经上腔静脉逆行灌注脑保护在主动脉瘤手术中的应用

目的　探讨在主动脉瘤手术中应用经上腔静脉逆行灌注的脑保护效果。　方法　 65例主动脉瘤患者分 2组 ,15例采用深低温停循环 (DHCA) ,5 0例经上腔静脉逆行灌注 (RCP)进行脑保护。术中比较 2组患者不同时间颈内静脉的血乳酸含量 ,对部分RCP患者测定了灌注血和回流血的流量分布 ,以及灌注血和回流血的氧含量。　结果　DHCA组停循环时间为 10 0～ 63 0min ,平均(3 5 9± 18 8)min ;RCP组为 16 0～ 81 0min ,平均 (45 5± 17 2 )min。术后至清醒时间DHCA组为4 4～ 9 4h ,平均 (7 1± 1 6)h ;RCP组 2 0～ 9 0h ,平均 (5 4± 2 2 )h。DHCA组手术死亡 3例 ,RCP组死亡 1例 ;术后神经系统并发症DHCA组 3例 (死亡 2例 ,成活 1例 ) ,RCP组 1例 (存活 )。手术总成功率和神经系统并发症发生率RCP组分别为 96%和 2 % ,DHCA组为 67%和 2 0 % (P <0 0 5 )。RCP组再灌注期间颈内静脉血乳酸含量增高幅度低于DHCA组 [(4 4± 0 6)mmol/Lvs (6 2± 0 9)mmol/L ,P <0 0 1],经头臂和下腔静脉血流量测定显示约 2 0 %血液经头臂动脉回流 ,灌注血和回流血氧差9 0 0～ 13 67ml/L ,证实RCP期间脑组织有氧利用。　结论　在主动脉瘤手术中 ,应用RCP可以延长停循环的安全时限 ,是可行的脑保护方法     

不同脑灌注方法对深低温停循环脑组织温度、温差的影响

目的比较不同脑灌注方法对深低温停循环(DHCA)中脑组织温度、温差的影响,以及与自由基及脑皮质超微结构改变的关系,评价不同灌注方式的脑保护效果。方法健康成年杂种犬15只,随机分为3组(n=5)。Ⅰ组单纯行DHCA,Ⅱ组DHCA RCP,Ⅲ组DHCA 选择性顺行脑灌注(SACP)。转流降温至鼻咽部温18℃时停循环,期间Ⅱ、Ⅲ组分别行逆行脑灌注(RCP)及SACP,90 min后复温,再灌注90 min。结果停循环后犬脑组织温度缓慢上升,脑皮质温度(BCT)及脑深部温度(BBT)在不同时间点间差异有统计学意义(P<0.01);3组之间BCT、BBT亦有明显差异(P<0.01),停循环时间与不同脑灌注方式之间存在交互效应。停循环过程中及复温后各组脑皮质-深部温差(Dc-bT)、SOD活性及MDA含量均有明显差异(P<0.05),Ⅰ组复温30 min时Dc-bT最大,Ⅲ组停循环前Dc-bT最小。Ⅲ组脑超微结构改变轻于Ⅰ、Ⅱ组。结论DHCA中存在脑组织自然复温及较明显的脑皮质-深部温差。RCP有利于维持脑部低温,但不能有效降低脑皮质-深部温差。SACP可保持脑温低温,有效减小脑皮质-深部温差,脑保护效果优于RCP和DHCA。     

经右锁骨下动脉顺行选择性脑灌注技术的临床应用

我们采用经右锁骨下动脉插管深低温停循环(DHCA)行持续选择性脑灌注技术，手术治疗累及主动脉弓的胸主动脉瘤或主动脉夹层病人19例，均获得良好的临床效果。现总结报道如下。     

氟碳携氧液逆行灌注脑保护的实验研究

目的　探讨经上腔静脉逆行脑灌注氟碳携氧液在深低温停循环中的脑保护作用。方法　生后 6～ 8周约克猪 1 6头 ,体重 1 5～ 1 6kg。随机分为氟碳携氧液 (PFC)组和血液组。两组除灌注液不同外 ,其余条件相同 ,PFC组上腔静脉逆行灌注氟碳携氧液 ,血液组用自体血液。逆行灌注压力 2 0mmHg,鼻咽温度 1 8～ 2 0℃ ,维持 1 2 0min ,复温至 37℃ ,取脑行病理学检查并记录逆行灌注时的流量。结果　深低温逆行脑灌注时 ,PFC组每分钟的脑灌注量显著高于血液组 [(2 1 7± 3 6)ml/1 0 0g对 (1 2± 0 9)ml/1 0 0g ,P <0 0 1 ] ,除桥脑外 ,海马、扣带回、尾状核、壳核、丘脑、新皮质、中脑灰质和浦肯野细胞各区病理损害较血液组轻。结论　经上腔静脉逆行脑灌注时 ,氟碳携氧液通过改善微循环 ,高效供氧 ,减少氧自由基产生 ,抑制白细胞的趋化和聚集等发挥显著的脑保护作用     

