Fractional spinal anesthesia and systemic hemodynamics in frail elderly hip fracture patients

Background: Aging and frailty make the elderly patients susceptible to hypotension following spinal anesthesia. The systemic hemodynamic effects of spinal anesthesia are not well known. In this study, we examine the systemic hemodynamic effects of fractional spinal anesthesia following intermittent microdosing of a local anesthetic and an opioid.Methods: We included 15 patients aged over 65 with considerable comorbidities, planned for emergency hip fracture repair. Patients received a spinal catheter and cardiac output monitoring using the LiDCOplus system. Invasive mean arterial pressure (MAP), cardiac index, systemic vascular resistance index, heart rate and stroke volume index were registered. Two doses of bupivacaine 2.25 mg and fentanyl 15µg were administered with 25 minutes in between. Hypotension was defined as a fall in MAP by >30% or a MAP <65 mmHgResults: The incidence of hypotension was 30%. Hypotensive patients (n=5) were treated with low doses of norepinephrine (0.003-0.12 µg/kg/min). MAP showed a maximum reduction of 17% at 10 minutes after the first dose. Cardiac index, systemic vascular resistance index and stroke volume index decreased by 10%, 6%, and 7%, respectively, while heart rate was unchanged over time. After the first dose, none of the systemic haemodynamic variables were affected.Conclusion: Fractional spinal anesthesia causes a low incidence of hypotension, induced mainly by a systemic venodilation, causing a decrease in venous return and fall in cardiac output. Our results show that fractional spinal anesthesia is a safe technique from a hemodynamic point of view and is probably underutilized in high-risk, elderly hip fracture patients