* Autologous transfusion reduces the need for allogeneic transfusion and is most widely used in elective surgery
* Autologous transfusion is one of several techniques used to reduce the need for allogeneic transfusion
* The three main techniques are predeposit transfusion, intraoperative haemodilution, and intraoperative and postoperative salvage
* Evidence from clinical trials shows that autologous transfusion is more cost effective than allogeneic transfusion and that clinical outcomes are improved
Predeposit autologous transfusion entails repeated preoperative phlebotomy (fig 2). Blood collection begins three to five weeks before elective surgery, depending on the number of units required, usually 2-4 units (about 1-2 litres). The last donation takes place at least 48-72 hours before surgery to allow for re-equilibration of the blood volume. On each occasion, about half a litre of the patient's own blood is taken and put into sterile plastic bags. Anticoagulation is maintained with citrated glucose solution, and the blood is stored until the time of surgery.Advantages
Predeposit autologous transfusion virtually eliminates the risks of viral transmission and immunologically mediated haemolytic, febrile, or allergic reactions. These adverse effects range in frequency from 1 in 1 000 000 (HIV) to as high as 5% (febrile reactions). In addition, it may decrease the risk of postoperative infection and recurrence of cancer because immunomodulation as a result of transfusion is avoided.2–4 Immunomodulation refers to decreases in cellular immune function that have been documented after allogeneic, but not autologous, transfusions.7
Disadvantages
Up to half of the blood that is collected may be discarded because the amount drawn off needs to exceed the median routinely needed to avoid additional allogeneic transfusions. Leftover blood can rarely be used for other patients because most autologous donors do not meet the stringent health requirements for allogeneic blood donation. This wastage of blood and the costs of administering autologous programmes result in collection costs that are higher than those for allogeneic transfusion. Volume overload, bacterial contamination, and ABO haemolytic reactions to the transfusion resulting from administrative or clerical errors are further risks.
Suitability of patients
Predeposit autologous donation is practical only for elective surgery. Patients must be willing and able to travel to a donation centre before their operation, which can be inconvenient and stressful and may decrease their productivity at work. Because preoperative donation results in perioperative anaemia (which may not be completely resolved before surgery) blood volume, venous access, packed cell volume, and haemodynamic stability are important determinants of who is an appropriate candidate for the procedure. Children who weigh less than 30-40 kg are usually not suitable, but adult patients are deferred from donation only if they have severe haemodynamic problems, active systemic infections, or a history of serious reactions to donation (such as seizure). Patients with diarrhoeal illnesses in the days or weeks before donation should not donate as they may be at increased risk of bacterial contamination of their donated blood. Although autologous donors have a higher incidence of reactions such as fainting or dizziness than voluntary donors (presumably because they are inexperienced donors and not as young and fit), their reactions are seldom severe.
Intraoperative acute normovolaemic haemodilution
Acute normovolaemic haemodilution (“haemodilution”) is a type of autologous donation that is performed preoperatively in the operating theatre or anaesthetic area. It is usually restricted to patients in whom substantial blood loss is predicted (>1 litre or 20% of blood volume). Whole blood (1.0-1.5 litres) is removed, and simultaneously intravascular volume is replaced with crystalloid or colloid, or both, to maintain blood volume. The anticoagulated blood is then reinfused in the operating theatre during or shortly after surgical blood loss has stopped. The blood sparing benefit of haemodilution is the result of the reduced red cell mass lost during surgical bleeding.
Advantages
Haemodilution provides the advantages of predeposit autologous donation and some additional benefits. It may be used before any type of surgical procedure, and systemic infection does not preclude its use. The patient is under anaesthesia during the procedure, which reduces stress, and the anaesthetist can ensure expert monitoring of blood circulation. Blood is stored at room temperature for a short time, so deterioration of clotting factors and cells is minimal. Additional advantages include a lower cost than for predeposit transfusion (because testing and cross matching are not usually required) and minimal wastage, as most or all blood is reinfused. Blood is maintained at the point of care, incurring little or no administrative expense, and the risk of ABO incompatibility because of administrative or clerical error is further minimised.
