Continuous ultrasound-guided rhomboid intercostal–subserratus plane block versus thoracic paravertebral block for analgesia and respiratory recovery in patients with multiple rib fractures: a single-center randomized trial

Effective analgesia is essential in multiple rib fractures to preserve respiratory function. Thoracic paravertebral block (TPVB) is effective but may be limited by technical difficulty and complications. Rhomboid intercostal–subserratus (RISS) plane block is a newer ultrasound-guided alternative. To compare the analgesic efficacy and pulmonary function recovery associated with ultrasound-guided RISS block and TPVB in patients with traumatic multiple rib fractures. In this prospective, randomized, blinded trial conducted in an emergency ICU, 50 adults aged 18–60 years with unilateral traumatic fractures of three or more ribs were randomized 1:1 to receive continuous ultrasound-guided TPVB or RISS block with catheter infusion in addition to standardized systemic analgesia. The primary endpoint was pulmonary function at 24 h, assessed using forced expiratory volume in one second (FEV1). Secondary outcomes included pain scores at rest and during coughing, pulmonary function, diaphragmatic excursion, rescue opioid consumption, adverse events, and ICU and post-ICU ward stay. Fifty patients were randomized, with 25 patients in each group. At 24 h, FEV1 increased from 56.2 ± 3.2% to 72.8 ± 5.4% in the TPVB group and from 57.7 ± 3.0% to 73.8 ± 5.6% in the RISS group. The baseline-adjusted between-group difference was not statistically significant (adjusted RS–TP difference, 0.47 percentage points; 95% CI, −2.63 to 3.57; p = 0.768). At 24 h, median VAS pain scores at rest were 1 (0–2) and 0 (0–2), while scores during coughing were 3 (2–4) and 2 (2–4), in the TPVB and RISS groups, respectively. Total rescue morphine consumption over 72 h was comparable between groups (13.3 ± 3.2 mg vs 11.7 ± 4.6 mg; p = 0.205). Needle visibility was significantly better with RISS. Vascular puncture and block-related pneumothorax each occurred in two TPVB patients and no RISS patients, although the between-group differences were not statistically significant. Continuous ultrasound-guided RISS block provided analgesia and 24 h pulmonary-function recovery similar to TPVB in stable, spontaneously breathing patients with unilateral multiple rib fractures. RISS also provided better needle visibility. Although procedure-related complications were observed only in the TPVB group, this trial was not powered to establish comparative safety. ClinicalTrials.gov, NCT05898958. Registered on June 12, 2023. Retrospectively registered.