预防心脏手术中体外循环致肺损伤的研究进展

体外循环是心内直视手术的一种重要手段,随着体外循环装置、心肌保护措施和心脏外科技术的不断完善与提高,心内直视手术并发症的发生率和死亡率已大大下降。但肺损伤仍是CPB后的主要并发症之一,而肺损伤后气体交换障碍可能造成严重的并发症,甚至死亡。本文综述了体外循环心脏手术后肺损伤的发生机制及预防措施的研究进展。     

超滤方法在体外循环中应用的探讨

目的：观察和研究超滤方法在体外循环心内直视手术中应用的效果。方法：统计自1989年9月至2002年1月间共实行8622例体外循环心内直视手术中应用超滤方法,其中男性4825例,女性3837例。体外循环中超滤法是在心内操作基本完成,且在机体给予复温时进行的。结果：全组病例超滤时间10-46分,超滤液量为300-1800ml,监测超滤液中未发现细胞成分,蛋白定性为阴性。超滤后血液得到浓缩,检测血液尿素氮,肌酐及炎性介质均比以前降低。结论：体外循环中应用超滤方法可以减轻病人术后组织水肿,并能迅速地浓缩血液,提高病人的血细胞压积,血红蛋白和各种凝血物质,超滤方法还能降低体外循环中的炎性介质的浓度,有利于患者术后的康复。     

体外循环时的微栓塞和血液过滤器使用

自1953年Gibbon研制成人工心肺机后,三十年来,体外循环技术和人工心肺机均有了很大的改进,应用范围亦越趋扩大,但距生理和临床要求相差毕竟还很远,转流后(特别是两小时以上的长时间转流)还可产生许多并发症,其中微栓塞颇为常见,临床危害很大,直接影响心内直视手术的效果。     

体外循环时的微栓塞和血液过滤器使用

自1953年Gibbon研制成人工心肺机后,三十年来,体外循环技术和人工心肺机均有了很大的改进,应用范围亦越趋扩大,但距生理和临床要求相差毕竟还很远,转流后(特别是两小时以上的长时间转流)还可产生许多并发症,其中微栓塞颇为常见,临床危害很大,直接影响心内直视手术的效果。     

体外循环心内直视手术中甲基强的松龙对肺保护作用的临床研究

目的：研究在体外循环心脏手术中应用甲基强的松龙的肺保护效果。方法：2000年1月至2001年5月,85例患者在体外循环中应用了甲基强的松龙,作为研究组;1996年9月至1999年12月,143例患者未在体外循环中应用甲基强的松龙,作为对照组。两组病例均静脉复合麻醉,气管插管,中度低温,中深度血液释释,应用冷晶体心肌保护液进行心肌保护。结果：研究组患者体外循环结束时的气道压力、肺泡-动脉血氧分压差的升高幅度和机械通气时间明显少于对照组患者。结论：在体外循环心内直视手术中应用甲基强的松龙,可有效减轻肺损伤,取得良好的肺保护效果。     

抑肽酶在体外循环心脏直视手术中的肺保护作用研究

目的 :体外循环中 ,血液与异物表面直接接触 ,导致许多炎性介质和血管活性物质的形成及释放 ,形成的肺损伤是手术患者的一个重要而危险的并发症。本文总结了CPB中应用抑肽酶进行肺保护的研究和临床应用。方法 :2 0 0 1年 1月至 11月 ,在本院施行二尖瓣置换手术的患者随机分为研究组和对照组 ,手术中应用抑肽酶的患者作为研究组 ,未用抑肽酶的患者作为对照组。记录两组患者术前、麻醉诱导时、体外循环结束时的气道压力 (Paw)、肺泡———动脉血氧分压差 [(A a)DO2 ]、两组患者回病房后的机械通气时间。结果 :两组患者的术前、前中情况均无显著性差异。而研究组患者体外循环结束时的气道压力和肺泡 动脉血氧分压差的升高幅度明显小于对照组患者 (P <0 0 5 ) ,预示着研究组患者的肺功能在体外循环过程中受到的损伤程度显著小于对照组患者。研究组患者的机械通气时间比对照组患者显著减少 (P <0 0 5 ) ,说明研究组患者术后肺功能比对照组患者恢复得快。结论 :在体外循环心内直视手术中应用抑肽酶 ,充分发挥其血液麻醉作用 ,可有效减轻肺损伤 ,促进术后恢复 ,取得良好的肺保护效果 ,而且简便易行、安全实用 ,对医患双方都有着积极意义     

