Cerebral air embolism occurring at angiography and diagnosed by computerized tomography. Case report

Cerebral arterial gas embolism from attempted mechanical thrombectomy: recovery following hyperbaric oxygen therapy

Cerebral arterial gas embolism is a recognised complication of endovascular intervention with an estimated incidence of 0.08%. Its diagnosis is predominantly clinical, supported by neuroimaging. The treatment relies on alleviating mechanical obstruction and reversing the proinflammatory processes that contribute to tissue ischaemia. Hyperbaric oxygen therapy is an effective treatment and has multiple mechanisms to reverse the pathological processes involved in cerebral arterial gas embolism. Symptomatic cerebral arterial gas embolism is a rare complication of endovascular intervention for acute ischaemic stroke. Although there are no previous descriptions of its successful treatment with hyperbaric oxygen therapy following mechanical thrombectomy, this is likely to become more common as mechanical thrombectomy is increasingly used worldwide to treat acute ischaemic stroke.

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.

Symptomatic Cerebral Air Embolism During Stent-assisted Coiling of an Unruptured Middle Cerebral Artery Aneurysm: Intraoperative Diagnosis and Management of a Rare Complication

Symptomatic cerebral air embolism during cerebral angiography is extremely rare. We report on the case of a 69-year-old woman undergoing elective stent-assisted coiling of an unruptured right middle cerebral artery (MCA) bifurcation aneurysm, who was found to have severe attenuation of somatosensory evoked potential (SSEP) and electroencephalography (EEG) during the procedure. Intra-operative DynaCT showed hypodense cortical vessels consistent with cerebral air embolism. Diagnostic and management strategies for this rare complication are reviewed.

Suspected cerebral arterial gas embolism during a laparoscopic Nissen fundoplication

We present the first case report known to us of a suspected cerebral arterial gas embolism (CAGE) leading to transient left-sided hemiparesis after a laparoscopic Nissen fundoplication. During the operation there was no evidence of hemodynamic compromise and the end-tidal carbon dioxide level and oxygen saturation had been within normal limits. Radiological studies and transesophageal echocardiography showed no abnormalities. We conclude that CAGE can occur during uncomplicated laparoscopic surgery even in the absence of demonstrable intracardiac shunts.

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.

Symptomatic cerebral air embolism during neuro-angiographic procedures: incidence and problem avoidance

BACKGROUND

While clinically symptomatic cerebral air embolism secondary to neuro-angiographic procedures is rare, the incidence in a large series of procedures is unknown. Understanding this complication's frequency and etiology is critical if systems are to be instituted to reduce its incidence.

METHODS

We prospectively reviewed 4,568 consecutive neuro-angiographic procedures performed between June 2000 and July 2005. The occurrence and etiology of a symptomatic air embolus was noted, and an incidence was calculated for all procedures and for diagnostic arteriograms and interventional procedures individually.

RESULTS

Four symptomatic cerebral arterial air emboli occurred in 4,568 neuro-angiographic procedures over the five-year period (0.08%). No events occurred in 3,150 diagnostic angiograms while four occurred during 1,418 interventional procedures (0.2%). Two cases occurred during aneurysm coiling embolization (2/548; 0.4%); one case occurred during a carotid stent placement (1/138; 0.7%); one occurred during an internal carotid artery balloon occlusion test (1/73; 1.3%). Three of these complications resulted in permanent neurologic deficits while one resulted in a transient neurologic change that cleared within 60 min of onset. Sources for the emboli included the pressurized arterial flush lines connected to internal carotid artery catheters (three cases) and sudden hypotension with air subsequently entering the internal carotid artery catheter (one case). Two patients were treated with hyperbaric oxygen therapy.

CONCLUSION

Symptomatic cerebral air embolism is a rare event during neuro-angiographic procedures. Analysis of the etiologies of this infrequent event may permit us to further reduce its incidence.

Positive End-expiratory Pressure Reduces Pneumocephalus in Spinal Intradural Tumor Surgery

We tested the hypothesis that 5 cm H2O of positive end-expiratory pressure (PEEP) reduces the incidence of pneumocephalus in patients who undergo spinal intradural tumor surgery. Fifty-three ASA I to III patients who underwent thoracolumbar intradural tumor surgery between the years 2003 and 2006 were included in this study. All patients received propofol, fentanyl, and cisatracurium for induction of the anesthesia. Maintenance was provided by propofol infusion and, oxygen (50%) and air (50%). Group I (n=28) did not receive PEEP whereas group II (n=25) received PEEP as 5 cm H2O. Cranial computerized tomography was taken at 8 hours after the surgery and cases were evaluated for pneumocephalus using BAB Bs200ProP Image System software. Pneumocephalus areas between 0.03 and 4.24 cm2 were observed in 9 patients, 8 in group I and 1 patient in group II at the 8th postoperative hour, at various localizations. There were no neurologic findings in other patients except for 2 patients in group I who presented with headache and mental status change. Although the cerebrospinal fluid leakage is minimal, N2O is not used and the patients are well hydrated, pneumocephalus with neurologic deficits may occur in patients undergoing microsurgical spinal intradural tumor surgery in prone position. In our study, we showed that using 5 cm H2O PEEP perioperatively reduced the risk of pneumocephalus. However, more cases must be studied to support this hypothesis.