深低温停循环与逆行脑灌注的脑保护实验研究

我们用犬体外循环模型比较深低温停循环（ＤＨＣＡ）和经上腔静脉逆行脑灌注（ＲＣＰ）时肌酸激酶脑型同功酶（ＣＫＢＢ）含量的变化及脑组织超微结构的改变,为临床推广应用ＲＣＰ行脑保护提供实验基础和理论依据。材料和方法健康杂种犬１４只,雌雄各半;体重１０～２...     

利多卡因对逆行脑灌注脑保护的影响

目的:观察利多卡因能否改善逆行脑灌注的脑保护作用。方法:16只杂种犬接受体外循环并降温至20C,停循环,逆行脑灌注120分钟,恢复体外循环并复温至36℃。利多卡因组(n=8)实验期间持续给予利多卡因(4mg·kg~(-1)后0.2mg·kg~(-1)·min~(-1),逆行脑灌注期间为0.5mg·min~(-1));对照组(n=8)则给予等量生理盐水。结果:实验末利多卡因组脑组织磷酸肌酸、三磷酸腺苷含量和能量指数均明显高于对照组(分别为磷酸肌酸:2.44±0.53比1.61±0.49μmol/gwetw,P<0.01;三磷酸腺苷:0.71±0.18比0.50±0.17μmol/gwetw,P<0.05;能量指数:0.59±0.10比0.48±0.09,P<0.05)。但两组间脑组织丙二醛含量无显著差异。结论:围逆行脑灌注期间持续给予利多卡因改善脑保护作用,可能与恢复体外循环后犬脑组织高能磷酸盐含量增加有关。     

不同深低温停循环方法对脑组织S-100蛋白表达的影响

目的观察不同深低温停循环方法对脑组织S—100蛋白表达及组织结构的影响。方法将18只实验犬随机分为3组，深低温停循环（deep hypothermic circulatory arrest，DHCA组）组，深低温停循环结合逆行脑灌注（retrograde cerebral perfusion，RCP，DHCA＋RCP组）组，深低温停循环结合顺行性间断脑灌注（intermittent antegrade cerebral perfusion，IACP，DHCA＋IACP组）组。3组犬体外循环开始后将鼻咽温降至18℃，随后停循环90min，开放循环后复温至36℃，随后停机。在停循环前、停循环后45min、90min及开放循环后15min和30min由颈静脉插管留取血液标本进行S-100蛋白含量测定。手术结束时取脑海马组织作透射电子显微镜检查，观察脑组织及神经细胞超微结构的变化。结果3组犬在停循环前颈静脉血S-100蛋白含量差异无统计学意义（P〉0．05），停循环后DHCA组和DHCA＋RCP组S-100蛋白含量较停循环前显著升高（P〈0．01），DHCA＋IACP组S-100蛋白含量停循环前后无显著变化。结论DHCA时间较长时，脑组织会发生缺血缺氧性损伤；RCP对脑组织有一定的保护作用，但易发生脑组织及神经细胞水肿；IACP的脑保护效果较为理想。     

深低温停循环中不同脑灌注方式皮层超氧化物歧化酶、丙二醛及超微结构的变化

目的观察不同脑灌注方法对深低温停循环（DHCA）中脑皮质超氧化物歧化酶（SOD）、丙二醛（MDA）及超微结构的影响，比较不同灌注方式的脑保护效果。方法健康成年杂种犬15条，随机分为3组。Ⅰ组单纯行DHCA为对照，Ⅱ组DHCA＋逆行脑灌注（RCP），Ⅲ组DHCA＋选择性顺行脑灌注脑保护（SACP）。转流降温至鼻咽部温18℃时停循环90min，然后复温再灌注90min。结果停循环期皮层SOD活性下降而MDA含量上升，复温再灌注时变化更明显，各时间点差异有统计学意义（P〈0．05）。增加或下降程度以Ⅰ组最为明显，Ⅱ组次之，Ⅲ组最小。Ⅱ、Ⅲ组与Ⅰ组比较SOD、MDA变化明显减轻（P〈0．01），Ⅱ、Ⅲ组间亦差异有统计学意义（P〈0．05），与电镜观察结果一致。结论深低温停循环期间SACP有明显脑保护作用，RCP亦可减轻DHCA中脑损害。     

