Kinetics of elimination and acute consequences of cerebral air embolism

Systemic arterial gas embolism (SAGE) as a complication of bronchoscopic lung biopsy: a case report and systematic literature review

Background

Systemic arterial gas embolism (SAGE) is a rare yet serious and underrecognized complication of bronchoscopic procedures. A recent case of presumed SAGE after transbronchial needle aspiration prompted a systematic literature review of SAGE after biopsy procedures during flexible bronchoscopy.

Methods

We performed a systematic database search for case reports and case series pertaining to SAGE after bronchoscopic lung biopsy; reports or series involving only bronchoscopic laser therapy or argon plasma coagulation (APC) were excluded. Patient data were extracted directly from published reports.

Results

A total of 29 unique patient reports were assessed for patient demographics, specifics of the procedure, clinical manifestations, diagnostic findings, and clinical outcomes. Cases of SAGE occurred after multiple types of bronchoscopic biopsy and under both positive and negative pressure ventilation. The most common clinical findings were neurologic, followed by cardiac manifestations; temporal patterns included acute onset of cardiac or neurologic emergencies immediately after biopsy, or delayed awakening post-procedure. There was a high mortality rate among cases (28%), with residual neurologic deficits also common (24%).

Discussion

SAGE is an underrecognized but severe adverse effect of bronchoscopic lung biopsy, which often presents with acute coronary or cerebral ischemia or delayed awakening from sedation. It is important for all physicians who perform bronchoscopic biopsies to be aware of the clinical manifestations and therapeutic management of SAGE in order to mitigate morbidity and mortality among patients undergoing these procedures.

Spontaneous Absorption of Cerebral Air Embolus Developed Accidentally during an Intra-arterial Procedure

Cerebral arterial air embolism (CAAE), although infrequent, is a complication that can occur at any time during an invasive medical procedure. We experienced two cases of CAAE during cerebral angiography accidentally. The author reports the two cases of CAAE wherein air emboli dissolved spontaneously and immediately under normal atmospheric pressure, not under therapeutic hyperbaric environment. One of the cases shows entire dissolution of the air embolus on the moving image. This report shows that arterial air embolus can be absorbed spontaneously, and air embolus size is one of the factors that influence air embolus dissolution besides hyperbaric oxygen condition.

Changes over Time in Intracranial Air in Patients with Cerebral Air Embolism: Radiological Study in Two Cases

Cerebral air embolism can be easily identified on computed tomography (CT) scans. However, changes in the distribution and amount of intracranial air are not well known. We report two patients with cerebral air embolism and present imaging findings on the serial changes in the intracranial air. We thought that the embolic source was venous in one patient because CT showed air inflow in cortical veins in the bilateral frontal areas, reflecting air buoyancy. In the other patient, CT showed air inflow into not only the cortical veins but also the bilateral cerebral hemispheres and we thought this to be a paradoxical cerebral air embolism. We found that intracranial air can be promptly absorbed and while cerebral infarcts due to air are clearly visualized on diffusion-weighted images (DWI), the air may rapidly disappear from images. In patients with suspected cerebral air embolism whose CT findings show no intracranial air, DWI should be performed because it may reveal cerebral infarction due to cerebral air embolism.

In vitro observation of air bubbles during delivery of various detachable aneurysm embolization coils

Objective

Device- or technique-related air embolism is a drawback of various neuro-endovascular procedures. Detachable aneurysm embolization coils can be sources of such air bubbles. We therefore assessed the formation of air bubbles during in vitro delivery of various detachable coils.

Materials and Methods

A closed circuit simulating a typical endovascular coiling procedure was primed with saline solution degassed by a sonification device. Thirty commercially available detachable coils (7 Axium, 4 GDCs, 5 MicroPlex, 7 Target, and 7 Trufill coils) were tested by using the standard coil flushing and delivery techniques suggested by each manufacturer. The emergence of any air bubbles was monitored with a digital microscope and the images were captured to measure total volumes of air bubbles during coil insertion and detachment and after coil pusher removal.

Results

Air bubbles were seen during insertion or removal of 23 of 30 coils (76.7%), with volumes ranging from 0 to 23.42 mm³ (median: 0.16 mm³). Air bubbles were observed most frequently after removal of the coil pusher. Significantly larger amounts of air bubbles were observed in Target coils.

Conclusion

Variable volumes of air bubbles are observed while delivering detachable embolization coils, particularly after removal of the coil pusher and especially with Target coils.

Animal models of cerebral arterial gas embolism

Cerebral arterial gas embolism is a dreaded complication of diving and invasive medical procedures. Many different animal models have been used in research on cerebral arterial gas embolism. This review provides an overview of the most important characteristics of these animal models. The properties discussed are species, cerebrovascular anatomy, method of air embolization, amount of air, bubble size, outcome parameters, anesthesia, blood glucose, body temperature and blood pressure.

Cerebral air embolism: acute imaging

Iatrogenic cerebral air embolism secondary to right subclavian vein recatheterization was imaged acutely by computed tomography (CT) and magnetic resonance imaging (MRI). However, CT showed intravascular air with misleadingly high attenuation values sampled to a minimum of -39 HU. Diffusion-weighted imaging, not previously reported in this setting, clearly showed hyperintense acute infarctions in corresponding vascular territories 8.5 hours postprocedure (less than 6 hours after referable symptomatology noted), whereas T2-weighted fluid-attenuated inversion recovery and turbo gradient spin echo images did not. The combination of CT and diffusion-weighted MRI appears ideal for evaluating suspected cerebral air embolism in the acute setting.

