Paradoxical Fat Embolism Syndrome During Total Hip Arthroplasty Without a Patent Foramen Ovale: A Case Report With Transesophageal Echocardiographic Findings.

Fat embolism syndrome (FES) is a severe orthopedic complication leading to respiratory failure and neurological impairment. While bone marrow or fat entry into venous circulation is common during total hip arthroplasty (THA), cardiac arrest rarely results. An 82-year-old woman developed pulseless electrical activity (PEA) during elective THA. During femoral reaming, a sudden decline in peripheral oxygen saturation (SpO2: 100% to 89%) and end-tidal carbon dioxide (EtCO2: 28 to 12 mmHg) was observed, followed by precipitous circulatory collapse. Transesophageal echocardiography (TEE) captured real-time video of numerous microemboli in all cardiac chambers, confirming pulmonary and paradoxical embolism. Despite successful resuscitation and surgical termination, TEE showed persistent embolic flow from the inferior vena cava (IVC). Postoperatively, the patient remained unconscious due to extensive cerebral infarction, resulting in permanent neurological sequelae. Fat embolism during THA can be fatal. This case, documented via intraoperative imaging, highlights the need for rapid point-of-care diagnosis and proactive surgical techniques to minimize intramedullary pressure.