深低温停循环后梯度灌注复温的脑保护作用

目的 探讨深低温停循环(deep hypothermia circulatory arrest,DHCA)后应用梯度灌注复温,调整脑组织血流-温度-代谢平衡,籍以优化体外循环复温过程中的神经保护策略.方法 3～4周龄上海白猪12只,雌雄不拘,体质量(9.78 ±0.93)kg.通过简单随机分为实验组和对照组,每组6只,建立微创的乳猪DHCA灌注模型(肛温18℃).实验组DHCA停循环90 min,术后复温策略为梯度灌注复温,肛温每升高5℃,维持平台温度15 min;对照组DHCA停循环90 min后常规复温.以肛温33℃为目标恢复温度.两组均采用pH稳态方法管理血气,分别于转流开始后10 min,复温开始后15、30和45 min采样,监测肛温、心率、心电图、血气分析、颈动脉血流量、颈静脉谷氨酸/天冬氨酸浓度,术后1h取实验动物脑组织,对海马CA1区进行组织学评估,并应用免疫组化方法测定脑组织内的损伤敏感因子、NF-κB组分p50蛋白的表达.结果 实验组的复温时间为(67.3 ±7.8) min,对照组的复温时间为(41.8±3.6) min(P ＜0.05).复温后15 min时,实验组和对照组脑血流量的差异无统计学意义.升温30 min和45 min时,实验组的脑血流量显著低于对照组(P＜0.05).高压液相色谱( HPLC)分析显示,升温30 min和45 min时对照组颈静脉谷氨酸浓度高于实验组,仅在升温45 min时,对照组的颈静脉天冬氨酸的浓度高于实验组.组织学评估显示梯度复温组海马CA1区椎体细胞层损失较少,免疫组化分析示实验组和对照组NF-κB的表达差异无统计学意义.结论 深低温停循环后,梯度灌注复温有一定的神经保护作用,其神经保护效应可能与保持复温阶段脑部血流-代谢-温度平衡有关.     

深低温停循环逆行脑灌注行胸主动脉瘤手术体会

20 0 1年 7月至 2 0 0 2年 4月 ,我们采用用深低温停循环(DHCA)辅以上腔静脉持续逆行脑灌注 (CRCP)方法 ,手术治疗 2例急性DeBakeyI型夹层动脉瘤 (DAA)和 1例急性钝性创伤性主动脉峡部破裂伴假性动脉瘤 (FA)病人 ,效果满意。现报道如下。临床资料　 2例DAA均为男性 ;年龄 32、4 4岁。急性胸痛入院 ;经CT、MRI确诊 ;单个内膜裂口 ,分别位于导管韧带旁、左锁骨下动脉旁 ;升主动脉直径 5 4cm、4 6cm ;超声心动图示主动脉瓣微量反流。 1例行升主动脉加半弓置换术 ,1例行升主动脉、全弓置换加“象鼻”术。1例FA为女性 ,38岁。车祸…     

Arch-first reconstruction via median sternotomy. Short retrograde cerebral perfusion

In December 1998, we introduced arch-first reconstruction for total aortic arch replacement via conventional median sternotomy in order to shorten the duration of retrograde cerebral perfusion (RCP). We used a separate straight graft for an elephant trunk, which allowed an easy subsequent distal anastomosis. The average RCP duration in this series was 32.1+/-5.8 min (mean+/-SD, range, 24-40 min, n=12), which was significantly shorter (p<0.05) than that of the conventional procedure (45.6+/-12.4 min, range, 34-65 min, n=8), in which we first perform a distal anastomosis. No significant differences in cardiopulmonary bypass time (268+/-81 min vs 258+/-42 min) nor operation time (518+/-213 min vs 517+/-82 min) between the two groups were observed. There was no hospital death in either group. One patient in the second series (conventional method) suffered temporary neurological disturbance. For acceptable RCP duration, total aortic arch replacement is currently the standard procedure in our institution for Stanford A type aortic dissection.     

