心脏手术脑损伤与脑保护

心脏术后脑损伤主要表现为中风．病理性脑病和神经认知功能障碍。脑栓塞和／或脑低灌注是围术期脑损伤的主要原因。本文从以下几个方面对心脏手术的脑保护进行综述：体外循环装置,升主动脉粥样硬化的管理。减少栓子的措施,体外循环期间血压,血糖．温度的管理,输血指征,药物脑保护和脑监测措施等。     

利多卡因对心脏手术后病人早期认知功能障碍发生率的影响

目的评价术中应用利多卡因能否减少冠脉分流手术后病人早期认知功能障碍的发生率。方法118例择期体外循环下行冠状动脉分流术的病人随机分为两组。利多卡因组(n=57)在切开心包后静注利多卡因1.5 mg/kg,继以4 mg/min持续输注至术毕,体外循环预充液中另加4mg/kg;对照组(n=61)给予等量生理盐水。分别在术前1 d和术后第9天对病人进行神经精神功能9项测验。各测验项目术后值与术前值相比功能降低等于或超过全部病人该项目术前值的1个标准差判断该项测验出现术后功能恶化;一个病人有2个或2个以上的测验项目术后出现功能恶化判断该病人发生了术后认知功能障碍。结果 88例病人全部完成手术前后神经精神功能测验,其中对照组45例、利多卡因组43例。术后认知功能障碍发生率对照组为42.2％(19例)、利多卡因组为20.9％(9例),利多卡因组明显低于对照组(P<0.05)。结论术中给予利多卡因可明显降低体外循环下冠脉分流手术后病人早期认知功能障碍的发生率。     

全麻下颈椎手术后严重认知功能障碍三例

术后认知功能障碍(POCD)是指术前无精神异常的病人于术后出现大脑功能活动紊乱,导致认识、情感、行为和意志等不同程度的活动障碍。全麻后认知功能障碍多见于体外循环手术,但在颈椎手术发生POCD报道极少。我院于2004年1月～2005年6月30日在全麻下颈椎手术20例,发生POCD3例,现报     

大剂量抑肽酶对体外循环导致凝血机制紊乱的作用

３０例行心脏直视手术病人随机分为对照组和抑肽酶用药组。于麻醉后、主动脉阻断开放时、体外循环结束后１０ｍｉｎ、２ｈ和术后２４ｈ，分别观察血小板计数、血小板聚集率、ＴＸＢ２、６－ｋｅｔｏ－ＰＧＦ１α、ⅧＲ：Ａｇ、ＡＴⅢ：Ａ与ＦＤＰ，并记录术后２４ｈ纵隔心包引流量。结果表明，大剂量抑肽酶可增加术后血小板功能、抑制纤溶、提高术后凝血因子含量等，从而减少了术后出血。     

小儿体外循环心脏手术的炎症反应和器官功能障碍

小儿体外循环下行心脏手术中所发生的炎症反应和器官功能障碍与成人有所不同。本综述主要介绍小儿体外循环下心脏手术麻醉所引起的炎症和器官损伤的特点，以及减少炎症反应的措施。     

开放前热血加甘露醇灌注在危重心脏瓣膜疾病患者术中的应用

目的 了解较好地进行心肌保护,研究主动脉开放前热血加甘露醇灌注在危重心脏瓣膜病患者体外循环术中的应用。方法 选取我院1998年6月－1999年6月间80例心脏瓣膜病患者,随机分为实验组生对照组,每组各40例,常规行二尖瓣和／或主动脉瓣置换术。两组均采用中度低温含血心肌保护,实验组于主动脉开放前给予热血加甘露醇灌注。比较两组患者体外循环术后心功能恢复情况。结果 在自动复跳率、主动脉开放后体外循环时间、24小时内心排轿指数恢复速度、肌酸激酶下降幅度等指标实验组明显优于对照组（P＜0．05）,在术后呼吸机支持时间、ICU滞留时间、正性肌力药物使用率、手术死亡率等方面两组无明显差异（P＞0．05）。结论 主动脉开放前热血加甘露醇灌注能明显减轻再灌注损伤,加快术后早期心功能恢复。     

