Porter J M, Pidgeon C, Cunningham A J
Department of Anaesthesia, College of Surgeons in Ireland/Beaumont Hospital, Dublin, Ireland.
Br J Anaesth. 1999 Jan;82(1):117-28. doi: 10.1093/bja/82.1.117.
The potential for serious complications after venous air embolism and successful malpractice liability claims are the principle reasons for the dramatic decline in the use of the sitting position in neurosurgical practice. Although there have been several studies substantiating the relative safety compared with the prone or park bench positions, its use will continue to decline as neurosurgeons abandon its application and trainees in neurosurgery are not exposed to its relative merits. How can individual surgeons continue to use this position? Will individual, difficult surgical access cases be denied the obvious technical advantages of the sitting position? Limited use of the sitting position should remain in the neurosurgeon's armamentarium. However, several caveats must be emphasized. Assessment of the relative risk-benefit, based on the individual patient's physical status and surgical implications for the particular intracranial pathology, is of paramount importance. The patient should be informed of the specific risks of venous air embolism, quadriparesis and peripheral nerve palsies. Appropriate charting of patient information provided and special consent issues are essential. An anaesthetic input into the decision to use the sitting position is a sine qua non. The presence of a patient foramen ovale is an absolute contraindication. Preoperative contrast echocardiography should be used as a screening technique to detect the population at risk of paradoxical air embolism caused by the presence of a patent foramen ovale. The technique involves i.v. injection of saline agitated with air and a Valsalva manoeuvre is applied and released. Use of this position necessitates supplementary monitoring to promptly detect and treat venous air embolism. Doppler ultrasonography is the most sensitive of the generally available monitors to detect intracardiac air. The use of a central venous catheter is recommended, with the tip positioned close to the superior vena cava junction with the right atrium, to aspirate intravascular gas. Measures to minimize hypotension associated with the sitting position include a slow, staged positioning over 5-10 min and use of the 'G suit' inflated with compressed air applied to the lower extremities and pelvis. Use of the sitting or upright position for patients undergoing posterior fossa and cervical spine surgery presents unique challenges for the anaesthetist. With appropriate patient selection and preparation, and using prudent intraoperative monitoring and anaesthetic techniques, selected patients should still benefit from the optimum access to mid-line lesions, improved cerebral venous decompression, lower intracranial pressure and enhanced gravity drainage of blood and CSF associated with the sitting position.
静脉空气栓塞后出现严重并发症的可能性以及成功的医疗事故责任索赔是神经外科手术中坐位使用急剧减少的主要原因。尽管有多项研究证实与俯卧位或公园长椅位相比其相对安全，但随着神经外科医生放弃使用该体位且神经外科实习生未接触到其相对优点，其使用仍将继续减少。个别外科医生如何继续使用该体位呢？个别手术入路困难的病例会因坐位明显的技术优势而被放弃吗？坐位的有限使用应保留在神经外科医生的技术储备中。然而，必须强调几个注意事项。根据个体患者的身体状况以及特定颅内病变的手术影响来评估相对风险效益至关重要。应告知患者静脉空气栓塞、四肢瘫痪和周围神经麻痹的具体风险。对所提供的患者信息进行适当记录以及特殊的知情同意问题至关重要。麻醉医生参与坐位使用的决策是必不可少的。患者存在卵圆孔未闭是绝对禁忌证。术前对比超声心动图应用作筛查技术，以检测因卵圆孔未闭而有反常空气栓塞风险的人群。该技术包括静脉注射与空气混合振荡的生理盐水，并应用和释放瓦尔萨尔瓦动作。使用该体位需要进行辅助监测，以便及时检测和治疗静脉空气栓塞。多普勒超声是一般可用监测设备中检测心内空气最敏感的。建议使用中心静脉导管，其尖端靠近上腔静脉与右心房的交界处，以抽吸血管内气体。将与坐位相关的低血压降至最低的措施包括在5 - 10分钟内缓慢、分阶段地摆放体位，以及使用充有压缩空气的“G服”，应用于下肢和骨盆。对于接受后颅窝和颈椎手术的患者，使用坐位或直立位给麻醉医生带来了独特的挑战。通过适当的患者选择和准备，并采用谨慎的术中监测和麻醉技术，特定患者仍应能从坐位提供的最佳中线病变入路、改善的脑静脉减压、降低的颅内压以及增强的血液和脑脊液重力引流中获益。