Total aortic arch grafting via median sternotomy using integrated antegrade cerebral perfusion

BACKGROUND: In aortic arch grafting, antegrade cerebral perfusion prolongs the safe time of arch exclusion. However, there are the problems of cerebral embolism and distribution of the cerebral perfusion. We describe and analyze mortality and cerebral complications in patients undergoing total arch grafting using our refined technique. METHODS: Between June 1994 and March 2002, 100 consecutive patients underwent total arch grafting through median sternotomy. There were 49 atherosclerotic aneurysms and 51 aortic dissections. Fifty-four patients were operated on an emergency basis because of rupture or acute type A dissection. We conducted total arch grafting using hypothermic antegrade cerebral perfusion from every cervical vessel. Carbon dioxide gas was added to the cerebral perfusion in order to inhibit the increase in the cerebral vascular resistance during hypothermic cerebral perfusion. RESULTS: Hospital mortality was 4%. The causes of death were dysarrhythmia (n = 1), mesenteric necrosis (n = 1), and preoperative cardiac arrest (n = 2). On univariate analysis, preoperative shock and concomitant cardiac procedures were risk factors for hospital death. The rate of postoperative neurologic damage was 5%. Two patients suffered from cerebral infarction. Temporary neurologic dysfunction occurred in 3 patients. On univariate analysis, emergency surgery was a risk factor for postoperative neurologic damage. On multivariate analysis, there was no significant independent predictor of hospital mortality and neurologic damage. Actuarial survival at 96 months was 66.4 +/- 9.1%, and freedom from aortic accidents (reoperation, rupture, and cholesterol embolism) was 74.9 +/- 7.9%. CONCLUSIONS: The early- and long-term results of total arch grafting using integrated antegrade cerebral perfusion were found to be satisfactory.     

Does retrograde cerebral perfusion via superior vena cava cannulation protect the brain?

Objective: The retrograde cerebral perfusion via cannulation of the superior vena cava is a widespread method for optimising protection of the brain during hypothermic circulatory arrest. Methods: In 14 cadavers (8 females, 6 males) of the local department of pathology, an examination was performed to check the competence of the valves of the internal jugular veins. After a complete preparation of the superior vena cava, the innominate vein and both internal jugular veins, ligating all side branches, a retrograde perfusion on 7 cadavers was installed, documenting flow and pressure of each internal jugular vein (IJV) in vitro. Afterwards, the veins were opened and their valves inspected. Results: In all 14 cadavers, anatomically and functionally competent valves on the right proximal IJV were found. Only 1/14 cadaver had no valve in the left proximal IJV. Additional rudimentary and incompetent valves could be identified in 1/14 cadaver on the distal right IJV, and in 2/14 cadavers on the left IJV. Retrograde flow measurement of 7/14 cadavers revealed 0 ml/min in 4/7 cadavers, 6 ml/min in 1/7, 340 ml/min in 1/7 and 2500 ml/min in 1/7 cadaver. Conclusions: As a rule, anatomically and functionally competent valves in the proximal IJV are present. In human beings, they obstruct the direct retrograde inlet to the intracranial venous system, which suggests an unbalanced and unreliable perfusion of the brain. Therefore, retrograde cerebral perfusion by cannulating the superior vena cava may help flushing out embolism and supporting ‘the cold jacket’ of the brain. However, its effect of retrograde backflow cannot be a sign of adequate cerebral perfusion.     

pH-stat blood gas management provides better cerebral perfusion during deep hypothermic retrograde cerebral perfusion

We performed a retrospective comparative clinical study to evaluate whether pH-stat (n=14) or alpha-stat strategy (n=15) provides better perfusion or oxygen metabolism during hypothermic retrograde cerebral perfusion (RCP). The pH-stat group showed significantly lower superior vena cava (SVC) pressure (21+/-4 versus 27+/-6 mmHg, P<0.0001), apparently lower retrograde cerebral vascular resistance index (7.4+/-2.1 versus 10.1+/-3.8 dynes/s cm(-5) m(-2), P=0.009) but there were no significant differences in RCP flow index, oxygen supply or oxygen extraction between groups. Further studies are necessary to determine which blood gas management is better for RCP, however, pH-stat strategy should be useful in deep hypothermic RCP.     

Functional imaging of cerebral perfusion

The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hemodynamic disorders in patients suffering from Alzheimer's disease or with arteriovenous malformations revealed by epilepsy. Functional MRI of the vasoreactivity also helps to better interpret the functional MRI activation in practice and in clinical research.     