30例心脏直视手术的护理配合体会

随着体外循环下心内直视手术的广泛开展,对先天性心脏病、心脏瓣膜等疾病实施手术治疗的技术已成熟和安全。我院自2007年6月至2009年5月对30例心脏病患者实施手术治疗,现将手术护理配合总结如下。     

心内直视手术中七十岁以上患者的体外循环管理

目的总结分析心内直视手术中七十岁以上患者的体外循环特点和管理方法。方法 2005年3月至2008年7月间7000余例手术中70岁以上患者共有194例,分类进行心内直视手术。体外循环时全部应用进口膜肺,勃脉力A和胶体预充,常规加入白蛋白、激素和乌司他丁;心肌保护采用间断灌注4：1冷含血停搏液,顺灌逆灌和桥灌相结合;常规监测混合静脉氧饱和度和血细胞压积,积极应用超滤技术。结果术中转流平稳,血流动力学稳定,监测指标均在正常范围,平均体外循环时间和主动脉阻断时间分别为111.5±40.4m in和63.6±21.0m in,自动复跳率52.6%,平均搭桥数目3.4±0.8支,术后平均气管拔管时间24.0±12.7h,平均ICU时间4.7±3.5d。结论 70岁以上患者以瓣膜和冠状动脉病变为主、病变复杂,体外循环时间和主动脉阻断时间较长,各脏器保护要求高,针对高龄患者的特点,制定相应的体外循环管理方法,是保证手术成功的重要因素。     

CH—Ⅰ型人体升、降温机的研制

在体外循环下进行心内直视手术时,需要将病人的体温由正常体温降至25℃左右;手术完毕以后,又需要迅速将病人的体温回升到35℃～37℃左右,才能维持人体心脏的正常生理功能。因此,严格控制病人的体温变化,是心脏外科手术工作中重要的环节之一。一、研制目的心内直视手木后,为了缩短升温时间,在采用血液升温的同时,配合进行体表升温。在通常情况下,使用只有一个出口的橡皮袋,放在病人的躯干下面,从出口处向袋     

围心内手术期国产SC-500型呼吸机的临床应用和实验测试

由航天工业部二院第四总体设计部和上海医疗器械四厂共同研制成功的SC-500型呼吸机,我院自1985年10月21日起,在体外循环心内直视手术中进行了应用,并经实验测试30例,证明其主要技术指标和性能均能满足临床要求,兹报道如下: 临床应用〔病例资料〕体外循环心内直视手术30例,男16女14,平均年龄18±4.6岁(范围7～39岁),平均体重35±3.8 kg(范围18～60 kg)。其中先天性心脏病18例(房间隔缺损6、室间隔缺损7和法乐氏四联症5)和风湿性心脏病12例(施行二尖瓣置换术10、主动脉瓣置换术1、二尖瓣和主动脉双瓣置换术1)。     

Cognitive dysfunction after cardiac surgery: Pathophysiological mechanisms and preventive strategies

Despite improvements in surgical techniques and the implementation of effective brain protection strategies, the incidence of brain injury after cardiac surgery has remained relatively constant over the years as patients have become older and sicker. Cognitive dysfunction is the most common clinical manifestation of brain injury after cardiac surgery. Its occurrence is related to a combination of three factors that are often associated with cardiopulmonary bypass (CPB): embolism, hypoperfusion, and the inflammatory response. However, such factors and their potential cerebral consequences are not exclusive to CPB. Postoperative cognitive dysfunction also afflicts patients who undergo cardiac surgery without CPB as well as nonsurgery patients who undergo transcatheter interventions. There is growing evidence that patient-related factors such as the presence of (cerebro)vascular risk factors play an important role in both early and late postoperative cognitive dysfunction.     

