March 21, 2005[每周一问]No.1 关于肥胖患者的麻醉问题
This week we are discussing obesity and its relationship to anesthesia. Today, we'll focus on some special considerations in obese individuals.
What are the causes for the increased risk of thromboembolic disease in obese patients?
Are there special anesthetic considerations in the obese parturient?
问题：本周我们讨论肥胖与麻醉的关系。今天我们重点讨论肥胖患者的一些特殊问题：
1.肥胖患者患血栓栓塞性疾病风险增加的原因是什么？
2.肥胖患者实施麻醉需要特殊考虑什么问题？
答案：
1.肥胖患者患血栓栓塞性疾病风险增加的原因是什么？
血栓栓塞性疾病的危险（包括肺栓塞）在承受非恶性腹部外科手术的肥胖患者表明有明显的增高。
原因包括：
•静脉淤滞
•红细胞增多
•下肢深静脉压力增高，仅次于腹部压力增加
•纤维蛋白溶解活性降低，伴随纤维蛋白素原增加
•心力衰竭
忽视这种增加的风险，在晚近进行的美国肥胖治疗外科专家协会的调查中发现，阻止和治疗静脉血栓栓塞仍保持非常不确定。与麻醉有关的治疗包括抗血栓药预防性的应用，特别是低分子肝素应用的增加。
2.肥胖患者实施麻醉需要特殊考虑什么问题？
除了关心肥胖患者外，妊娠在该人群的因素也增加了需要关注的特殊问题。包括：
•慢性高血压、先兆子痫、糖尿病的风险增加
•难产的危险增加，器械助产的可能性增加，剖妇产的可能性增加
•剖宫产术中和术后并发症的几率增加（包括大出血、DVT、伤口裂开等）
•插管失败和胃液误吸的风险增加
•局部麻醉（主要是椎管内麻醉）实施的困难和失败率增加
•胎儿发病率和死亡率增加；胎儿窘迫的危险大大增加
•主动脉-腔静脉压迫发生几率增加
肥胖患者妊娠行急诊剖宫产是很常见的，清晰的活动计划必须得到包括产科医生、助产护士和麻醉科医生在内的所有保健提供者的一致同意。母亲的安全是优先的，然后是胎儿的安全，因此，患者呼吸道的早期评估和硬膜外导管在产程的早期置入（即使后来不用）应该考虑到。全身麻醉应该尽可能避免，部分是因为困难呼吸道的可能，这也成为产程中如剖宫产一样的很麻烦的问题之一。
What are the causes for the increased risk of thromboembolic disease in obese patients?
The risk of thromboembolic disease, including pulmonary emboli, in obese individuals undergoing non-malignant abdominal surgery has been noted to be significantly higher (1).
The causes for this increased risk of thromboembolic disease include (2):
• venous stasis
• polycythemia
• increased pressure in deep venous channels of the lower limb, secondary to increased abdominal pressure
• decreased fibrinolytic activity, with increased fibrinogen concentrations
• cardiac failure
Despite this increased risk, in the most recent survey of the American Society for Bariatric Surgery, measures to prevent and treat venous thromboembolism remain extremely variable (3). Treatments of concern to the anesthesiologist include the use of antithrombotic agents prophylactically, especially the increasing use of low molecular weight heparins.
Are there special anesthetic considerations in the obese parturient?
In addition to the concerns of an obese patient, pregnancy in this population adds several special considerations. These include (4):
• increased risk of chronic hypertension, pre-eclampsia, and diabetes
• increased incidence of difficult labor with increased likelihood of instrumental (including cesarean) delivery
• increased incidence of intra- and post- cesarean delivery complications (including greater blood loss, DVT, wound dehiscence)
• increased risk for failed intubation and gastric aspiration
• increased incidence of failed or difficult regional anesthetic placement
• increased incidence fetal morbidity and mortality; with greater risk of fetal distress
• increased incidence of profound aorto-caval compression
As emergent cesarean deliveries are common in pregnant obese patients, a clear plan of action must be agreed upon by all health care providers involved, including the obstetrician, labor nurse, and anesthesiologist. The mother's safety is the overriding priority, followed by that of the fetus, and as such, early evaluation of the airway of the patient and the placement of an epidural catheter early in labor (even if it is not utilized) should be considered. General anesthesia should be avoided if at all possible, in part due to the possibility of a difficult airway, which may actually become worse during labor as well as following cesarean delivery (5).
References:
1. Cohen AT. Venous thromboembolic disease management of the nonsurgical moderate- and high-risk patient. Semin Hematol 2000;37(3 Suppl 5):19-22.
2. Adams JP, Murphy PG. Obesity in anaesthesia and intensive care. Br J Anaesth 2000;85:91-108.
3. Wu EC, Barba CA. Current practices in the prophylaxis of venous thromboembolism in bariatric surgery. Obes Surg 2000;10(1):7-13.
4. Hood DD, Dewan DM. Anesthetic and obstetric outcome in morbidly obese parturients. Anesthesiology. 1993;79:1210-8.
5. Bhavani-Shankar K, Lynch EP, Datta S. Airway changes during Cesarean hysterectomy. Can J Anaesth 2000;47(4):338-41.
Site Editor: Stephen B. Corn, M.D. and B. Scott Segal, M.D.
Department of Anesthesia, Harvard Medical School
