dxy

背景：

每年输血拯救数以万计心脏外科手术及其他手术患者。但一项最新研究表明，心脏旁路外科手术的患者接受输血，术后有潜在的感染和死亡高风险。事实上，增加的风险有助于解释长期存在的医学谜团：为什么女性旁路手术患者同男性患者相比，术后前几个月中更易死亡。女性患者心脏旁路手术中更容易接受输血（每年超过465,000名美国人完成心脏旁路手术）。

简介：

密西根大学健康系统进行的增强患者安全性项目（PSEP）研究，数据主要来自于密西根州9,218名心脏旁路患者。调整一些因素如紧急手术后，那些接受供体输血的患者同未接受输血的患者相比，术后100天内死亡率增加5倍以上。该研究结果发表于《美国心脏病杂志》12月刊上。该研究基于先前U-M研究小组发现，即感染率的差异可以解释男性和女性旁路手术患者死亡率的差异。U-M研究小组在罗彻斯特大学医学中心Neil Blumberg博士的帮助下，重点研究输血是否为死亡因素之一。初期研究表明，接受输血的患者出现更多例术后感染，而女性患者更容易发生感染，因为她们血液中血红蛋白浓度低。该新研究同上述问题的关键点相结合。“就我们目前所知道的情况，该研究是首次表明同种异体输血可能是女性旁路手术患者死亡率比男性旁路手术患者更高的原因，” 负责该项研究的内科学助教授 Mary A.M. Rogers博士说道。同种异体输血即血液来自于其他人。研究人员坚定的认为：输血仍旧是拯救生命的好方法，本研究中观察到的输血后感染并不是由于血液的污染。输血后感染可能来自于其他因素，如患者对供体储存血中白细胞的免疫反应。这些发现可能有助于指导医院和血库可以通过对供体血的滤过减少血中白血球的水平。在美国，滤过方法应用逐渐增加，但尚不普遍。

方法和结果：

该研究对密西根州一年内年龄等于或大于65岁进行冠脉旁路手术的医疗保险受益人进行分析调查。研究人员完成患者输血状况、并存的疾病、年龄、种族、性别、是否旁路手术有选择的完成及病情紧急或急症的统计学分析。他们观察术后100天内的感染及死亡情况。总计88%的女性患者在旁路手术中接受了输血，而男性接受输血的患者接近67%。研究人员调整其它因素后，女性患者输血比例几乎是男性患者的3.4倍。不管手术是否有选择性，病情紧急或急症，性别差异是明显的。接受同种异体输血的患者感染的几率是未接受输血患者的3倍左右。接受的血越多，感染风险越大。这种“剂量依赖性”更进一步证明输血同感染相关。输血患者感染类型均不相同，表明体内广泛的免疫反应，这同切口处感染不同。分析揭示女性旁路手术患者同男性患者相比更易发生感染，主要由于女性旁路手术患者中输血量的增加。最终的结果为女性死亡率增加。术后100天内，总共9%的女性患者和6%的男性患者死亡。

结论：

在术前将自己的血液储存起来，或输血只接受自身血液的患者，感染风险同未接受输血患者相似。Rogers提醒，如果可能的话，旁路手术或其它手术前，患者应尽量让医生在术前储存自身的血液。除此以外，医生在旁路手术中应广泛应用输血的替代方法如血液“扩张器”，血液替代品以及血液保存程序。该研究结果同样提示要重视外科手术后住院病人要合理应用抗生素控制感染。U-M研究小组对该问题进行了更进一步研究，如由密歇根州蓝十字保险蓝盾牌基金支持的对密西根州近期接受旁路手术老年患者的研究。

Blood Transfusions Raise Heart Patients' Infection And Death Risk -- Especially Women

Main Category: Blood / Hematology News
Article Date: 31 Dec 2006 - 11:00 PST

Blood transfusions save the lives of millions of heart surgery patients and others each year. But a new study suggests that patients who receive transfusions during heart bypass surgery have a higher risk of developing potentially dangerous infections, and dying, after their operation.

In fact, this increased risk may help explain a longstanding medical mystery: why women bypass patients are more likely than men to die in the first few months after surgery. Women are more likely to receive blood during heart bypass operations, which are performed on more than 465,000 Americans each year.

The findings, from the Patient Safety Enhancement Program (PSEP) at the University of Michigan Health System, are based on data from 9,218 Michigan bypass patients. After adjusting for factors such as the urgency of the operation, those who received blood transfusions from donors were five times more likely to die within 100 days of their operation than those who did not.

The paper is published in the December issue of the American Heart Journal. It builds on a previous U-M analysis that found that a difference in infection rates accounted for the difference in death risk between men and women bypass patients.

The U-M team, with the help of Neil Blumberg, M.D., of the University of Rochester Medical Center, focused on blood transfusions as a contributing factor. Prior research has shown that recipients of stored donor blood have more post-surgical infections, and that women receive more transfusions because they tend to have lower hemoglobin concentrations.

This new study connects the dots. "To the best of our knowledge, this is the first study to state that allogeneic transfusions may be the reason why women have a greater post-bypass surgery mortality risk than men," says author Mary A.M. Rogers, Ph.D., M.S., PSEP, research director and research assistant professor of internal medicine. Allogeneic is the term for blood from another person.

The authors strongly note that blood transfusions can be life-saving, and that the infections observed in this study are not likely due to contamination of the blood. Rather, they may be due to other factors, including the patient's immune response to substances such as white blood cells that are present in stored donor blood. These findings may help guide hospitals and blood banks in deciding whether to filter donated blood to reduce the levels of white blood cells. This practice is increasingly common, but not yet universal, in the United States.

The study is based on analysis of data from all Medicare beneficiaries ages 65 and older who had coronary artery bypass operations in Michigan in a single year.

The researchers performed statistical analyses that took into account the patients' blood transfusion status, their co-existing diseases, age, race, sex, and whether the bypass operation was done on an elective, urgent or emergency basis. They looked at infections and deaths that were reported during the 100 days after surgery.

In all, about 88 percent of women received an allogeneic blood transfusion during bypass surgery, compared with nearly 67 percent of men. When the researchers adjusted for other factors, women were 3.4 times as likely as men to receive blood. This gender difference was evident regardless of whether the operation was elective, urgent or emergency.

The odds of having an infection of any kind were about three times greater in patients who received allogeneic blood than in patients who did not. The more blood they received, the higher their infection risk. This "dose dependent" relationship strengthens the evidence that transfusions may be related to infections.

No single type of infection stood out as more common among blood recipients, which suggests a body-wide immune response issue rather than a problem, for example, at the site of the incision.

The analyses revealed that women were more likely to experience an infection than men after bypass surgery, which appeared to be due to the increased number of transfusions in women. This resulted in an increased mortality rate in women. Overall, 9 percent of women and 6 percent of the men died within 100 days of their operation.

For patients who had banked their own blood ahead of the operation and who received only their own blood, the infection risk was similar to that of patients who received no blood transfusions. Rogers notes that patients should ask their doctors regarding banking their own blood if possible, when scheduled for a bypass operation or other kind of surgery.

In addition, physicians are increasing their use of transfusion alternatives such as blood "expanders," blood substitutes and blood-conserving procedures during bypass surgeries.

The results also highlight the importance of the proper use of antibiotics and infection control practices in patients hospitalized for a surgical procedure, says Rogers.

The U-M team is investigating the issue further, including a new study funded by Blue Cross Blue Shield of Michigan Foundation to extend the research into elderly patients who recently underwent bypass surgeries in Michigan.

http://www.medicalnewstoday.com/medicalnews.php?newsid=59492

编辑：蓝色幻想