Acute renal dysfunction after cardiac surgery with cardiopulmonary bypass is associated with plasmatic IL6 increase

Background: Acute renal dysfunction (ARD) is common after cardiac surgery with cardiopulmonary bypass (CPB). CPB results in a sudden systemic inflammatory response. Systemic and local pro-inflammatory cytokines synthesis has been linked with sub-clinical renal injury, especially tubular lesions. Therefore, we sought to assess the systemic synthesis pro-inflammatory cytokines and its association with perioperative ARD after cardiac surgery with CPB. Methods: Sixty-two patients undergoing cardiac surgery with CPB were prospectively included. Four groups of patients were defined according to blood creatinine increase: no ARD (less than 25% increase), faint ARD (25–50% increase), moderate ARD (50–100% increase), severe ARD (more than 100% increase). Results: Within the 48 post-operative hours was ARD observed as no dysfunction (41.9%), faint (32.2%), moderate (16.1%), severe (9.6%). One patient had to undergo a dialysis. Pre-operative characteristics were homogenous between the four groups excepted the left ventricle ejection fraction. ARD was associated with a low urinary output with high sodium excretion fraction. Significant increase of IL-6 level occurred when patients underwent a severe ARD despite no significant differences for the CRP and TNF-α concentrations. Conclusion: Severe acute renal dysfunction after cardiac surgery with CPB is associated with a significant increased IL-6 systemic production.     

Reversal of anemia with allogenic RBC transfusion prevents post-cardiopulmonary bypass acute kidney injury in swine

Anemia during cardiopulmonary bypass (CPB) is strongly associated with acute kidney injury in clinical studies; however, reversal of anemia with red blood cell (RBC) transfusions is associated with further renal injury. To understand this paradox, we evaluated the effects of reversal of anemia during CPB with allogenic RBC transfusion in a novel large-animal model of post-cardiac surgery acute kidney injury with significant homology to that observed in cardiac surgery patients. Adult pigs undergoing general anesthesia were allocated to a Sham procedure, CPB alone, Sham+RBC transfusion, or CPB+RBC transfusion, with recovery and reassessment at 24 h. CPB was associated with dilutional anemia and caused acute kidney injury in swine characterized by renal endothelial dysfunction, loss of nitric oxide (NO) bioavailability, vasoconstriction, medullary hypoxia, cortical ATP depletion, glomerular sequestration of activated platelets and inflammatory cells, and proximal tubule epithelial cell stress. RBC transfusion in the absence of CPB also resulted in renal injury. This was characterized by endothelial injury, microvascular endothelial dysfunction, platelet activation, and equivalent cortical tubular epithelial phenotypic changes to those observed in CPB pigs, but occurred in the absence of severe intrarenal vasoconstriction, ATP depletion, or reductions in creatinine clearance. In contrast, reversal of anemia during CPB with RBC transfusion prevented the reductions in creatinine clearance, loss of NO bioavailability, platelet activation, inflammation, and epithelial cell injury attributable to CPB although it did not prevent the development of significant intrarenal vasoconstriction and endothelial dysfunction. In conclusion, contrary to the findings of observational studies in cardiac surgery, RBC transfusion during CPB protects pigs against acute kidney injury. Our study underlines the need for translational research into indications for transfusion and prevention strategies for acute kidney injury.     

Départ imprévu en CEC

The cardio pulmonary bypass (CPB) is used in heart surgery for circulatory and respiratory replacement. The effectiveness of this technique, as well circulatory as respiratory goes and will go to spread its use far beyond the strictly surgical field. The unexpected starts on CPB include not provided starts, anticipated stars, and renewed stars. The not provided starts concern going on CPB for a cardiac or respiratory failure, not reacting to the conventional techniques of cardiopulmonary resuscitation and rare cases of inability to access the airway in emergency. This could be an exceptional complement to external cardiac massage. The anticipated departures involve patients in the operating room for cardiac surgery for which the establishment of the CPB has to treat with emergency life threatening brutal cardiac failure on valvular or coronary artery disease. The renewed starts are being on CPB or after weaning of CPB. It is being CPB to change a failed oxygenator responsible for a tissue hypoxia or replace a piece of tube main circuit of the CPB. A new start on CPB after weaning is essentially for circulatory assistance made necessary by postcardiotomy heart failure, by side effects of protamine injection, excessive bleeding or intra cardiac thrombosis. The oxygenator replacement techniques in emergency are exposed. This techniques demand a well trained and mobile medical and para medical staff.     