心脏外科手术后急性肾功能衰竭的防治进展

急性肾功能衰竭（acute renal failure，ARF）是心脏手术后的严重并发症之一，是增加手术死亡率，延长机械通气时间和重症监护室停留时间，导致认知功能障碍、呼吸功能衰竭等主要脏器并发症，增加住院费用等的重要影响因素。研究表明体外循环和主动脉球囊反搏（IABP）的使用，术前肾功能不全、糖尿病以及外周血管疾病是术后ARF的风险因素，经过容量血管收缩、肾脏灌注不足、缺血一再灌注损伤等病理生理改变，导致ARF的发生。适当使用药物治疗、血液透析、血液滤过可以保护肾功能，改善ARF的预后。     

主动脉夹层术后并发神经系统损伤的原因分析及护理

目的分析主动脉夹层术后神经系统损伤的原因。方法对35例主动脉夹层患者术后并发神经系统损伤的原因进行分析。结果高血压病史、手术时间、体外循环时间是主动脉夹层术后神经系统损伤的危险因素。结论主动脉夹层术后神经系统损伤严重影响患者恢复健康,需采取针对性护理。     

先天性心脏病患儿术后多脏器功能障碍的预后分析

目的 探讨小儿先天性心脏病（先心病）术后多脏器功能障碍（MODS）预后情况及其影响因素，为对此类患儿进行针时性护理提供依据。方法 收集先心病术后并发MODS 77例患儿的临床资料。结果 11例放弃治疗出院，66例中44例救治存活，22例死亡。出现时间最早、累及最多的脏器为心脏；病死率最高的为累及中枢神经系统的患儿（57．69％），其次是累及血液系统的患儿（55．56％）；患儿的病死率与累及脏器的数量呈显著正相关（P〈0.01）。死亡患儿手术体外循环时间和主动脉阻断时间显著长于存活患儿（均P〈0．05），术中意外及术后心肺复苏发生率显著高于存活患儿（均P〈0．05）。结论 心病术后患儿应加强心功能监护，特别是体外循环时间〉120min，主动脉阻断时间〉60min及术中发生过意外情况、术后采取过心肺复苏术的患儿；尽早采取有利措施避免其他脏器功能受损是提高患儿存活率的关键。     

人体白蛋白和羟乙基淀粉在体外循环围术期应用的若干问题

用于扩容和体外循环预充的胶体溶液对凝血功能有影响。代血浆HES对血小板和凝血因子的不良作用损害了凝血功能，使术后过量失血的风险增加。白蛋白对凝血机制无不良作用；可降低CPB后SIRS和ARDS的程度；更节省治疗费用。     

A pilot study of cerebral tissue oxygenation and postoperative cognitive dysfunction among patients undergoing coronary artery bypass grafting randomised to surgery with or without cardiopulmonary bypass*

Coronary artery bypass surgery, performed with or without cardiopulmonary bypass, is frequently followed by postoperative cognitive decline. Near‐infrared spectroscopy is commonly used to assess cerebral tissue oxygenation, especially during cardiac surgery. Recent studies have suggested an association between cerebral desaturation and postoperative cognitive dysfunction. We therefore studied cerebral oxygen desaturation, defined as area under the cerebral oxygenation curve < 40% of > 10 min.%, with respect to cognitive performance at 4 days (early) and 3 months (late) postoperatively, compared with baseline, using a computerised cognitive test battery. We included 60 patients, of mean (SD) age 62.8 (9.4) years, scheduled for elective coronary artery bypass grafting, who were randomly allocated to surgery with or without cardiopulmonary bypass. Cerebral desaturation occurred in only three patients and there was no difference in cerebral oxygenation between the two groups at any time. Among patients who received cardiopulmonary bypass, 18 (62%) had early cognitive decline, compared with 16 (53%) in the group without cardiopulmonary bypass (p = 0.50). Three months after surgery, 11 patients (39%) in the cardiopulmonary bypass group displayed cognitive dysfunction, compared with four (14%) in the non‐cardiopulmonary bypass group (p = 0.03). The use of cardiopulmonary bypass was identified as an independent risk factor for the development of late cognitive dysfunction (OR 6.4 (95% CI 1.2–33.0) p = 0.027. In conclusion, although cerebral oxygen desaturation was rare in our population, postoperative cognitive decline was common in both groups, suggesting that factors other than hypoxic neuronal injury are responsible.     

