【作者】 于文滨；

【导师】 胡三元；

【作者基本信息】 山东大学 ， 外科学， 2009， 博士

【摘要】 研究背景甲状腺疾病发病率女性高于男性,传统的甲状腺手术由于颈部留有手术瘢痕,给女性患者造成很大的心理负担,使得切口的美容要求在甲状腺手术中体现得尤为重要。近年来腔镜手术在许多领域取得了长足的发展,使这一微创技术应用于甲状腺手术具备了一定的基础和条件。腔镜甲状腺切除术是近年来随着腹腔镜内镜技术的发展而逐渐开展起来的一种新的术式,通过借助腔镜和一些特殊操作器械的辅助作用,在取得传统甲状腺手术相同治疗效果的同时,追求最大限度地缩小或隐蔽手术瘢痕以达到美容目的。腔镜甲状腺手术开展的初期,由于在颈部建立的手术腔隙狭窄、手术空间小、手术操作和止血均较困难,中转开放手术比例高。同时,腔镜甲状腺手术中CO₂充气对机体的不良影响等因素也制约着这项新技术的发展。但随着腔镜技术和器械以及配套设备的不断发展,经验的不断丰富,越来越多的医生加入到腔镜甲状腺手术的行列中,甲状腺手术的适应证范围越来越广,手术技巧已经日趋完善,已有大量甲状腺恶性肿瘤成功施行腔镜甲状腺手术的报道。目前在腔镜下甲状腺手术中,手术空间的维持,多采用皮下灌注CO₂的方法。CO₂具有不助燃烧、在血中溶解度高、吸收和排泄快、形成气栓可能性小的特点,是目前临床广泛应用的充气介质。但随手术时间延长,在手术过程中CO₂气体灌注时机体发生的病理生理变化明显显现出来,已引起众多学者的注意。二氧化碳充气对机体的负面影响,特别是潜在的对心肺功能和大脑等重要脏器的影响,其风险性正在受到越来越多地重视。继续深入研究其对机体的影响,特别是对重要脏器的影响,尽量减少这种副作用,对于具有特定基础疾病的患者,有重要的临床意义;对于甲状腺外科的发展有重要的推动作用。目前研究发现,腔镜甲状腺手术中CO₂气体灌注可以引起颅内压的改变,而且这种改变与充气压力和时间关系密切。这说明,二氧化碳充气对大脑存在某种程度的影响。这种影响能否造成脑损伤?脑损伤的程度与充气压力是否相关?如何避免或减少脑损伤的发生?这是腔镜甲状腺外科中急需回答的问题,同时也是腔镜甲状腺手术基础研究的一个薄弱环节。基于腔镜甲状腺手术的发展需要和其基础研究的现状,研究二氧化碳充气对大脑的影响以及可能导致的脑损伤具有十分重要的临床意义。以上研究需要一个稳定的、可以重复的、与人类相似的实验动物模型供研究。猪的解剖、生理学特性、营养代谢等方面与人类非常相似。中国实验用小型猪是中国农业大学封闭培育的实验用猪,具有体重轻、抗逆性强、遗传性状稳定等优点。我们选择中国实验用小型猪为实验动物,试图建立腔镜甲状腺手术的动物模型,并通过此模型来研究颈部腔镜手术中二氧化碳充气对大脑的影响以及可能导致的脑损伤。目的1.建立腔镜甲状腺手术的中国小型猪动物模型。2.了解小型猪对手术的耐受性,腔镜甲状腺手术动物模型的安全性、稳定性和可重复性。方法中国实验用小型猪9只,随机分为3组。A组为无损伤对照组,仅实施麻醉而不做手术;B组为传统甲状腺手术组,行开放手术;C组为腔镜甲状腺手术组,采取改良的胸骨上窝径路,在CO₂充气维持的人造空间中行腔镜甲状腺切除术。每组动物在麻醉成功后,手术开始前解剖右侧股动静脉,分别向近端穿刺留置针,以备术中监测动脉血压和中心静脉压。于右侧顶骨用开颅钻钻孔,向硬脑膜下穿刺置管,监测颅内压。以手术开始前为基础值,于1小时、2小时、3小时、4小时和停止充气后30分钟测量上述指标并记录。手术后切除甲状腺组织称重,并做病理检查。用SPSS 16.0统计分析软件对数据进行分析。各组计量结果数据均采用均数±标准差（Mean±Std.）进行统计。两组间均数比较采用独立样本t检验,多组间均数比较采用方差分析,P＜0.05为差异有显著性意义。结果所有动物都较好地耐受了整个过程,开放手术组和腔镜手术组手术均顺利完成手术,无严重并发症发生,成功建立了腔镜甲状腺小型猪动物模型。腔镜手术组动物24小时内对外界反应稍差。通过实验确定了所有监测指标的基础值,作为小型猪的正常生理参考值。各组颅内压比较无显著性差异（P＞0.05）。无损伤对照组和传统手术组比较,各时点血流动力学参数无显著性差异（P＞0.05）。而腔镜甲状腺手术组与开放手术组手术时间（P＜0.01）、切口长度（P＜0.05）有显著性差异,切除甲状腺组织重量及出血量无显著性差异（P＞0.05）。腔镜甲状腺手术组手术手术过程中,心率、平均动脉压、中心静脉压、动脉二氧化碳分压、PH值等均有不同程度改变。各组动物（n=9）在实验开始前测定各基础监测值的变异系数除中心静脉压（CV=12.43%）外,其余均低于10%。结论1.所有小型猪都较好地耐受了麻醉和手术,确定了所有监测指标的正常参考值。2.成功建立了中国小型猪的腔镜甲状腺手术动物模型,此模型具有较好的安全性、稳定性和可重复性,能够比较灵敏地反应机体血流动力学和颅内压的情况,是一种理想的腔镜甲状腺手术模型,可用于研究腔镜甲状腺手术中CO₂充气对大脑的影响。研究背景腔镜甲状腺手术因其创伤小、出血少、恢复快、美容效果好等优势,逐渐被广大患者所接受。颈部不像腹腔和胸腔,没有自然存在的腔隙,如果颈部行腔镜手术必需人工建立一个操作空间。腔镜甲状腺手术中手术操作空间建立后的维持,目前多采取皮下充入一定压力的二氧化碳气体来实现,此法的优点在于空间开阔,视野清楚,应用简单。CO₂具有不助燃烧、在血中溶解度高、吸收和排泄快、形成气栓可能性小的特点,是目前临床广泛应用的充气介质。随腔镜甲状腺外科的发展,手术难度和种类都有所增加。随手术时间延长,在手术过程中CO₂气体灌注时机体发生的病理生理变化明显显现出来。这种CO₂在组织中吸收和其直接压力造成的对机体的负面影响,特别是潜在的对心肺功能和大脑等重要脏器的影响,其风险性正在受到越来越多地重视。继续深入研究其对机体的影响,特别是对重要脏器的影响,尽量减少这种副作用,对于具有特定基础疾病的患者,有重要的临床意义;对于甲状腺外科的发展有重要的推动作用。文献报道腹腔镜腹部术后患者头痛与恶心发生率高于开腹手术,分析其原因可能与颅内压增高有关。动物实验和临床观察表明,无论是腹腔镜腹部手术还是颈部手术,依靠CO₂维持手术操作空间都有可能引起颅内压增高,而且这种改变与充气压力和时间关系密切。这说明,二氧化碳充气对大脑存在某种程度的影响。但目前腔镜甲状腺手术中二氧化碳充气对机体影响的动物实验研究仅局限于对颅内压的影响,而对于二氧化碳充气引起的颅内高压可能引起的脑损伤,以及脑损伤的的病理和电镜表现研究很少。这也是腔镜甲状腺手术基础研究的一个薄弱环节。鉴于甲状腺腔镜手术的发展需要和其基础研究的现状,我们通过腔镜甲状腺手术的实验动物模型来研究颈部腔镜手术中二氧化碳充气对大脑的影响,了解是否会产生脑损伤,脑损伤的病理及电镜表现以及如何避免脑损伤的发生,填补腔镜甲状腺手术基础研究的空白。目的1.观察腔镜甲状腺手术中,不同CO₂充气压力对机体血流动力学和颅内压的影响。2.观察脑组织的病理和电镜下表现,了解腔镜甲状腺手术中不同CO₂充气压力可能导致的脑损伤。3.确定对大脑负面影响相对较小的CO₂安全充气压力。方法将12只中国小型猪随机分成A、B、C、D共4组,每组3只动物。A组为对照组采用开放切口行传统甲状腺切除术;B、C、D组均采用腔镜甲状腺切除术,CO₂充气气压分别为5mmHg、10mmHg和15mmHg。分别于充气前、充气后1h、2h、3h、4h及充气结束后30min监测HR、CVP、MAP、PaCO₂、PH值和ICP。腔镜甲状腺切除术采取胸骨上窝径路、三戳孔技术。在充分显露甲状腺后,行左叶甲状腺全切,并解剖显露同侧的颈血管鞘,清除周围脂肪组织和淋巴结。