Abstract Introduction Diffuse alveolar hemorrhage (DAH) is a life-threatening syndrome with diverse etiologies, including vasculitis, autoimmune disorders, drugs, and infection. However, non-immune mechanisms such as negative-pressure pulmonary hemorrhage (NPPH) are rarely recognized. Negative pressure pulmonary edema (NPPE) is an uncommon condition that typically results from the acute generation of markedly negative intrapleural pressure during forceful inspiration against an obstructed airway (i.e. the Mueller maneuver), as seen in cases of infection, tumor, or laryngospasm. Case A 50-year-old male with a history of seizure disorder and intermittent compliance with antiepileptic therapy was admitted for acute hemoptysis and hypoxia requiring HFNC(High flow nasal canula) following a seizure episode. CT chest demonstrated diffuse ground-glass opacities. (Figure 1) Both hemoptysis and hypoxia resolved within 24 hours, and a follow-up chest radiograph showed marked improvement. (Figure 2) Two months earlier, he was admitted to the ICU for acute hypoxic respiratory failure following a witnessed seizure requiring intubation. Chest CT revealed diffuse airway-centered nodular consolidations and ground-glass opacities in all lobes (Figure 3). Bronchoalveolar lavage showing progressively bloodier aliquots confirmed DAH. Extensive infectious and autoimmune evaluations were negative. He was treated with corticosteroids and discharged on a tapering regimen, but was noncompliant. Radiographic abnormalities resolved by day 4 (Figure 4). Five months before ICU admission, he was hospitalized with hemoptysis and dyspnea upon awakening, requiring HFNC and tranexamic acid nebulization. Imaging showed diffuse alveolar infiltrates, which resolved within one week without antibiotics or immunosuppressants. Autoimmune and infectious studies were again negative. Discussion The close temporal relationship between seizure activity and the onset of diffuse alveolar infiltrates, followed by rapid clinical and radiographic resolution without immunosuppressive therapy, supports a diagnosis of bland pulmonary hemorrhage. The absence of systemic vasculitis features and serologic markers further supports this entity. The likely mechanism is NPPH secondary to the Mueller maneuver—a forceful inspiratory effort against a closed glottis following tonic-clonic seizure. That generates substantial negative intrathoracic pressure, leading to an abrupt elevation in pulmonary capillary transmural pressure, mechanical stress failure of the alveolar-capillary membrane, and subsequent alveolar bleeding. Recognition of this phenomenon is crucial as it may mimic immune or infectious causes of DAH but requires supportive rather than immunosuppressive management. Conclusion This case highlights seizure-related negative pressure pulmonary hemorrhage as a reversible and underrecognized cause of diffuse alveolar hemorrhage. Awareness of this entity can prevent unnecessary immunosuppressive therapy and guide appropriate management aimed at seizure control and airway protection to reduce recurrence. This abstract is funded by: None
Thapa et al. (Fri,) studied this question.