207: The Silent Gut & Screaming Nerve: Multimodal Rescue of Pediatric Hostile Abdomen

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic postsurgical pain, Pharmacological treatments

Background and Aims: Pediatric "hostile abdomen" syndrome presents a complex therapeutic challenge, characterized by refractory visceral nociception and extensive adhesive disease. Standard mu-opioid monotherapy often fails in this setting, precipitating opioid-induced hyperalgesia (OIH) and exacerbating ileus. This case report aims to demonstrate the efficacy of a mechanism-based multimodal analgesic strategy—specifically opioid rotation to kappa-agonists and NMDA receptor antagonism—in a 14-year-old female with a frozen abdomen. Furthermore, we analyze the diagnostic management of rare iatrogenic sequelae, including sensorineural hearing loss and metabolic mimics of neurotoxicity, to highlight critical clinical distinctions in pediatric critical care.

Methods: We conducted a retrospective chart review of a 14-year-old female admitted for gangrenous appendicitis complicated by generalized peritonitis, necessitating seven laparotomies over a 118-day hospitalization. Clinical data were extracted regarding the evolution of analgesic strategies, transitioning from epidural morphine to high-dose intravenous fentanyl PCA, and subsequently to oxycodone and ketamine. We evaluated the physiological rationale for rotating from hydrophilic to lipophilic opioids and the introduction of adjuvants. Additionally, we analyzed the diagnostic workup for systemic complications, including sudden hearing loss, acute encephalopathy (Wernicke’s mimic), and hemodynamic instability requiring atypical vasopressor management with nitroglycerin.

Results: Escalation of fentanyl PCA (peaking at 60-80 mcg/hr basal) precipitated worsening allodynia (OIH) and severe ileus. Rotation to oxycodone (targeting visceral kappa-receptors) combined with sub-anesthetic ketamine infusion (2-2.5 mg/hr) successfully reduced pain scores and facilitated weaning. The course was complicated by sudden bilateral sensorineural hearing loss, attributed to synergistic ototoxicity from synthetic opioids and aminoglycosides. Concurrently, the patient developed nystagmus and ataxia; MRI confirmed non-alcoholic Wernicke’s Encephalopathy, which resolved with thiamine. During septic shock, nitroglycerin was paradoxically co-administered with vasopressors to preserve splanchnic microcirculation, preventing further bowel necrosis.

Conclusions: In refractory pediatric visceral pain, reliance on high-dose mu-opioids carries significant risks of OIH and bowel dysfunction. Early rotation to opioids with kappa-affinity (oxycodone) and the addition of NMDA antagonists (ketamine) is a protective, mechanism-based strategy. This case underscores the necessity for high vigilance regarding rare iatrogenic complications: specifically, distinguishing metabolic encephalopathies from pharmacological toxicity and monitoring for opioid-associated ototoxicity. Furthermore, the use of nitroglycerin for splanchnic resuscitation represents a nuanced physiological approach to preventing ischemic bowel injury in the critically ill surgical child.

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Presenting Author: Dr. Tiffany Joy Chavez
Submitting Author: Tiffany Joy Chavez

Senior Author: Dr. Maria Elena Basco-Tiamson

IASP 2026 Global Year theme of Neuropathic Pain: No

• Maria Elena Basco-Tiamson: MD, DPBA, FPSA, DPBPM - St. Luke's Medical Center Quezon City