設(shè)計(jì)成肺部挫傷[16]。目前有多種方法可以制成肺挫傷模型，如槍擊傷、墜落傷、沖擊傷和肺擠壓傷等。Davis等[17,18]在研究HS合并肺挫傷(槍擊傷致肺挫傷模型)時(shí)發(fā)現(xiàn)，輸入吲哚美辛、環(huán)氧酶(COX)、腺苷調(diào)節(jié)劑和HBOC可以有效控制炎癥級(jí)聯(lián)反應(yīng)的進(jìn)展。Gryth等[19]也用豬HS合并肺損傷模型研究了高滲鹽水復(fù)蘇對(duì)繼發(fā)性肺損傷的影響。Feinstein等[20]設(shè)計(jì)了控制性HS和非控制性HS兩種實(shí)驗(yàn)?zāi)Ｐ停靡詸z測(cè)精氨酸加壓素治療豬HS合并肺挫傷模型的效果。Pape等[21]評(píng)估了羊HS合并肺挫傷(肺擠壓傷)后再次遭受髓內(nèi)插釘術(shù)打擊后的肺內(nèi)損害。研究發(fā)現(xiàn)，其可導(dǎo)致肺微血管通透性紊亂，如果使用未經(jīng)擴(kuò)眼的小口徑圓釘就可以防止這種情況出現(xiàn)。

1.3 骨折合并HS 臨床上HS經(jīng)常與骨折伴隨發(fā)生，而且近年對(duì)骨折后的免疫反應(yīng)研究顯示，骨折與失血的反應(yīng)非常相似。因此，許多動(dòng)物實(shí)驗(yàn)研究將骨折作為HS模型的追加影響因素進(jìn)行研究[22-28]。Monroy等[29]和Strong等[30]使用小鼠HS合并股骨骨折模型進(jìn)行研究，發(fā)現(xiàn)創(chuàng)傷可以誘導(dǎo)COX-2表達(dá)上調(diào)和PGE2合成增加，而且用選擇性COX-2抑制劑(NS-398)阻滯PGE2合成后可以減輕前炎性細(xì)胞因子的產(chǎn)生和COX-2 mRNA的表達(dá)。Pelinka等[22]對(duì)HS合并雙側(cè)股骨骨折的大鼠進(jìn)行觀察，以明確神經(jīng)元特異性烯醇化酶是否是創(chuàng)傷性顱腦損傷的可靠標(biāo)記物，并檢測(cè)了晶體和膠體兩種復(fù)蘇液體復(fù)蘇后的總肺水量和血管外肺水量。Gray等[31]、Hildebrand等[32]和Mousavi等[33,34]分別用綿羊模型評(píng)估了HS后股骨髓內(nèi)插釘術(shù)對(duì)全身的影響，研究證實(shí)，這可導(dǎo)致肺功能不全和顱內(nèi)壓升高。另外，豬和羊也被用于研究HS對(duì)骨折愈合的影響[35，36]。

1.4 軟組織損傷合并HS 有研究者將剖腹探查術(shù)應(yīng)用于HS模型，Chaudry等[37]證實(shí)HS合并腹部探查手術(shù)后的動(dòng)物病死率要顯著高于單純HS的動(dòng)物。另外，Pretorius等[28]在用狒狒研究骨折及軟組織損傷等創(chuàng)傷和HS的實(shí)驗(yàn)中發(fā)現(xiàn)，要制成HS合并肺損傷模型就必須同時(shí)造成骨折和軟組織損傷。Cai等[38]建立了鼠的HS合并骨折及軟組織損傷模型，用以觀察器官受到創(chuàng)傷時(shí)肥大細(xì)胞對(duì)免疫功能的影響。

1.5 多發(fā)傷合并HS Howes等[25]用豬制備了多處鈍傷模型(股骨骨折、肝臟撕裂傷和軟組織擠壓傷)，以研究傷后注射重組VIIa因子是否可以減少出血。Matsutani等[39]研究證實(shí)小鼠在經(jīng)歷因創(chuàng)傷(骨折、剖腹手術(shù))和HS而制成的創(chuàng)傷性HS后，是否出現(xiàn)肝臟損傷主要取決于年齡。Guan等[24]研究了大鼠HS合并多發(fā)創(chuàng)傷(雙側(cè)股骨骨折和剖腹手術(shù))后器官的凋亡情況。這一模型與臨床實(shí)際非常接近，因此更適用于創(chuàng)傷患者的研究。然而，如果多發(fā)創(chuàng)傷的傷情過(guò)于嚴(yán)重，動(dòng)物會(huì)出現(xiàn)立即死亡。因此，這一模型適于研究多發(fā)創(chuàng)傷后的早期病理改變，但實(shí)驗(yàn)結(jié)果可能難以重復(fù)。