Disadvantages
The circulating red cell mass is lowered appreciably and acutely. If colloid is used for volume replacement the risk of allergic reactions or haemostatic abnormalities increases. Other disadvantages are the additional expense of, and inconvenience to, the anaesthetist who performs the procedure. The procedure may require additional training and experience on the anaesthetist's part. No large studies have investigated morbidity or mortality that may occur with acute anaemia, so the general belief that haemodilution is safe is largely anecdotal at this time.
Suitability of patients
Elective operations with typical blood losses of 1-2 litres are particularly suitable for haemodilution (for example, replacement of cardiac valves, revision of hip arthroplasty, or spinal reconstruction). The major limiting factor in choosing candidates for haemodilution is the patient's ability to tolerate a low volume of red blood cells. Patients with severe anaemia are usually poor candidates.
Salvage autologous transfusion
Intraoperative red blood cell salvage entails the collection and reinfusion of blood lost during surgery. Shed blood is aspirated from the operative field into a specially designed centrifuge. Citrate or heparin anticoagulant is added, and the contents are filtered to remove clots and debris. Centrifuging concentrates the salvaged red cells, and saline washing may be used. This concentrate is then reinfused. Devices used can vary from simple, inexpensive, sterile bottles filled with anticoagulant to expensive, sophisticated, high speed cell washing devices. Postoperative salvage refers to the process of recovering blood from wound drains and reinfusing the collected fluid with or without washing.
:victory:advantage
Salvage is considered a safe and efficacious alternative to allogeneic red cell transfusion, but fewer data are available about clinical outcomes than for predeposit autologous donation or haemodilution.1 These techniques offer advantages similar to those of haemodilution but do not require infusions of crystalloid or colloid to preserve blood volume. Many litres of blood can be salvaged intraoperatively during extensive bleeding, far more than with other autologous techniques.
Disadvantages
Although the oxygen transport properties and survival of red cells are similar to that of allogeneic blood, salvaged blood is not haemostatically intact compared with blood derived by haemodilution. Coagulation in the wound leads to consumption of coagulation factors and platelets. Salvaged blood that is not washed contains raised concentrations of various tissue materials. Uncommon complications of extensive intraoperative salvage include disturbances to pH and electrolytes, systemic dissemination of non-sterile material, infectious agents or malignant cells, air or fluid embolism, and dilutional coagulopathy. A “salvaged blood syndrome” has been described, which entails multiorgan failure and consumption coagulopathy.8
