The slippery slope to hypoventilation: multimorbidity and trauma

Alveolar hypoventilation is a recognized cause of hypoxemia, typically accompanied by hypercapnia. It may result from neuromuscular, central or peripheral disorders or thoracic structural abnormalities. A 78-year-old female, retired, with a history of severe obesity, OSAS (on nocturnal APAP since 2018), underwent right mastectomy in 2017, causing chronic right hemidiaphragmatic elevation and 2/3 right lung collapse (at the time respiratory function study and ABG normal), diabetes, high blood pressure and osteoporosis. She was admitted in May 2025 after a domestic fall with thoracic trauma (right 3rd–4th rib fractures), a left humeral shaft fracture, and D12 vertebral fracture. Surgical fixation of the humerus and spine was performed. Postoperatively, she developed radial nerve neuropraxia and pulmonary embolism, initiating anticoagulation with Rivaroxaban. During admission, she had acute-on-chronic respiratory failure with respiratory acidosis (pH 7.30, pCO2 81mmHg, pO2 81mmHg, HCO3- 40mEq/L), requiring NIV (initial BiPAP 16/8, later titrated to 18/7) with clinical and gasometric improvement. She was discharged with oxygen therapy (1.5 L/min) and nocturnal BiPAP. At follow-up, she was clinically stable, eupneic, and compliant with therapy (NIV adherence 91%, median 7h39/night, tidal volume 460 mL, AHI 0.7). ABG showed compensated hypercapnia (pH 7.38, pCO₂ 51mmHg, pO₂ 59mmHg), with median transcutaneous CO₂ 47mmHg). This case illustrates the complexity of managing respiratory failure in elderly patients with multiple comorbidities, trauma, and surgical sequelae, underlining the need for integrated multidisciplinary care, social support, respiratory follow-up, and structured rehabilitation strategies.