Mixed baricity 2020

Orthopedic surgeries in geriatrics carry a significant risk of both morbidity and mortality[1]; and rapid surgical intervention is warranted to reduce the incidence of complications and fasten the hospital discharge[2,3]. Despite the debate regarding the preferred type of anesthesia in the elderly population, spinal anesthesia has shown the advantage of the simplicity of the technique, the better analgesic profile, and the lower incidence of thromboembolic events, However, the hemodynamic consequences of sympathetic blockade under spinal anesthesia remains a major concern especially in such frail patients.[4,5]
Many modifications of the spinal anesthesia technique in the elderly population were used to avoid complications like hypotension, bradycardia, cerebral hypoperfusion, and higher block levels, these techniques included unilateral spinal techniques or lowering the dose of local anesthetics (LA) [6–8]. Yet, if the patient position and the LA dose are fixed, the principal factor controlling the intrathecal diffusion of injected anesthetic medications and the resulting sympathetic blockade would the baricity injected solution. While the hyperbaric solutions spread is mainly controlled by gravity, the isobaric LA solutions have a limited spread in the cerebrospinal fluid (CSF), especially in small doses.[9–11]
In this study, we studied the sequential administration of a low dose of isobaric and hyperbaric bupivacaine in geriatric patients undergoing orthopedic surgery. This sequence of injection is assumed to avoid the disadvantages of hyperbaric and isobaric LA solutions while maintaining the privileges of both. The low dose hyperbaric bupivacaine achieves less dense anesthesia at lower dermatomal levels, while the sequential low dose plain bupivacaine would secure sufficient segmental anesthesia for the surgical procedure, sparing the sympathetic system integrity and maintaining hemodynamic stability. The primary outcome was the incidence of arterial hypotension in elderly patients after spinal anesthesia, and secondary outcomes included the use of vasopressors, spinal block characteristics, and perioperative complications including nausea, vomiting, shivering, pruritus, respiratory depression, shivering, and delirium.

在老年病学领域，骨科手术伴随着显著的发病率和死亡率风险[1]；为降低并发症发生率并加速出院，迅速的手术干预显得尤为必要[2,3]。尽管关于老年人群适宜麻醉类型的争论持续存在，但硬脊膜外麻醉因其技术简便、镇痛效果优良以及血栓栓塞事件发生率较低而显示出优势。然而，在硬脊膜外麻醉下交感神经阻滞的血流动力学后果，尤其是在此类脆弱患者中，仍是一个主要关注点[4,5]。针对老年人群的硬脊膜外麻醉技术进行了许多改良，以避免低血压、心动过缓、脑灌注不足以及更高阻滞水平等并发症，这些技术包括单侧硬脊膜外技术或降低局部麻醉剂（LA）的剂量[6–8]。然而，若患者体位和LA剂量固定，控制注入麻醉药物在椎管内扩散及其所致交感神经阻滞的主要因素将是注入溶液的比重。尽管超比重溶液的扩散主要受重力控制，但等比重LA溶液在脑脊液（CSF）中的扩散有限，尤其是在小剂量时[9–11]。在本研究中，我们研究了在行骨科手术的老年患者中低剂量等比重和超比重布比卡因的顺序给药。这种注射顺序旨在避免超比重和等比重LA溶液的缺点，同时保持两者的优势。低剂量超比重布比卡因在较低皮节水平上实现较稀疏的麻醉，而顺序低剂量普鲁卡因则可确保手术过程所需的足够节段性麻醉，从而保护交感神经系统的完整性并维持血流动力学稳定。主要结局指标为硬脊膜外麻醉后老年患者的动脉低血压发生率，次要结局指标包括血管加压素的使用、硬脊膜外阻滞特征以及围术期并发症，包括恶心、呕吐、颤抖、瘙痒、呼吸抑制、颤抖和谵妄。