Integrating Plethysmography and Point-of-Care Ultrasound for Rapid Bedside Detection of Cardiac Tamponade: A Non-Invasive Duo — A Case Report

Abstract

Background: Cardiac tamponade is a life-threatening condition caused by pericardial fluid accumulation leading to impaired cardiac filling and circulatory collapse. Diagnosing tamponade in children can be challenging due to nonspecific symptoms and limited access to echocardiography in resource-limited settings. Point-of-care ultrasound (POCUS) and plethysmography waveform analysis provide rapid, non-invasive bedside assessment tools for timely recognition and intervention. Case Presentation: An 8-year-old boy with recurrent meningitis and ear infections presented with fever, vomiting, lethargy, and signs of shock. On admission, he was tachycardic, tachypneic, hypotensive, and poorly perfused. Arterial blood gas showed rising lactate levels (6.0 → 7.3 mmol/L). Bedside POCUS revealed a large circumferential pericardial effusion with right atrial and ventricular diastolic collapse, while plethysmography waveform demonstrated marked respiratory variation indicating pulsus paradoxus. The diagnosis of cardiac tamponade was made. Due to rapid deterioration, an ultrasound-guided pericardiocentesis was performed by the pediatric intensivist, draining 400 mL of thick purulent fluid. Results: Post-procedure, blood pressure became recordable, heart rate improved from 170 bpm to 110 bpm, and lactate normalized. Pericardial fluid culture grew Streptococcus pneumoniae. Immunologic testing confirmed common variable immunodeficiency (CVID). The patient received intravenous vancomycin followed by prophylactic antibiotics and was discharged stable without recurrence. Conclusion: This case highlights the practical integration of plethysmography and POCUS in the rapid recognition of cardiac tamponade, particularly in pediatric patients and low-resource settings. Their combined use facilitates early diagnosis, prompt management, and favorable outcomes. Evaluation for underlying immunodeficiency is essential in children with recurrent infections and severe complications such as purulent pericarditis.