手术后一周在静脉麻醉下开颅完整取出脑组织。立即于左顶叶大脑皮质切取1×1×1mm组织块,用3%戊二醛固定后,用于电子显微镜检查。剩余脑组织用10%中性甲醛固定,用于病理检查。用SPSS 16.0统计分析软件对数据进行分析。各组计量结果数据均采用均数±标准差（Mean±Std.）进行统计。两组间比较采用独立样本t检验,多组间均数比较采用方差分析,P＜0.05认为差异有显著性意义。结果所有动物都较好地耐受了整个过程。开放手术组和腔镜手术组手术均顺利完成,未出现严重并发症。手术后所有动物清醒后均有自主排尿,但D组动物相对于B组和C组动物,手术区域附近（颈部和胸部）皮下气肿发生率高、皮下气肿面积大,且手术后48-72小时内活动明显减少、嗜睡、对外界反应差、进食少或不进食。腔镜甲状腺手术中,10mmHg二氧化碳充气时,可引起轻度高碳酸血症和酸中毒,动脉血压和中心静脉压轻度升高;15mmHg时,可引起明显高碳酸血症和酸中毒,动脉血压和中心静脉压升高。A组、B组在各时间点观测值比较均无显著性差异（P＞0.05）;C组随充气时间延长,PaCO₂逐渐升高、pH值逐渐下降,有统计学意义;颅内压有所上升,但无统计学意义（P＞0.05）;D组随充气时间延长,PaCO₂逐渐升高、pH值逐渐下降以及颅内压增高,且均有统计学意义。病理观察,与A组相比,B、C、D组具有脑水肿表现,B组轻微,C、D组较明显。A组、B组胶质细胞数比较无统计学意义;C组、D组之间及其分别与另两组之间均有显著差异（P＜0.05）。电镜观察,C组、D组神经元及胶质细胞凋亡明显增多。结论1.长时间高压力CO₂充气可引起高碳酸血症和酸中毒,并引起血流动力学和颅内压的改变。2.在颈部腔镜手术中运用CO₂气体长时间维持颈部手术空间,在较高气压（15mmHg）甚至是压力为10mmHg时,可以导致脑水肿,并可诱发脑神经细胞的凋亡。3.腔镜甲状腺手术中CO₂充气应尽量低于10mmHg,为保证对脑组织的影响降到最低,我们推荐5mmHg是相对安全的压力值。更多还原

【Abstract】 Part oneEstablishment of animal model for endoscopic thyroidectomyBackgroundThe incidence rate of thyroid disease in female is higher than in male. The postoperative incisional scar, paraesthesia and complaint in the neck （near the wound region） brought some serious psychological problems to female patients who accepted traditional thyroidectomy. The cosmetic requests of the incision in thyroid operations had been proposed by more and more female patients. In recent years the endoscopic surgery developed rapidly and it is the time for this minimally invasive technique used in thyroid surgery. Endoscopic thyroidectomy is the new technique to comply with the cosmetic requests. The targets of this minimally invasive surgery could be summarized by: achievement of the same results as those obtained with traditional surgery, less trauma, better post-operative course, early discharge from hospital and improved cosmetic results.At the beginning of this new technique, conversion to the traditional approach was often occurred due to the bleeding from the vessels or the thyroid dimension. But accompanying with the development of new technique and matched instruments of endoscopy, endoscopic thyroidectomy became more and more consummate. The indication of endoscopic thyroidectomy gradually enlarged. Many reports indicated thyroid carcinoma had been treated by endoscope, although it limited in those small differentiated carcinoma without lymph node involvement.At present the operative cavity during endoscopic thyroidectomy is usually established and maintained by CO₂ insufflation. CO₂ insufflation proved to be a feasible, safe and convenient method for setting up the operative cavity by its rapid absorptive nature. But along with the prolong of the operative time, the pathophysiological changes caused by CO₂ insufflation was apparently observed.The negative influence to cardiopulmonary function and cerebrum caused by CO2 insufflation was gradually noticed. It is very important that lucubrate and decrease these negative effects to the development of endoscopic throid surgery and to the patients who combine with some specific disease.Now the researches revealed CO₂ insufflation during endoscopic thyroidectomy could affect intracranial pressure and those effects were related