RESUMEN
BACKGROUND: Fascia iliaca compartment block (FICB) is an increasingly popular analgesic technique in elderly patients with hip fracture. Despite requiring large volumes of local anaesthetic, there are no plasma pharmacokinetic data on FICB in elderly patients. OBJECTIVES: The objective of this study was to determine the pharmacokinetic profile of a levobupivacaine 75 mg (30 mL 0.25%) FICB dose in patients aged ≥ 80 years with fractured femur. METHODS: This was a single-arm descriptive pilot study. Twelve adults aged ≥ 80 years with hip fracture received FICB performed under ultrasound guidance. Venous blood was sampled at 10, 20, 30, 45, 60, 75, 90, 105, 120 and 240 min after injection. Total plasma levobupivacaine concentration was measured by mass spectrometry. The main outcome measures were pharmacokinetic parameters, including maximum observed plasma concentration (Cmax), time to reach Cmax (tmax) and area under the plasma concentration-time curve. RESULTS: The median (interquartile range [IQR]) Cmax was 0.82 µg/mL (0.47-1.03). tmax was 45 min (41:20-60:00). No evidence of toxicity was identified. Plasma levobupivacaine concentrations were below the threshold associated with toxicity in younger, healthy patients (2.6 µg/mL). No association was found between individual patient Cmax and α1-acid glycoprotein, weight or body mass index, although the study was not powered for these outcomes. CONCLUSIONS: Absorption of levobupivacaine was slow and all patients had plasma concentrations below the toxic threshold. This pharmacokinetic analysis concludes that the technique appears to be well-tolerated and efficacious at reducing pain and is associated with systemic plasma concentrations unlikely to be associated with major adverse effects in elderly patients. CLINICAL TRIAL REGISTRATION: ISRCTN27364035 (UK Clinical Trials Gateway).