Sequential Intrathecal Injection of Hyperbaric and Isobaric Bupivacaine in Orthogeriatric Lower Limb Surgery, a Prospective Randomized Study.

BACKGROUND: The hemodynamic consequences of sympathetic blockade under spinal anesthesia remains a major concern especially in elderly frail patients. The baricity of the injected solution remains the principal factor controlling the diffusion of spinal anesthetics and the resulting sympathetic blockade. In this study, the sequential administration of isobaric and hyperbaric bupivacaine (HB) is evaluated regarding the incidence of hypotension during orthogeriatric surgery.

METHODS: Fifty elderly patients (age ＞ 60), scheduled for lower limb orthopedic surgery were randomly divided into two groups. In group HIB (n = 25), sequential injection of two syringes, 1.5 mL of 0.5% HB with 15 μ of fentanyl was injected, followed immediately by 1.5 mL of 0.5% isobaric bupivacaine, and in group HB (n = 25), 3 mL of 0.5% HB mixed with 15 μ of fentanyl citrate (0.3 mL of fentanyl 50 μg/mL) were used for spinal anesthesia.

RESULTS: No statistical difference was found between the two groups regarding patient demographics, comorbidities, or preoperative laboratory data. The absolute incidence of hypotension (16% vs. 44%, P = 0.03) was statistically lower in the HIB group than the HB group. Also, the total number of hypotensive episodes and the need for vasopressor medications were statistically lower in the HIB group than the HB group (P = 0.02 vs. P = 0.01).

CONCLUSIONS: Our results show a better hemodynamic profile of the sequentially injected mixture with a lower incidence of intraoperative hypotension and subsequent lower vasopressor requirements.