Background and Goal of Study: Continuous spinal anesthesia (CSA) for surgical repair of hip fracture in elderly patients has been shown to preserve hemodynamics better than general and single shoot SA [1]. However, hypotension still occurs with CSA. Our goal is to show that hypobaric bupivacaine in CSA is more effective in preserving hemodynamics than isobaric bupivacaine when patients are operated in the lateral position.
Materials and methods: It is a prospective, randomized, controlled, single-blinded study. Patients aged more than 65 years and scheduled for a surgical repair of a hip fracture were eligible. In order to provide analgesia for positioning, ultrasound guided femoral nerve block was performed. Patients were then placed in the lateral position with the operated side up. A spinal catheter was inserted. Patients were randomized to receive either hypobaric (HB) or isobaric bupivacaine (IB). Repeated doses of 2.5 mg bupivacaine were injected until sensory blockade reached T12, so surgery can start. Hypotension and severe hypotension were defined as a decrease of more than 20% and 30% from the baseline systolic arterial blood pressure. Hypotension was treated with ephedrine. Our primary outcome was the incidence of hypotension and severe hypotension among the 2 groups. Ephedrine consumption and fluid therapy were secondary outcomes. Qualitative data were analyzed by χ2 test and quantitative data by Student t-test. 
Results: One hundred and ten patients were analyzed. The two groups were comparable in age, BMI and ASA class. There was no difference in type and course of surgery. Significantly less patients experienced hypotension and severe hypotension in HB group than in IB group (respectively 53% vs 73%; p<0,05 and 53% vs 22%; p< 0,01). Significantly less ephedrine was used in HB group (5,6 vs 1,9 mg; p<0,01). Total consumption of bupivacaine was not significantly different.
Conclusion: In elderly patients operated under CSA in the lateral position with the operated side up, hypobaric bupivacaine may be used rather than isobaric bupivacaine for further preserving hemodynamics.

Hypobaric versus isobaric bupivacaine to prevent anesthesia-induced hypotension in elderly patients undergoing surgical repair of hip fracture under continuous spinal anesthesia: a prospective randomized controlled study