Development of post-pump syndrome in a sheep after mitral valve stenting

A one-year-old healthy sheep received an implant stenting the mural ('posterior') leaflet of the mitral valve. The experiment was authorized by the Cantonal Ethical Committee. The surgery was performed on the open, beating heart during cardiopulmonary bypass (CPB). Management of anaesthesia was based on isoflurane with mechanical intermittent positive pressure ventilation (IPPV) of the lungs, combined with intercostal nerve blocks and intravenous fentanyl and lidocaine. Marked cardiovascular depression occurred towards the end of CPB time and required high doses of dopamine, dobutamine, lidocaine and ephedrine to allow for weaning off the CPB pump. Moreover, severe pulmonary dysfunction developed when IPPV was re-initiated after CPB. Hypoxaemia persisted throughout the recovery from general anaesthesia. Multiple organ failure developed gradually during the three postoperative days, leading to euthanasia of the animal. As described in this case, marked lung injury associated with some degree of failure of other vital organs may occur in sheep after CPB. Intraoperative cardiorespiratory complications when weaning-off may indicate the development of 'post-pump syndrome'.     

Plasma and urinary cytokine homeostasis and renal function during cardiac surgery without cardiopulmonary bypass

Cardiopulmonary bypass (CPB) significantly contributes to the plasma pro-inflammatory cytokine response at cardiac surgery. Complementary plasma and urinary anti-inflammatory cytokine responses have been described. The pro-inflammatory cytokines interleukin 8 (IL-8), tumour necrosis factor alpha (TNF-alpha) and interleukin 1beta (IL-1beta) have lower molecular weights than the anti-inflammatory cytokines interleukin 10 (IL-10), interleukin 1 receptor antagonist (IL-1ra) and TNF soluble receptor 2 (TNFsr2) and thus undergo glomerular filtration more readily. In vitro work suggests that proximal tubular cells are vulnerable to pro-inflammatory cytokine mediated injury. Accordingly, this study investigated the hypothesis that cardiac surgery without CPB would not have significant changes in plasma and urinary cytokines and proximal renal dysfunction. Eight patients undergoing coronary artery bypass grafting (CABG) without CPB were studied. Blood and urine samples were analysed for pro- and anti-inflammatory cytokines. Proximal tubular dysfunction was measured using urinary Nu-acetyl-beta-D-glucosaminidase (NAG)/creatinine and alpha(1)-microglobulin/creatinine ratios. Plasma IL-8, IL-10, IL-1ra and TNFsr2 were significantly elevated compared with baseline. Urinary IL-1ra and TNFsr2 were significantly elevated, as were urinary NAG/creatinine and alpha(1)-microglobulin/creatinine ratios. Two hours following revascularization, urinary IL-1ra correlated with urinary alpha(1)-microglobulin/creatinine ratios (P<0.05). As previously reported in CABG surgery with CPB, we now report that non-CPB cardiac surgery also has significant changes in plasma and urinary cytokine homeostasis and early proximal tubular injury. The correlation between urinary IL-1ra and alpha(1)-microglobulin/creatinine ratios is consistent with earlier suggestions of a mechanistic link between cytokine changes and proximal tubular dysfunction. The relative roles of CPB and non-CPB processes in producing inflammation still require definition.     

Low degree of activation of circulating neutrophils determined by flow cytometry during cardiac surgery with cardiopulmonary bypass

BACKGROUND: Enhanced expression of adhesion molecules LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18) following cardiac surgery with cardiopulmonary bypass (CPB) is held responsible for postoperative complications. Surface expression of these molecules, intracellular pH (pH(i)), and oxidative burst capacity was analyzed to test for neutrophil activation during pediatric cardiac surgery. METHODS: Blood samples were drawn from 36 patients (age: 3--16 years) 24 h preoperatively, after onset of anesthesia, after connection to CPB (CPB1, before and after passing CPB, n = 15), at reperfusion (CPB2), and up to 7 days postoperatively. Cells adhering to CPB filters were isolated (n = 11). Antigen expression, pH(i), and oxidative burst capacity on neutrophils was analyzed by flow cytometry. RESULTS: During surgery, oxidative burst capacity was at low level with a mild increase only 1 day after surgery. pH(i) was decreased throughout the surgery. Surgery induced more than 36% decrease of LFA-1 and Mac-1 expression (P < 0.03). Up to postoperative day 7, no increase of antigen expression above baseline was found. Neutrophils isolated from filters of the CPB had increased LFA-1 and Mac-1 expression (all P < 0.05). Integrin expression on neutrophils passing the CPB at CPB1 was decreased (P < 0.05). CONCLUSION: Reduced adhesion molecule expression on neutrophils may be due to selective filtration of highly adhesive cells. This, in combination with low-level oxidative burst capacity, induced by immunosuppressive cytokines (e.g., interleukin-10), reduced the neutrophil activity. Our data indicate that increased activity of circulating neutrophils cannot exclusively be held responsible for postoperative complications after surgery with CPB.     

