Cerebrovascular accident secondary to paradoxical embolism following arteriovenous graft thrombectomy

Cerebral air embolism: neurologic manifestations, prognosis, and outcome

Background

Cerebral air embolism (CAE) is an uncommon medical emergency with a potentially fatal course. We have retrospectively analyzed a set of patients treated with CAE at our comprehensive stroke center and a hyperbaric medicine center. An overview of the pathophysiology, causes, diagnosis, and treatment of CAE is provided.

Results

We retrospectively identified 11 patients with cerebral venous and arterial air emboli that highlight the diversity in etiologies, manifestations, and disease courses encountered clinically. Acute-onset stroke syndrome and a progressive impairment of consciousness were the two most common presentations in four patients each (36%). Two patients (18%) suffered from an acute-onset coma, and one (9%) was asymptomatic. Four patients (36%) were treated with hyperbaric oxygen therapy (HBTO), high-flow oxygen therapy without HBOT was started in two patients (18%), two patients (18%) were in critical care at the time of diagnosis and three (27%) received no additional treatment. CAE was fatal in five cases (46%), caused severe disability in two (18%), mild disability in three (27%), and a single patient had no lasting deficit (9%).

Conclusion

Cerebral air embolism is a dangerous condition that necessitates high clinical vigilance. Due to its diverse presentation, the diagnosis can be missed or delayed in critically ill patients and result in long-lasting or fatal neurological complications. Preventative measures and a proper diagnostic and treatment approach reduce CAE's incidence and impact.

Thrombectomy approach for access maintenance in the end stage renal disease population: a narrative review

Objective

This article reviews current practices and outcomes in endovascular thrombectomy techniques for the treatment of thrombosed arteriovenous grafts (AVGs) and fistulas (AVFs).

Background

Arteriovenous (AV) access allows patients with end-stage renal disease (ESRD) to receive hemodialysis. Thrombosis of AV access can lead to delay in hemodialysis or abandonment of access requiring dialysis catheter placement. Endovascular approach has become the preferred treatment option for thrombosed access over surgery. Interventions include removal of thrombus from the AV circuit and treatment of the underlying anatomical abnormality, such as an anastomotic stenosis. Thrombolysis, or the act of dissolving thrombus, is performed by using infusion catheters or pulse injector devices for the administration of fibrinolytic agents. Thrombectomy, or the mechanical removal of thrombus, is performed by using embolectomy balloon catheters, rotating baskets or wires, rheolytic and aspiration mechanisms. Adjunctive methods such as cutting balloon angioplasty, drug-coated balloon (DCB) angioplasty, and stent placement are also used to treat stenoses in the AV circuit. Complications of these procedures include vessel rupture, arterial embolism, pulmonary embolism (PE), and paradoxical embolism to the brain.

Methods

This narrative review article was written based on literature search from electronic databases, including PubMed and Google Scholar.

Conclusions

The understanding of thrombectomy techniques and their potential complications is essential in the management of patients with thrombosed AV access.

Fatal Cerebral Air Embolism: A Case Series and Literature Review

Cerebral air embolism (CAE) is an infrequently reported complication of routine medical procedures. We present two cases of CAE. The first patient was a 55-year-old male presenting with vomiting and loss of consciousness one day after his hemodialysis session. Physical exam was significant for hypotension and hypoxia with no focal neurologic deficits. Computed tomography (CT) scan of head showed gas in cerebral venous circulation. The patient did not undergo any procedures prior to presentation, and his last hemodialysis session was uneventful. Retrograde rise of venous air to the cerebral circulation was the likely mechanism for venous CAE. The second patient was a 46-year-old female presenting with fever, shortness of breath, and hematemesis. She was febrile, tachypneic, and tachycardic and required intubation and mechanical ventilation. An orogastric tube inserted drained 2500 mL of bright red blood. Flexible laryngoscopy and esophagogastroduodenoscopy were performed. She also underwent central venous catheter placement. CT scan of head performed the next day due to absent brain stem reflexes revealed intravascular air within cerebral arteries. A transthoracic echocardiogram with bubble study ruled out patent foramen ovale. The patient had a paradoxical CAE in the absence of a patent foramen ovale.

Evidence for the prevention and treatment of stroke in dialysis patients

The risks of both ischemic and hemorrhagic stroke are particularly high in dialysis patients of any age and outcomes are poor. It is therefore important to identify strategies that safely minimize stroke risk in this population. Observational studies have been unable to clarify the relative importance of traditional stroke risk factors such as blood pressure and cholesterol in those on dialysis, and are affected by biases that usually make them an inappropriate source of data on which to base therapeutic decisions. Well-conducted randomized trials are not susceptible to such biases and can reliably investigate the causal nature of the association between a potential risk factor and the outcome of interest. However, dialysis patients have been under-represented in the cardiovascular trials which have proven net benefit of commonly used preventative treatments (e.g., antihypertensive treatments, low-dose aspirin, carotid revascularization, and thromboprophylaxis for atrial fibrillation), and there remains uncertainty about safety and efficacy of many of these treatments in this high-risk population. Moreover, the efficacy of renal-specific therapies that might reduce cardiovascular risk, such as modulators of mineral and bone disorder, online hemodiafiltration, and daily (nocturnal) hemodialysis, have not been tested in adequately powered trials. Recent trials have also demonstrated how widespread current practices could be causing stroke. Therefore, it is important that reliable information on the prevention and treatment of stroke (and other cardiovascular disease) in dialysis patients is generated by performing large-scale randomized trials of many current and future treatments.