体外循环期间低温肺灌注对肺的保护作用

研究体外循环（ＣＰＢ）期间低温保护液肺动脉灌注对肺脏的保护作用。方法将１２条杂种犬随机分为２组。主动脉阻断后,对照组右肺动脉灌注４℃乳酸林格液,实验组灌注４℃肺保护液。结果ＣＰＢ结束后实验组气道压、肺血管阻力（ＰＶＲ）、右房白细胞／右肺静脉白细胞及丙二醛（ＭＤＡ）低于对照组;两组右肺静脉血氧分压均较左肺高;组织学观察实验组右肺组织结构基本正常。结论ＣＰＢ期间肺动脉灌注低温肺保护液可以明显减轻ＣＰＢ对肺脏造成的损伤。     

Effect of cardiopulmonary bypass on pulmonary clearance of adrenomedullin in humans

BACKGROUND: Adrenomedullin is a potent vasodilatory peptide and its plasma concentration increases after cardiopulmonary bypass. We analyzed the contribution of the lung to the disposition of adrenomedullin before and after cardiopulmonary bypass in humans. METHODS: Thirty-five patients undergoing cardiac surgery with cardiopulmonary bypass were studied. Bloods were sampled from the pulmonary artery and left atrium at the following times: prior to systemic heparinization, during pulmonary reperfusion and after cardiopulmonary bypass. Plasma concentrations of total and mature adrenomedullin were measured using an immunoradiometric assay kit specific for human adrenomedullin. Intermediate adrenomedullin was calculated as the difference between total adrenomedullin and mature adrenomedullin. RESULTS: Before cardiopulmonary bypass, mature and intermediate adrenomedullin concentrations were reduced by the pulmonary circulation by approximately 30% and 20%, respectively. However, these effects were not observed during pulmonary reperfusion. Mature, but not intermediate, adrenomedullin was reduced after cardiopulmonary bypass. Furthermore, pulmonary clearance quantity of mature adrenomedullin was significantly enhanced after cardiopulmonary bypass. CONCLUSION: These results indicate that cardiopulmonary bypass temporally impairs the pulmonary clearance of mature and intermediate adrenomedullin, but clearance of mature, not intermediate adrenomedullin is enhanced after cardiopulmonary bypass.     

Rupture of extra-corporeal circuit tubing during cardiopulmonary bypass

Roller pumps are widely used for cardiopulmonary bypass in developing nations by virtue of proven safety during several years of institutional use and cost effectiveness. However, careful adjustment of roller occlusion is needed because they are known to cause spallation, tubing wear, and the occasional incident of rupture of tubing in the extracorporeal circuit. Rupture of polyvinylchloride tubing in the pump raceway during repair of a ventricular septal defect in a 4-year-old child is discussed. The event was managed by exclusion and replacement of the defective tubing during a short period of arrest. Use of an inappropriate boot pump and failure to detect its inclusion in the bypass circuit was a significant departure from protocol. However, because occlusion settings and duration of perfusion were within acceptable limits, a manufacturing flaw could also have contributed to tubing failure, and the event may or may not have been averted by the use of larger tubing. In conclusion, this incident reiterates the need for adherence to established protocol during assembly of the pump and draws attention to the fact that tubing integrity is not a guarantee and vigilance is warranted to handle its failure.     

Activation of pulmonary mitogen-activated protein kinases during cardiopulmonary bypass

PURPOSE: Cardiopulmonary bypass (CPB) produces an inflammatory response associated with pulmonary dysfunction. Mitogen-activated protein kinases (MAPK) have been shown to mediate pulmonary injury. We hypothesized that MAPK are activated during CPB and potentially contribute to lung injury. METHODS: Pigs were placed on CPB (n = 6) for 90 min, which included 80 min of cardioplegic arrest, followed by 180 min of post-CPB reperfusion. Control animals (n = 6) underwent sternotomy and heparinization only. Lung samples were collected at baseline, during CPB, and during post-CPB reperfusion. Activated forms of extracellular signal-regulated kinases 1/2 (ERK1/2) and p38 were measured by Western blot. Immunohistochemistry was used for tissue localization of activated MAPK. Pulmonary inflammation was determined by histology. Pulmonary edema was estimated by tissue water percentage. RESULTS: Activated ERK1/2 and p38 were increased after 90 min of CPB compared with controls (3.94 +/- 0.61- and 2.49 +/- 0.15-fold increase, respectively; both P < 0.01). At 180 min of post-CPB reperfusion, ERK1/2 activity was increased by nearly 5-fold compared with controls (P < 0.01), whereas p38 activity returned to baseline levels. By immunohistochemistry, activated ERK1/2 and p38 in the CPB group were localized to alveolar epithelial cells, vascular endothelial cells, and bronchial smooth muscle. Histologic signs of lung injury included leukocyte infiltration in the CPB group. Tissue water percentage was increased with CPB (89.9 +/- 1.5% versus 82.5 +/- 1.0%, CPB versus control, P < 0.05). CONCLUSIONS: The results of our study demonstrate that CPB increases pulmonary p38 activity and causes sustained activation of ERK1/2. MAPK activation thus may in part mediate the pulmonary inflammatory response and provide a potential site of intervention to prevent pulmonary dysfunction due to CPB.     

