Lidocaine Infusions for Pain in Patients With Malignant Bowel Obstruction

Malignant bowel obstruction is a frequent complication of advanced cancer, particularly of abdominal and pelvic origin, and most affected patients experience pain. Opioids are the mainstay of analgesic treatment, but some patients have pain that does not respond adequately or cannot tolerate further opioid dose increases. Lidocaine infusions are sometimes used as an adjuvant pain treatment in this setting, but specific evidence is limited to case reports and small series. This retrospective cohort study will review the medical records of adults with cancer and malignant bowel obstruction who received lidocaine infusions for pain as part of routine palliative care at Hospital Universitario Fundación Santa Fe de Bogotá (Bogotá, Colombia) between 2015 and 2025. The study will describe patient characteristics and lidocaine regimens, and will evaluate changes in pain intensity and opioid requirements before and after the start of the infusion, the proportion of patients with a clinically meaningful pain reduction, adverse events, treatment discontinuation due to toxicity, and hospital outcomes. The investigators will not assign or modify any treatment.

Inclusion Criteria: * Adults aged 18 years or older with a diagnosis of cancer. * Diagnosis of malignant bowel obstruction confirmed by clinical criteria and/or imaging studies and documented in the medical record. * Moderate to severe or refractory pain documented with the Numeric Rating Scale (NRS), ideally with a baseline NRS recorded within the 24 hours before infusion start and at least one NRS recorded within 24 to 48 hours after infusion start. * Receipt of a lidocaine infusion with analgesic intent as adjuvant pain treatment. * Available information on opioid requirements, expressed as oral morphine milligram equivalents (MME), after infusion start. * Sufficient clinical information to document clinical outcomes and adverse events. Exclusion Criteria: * Age under 18 years. * Use of lidocaine for an indication other than pain management (procedural sedation or anesthesia). * Incomplete clinical information that does not allow assessment of the primary outcome. * Surgical, endoscopic or radiological intervention to relieve the obstruction within the first 24 hours after infusion start, when this precludes post-infusion NRS measurement. * Documented absolute contraindications to lidocaine that led to early discontinuation of treatment without the possibility of evaluation.