Suitability of patients
Intraoperative salvage is used extensively in cardiac surgery, trauma surgery, and liver transplantation. Contraindications to its use are bacterial infection or malignant cells in the operative field, and use of microfibrillar collagen or other foreign material at the operative site. Salvage can be one of the most expensive autologous techniques because costly capital equipment and disposables are used, and it is usually restricted to procedures resulting in substantial blood loss (>1-2 litres).作者: 丘小庆 时间: 2008-10-30 21:20
除了羡慕，还能有什么呢！作者: qsj2008 时间: 2008-10-30 22:27
惭愧之外，为前进，务必加油呀！否则就挨打屁股喔。作者: rextao 时间: 2008-10-31 00:15
（五）保留自主呼吸和非气管插管的紧急麻醉
如果迫切需要继续手术而产妇的气管插管操作又无法完成时，迅速采取措施改用保留自主呼吸的麻醉方法极为重要。只要能采用某一种方法维持有效的肺通气（见通气失败处理方案），即宜尽可能快地加深麻醉，以确保在手术刺激开始前达到安全的手术麻醉深度。由于要进行直接喉镜操作或气管插管，所以吸入麻醉药的输入有所延迟。这意味着在输入足量吸入麻醉药之前，静脉麻醉诱导药物的麻醉作用将逐渐消退，结果可使麻醉深度处于可引起兴奋并增加呕吐发生率的潜在危险阶段。
为了解决吸入麻醉药输入延迟的问题，在采用该紧急麻醉方法的早期应输入高浓度的麻醉药。用100%的氧输送3MAC的吸入麻醉药可迅速将麻醉加深至手术所需的满意水平。吸入麻醉药的选择取决于其可用性。据知，吸入麻醉药可抑制子宫的收缩和导致出血过多，特别是氟烷。但是，对于一种能够迅速和平稳进行麻醉诱导的药物来讲，出血只是次要的考虑因素。如果在任何时期发生呼吸道管理困难，应采用上述的“通气失败"处理方法。
一旦麻醉达到足够深度，手术即可开始。在娩出胎儿时，可适量静脉滴入镇痛药加深麻醉和静脉滴入催产素控制出血。必须注意的是，既要使麻醉深度满意，而又不能造成呼吸抑制。有人建议全身麻醉期间应插入一根口径粗大的鼻胃管，以吸出胃内容物。但是，该建议仅适用于气管插管；在未行气管插管的紧急情况下，尽可能不要在咽部实施任何器械操作，因为其可诱发呕吐或使呼吸道发生梗阻。手术结束后，应将产妇转为侧卧位，在整个恢复期均应有麻醉医师陪同。
术后处理包括向产妇交代其曾发生了困难气管插管，并对其将来接受麻醉提出建议。然而一种常见的情况是，在孕期曾出现困难气管插管或无法气管插管的女性患者，在非妊娠时可能并不会发生这些问题。作者: rextao 时间: 2008-11-1 18:15 标题: 中华麻醉在线学习 美国产科麻醉临床指南
Update of Practice Guidelines for Obstetrical Anesthesia in US
Yun Xia, M.D., Ph.D. Dept. of Anesthesiology, The Ohio State University, Columbus, Ohio U.S.A
前言
美国产科麻醉学会于1999年发表了产科麻醉的临床指南（Practice Guideline for Obstetrical Anesthesia）。 此后，每年都根据临床实践和科研成果做新的补充或更改。 本文将介绍一下美国产科麻醉学界的一些新近共识。
Reference:
1. Practice Guidelines for Obstetrical Anesthesia. ASA Publication Department 1999.
2. Hawkins JL, et al. Anesthesia-related deaths during obstetric delivery in the United States 1979-1990. Anesthesiology 1997; 86: 277-283
3. Cynthia A. Wong, et al. The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. N Engl J Med. 2005; 325(7): 655-720作者: rextao 时间: 2008-11-1 18:16 标题: 中华麻醉在线学习 美国产科麻醉临床指南
Update of Practice Guidelines for Obstetrical Anesthesia in US
Yun Xia, M.D., Ph.D. Dept. of Anesthesiology, The Ohio State University, Columbus, Ohio U.S.A
前言
美国产科麻醉学会于1999年发表了产科麻醉的临床指南（Practice Guideline for Obstetrical Anesthesia）。 此后，每年都根据临床实践和科研成果做新的补充或更改。 本文将介绍一下美国产科麻醉学界的一些新近共识。
Reference:
1. Practice Guidelines for Obstetrical Anesthesia. ASA Publication Department 1999.
2. Hawkins JL, et al. Anesthesia-related deaths during obstetric delivery in the United States 1979-1990. Anesthesiology 1997; 86: 277-283
3. Cynthia A. Wong, et al. The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. N Engl J Med. 2005; 325(7): 655-720作者: rextao 时间: 2008-11-1 18:27 标题: 中华麻醉在线学习—术前评估要问下孩子是顺产还是剖腹产 剖腹产出生婴儿易患哮喘病
爱思唯尔期刊《儿科学杂志》（The Journal of Pediatrics）近期刊登了挪威公众卫生研究机构的最新发现：同自然分娩的婴儿相比，剖腹产出生婴儿患哮喘病的几率要高50%。