体外循环中有效的肺动脉灌注方式

目的 探索方便、有效的肺动脉灌注模式,以缓解体外循环心脏术后肺损伤.方法 14只健康家犬模拟临床体外循环肺损伤特点建立动物模型,随机平均分为对照组及灌注组.体外循环期间,分别于实验肺缺血之初及再灌注之前,以15～20 mm Hg(1 mm Hg=0.133 kPa)的灌注压力短时间对灌注组动物实验肺实施改良低钾右旋糖酐保护液灌注;对照组动物无保护液灌注.90 min体外循环肺缺血后,再灌注4 h,行实验肺肺功能变化测定.结果 再灌注后,两组动物实验肺肺功能均有不同程度的恶化.对照组,再灌注后实验肺顺应性及氧合指数均有较大幅度的下降,分别为(30±4)%及(45±5)%,肺血管阻力指数明显上升,幅度为(76±7)%;与对照组比较,灌注组上述指标的变化幅度均明显降低,分别为[(12±2)%,t0.01/2,12=4.885,P＜0.01];[(19±2)%,t0.01/2,12=5.656,P＜0.01];[(28±3)%,t0.01/2,12=6.853,P＜0.01)].结论 应用肺动脉灌注方式可明显减轻体外循环过程中肺组织的损伤,保护肺功能;实验的灌注方式可望方便地应用于临床体外循环心脏手术过程,不会明显干扰既定手术进程.     

No effect of L-arginine supplementation on pulmonary endothelial dysfunction after cardiopulmonary bypass

BACKGROUND: Acetylcholine is an endothelium-dependent vasodilator through the L-arginine-nitric oxide pathway. After ischemia-reperfusion this effect is attenuated, also demonstrated in the pulmonary circulation after cardiopulmonary bypass. Administration of L-arginine has been shown to have a protective effect on endothelial function in reperfusion injury. The aim of the current study was to test the possible effect of L-arginine on the acetylcholine reactivity in the pulmonary circulation after cardiopulmonary bypass. METHODS: Thirty-five patients with ischemic and/or valvular heart disease were investigated in a randomized, double-blinded, placebo-controlled study. The patients were divided into three groups. Group 1: high dose L-arginine (n=10), group 2: low dose L-arginine (n=10), group 3: placebo, no L-arginine, (n=15). The acetylcholine reactivity was tested with measurements of pulmonary vascular resistance before surgery and 1, 2 and 3-4 h after cardiopulmonary bypass. RESULTS: After cardiopulmonary bypass an attenuation of the acetylcholine reactivity over time was observed in all groups, with no differences between groups. CONCLUSION: In the current study L-arginine had no protective effect on the pulmonary endothelium after cardiopulmonary bypass, measured as reactivity to an infusion of acetylcholine.     

Cognitive dysfunction after cardiopulmonary bypass

Cognitive dysfunction remains a significant complication after cardiopulmonary bypass, despite continuous improvement in the overall outcome in open‐heart surgery. Embolization of the atheromatous material, most notably during removal of the aortic clamp, is a major cause. Strategies have been developed to minimize cerebral embolization. Modified surgical techniques include the use of hypothermic circulatory arrest, venting of the left ventricle, minimizing aortic manipulation, and the use of epiaortic ultrasound to locate and avoid trauma to the aortic atheromatous plaque. Use of an intra‐aortic filter has been shown recently to reduce intraoperative cerebral embolic events and improve postoperative neurocognitive outcomes. Off‐pump coronary artery bypass technique has also been claimed to have lower neurological complications, which is probably attributable to the avoidance of aortic cannulation and cardiopulmonary bypass. Its role on cerebral protection is, however, debatable. Chinese Abstract