Retrograde cerebral perfusion versus selective cerebral perfusion as evaluated by cerebral oxygen saturation during aortic arch reconstruction.

BACKGROUND: Time limits for neuroprotection by retrograde cerebral perfusion (RCP) and selective cerebral perfusion (SCP) in aortic arch aneurysm repair or dissection are undergoing definition. METHODS: Using near-infrared optical spectroscopy, changes in regional cerebrovascular oxygen saturation (rSO2) were compared between the two perfusion methods. RESULTS: Immediately before cardiopulmonary bypass, baseline rSO2 was 63.9%+/-6.9% for the RCP and 66.1%+/-5.3% for the SCP group (no significant difference). As patients were core-cooled to 20 degrees C, rSO2 increased to 73.1%+/-8.8% and 74.1%+/-7.9% in the RCP and SCP groups, respectively. With circulatory arrest, rSO2 suddenly decreased. After starting cerebral perfusion, rSO2 returned to prearrest values in the SCP group but continued decreasing steadily in the RCP group, to levels below baseline after about 25 minutes. At the end of perfusion, rSO2 was 57.4%+/-12.2% for the RCP group and 71.7%+/-6.9% for the SCP group, and the ratio of rSO2 to baseline value was 0.89 for RCP and 1.08 for SCP despite a shorter brain perfusion time for RCP (38.8+/-18.0 versus 103.3+/-43.3 minutes). Three of 5 patients whose ratios of rSO2 to baseline at the end of brain protection were 0.7 or less had neurologic deficits. CONCLUSIONS: Although SCP showed no clinically important time limitation, rSO2 continued to decrease with time during RCP. An rSO2 ratio less than 0.7 could represent a critical lower limit.     

Use of a pH-stat strategy during retrograde cerebral perfusion improves cerebral perfusion and tissue oxygenation

BACKGROUND: Although it is well documented that the use of a pH-stat strategy during hypothermic cardiopulmonary bypass improves cerebral blood flow, an alpha-stat strategy has been almost exclusively used during retrograde cerebral perfusion. We investigated the effects of pH-stat and alpha-stat management on brain tissue blood flow and oxygenation during retrograde cerebral perfusion in a porcine model to determine if the use of a pH-stat strategy during retrograde cerebral perfusion improves brain tissue perfusion. METHODS: Fourteen pigs were managed by an alpha-stat strategy (alpha-stat group, n = 7) or by a pH-stat strategy (pH-stat group, n = 7) during 120 minutes of hypothermic retrograde cerebral perfusion. Retrograde cerebral perfusion was established through the superior vena cava. Brain tissue blood flow and oxygenation were measured continuously with a laser flowmeter and near infrared spectroscopy, respectively. Brain tissue water content was determined at the end of the experiments. RESULTS: During cooling, brain tissue blood flow was significantly higher with use of the pH-stat strategy than with the alpha-stat strategy (86% +/- 10% versus 40% +/- 3% of baseline). During retrograde cerebral perfusion, brain tissue blood flow was also significantly higher (about three times higher) in the pH-stat group than in the alpha-stat group (15% +/- 4% versus 5% +/- 1% of baseline at 60 minutes of retrograde cerebral perfusion). Tissue oxygen saturation appeared to be higher during retrograde cerebral perfusion in the pH-stat group than in the alpha-stat group. Brain tissue blood flow during rewarming remained significantly higher with the use of pH-stat than with the use of alpha-stat. Brain tissue water contents were similar in both groups. CONCLUSIONS: In our pig model, the use of a pH-stat strategy during retrograde cerebral perfusion significantly improves brain tissue perfusion. Therefore, to improve retrograde cerebral blood flow during retrograde cerebral perfusion, it may be preferable to use a pH-stat strategy, rather than an alpha-stat strategy.     

Monitoring cerebral perfusion during carotid endarterectomy

Transcranial pulsed Doppler ultrasound was used to monitor blood velocity in the middle cerebral artery (MCA) of two patients during ipsilateral carotid endarterectomy. In the first patient the ultrasound data demonstrated a non-functioning shunt which was corrected by repositioning the distal end of the shunt. In the second patient MCA blood velocity data demonstrated that clamping of the external carotid artery would have resulted in complete cessation of MCA flow throughout endarterectomy. These cases illustrate the benefit that this technique offers to the individual patient undergoing carotid surgery.