Cerebral dysfunction after coronary artery bypass surgery

Cerebral dysfunction after cardiac surgery remains a devastating complication and is growing in importance with our aging populations. Neurological complications following cardiac surgery can be classified broadly as stroke, encephalopathy (including delirium), or postoperative cognitive dysfunction (POCD). These etiologies are caused primary by cerebral emboli, hypoperfusion, or inflammation that has largely been attributed to the use of cardiopulmonary bypass. Preventative operative strategies, such as off-pump coronary artery bypass grafting (CABG), can potentially reduce the incidence of postoperative neurological complications by avoiding manipulation of the ascending aorta. Although off-pump CABG is associated with reduced risk of stroke, there are no convincing differences in POCD between off-pump and on-pump CABG. Recently, the focus of postoperative neurological research has shifted from managing cardiopulmonary bypass to patient-related factors. Identifying changes in brains of aged individuals undergoing cardiac surgery may improve strategies for preventing cerebral dysfunction. Advanced age is associated with more undiagnosed cerebrovascular disease and is a major risk factor for stroke and POCD following cardiac surgery. Preoperative cerebrovascular evaluation and adaptation of surgical strategies will provide preventative approaches for cerebral dysfunction after CABG. This review focuses on recent findings of the relationship between perioperative stress and underlying fragility of the brain in cardiac surgical patients.     

Cerebral dysfunction after cardiac surgery--are we moving forward?

This review focuses on the effects of cardiac surgery and cardiopulmonary bypass on the brain, with special emphasis on the results of recently conducted studies. The incidence of postoperative neurological and neuropsychological deficits and risk factors for cerebral injury are reviewed. The relationships between cerebral embolic load, release of biochemical markers of brain injury and cognitive dysfunction after cardiac surgery are also reviewed. Finally, recently gained information on the management of cardiopulmonary bypass is discussed, along with the results of recent pharmacological neuroprotective trials in patients undergoing cardiac surgery.     

The impact of postoperative atrial fibrillation on neurocognitive outcome after coronary artery bypass graft surgery.

Neurocognitive decline is a continuing source of morbidity after cardiac surgery. Atrial fibrillation occurs often after cardiac surgery and has been linked to adverse neurologic events. We sought to determine whether postoperative atrial fibrillation was associated with postoperative cognitive dysfunction. Four-hundred-eleven patients were enrolled to receive a battery of neurocognitive tests both preoperatively and 6 wk after elective coronary artery bypass graft surgery. Neurocognitive test scores were separated into four cognitive domains, with a composite cognitive index (the mean of the four domain scores) determined for each patient at every testing period. Multivariable analysis controlling for age, years of education, diabetes mellitus, left ventricular ejection fraction, and preoperative atrial fibrillation compared the presence of postoperative atrial fibrillation with change in cognitive function. Three-hundred-eight patients completed both pre- and postoperative cognitive testing; 69 patients (22%) had postoperative atrial fibrillation. Those who developed atrial fibrillation showed more cognitive decline than those who did not develop postoperative atrial fibrillation (P = 0.036). Atrial fibrillation was associated with poorer cognitive function 6 wk after surgery. Although the mechanism of this association is yet to be determined, prevention of atrial fibrillation may result in improved neurocognitive function. IMPLICATIONS: Neurocognitive dysfunction is common after coronary artery bypass graft surgery. The relationship between atrial fibrillation and neurocognitive dysfunction has not been examined. Our study shows that postoperative atrial fibrillation is associated with neurocognitive decline.     