Figure Chinese Abstract Open in figure viewer PowerPoint

Volume 6 , Issue 1 February 2002

Pages 1-3     

术中持续输注胰岛素对心肺转流心脏手术患者心肌血流灌注的影响

目的： 探讨术中持续输注胰岛素对心肺转流（CPB）心脏手术患者心肌血流灌注的影响。
方法： 选择择期行CPB心脏手术患者48例,男21例,女27例,年龄55～80岁,BMI 18～28 kg/m²,ASA Ⅱ—Ⅳ级。将患者随机分为两组：胰岛素组（I组,n=25）和对照组（C组,n=23）。两组采用相同麻醉方案。麻醉诱导后I组静脉输注胰岛素30 mU·kg^-1·h^-1、葡萄糖0.12 g·kg^-1·h^-1、氯化钾0.06 mmol·kg^-1·h^-1混合液,C组予以生理盐水10 ml/h输注,均输注至术毕。术中目标血糖值为6.1～11.1 mmol/L。于麻醉诱导后10 min（T₂）和术毕（T₆）行经食管超声心动图（TEE）检测,记录冠状静脉窦（CS）血流频谱、直径及肺静脉血流频谱,并计算CS净向前血流流速时间积分（VTI）。记录T₂、CPB前2 min（T₃）、CPB结束时（T₅₂）和T6时的股动脉平均动脉压（MAP）、中心静脉压（CVP）、每搏量（SV）、心脏指数（CI）及外周血管阻力指数（SVRI）。记录麻醉诱导前5 min（T₁）、T₃、CPB后30 min（T₄）、T₅、T₆、术后6 h（T₇）、术后12 h（T₈）及术后24 h（T₉）时血糖及乳酸浓度。记录术前1 d、术后1、2 d时超敏C反应蛋白（hs-CRP）、高敏肌钙蛋白I（hs-TnI）和肌酸激酶同工酶（CK-MB）水平。
结果： 与C组比较,I组T₆时CS净前向血流VTI及每分钟CS血流量均明显增加（P<0.05）,肺静脉心房收缩期峰值流速（ARp）明显减小（P<0.05）,T₅、T₆时SV和CI明显增大、SVRI明显降低（P<0.05）,T₇、T₈时乳酸浓度明显降低（P<0.05）,术后1、2 d时hs-CRP和CK-MB水平明显降低（P<0.05）,术后2 d时hs-TnI明显降低（P<0.05）。
结论： CPB心脏手术中持续输注胰岛素,同时维持血糖6.1～11.1 mmol/L,可改善心肌血流灌注,减轻术后炎症反应及心肌损伤。     

Improved outcomes during cardiac surgery: a multifactorial enhancement of cardiopulmonary bypass techniques

Patients presenting for cardiac surgery with cardiopulmonary bypass (CPB) are more likely to have pre-existing comorbidities, which has resulted in a steady increase in the risk associated with CPB. The resulting challenge has mandated the optimization of perfusion care. The purpose of this study was to retrospectively evaluate the impact of a number of simultaneous, evidence based perfusion care changes on patient outcome. After Institutional Review Board approval, two groups of patients were compared. The control group (n = 317) included all patients undergoing CPB in a 12-month period preceding a multifaceted change in perfusion techniques. The treatment group (n = 259) included all patients undergoing CPB in the 12-month period after the changes, which included the incorporation of updated continuous blood gas monitoring, biocompatible circuitry, updated centrifugal blood propulsion, continuous autotransfusion technology, new generation myocardial protection instrumentation, plasmapheresis, topical platelet gel application, excluding hetastarch while increasing the use of albumin, viscoelastographic coagulation monitoring, and implementing a quantitative quality improvement program. After univariate analysis, propensity scoring and multiple conditional logistical regression were used to control for demographic, preoperative, operative, and postoperative parameters. Results of the primary endpoints revealed a lower mortality rate in the treatment group (4% vs. 9% [95% confidence interval 1.33, 7.72], p = 0.009), lower transfusion rate (51% vs. 59% [1.00, 2.11], p = 0.048), and lower complication rate (55% vs. 65% [1.06,2.19], p = 0.025) despite having similar predicted mortality (11 [2,22] vs. 11[3,22], p = NS) and other preoperative and operative parameters. The lower mortality rate was concurrent with a trend towards a lower incidence of complications, consistent with the differences in primary outcomes. In conclusion, the patients treated after the implementation of a multifactorial improvement plan using evidence based changes in CPB care had decreased complication and mortality rates.     

