Paradoxical embolism through a patent foramen ovale: an unexpected complication of tracheal extubation

Abstract

A 41-year-old male with insulin-dependent diabetes mellitus was admitted for an elective arthroscopic release of adhesive capsulitis of his left shoulder. At the end of the surgical procedure, he appeared to regain consciousness but then became unresponsive at the time of tracheal extubation after a violent bout of coughing, developing bilateral up-going plantar responses, decorticate posturing and abnormal pupillary reflexes. He was transferred to the intensive care unit. The following day, the patient made a full neurological recovery. Contrast echocardiography, performed using agitated saline delivered through a femoral venous line, revealed a large patent foramen ovale with evidence of right to left shunting. In the absence of risk factors for air embolism, the clinical diagnosis was one of paradoxical embolism of venous thrombus resulting in brain stem ischaemia. The patient was commenced on life-long aspirin to minimise future embolic risk. A patent foramen ovale is necessary in the fetal circulation to sustain intrauterine life. In utero, placental oxygenated blood enters the right atrium via the inferior vena cava and is directed towards the flap valve of the foramen ovale by the eustachian valve, thus enabling blood to enter the systemic circulation. At birth, the decrease in right-sided cardiac pressures and pulmonary vascular resistance reverses the right to left atrial pressure gradient and causes the flap of the foramen ovale to close against the atrial septum. Fusion is normally complete by the age of 2 years. In cases of incomplete fusion, the foramen ovale is kept sealed by the left atrial to right atrial pressure gradient but may be pushed open if right atrial pressure increases and exceeds that of the left atrium [1,2]. A patent foramen ovale is thus a potential route for emboli arising from the venous system to enter the systemic arterial circulation, resulting in the syndrome of 'paradoxical embolism'. We describe the case of a patient who experienced a paradoxical embolism induced by coughing during tracheal extubation. Case ReportA 41-year-old male with known microvascular complications secondary to insulin-dependent diabetes mellitus was admitted for an elective arthroscopic release of adhesive capsulitis of his left shoulder that had failed to respond to extensive physiotherapy. His past medical history included treated hypertension, micro-albuminuria, bilateral proliferative diabetic retinopathy and left exudative maculopathy with previous extensive panretinal photocoagulation. He had dyslipidaemia, drank alcohol occasionally and was a life-long non-smoker. Overall glycaemic control was good, but he had had several hospital admissions with symptomatic hypoglycaemia. Current medication included insulin, ramipril and over-the-counter analgesics.Six months previously, he had successfully undergone an elective arthroscopic release of his right shoulder with an excellent functional result. On this occasion, the general anaesthetic technique included fentanyl, propofol, atracurium and morphine...

Fatal Massive Cerebral Air Embolism in a Lung Transplant Patient

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Paradoxical Cardiac and Cerebral Arterial Gas Embolus During Percutaneous Lead Extraction in a Patient with a Patent Foramen Ovale

“…Evidence from TOE and bubble studies has shown that there is an increased risk of paradoxical embolism using femoral venous access due to the preferential direction of the inferior vena cava flow towards the inter-atrial septum, as compared to the superior vena cava. [6] Autopsy reports suggest that PFOs occur in 11-35% of the normal population, and are predominately a silent, innocent Paradoxical embolus during lead extraction phenomenon. [3] They can, however, be a source of paradoxical embolism, resulting in varied negative sequelae including cryptogenic stroke, peripheral embolism, brain abscess and decompression illness.…”

Paradoxical Air Embolism Successfully Treated With Hyperbaric Oxygen

“…6 In a review of all patients in the literature with cerebral air embolism associated with CVCs from 1975 to 1988, 54% occurred secondary to disconnection of CVCs, 31% occurred during removal of CVCs, and 15% occurred during insertion. 9 Other reported causes of cerebral air embolism include cardiopulmonary bypass, 10 intrathoracic anticancer drug administration, 11 endoscopic retrograde cholangiopancreatography, 12,13 contrast-enhanced computed tomography (CT), 14 CT-guided lung biopsy, 15 compressed air diving, 16 intra-aortic balloon pump rupture, 17 radial artery catheterization, 18,19 cardiopulmonary resuscitation, 20 tracheal extubation, 21 upper endoscopy, 22 endoscopic variceal ligation, 23 inadvertent aircraft depressurization, 24 diagnostic bronchoscopy, 25 transbronchial biopsy, 26,27 lung contusion, 28 inactive tuberculosis cavity, 29 esophageal carcinoma, 30 inhalation of pressurized helium, 31 pleurodesis, 32 cardiac ablation procedures, 33 and cerebral angiography. 34 Symptoms of venous air embolism (VAE) are referable to its effects on gas exchange and central hemodynamics.…”