Fatal brain gas embolism during non-invasive positive pressure ventilation

Gas embolism is a dreaded complication following invasive medical procedures, traumatic lung injury and decompression accidents. We report a case of fatal gas embolism following the use of non-invasive ventilation (NIV) with bilevel positive airway pressure (BiPAP). The patient initially underwent left bronchial artery embolisation for massive haemoptysis in the context of severe tuberculotic sequels. Under NIV and after heavy coughing he became hemiparetic and his level of consciousness suddenly dropped. Computed tomography of the brain showed multiple air embolism and ischaemic lesions were confirmed by magnetic resonance imaging. Echocardiographic investigations showed no intracardiac defect. Vasculo-pulmonary abnormalities in the context of heavy coughing and non-invasive ventilation may have played a major role in the occurrence of this event. New neurological events in a patient with tuberculotic sequels or any known vascular pulmonary abnormalities and NIV should raise the suspicion of brain gas embolism.

Cerebral Gas Embolism Caused by Pleural Fibrinolytic Treatment

Background and Purpose— Intrapleural fibrinolytic therapy is a technique used to treat empyemas and parapneumonic effusions. Cerebral air embolism is an unusual potentially severe complication of this technique.

Summary of Case— A patient with parapneumonic pleural effusion underwent pleural lavage with streptokinase when he suddenly demonstrated focal neurological signs and seizures. The CT revealed multiple air-isodense spots in right hemisphere of the brain, suggesting cerebral air embolism. As a result of early diagnosis and emergency hyperbaric oxygenation, the patient recovered without delayed sequelae.

Conclusions— Air embolism is a potentially severe complication which can occur during fibrinolytic pleural lavage, and clinicians should be aware of this risk. In this context, the onset of acute focal neurological signs or seizures should suggest the possibility of air embolism and lead to the transfer of the patient close to a hyperbaric facility within a few hours.

[Management and causes of pneumocephalus. Case report and review of the literature]

Pneumocephalus is commonly seen after head and facial trauma, tumors of the skull base, after neurosurgery or otorhinolaryngology, and rarely spontaneously. Venous air embolism can result from right-to-left shunting or pneumocephalus. We report two cases of pneumocephalus, one after surgery of the paranasal sinus and the other after transabdominal prostatectomy. Clinical signs of the pneumocephalus were headache followed by epileptic seizures and, respectively, severely impaired consciousness after the operation. Treatment was either revision of the skull base with craniotomy or conservative therapy of the brain edema. Based on these case reports and the medical literature on pneumocephalus, we review the causes and treatment of this rare condition.

Massive cerebral arterial air embolism following arterial catheterization

Microscopic cerebral arterial air embolism (CAAE) has been described in many patients undergoing cardiac surgery as well as other invasive diagnostic and therapeutic procedures. However, massive CAAE is rare. We report a 42-year-old woman who initially presented with thalamic and basal ganglia hemorrhages. Shortly after a radial arterial catheter was inserted, the patient suffered a generalized seizure and CT demonstrated intra-arterial air in bilateral cerebral hemispheres.

Gas embolism: pathophysiology and treatment

Based on a literature search, an overview is presented of the pathophysiology of venous and arterial gas embolism in the experimental and clinical environment, as well as the relevance and aims of diagnostics and treatment of gas embolism. The review starts with a few historical observations and then addresses venous air embolism by discussing pulmonary vascular filtration, entrapment, and the clinical occurrence of venous air emboli. The section on arterial gas embolism deals with the main mechanisms involved, coronary and cerebral air embolism (CAE), and the effects of bubbles on the blood-brain barrier. The diagnosis of CAE uses various techniques including ultrasound, perioperative monitoring, computed tomography, brain magnetic resonance imaging and other modalities. The section on therapy starts by addressing the primary treatment goals and the roles of adequate oxygenation and ventilation. Then the rationale for hyperbaric oxygen as a therapy for CAE based on its physiological mode of action is discussed, as well as some aspects of adjuvant drug therapy. A few animal studies are presented, which emphasize the importance of the timing of therapy, and the outcome of patients with air embolism (including clinical patients, divers and submariners) is described.

In vivo droplet vaporization for occlusion therapy and phase aberration correction

The objective was to determine whether a transpulmonary droplet emulsion (90%, <6 microm diameter) could be used to form large gas bubbles (>30 microm) temporarily in vivo. Such bubbles could occlude a targeted capillary bed when used in a large number density. Alternatively, for a very sparse population of droplets, the resulting gas bubbles could serve as point beacons for phase aberration corrections in ultrasonic imaging. Gas bubbles can be made in vivo by acoustic droplet vaporization (ADV) of injected, superheated, dodecafluoropentane droplets. Droplets vaporize in an acoustic field whose peak rarefactional pressure exceeds a well-defined threshold. In this new work, it has been found that intraarterial and intravenous injections can be used to introduce the emulsion into the blood stream for subsequent ADV (B- and M-mode on a clinical scanner) in situ. Intravenous administration results in a lower gas bubble yield, possibly because of filtering in the lung, dilution in the blood volume, or other circulatory effects. Results show that for occlusion purposes, a reduction in regional blood flow of 34% can be achieved. Individual point beacons with a +24 dB backscatter amplitude relative to white matter were created by intravenous injection and ADV.

Acute cerebral gas embolism from hydrogen peroxide ingestion successfully treated with hyperbaric oxygen

CASE REPORT

We present a case of an adult who suffered an apparent stroke shortly after an accidental ingestion of concentrated hydrogen peroxide. Complete neurologic recovery occurred quickly with hyperbaric therapy. Hydrogen peroxide can produce acute gas embolism. Hyperbaric therapy is the definitive treatment for gas embolism from hydrogen peroxide ingestion as it is for all other causes of acute gas embolism. This is the first case reported in the literature of hyperbaric therapy used successfully to treat cerebral gas embolism caused by hydrogen peroxide.