closely to the insufflation pressure and time. Could those effects lead to cerebral injury according to the different pressure? How to avoid or minimize the cerebral injury? All these problems have to be solved for the advancement of endoscopic thyroid surgery. It is necessary to study the effects of CO2 insufflation to cerebrum during endoscopic thyroidectomy.Then we need a stable animal model which could be repetitive and similar to the mankind for above destinations. The anatomy, physiological and metabolism characteristics of the swine are similar to the mankind. The Chinese experimental minipigs which reared closely by Chinese Agriculture University just possess these advantages such as light weight, perfect antireversion force and stable inheritable character and fit for the research. We choose them to establish the endoscopic thyroidectomy porcine model and study the effects of CO₂ insufflation to cerebrum.Objective1. To establish the animal model for endoscopic thyroidectomy in Chinese experimental minipigs.2. Validating the security, stability and repeatability of this animal model.MethodsNine Chinese minipigs were randomly divided into 3 groups. Group A underwent tracheal intubation general anesthesia without operative procedure and served as the matched controls, Group B underwent traditional thyroidectomy and Group C underwent endoscopic thyroidectomy with CO₂ pressure at 10 mm Hg. Hemodynamics parameters including heart rate （HR）, mean arterial blood pressure （MAP）, central venous pressure （CVP）, arterial partial pressure of CO₂ （PaCO₂）, pH and intracranial pressure （ICP） were measured at baseline, 1 h, 2 h, 3 h, 4 h and 30 min after desufflation. Excisional thyroid tissue was weighed and performed pathological examinations. All values are expressed as mean±standard deviation. Independent t-test and ANOVA were used followed by Bonferroni post hoc analysis using SPSS 16.0 analysis software. A probability value <0.05 was regarded as statistically significant.ResultsAll animals tolerated the whole procedure, the traditional thyroidectomy and endoscopic thyroidectomy were successfully performed in all cases with no serious complications. The animal model for endoscopic thyroidectomy was established successfully. But subcutaneous emphysema near operative region appeared in the animals of Group C while the extremity activities diminished within 24 hours postoperatively.All monitored index of the baseline could be served as the normal reference value of mimipigs.Comparison of ICP and the weight of excisional thyroid tissue among different groups were no significant difference （P>0.05）. The operative time （P<0.01） and the length of the incisions （P<0.05） between Group B and C were significantly different. The hemodynamics parameters of Group C varied in different time and some of them were statistical significance.Coefficient variation of the baseline monitored values of different index in all animals （n=9） were all lower than 10% except central venous pressure （CV=12.43%）. Conclusions1. All animals tolerated the anesthesia and operation, the baseline values of all parameters which could be served as the normal reference value were