Oxidative stress precedes peak systemic inflammatory response in pediatric patients undergoing cardiopulmonary bypass operation

Oxidative stress seems to contribute to cardiopulmonary bypass (CPB)-related postoperative complications. Pediatric patients are particularly prone to these complications. With this in mind, we measured oxidative stress markers in blood plasma of 20 children undergoing elective heart surgery before, during, and up to 48 h after cessation of CPB, along with inflammatory parameters and full analysis of iron status. Ascorbate levels were decreased by approximately 50% (P < 0.001) at the time of aorta cross-clamp removal (or pump switch-off in 4 patients with partial CPB), and associated with corresponding increases in dehydroascorbate (P < 0.001, r = -0.80) and malondialdehyde (P < 0.01, r = -0.59). In contrast to the immediate oxidative response, peak levels of IL-6 and IL-8 were not observed until 3-12 h after CPB cessation. The early loss of ascorbate correlated with duration of CPB (P < 0.002, r = 0.72), plasma hemoglobin after cross-clamp removal (P < 0.001, r = 0.70), and IL-6 and IL-8 levels at 24 and 48 h after CPB (P < 0.01), but not with postoperative lactate levels, strongly suggesting that hemolysis, and not inflammation or ischemia, was the main cause of early oxidative stress. The correlation of ventilation time with early changes in ascorbate (P < 0.02, r = 0.55), plasma hemoglobin (P < 0.01, r = 0.60), and malondialdehyde (P < 0.02, r = 0.54) suggests that hemolysis-induced oxidative stress may be an underlying cause of CPB-associated pulmonary dysfunction. Optimization of surgical procedures or therapeutic intervention that minimize hemolysis (e.g., off-pump surgery) or the resultant oxidative stress (e.g., antioxidant treatment) should be considered as possible strategies to lower the rate of postoperative complications in pediatric CPB.     

Tissue and plasma concentrations of antibiotic during cardiac surgery with cardiopulmonary bypass--microdialysis study

Aim: Surgical-site infections are very serious complications of cardiac operations. Use of cardiopulmonary bypass (CPB) is associated with profound physiological changes, which affects the pharmacokinetic behaviour of prophylactic antibiotics. The aim of this study was to monitor tissue concentrations of cefuroxime in peripheral tissue (skeletal muscle) during cardiac surgery using CPB by means of a microdialysis. Methods: Eleven adult patients operated on using CPB were included in the study. Cefuroxime was the prophylactic antibiotic and study drug given. Microdialysis was performed by probe CMA 60 inserted into the patient's left deltoid muscle. Samples of dialysates were collected at intervals: before CPB, each 30 minutes of CPB and at the end of CPB. Samples of blood were collected at intervals: incision, start of CPB, each 30 minutes of CPB, at the end of CPB and at the end of surgery. Results: The mean (+/- S.D.) concentrations of cefuroxime in peripheral tissue were 105.4+/-41.1, 81.7+/-32.8, 74.6+/-26.0, 70.4+/-34.7, 60.5+/-27.2, 138.0+/-42.6 (mg l(-1)). Total plasma concentrations of cefuroxime were 154.4+/-41.6, 73.3+/-20.7, 67.1+/-20.4, 59.2+/-21.0, 49.0+/-16.4, 110.9+/-33.6 (mg l(-1)) and concentrations of free plasma fraction were 110.7+/-37.1, 62.2+/-18.8, 58.9+/-18.6, 48.4+/-16.6, 41.7+/-15.6, 97.6+/-28.6 (mg l(-1)). The plasma and tissue concentrations exceed throughout the operation time the minimum inhibitory concentration for most common suspected pathogens in cardiac surgery. Conclusions: Results show that CPB can modify the time course of cefuroxime tissue and plasma concentrations. Microdialysis is suitable for antibiotic tissue measurement in cardiac surgery.