This case report demonstrates the value of transoesophageal echocardiography (TOE) in comparison with transthoracic echocardiography as it allows a better view of the thoracic aorta, the auricles, the interauricular septum and the cardiac valves, especially in the intubated and ventilated patients. A 84-year-old woman was admitted to the ICU for hypoxia after carotid-subclavian bypass surgery for acute ischaemia of the left upper limb. The TOE showed a dilated right heart and a patent foramen ovale, compatible with pulmonary embolism as well as two thrombi in the aortic arch. The patient died on the 8th postoperative day from refractory hypoxia. the autopsy confirmed the pulmonary embolism and the intraaortic thrombi. It is concluded that TOE, readily feasible is indicated in case of hypoxia, shock and systemic embolism without cause immediately recognizable, especially in ventilated patients.