Effects of organic nitrate vasodilators on platelet function before and after cardiopulmonary bypass

Various in vitro , ex vivo and in vivo tests have shown that organic nitrates attenuate platelet function. Because organic nitrates are commonly administered to patients undergoing cardiac surgery, the postoperative bleeding tendency observed in these patients might be strengthened by nitrates. Therefore, we compared the acute effects of nitroglycerin (0.5 μg kg^-1 min^-1) and isosorbide dinitrate (0.5 or 2.5 ng kg^-1 min^-1) with those of placebo on platelet function both before and after cardiopulmonary bypass in 40 patients undergoing coronary artery bypass grafting (CABG). Bleeding time, platelet retention on glass beads, i.e. platelet adhesiveness, and thromboel-astograph tracings were used as indicators of platelet function. Although nitroglycerin and isosorbide dinitrate induced significant haemodynamic changes, e.g. decreases in arterial and pulmonary arterial pressure, they had no significant effects on the indices of platelet function. We conclude that, when given in haemodynamically effective doses, neither nitroglycerin nor isosorbide dinitrate have any measurable acute effect on platelet function as evaluated with on-site tests in patients undergoing CABG surgery.     

黏附分子与心肺转流术肺损伤

急性肺损伤是心肺转流术(cardiopulmonary by-pass,CPB)后最常见的并发症,其中白细胞在肺内的“扣留”起到了主要作用,而细胞黏附分子参与了白细胞渗出及活化的各个环节。现就有关黏附分子与CPB肺损伤关系的研究作以下综述,并探讨目前抗黏附分子在这领域的应用,旨在进一步揭示C     

The management of insulin dependent diabetes during cardiopulmonary bypass and general surgery

Two groups of insulin dependent diabetic subjects have been studied: six undergoing general surgical procedures and six undergoing hypothermic cardiopulmonary bypass surgery for coronary artery vein grafting. Intravenous glucose insulin mixtures were infused from the onset of surgery in both groups of patients, supplying 0.4 units of insulin per gram of glucose per hour, and 0.6 units of insulin per gram of glucose per hour in general and cardiac surgical patients respectively. Postoperatively diabetes was controlled carefully with an insulin syringe pump regulated by venous blood glucose monitoring. In cardiac surgical patients far more insulin was required to control diabetes postoperatively than in the general surgery patients (at 1 hour 1.6 units, SEM 0.4 compared to 0.7 SEM 0.1, p less than 0.05; and at 4 hours 2.0 units SEM 0.3 compared to 0.8 units SEM 0.1, p less than 0.02). Five non-diabetic subjects who underwent surgery for coronary artery venous bypass grafting were also studied. They developed significant postoperative hyperglycaemia (5.0, SEM 0.2, mmol/litre pre-operatively, compared with 8.8, SEM 0.7, mmol/litre p less than 0.03 at 1 hour and 10.2, SEM 1.7, mmol/litre, p less than 0.02 at 4 hours after bypass terminated).     

乌司他丁对体外循环心脏手术后肺功能的影响

目的　观察体外循环 (CPB)心脏手术后肺功能受损的程度 ,研究乌司他丁 (Ulinastatin ,UTI)对体外循环心脏手术肺功能的影响。方法　择期行心脏瓣膜置换术病人 6 0例 ,随机分成对照组 (I组 ,2 0例 ) ,UTI 1万U kg组 (II组 ,2 0例 ) ,UTI 2万U kg组 (III组 ,2 0例 )。对术后肺功能指标OI、VD VT、PA -aO2 、CaO2 、SaO2 和PaO2 进行观察以及比较呼吸机支持的时间 ,气管插管拔除后 2 4h内的自主呼吸频率和呼吸情况的改变。结果　I组术后各时点所有病人OI、VD VT、PA -aO2 分别较CPB前增大 (P <0 0 5 ) ,而CaO2 、SaO2 和PaO2 均下降 (P <0 0 5 )。术后各时点III组的OI值均明显低于I、II组 (P <0 0 5 ) ;与I、II组比较 ,III组术后 12、2 4h的PA -aO2 值下降幅度显著 (P <0 0 5 ) ,CaO2 、SaO2 和PaO2 的下降较少 ,但差异有显著性 (P <0 0 5 )。III组呼吸机支持时间最短 ,气管插管拔除后自主呼吸频率最慢但平顺 ,肺部罗音的发生率最低 ,改变有统计学意义。结论　体外循环过程造成肺损害 ,表现为一些亚临床性肺功能损伤。乌司他丁对肺功能有保护作用 ,其中 2万U kg组肺保护作用优于 1万U kg组。