Pilot study comparing three analgesia approaches for rib fractures

Rib fractures in the elderly are associated with pulmonary complications and mortality. The erector spinae plane (ESP) block might reduce pain and improve pulmonary function. Lidocaine infusions offer a non-invasive alternative delivery of local anesthetic. This pilot study was designed to inform the design of a future large trial.

Patients ≥ 55 years of age with at least three unilateral rib fractures were randomly assigned to an ESP catheter, lidocaine infusion, or multimodal analgesia alone. Baseline measurements included the Duke Activity Status Index (DASI) score. Pain, opioid use, adverse effects, vital capacity, delirium, and sedation were assessed for 72 hours. Primary outcomes were average pain ratings and opioid consumption. Pulmonary complications, opioid use, functional status, and safety outcomes were assessed to determine feasibility of a definitive trial.

Twenty-four patients were included in analyses. Demographics and injury severity were similar. The recruitment rate was 2.4 patients per month with two patients withdrawals. The mean ± SD pain ratings did not differ between ESP, lidocaine, and control groups, respectively (day 1: (4.9 ± 3.1 versus 5.8 ± 3.1 versus 5.6 ± 3.3); day 2: (4.4 ± 3.3 versus 5.4 ± 3.0 versus 7.4 ± 2.6); and day 3: (4.4 ± 2.1 versus 5.8 ± 2.6 versus 5.2 ± 3.5; p=0.70). Median [IQR] opioid consumption did not differ between the same groups, respectively (25.0 [66.8] versus 26.7 [89.2] versus 20.0 [101.4]; p=0.68). Three lidocaine patients experienced possible local anesthetic systemic toxicity (LAST) despite our conservative dosing protocol. Two patients died before the 30-day assessments. Pneumonia occurred more frequently in controls and could be a future 4 primary outcome for a definitive trial, which would require enrolling 11 patients per month over three years. Delirium occurred less frequently in ESP patients.

Analgesia was comparable between groups. While this study does not rule out a modest early analgesic benefit of ESP block or lidocaine infusion, pulmonary complications or delirium may be the preferred endpoint. Possible LAST symptoms occurred in three lidocaine patients despite conservative dosing and should be systematically assessed in future trials, especially in the elderly.