determinded.2. The endoscopic thyroidectomy porcine model with comparative security, stability and repeatability was established successfully, it could respond the changes of hemodynamics and ICP sensitively during the operative procedure. Part twoEffects of CO₂ insufflation on cerebrum during endoscopic thyroidectomy in a porcine modelBackgroundEndoscopic thyroidectomy is accepted gradually by patients due to its advantages including minimal invasion, fewer bleeding, better post-operative recovery course, early discharge from hospital and improved cosmetic results. Unlike the abdominal and thoracic cavity, there is no natural cavity in the neck. A man-made operative cavity in the neck must be established before endoscopic thyroidectomy. At present the operative cavity during endoscopic thyroidectomy is usually maintained by CO₂ insufflation after its establishment. CO₂ insufflation proved to be a feasible, safe and convenient method for maintaining the operative cavity by its rapid absorptive nature.Accompanying with the development of endoscopic thyroidectomy. the operative time extends with the increasing difficulty and types of this operation. Long time CO₂ insufflation causes apparent pathophysiological changes of the organism. These changes led by CO₂ absorption in the tissue and its direct pressure are noticed by scholars.The negative influence to cardiopulmonary function and cerebrum caused by CO₂ insufflation is the obstacle to the development of endoscopic thyroidectomy. It is very important that lucubrate and decrease these negative effects as far as possible to the development of endoscopic thyroid surgery and to the patients who combine with any other specific disease.Some studies showed that the incidence rate of headache and vomiting after laparoscopic abdominal operations was higher than that after traditional abdominal operations and believed that it was related with the increase of the intracranial pressure. The clinical observations and animal experiments revealed the increase of ICP would happen whatever in the abdominal or cervical endoscopic operations when the operative cavity was maintained by CO₂ insufflation. The increase of ICP was correlated with the pressure and time of CO₂ insufflation. This showed CO₂ insufflation influenced the cerebrum to some degree. But at present the researches about these effects to cerebrum limited in the intracranial pressure and seldomly to the cerebral injury and its pathological and electronic microscopic changes. It is necessary for the development of endoscopic throid surgery to study the effects of CO2 insufflation to cerebrum during endoscopic thyroidectomy.In view of the current status of the fundamental research on endoscopic thyroid surgery, we plan to explore the effects to cerebrum caused by CO2 insufflation during endoscopic thyroidectomy through the porcine model.Objective1. To observe the effects on the hemodynamics and intracranial pressure causing by different CO₂ insufflation pressure during endoscopic thyroidectomy using the animal model.2. To observe the pathological and electronic microscopic findings of the cerebral tissue and explore the cerebral injury caused by