2 根據(jù)是否麻醉分類

2.1 創(chuàng)傷合并HS麻醉模型 目前大多數(shù)HS動(dòng)物模型均采用麻醉動(dòng)物進(jìn)行研究，采用這種動(dòng)物模型具有動(dòng)物依從性好、無(wú)道德倫理問(wèn)題等優(yōu)點(diǎn)，但其缺陷是不可避免地要受到麻醉的影響。Mohr等[40]研究了輕度低溫對(duì)豬創(chuàng)傷合并HS凝血功能的影響，結(jié)果發(fā)現(xiàn)，創(chuàng)傷合并HS在鎮(zhèn)靜狀態(tài)下輕度低溫對(duì)改善凝血系統(tǒng)功能有積極作用，而不加劇創(chuàng)傷合并HS對(duì)凝血功能造成的不良影響。George等[41]在研究環(huán)境低溫對(duì)豬創(chuàng)傷性HS預(yù)后的影響時(shí)也發(fā)現(xiàn)，環(huán)境低溫可以明顯降低實(shí)驗(yàn)動(dòng)物的氧耗，并改善細(xì)胞應(yīng)激和器官功能，有利于休克的復(fù)蘇。這些研究結(jié)果與習(xí)慣認(rèn)識(shí)明顯不同，也與目前臨床上的治療指南相反。本研究認(rèn)為：麻醉引起的誘導(dǎo)性低溫是導(dǎo)致基礎(chǔ)研究結(jié)果與臨床指南不一致的主要原因。由于麻醉引起的誘導(dǎo)性低溫明顯降低了機(jī)體的應(yīng)激反應(yīng)，有利于創(chuàng)傷后的復(fù)蘇，因此，環(huán)境低溫可從致傷因素轉(zhuǎn)變?yōu)楸Ｗo(hù)性因素[42]。鑒于麻醉對(duì)研究結(jié)果的影響，在選擇動(dòng)物模型時(shí)應(yīng)根據(jù)研究目的及需要選擇適當(dāng)?shù)膭?dòng)物模型。

2.2 創(chuàng)傷合并HS非麻醉模型 由于非麻醉動(dòng)物模型貼近臨床實(shí)際，因此研究者很早就開始采用這種模型。但由于這種模型需要特殊處理，同時(shí)又可能涉及道德倫理問(wèn)題，因此限制了其廣泛的應(yīng)用。Vázquez等[43]利用倉(cāng)鼠研究血管活性血紅蛋白溶液對(duì)HS預(yù)后的影響。結(jié)果發(fā)現(xiàn)血管活性血紅蛋白溶液對(duì)穩(wěn)定血流動(dòng)力學(xué)有益。Zhang等[44]研究非麻醉狀態(tài)下鼠失血性休克模型中聚羥亞烴188 (一種具有血液流變學(xué)與細(xì)胞保護(hù)功能的共聚物)的作用，發(fā)現(xiàn)它能延長(zhǎng)失血性休克鼠的生存時(shí)間，減少?gòu)?fù)蘇過(guò)程中液體的需求及組織損傷。Cai等[45]研究清醒時(shí)動(dòng)物失血性休克模型在復(fù)蘇過(guò)程中應(yīng)用乙基丙酮酸鹽比傳統(tǒng)的人工膠體能更迅速地恢復(fù)平均動(dòng)脈壓，降低血清腫瘤壞死因子TNF-α水平，從而進(jìn)一步減輕炎癥反應(yīng)。由于動(dòng)物處于清醒狀態(tài)，消除了麻醉可能對(duì)心血管系統(tǒng)和代謝系統(tǒng)的影響，因此，非麻醉動(dòng)物模型更多用于HS在此類方面的研究。但在采取這種動(dòng)物模型時(shí)，往往需要做好前期的處理工作。

3 結(jié) 語(yǔ)

在選取動(dòng)物模型研究時(shí)，研究者通常愿意選擇同性別、同年齡、同種屬的健康動(dòng)物以減少實(shí)驗(yàn)誤差。然而在臨床實(shí)際條件下，創(chuàng)傷患者的種族、年齡、性別及既往病史等實(shí)際條件各不相同。同時(shí)許多外部因素，如軟組織損傷程度、是否喝酒或吸毒以及環(huán)境低溫等也需考慮。因此，要想設(shè)計(jì)出一種既與臨床實(shí)際非常接近，又能將實(shí)驗(yàn)結(jié)果直接應(yīng)用于人類的創(chuàng)傷合并HS實(shí)驗(yàn)動(dòng)物模型是非常困難的。雖然人類和動(dòng)物之間的差異顯著，但醫(yī)學(xué)的進(jìn)步離不開動(dòng)物實(shí)驗(yàn)研究。了解不同模型的特點(diǎn)和不足，對(duì)于根據(jù)研究目的合理選擇實(shí)驗(yàn)動(dòng)物模型及分析實(shí)驗(yàn)結(jié)果很有裨益。

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