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.