CO2 insufflation.3. To validating the suitable pressure for CO2 insufflation during endoscopic thyroidectomy.MethodsTwelve Chinese minipigs were randomly divided into 4 groups. Group A underwent traditional thyroidectomy and served as the matched controls. Group B, C and D underwent endoscopic thyroidectomy and respectively with CO₂ pressure at 5 mm Hg, 10 mm Hg and 15 mm Hg. HR, CVP, MAP, Arterial partial pressure of CO₂ （PaCO₂）, pH and Intracranial pressure （ICP） were measured respectively at baseline, 1 h, 2 h, 3 h, 4 h and 30 min after desufflation. Three trocars’ inserted technique and suprasternal fossa approach was used during endoscopic thyroidectomy. After exposing the thyroid glands, left thyroid lobe and the fatty tissue and lymph nodes near right cervical vaginae vasorum was removed completely.Removed the whole cerebrum from the skull under intravenous anesthesia after a week postoperatively. The brain tissue was observed by pathological and electronic microscopic examinations respectively. All values are expressed as Mean±Std.. Independent t-test and ANOVA was used followed by Bonferroni post hoc analysis using SPSS 16.0 analysis software. A probability value <0.05 was regarded as statistically significant.ResultsEndoscopic thyroidectomy was successfully performed in all cases with no serious complications such as bleedings, gas embolism and postoperative death. But the incidence of subcutaneous emphysema near operative region （neck and upper thorax） in the animals of Group D were higher than those of Group B and C. In addition, extremity activities obviously diminished with lower reaction and food ingested in the animals of Group D within 48-72 hours postoperatively.In Group C, mild hypercarbia and acidosis, light increase of the arterial blood pressure and central venous pressure were observed; In Group D, obvious hypercarbia and acidosis, increase of the arterial blood pressure and central venous pressure were observed.All measured values in Group A and B were no significant difference （P>0.05）; In Group C the increase of PaCO₂ and the decrease of pH value in different time were significantly different while the mild increase ICP without statistical significance （P>0.05）. In Group D the increase of PaCO₂ and ICP, decrease of PH value were significantly different.Compared with Group A, mild cerebral edema was found in Group B while obvious cerebral edema in Group C and D. Comprison of the count of glial cells between Group A and B was not significantly different （P>0.05）; Comparisons between other each group have significantly changes （P<0.01）. Obvious increased apoptosis neurons and glial cells were observed in Group C and D under electron microscopy. Conclusions1. Long time CO₂ insufflation at high pressure （15 mm Hg） during endoscopic thyroidectomy could cause hypercarbia, acidosis and increase of ICP.2. CO₂ insufflation during endoscopic thyroidectomy could cause cerebral edema and the increase of the neuron and glial cells apoptosis.3. We suggest the pressure of CO₂ insufflation should be lower than 10 mm Hg, 5 mm Hg is the relatively safe and recommended pressure to minimize the negative effects of the cerebrum.更多还原