Abstract Body: Case Presentation
A 58-year-old man with Down Syndrome, Alzheimer’s dementia, and psoriatic arthritis (on adalimumab) was admitted for chest pain and dyspnea due to a loculated right pleural effusion, treated with thoracentesis, chest tube, and multiple doses of tPA with minimal output. 10-days upon admission, the patient became increasingly lethargic, hypoxic with shallow breathing and was emergently intubated at bedside. En route to the ICU, patient in PEA arrest, underwent ACLS and achieved ROSC after emergent intubation. Labs remarkable for lactic acidosis of 21.2 and acute transaminitis with AST > 12,000 and ALT > 2,000. Within the hour, he became hemodynamically unstable requiring multiple vasopressor support. Bedside POCUS suggestive of large pericardial effusion.

Differential Diagnosis
Given the patient’s sudden hemodynamic collapse, initial working differential diagnosis included autoimmune or drug-induced hemopericardium, iatrogenic cardiac tamponade, pulmonary embolism, acute coronary syndrome, pneumothorax, hemothorax, and septic shock.
Adalimumab-Induced Cardiac Tamponade: Pericardial fluid analysis revealed an inflammatory exudate: LDH 2220, pH 7.15, protein 4.9, WBC 17, RBC 0.016. Few reports link anti-TNF therapy to hemorrhagic pericardial effusion mimicking infection.
Iatrogenic hemopericardium: Considered due to the patient’s recent thoracentesis, chest tube placement, and multiple doses of intrapleural tPA for the loculated effusion. Our patient's pericardial fluid was serosanguinous with scant blood (RBC 0.016 x 10^12/L) not supportive of hemopericardium.

Treatment and Management
Emergent pericardiocentesis with drain placement.

Outcome and Follow-Up
Underwent emergent pericardiocentesis with 500cc of serosanguinous fluid drained with decreasing vasopressor requirements. Cultures and gram stains of pericardial fluid with no growth. Cytology of fluid was negative for malignancy. He ultimately required CRRT for persistent lactic acidosis and acute renal and hepatic failure for multiple weeks prior to being stabilized and discharged to LTAC in stable condition.

Teaching Points
1. Clinicians should be aware of this rare but potentially life-threatening adverse effect of anti-TNF therapies leading to inflammatory exudative pericardial effusion and cardiac tamponade.
2. We highlight the crucial role of POCUS in critical clinical scenarios.
3. Importance of considering a broad differential diagnosis in patients with sudden hemodynamic collapse.