The association of high jugular bulb venous oxygen saturation with cognitive decline after hypothermic cardiopulmonary bypass

This study was conducted to investigate whether jugular bulb venous oxygen saturation (SjVO(2)) predicted cognitive decline after cardiac surgery with hypothermic cardiopulmonary bypass (CPB). We studied 35 patients undergoing cardiac surgery. After the induction of anesthesia, a 5.5F fiberoptic oximetry catheter was retrogradely inserted into the jugular bulb, and SjVO(2) and other cerebral oxygenation variables were analyzed before, during, and after CPB. At each point, an oxyhemoglobin dissociation curve was drawn, and the P(50) value of jugular bulb venous blood was calculated by computer analysis. Cognitive function was assessed with the revised version of Hasegawa's Dementia Scale and the Benton Revised Visual Retention Test before and early after the operation. In 15 patients (the Decline group), cognitive function was declined after surgery, whereas it remained unchanged in 20 patients (the Normal group). SjVO(2) was significantly higher and cerebral oxygen extraction was significantly lower before and during CPB in the Decline group than in the Normal group (P < 0.05). The oxygen pressure at an oxygen saturation of 50% was significantly lower before and after CPB in the Decline group than in the Normal group (P < 0.05). Logistic regression analysis showed that high SjVO(2) was a predictor of cognitive decline after cardiac surgery. We conclude that high SjVO(2) was associated with cognitive decline after cardiac surgery with hypothermic CPB. IMPLICATIONS: Jugular bulb venous oxygen desaturation has been suggested as a predictor of cognitive decline after cardiac surgery. However, the clinical value of jugular bulb venous oxygen saturation (SjVO(2)) may be limited during hypothermic cardiopulmonary bypass (CPB) when oxygen affinity to hemoglobin is increased. This study shows that high SjVO(2) before and during hypothermic CPB is a predictor of subsequent cognitive decline.     

Intraoperative cerebral high-intensity transient signals and postoperative cognitive function: a systematic review

Background

Much attention in the literature has focused on the relationship between perioperative microemboli during cardiac and vascular surgery and postoperative cognitive decline. Transcranial Doppler ultrasonography (TCD) has been used to measure high-intensity transient signals (HITS), which represent microemboli during cardiac, vascular, and orthopedic surgery. The purpose of this study was to systematically examine the literature with respect to HITS and postoperative cognitive function.

Methods

Systematic PubMed searches identified articles related to the use of TCD and cognitive function in the surgical setting.

Results

The literature remains largely undecided on the role of HITS and cognitive impairment after surgery, with most studies being underpowered to show a relationship. Although the cognitive effects of HITS may be difficult to detect, subclinical microemboli present potential harm, which may be modifiable.

Conclusions

TCD represents a tool for intraoperative cerebral monitoring to reduce the number of HITS during surgery.     

Comparison of cerebral embolization during off-pump and on-pump coronary artery bypass surgery

BACKGROUND: Coronary artery bypass surgery with cardiopulmonary bypass carries a significant risk of perioperative brain injury. At least 1% to 5% will suffer a stroke, and at 3-months postoperatively approximately 30% are reported to have cognitive impairment assessed by neuropsychologic testing. In off-pump surgery cardiopulmonary bypass is not used and instrumentation on the ascending aorta is reduced. The main aim of this study was to assess if off-pump surgery reduces intraoperative cerebral embolization. METHODS: This was a prospective and randomized study of two comparable groups with regard to age, sex, years of education, preoperative cognitive functioning, and surgical characteristics. Fifty-two patients (29 off-pump) were monitored by the use of transcranial Doppler ultrasound for cerebral microembolization during surgery. Preoperative and postoperative clinical, cerebral magnetic resonance imaging, and neuropsychologic examinations were also carried out. RESULTS: There was a significant reduction in the number of cerebral microemboli during off-pump compared with on-pump surgery (16.3 [range 0 to 131] versus 90.0 [range 15 to 274], p < 0.0001). No significant difference with regard to the incidence of neuropsychologic performance (decline in 29% off-pump, 35% on-pump) or neuroradiologic findings at 3 months was found, and there was no association between the number of cerebral microemboli and cognitive outcome. CONCLUSIONS: This study clearly demonstrates that off-pump surgery leads to a reduction in intraoperative cerebral microembolization. A significant reduction in the number of off-pump patients with cognitive decline or ischemic brain lesions on cerebral magnetic resonance imaging could not be demonstrated in this relatively small patient population.     

Postoperative cognitive disorders in the elderly

TWO DISTINCT CATEGORIES: Postoperative cognitive disorders include delirium and long-term cognitive dysfunction. DELERIUM: Delirium is an acute state occurring early during the postoperative period. It may be considered as an acute cerebral insufficiency which may be consecutive both to the negative effects of aging and chronic illness on cognitive function, and to the cerebral impact of operative stress. In addition, precipitating postoperative medical factors may facilitate cerebral failure. Only a few studies have been devoted to prevention programs aimed at reducing the risk of postoperative delirium. Nevertheless, we can hypothesize that a preoperative gerontology assessment would be effective in determining risk factors of delirium in old patients and thus enable proposing individual postoperative management. LONG-TERM COGNITIVE DYSFUNCTION: The definition of this clinical picture is less precise than delirium. Long-term cognitive dysfunction corresponds to a loss of cognitive performance in the weeks and months after anesthesia. The IPOCD1 study conducted in a large cohort of elderly patients has shown that postoperative cognitive dysfunction was present in 25.8% of patients 1 week after surgery and in 9.9% 3 months after surgery. One to two years after surgery, cognitive dysfunction was observed in 10.4% of patients compared with 10.6% in a control population of non-operated patients. We would suggest that in many cases, postoperative cognitive dysfunction may result from preoperative dementia unmasked by surgery.     

Zerebrale Oxymetrie

The determination of cerebral oxygen saturation (S_cO₂) by means of near-infrared spectroscopy allows non-invasive assessment of the cerebral oxygen delivery and demand ratio in the frontal cortex region. Studies in cardiac as well as non-cardiac patients have shown that maintaining S_cO₂ in the preoperative range reduces the incidence of postoperative cognitive dysfunction and general morbidity; however, S_cO₂ is not only reflective of cerebral but also of systemic oxygen balance, is inversely related to cardiopulmonary function and has prognostic relevance in cardiac surgery patients. This suggests that cerebral oximetry is not only useful for neurological but also for hemodynamic monitoring and preoperative risk stratification of cardiac surgery patients.     

The effect of lidocaine on early postoperative cognitive dysfunction after coronary artery bypass surgery

We investigated the effect of lidocaine on the incidence of cognitive dysfunction in the early postoperative period after cardiac surgery. One-hundred-eighteen patients undergoing elective coronary artery bypass surgery with cardiopulmonary bypass (CPB) were randomized to receive either lidocaine (1.5 mg/kg bolus followed by a 4 mg/min infusion during operation and 4 mg/kg in the priming solution of CPB) or placebo. A battery of nine neuropsychological tests was administered before and 9 days after surgery. A postoperative deficit in any test was defined as a decline by more than or equal to the preoperative SD of that test in all patients. Any patient showing a deficit in two or more tests was defined as having postoperative cognitive dysfunction. Eighty-eight patients completed pre- and postoperative neuropsychological tests. Plasma lidocaine concentrations (microg/mL) were 4.78 +/- 0.52 (mean +/- SD), 5.38 +/- 0.95, 4.52 +/- 0.39, 5.82 +/- 0.76, and 7.10 +/- 1.09 at 10 min before CPB; 10, 30, and 60 min of CPB; and at the end of operation, respectively. The proportion of patients showing postoperative cognitive dysfunction was significantly reduced in the lidocaine group compared with that in the placebo group (18.6% versus 40.0%; P = 0.028). We conclude that intraoperative administration of lidocaine decreased the occurrence of cognitive dysfunction in the early postoperative period. IMPLICATIONS: Postoperative cognitive dysfunction is a commonly recognized complication after cardiac surgery. Intraoperative cerebral microembolism and hypoperfusion have been proposed to be the major mechanisms. The results of this study show that intraoperative administration of lidocaine decreased the occurrence of early postoperative cognitive dysfunction, perhaps because of its neuroprotective effects.