Hyperbaric treatment of cerebral air embolism in an infant with cyanotic congenital heart disease

PURPOSE

Infants with cyanotic congenital heart disease are at risk for cerebral arterial gas embolism (CAGE) from iv infusion lines. Concern about the hazards and difficulty of caring for such patients inside a hyperbaric chamber may deter referral. We report a complex case in which a small infant was managed successfully using a modified hyperbaric oxygen treatment (HBOT) schedule.

CLINICAL FEATURES

A four-month-old 6.19 kg male infant with a recent Glenn shunt for double-outlet right ventricle had a seizure and became unstable immediately after an iv drug infusion. The patient was sedated, intubated and ventilated and dobutamine was commenced. A computerized tomography (CT) scan performed ten hours later demonstrated three intracranial air bubbles. About ten hours later the patient was referred for HBOT which commenced soon afterwards in a multiplace chamber. Since the right-to-left shunt would greatly increase the risk of decompression illness from breathing hyperbaric air HBOT was modified by the use of an abbreviated schedule at reduced pressure. Two 90-min HBOT sessions were administered within 24 hr at 38 feet of sea-water pressure, equivalent to 2.15 atmospheres absolute without any air break. During treatment the infant was ventilated using an Oxford Penlon ventilator. A subsequent CT scan demonstrated the absence of air. After extubation he appeared neurologically intact except for some weakness of the left arm.

CONCLUSION

Hyperbaric oxygen may be utilized to treat CAGE in small infants with right-to-left shunt and should be commenced promptly.

Heparin and air filters reduce embolic events caused by intra-arterial cerebral angiography: a prospective, randomized trial

BACKGROUND

Intra-arterial cerebral angiography is associated with a low risk for neurological complications, but clinically silent ischemic events after angiography have been seen in a substantial number of patients.

METHODS AND RESULTS

In a prospective study, diffusion-weighted magnetic resonance imaging (DW-MRI) before and after intra-arterial cerebral angiography and transcranial Doppler sonography during angiography were used to evaluate the frequency of cerebral embolism. One hundred fifty diagnostic cerebral angiographies were randomized into 50 procedures, each using conventional angiographic technique, or systemic heparin treatment throughout the procedure, or air filters between the catheter and both the contrast medium syringe and the catheter flushing. There was no neurological complication during or after angiography. Overall, DW-MRI revealed 26 new ischemic lesions in 17 patients (11%). In the control group, 11 patients showed a total of 18 lesions. In the heparin group, 3 patients showed a total of 4 lesions. In the air filter group, 3 patients exhibited a total of 4 lesions. The reduced incidence of ischemic events in the heparin and air filter groups compared with the control group was significantly different (P=0.002). Transcranial Doppler sonography demonstrated a large number of microembolic signals that was significantly lower in the air filter group compared with the heparin and control groups (P<0.01), which did not differ from each other.

CONCLUSIONS

Air filters and heparin both reduce the incidence of silent ischemic events detected by DW-MRI after intra-arterial cerebral angiography and can potentially lower clinically overt ischemic complications. This may apply to any intra-arterial angiographic procedure.

Cerebral and coronary air embolism: an intradepartmental suicide attempt

Uncooperative but alert on arrival, a 21-year-old suicidal man was found suddenly unconscious with agonal respirations 2 h into his Emergency Department evaluation. Initially admitted for ingesting multiple pills and self-inflicting a deep wrist laceration, the patient now had a Glasgow Coma Scale score of 3, a dense left-sided hemiplegia, and an electrocardiogram suggestive of acute myocardial infarction. This constellation of physical findings, together with an echocardiogram revealing bi-ventricular gas artifact, led to a diagnosis of coronary and cerebral air emboli. The patient was urgently resuscitated and then underwent hyperbaric oxygen therapy. Subsequent examination confirmed a full recovery. This article details this unprecedented case, as well as clinically relevant aspects of air embolism.

Cerebral air emboli from angiography in a patient with stroke. A case report

A 42-year-old woman with subarachnoid and intracerebral hemorrhage was investigated with diagnostic angiography, disclosing an occlusion of the left internal carotid artery and the middle cerebral artery. CT examination immediately after the angiography revealed a 12-h-old infarct of the left middle cerebral artery territory. There was also gas in the arteries supplying the infarcted part of the brain, but not in other vessels. Air had most probably been introduced during the angiography and had consequently been "trapped" in the cortical arteries of the ischemic brain. In the non-ischemic parts of the brain air may have passed through the vessels leaving no trace.

Neurologic manifestations of cerebral air embolism as a complication of central venous catheterization

OBJECTIVE, PATIENTS, AND METHODS: A severe case of cerebral air embolism after unintentional central venous catheter disconnection was the impetus for a systematic literature review (1975-1998) of the clinical features of 26 patients (including our patient) with cerebral air embolism resulting from central venous catheter complications.

RESULTS

The jugular vein had been punctured in eight patients and the subclavian vein, in 12 patients. Embolism occurred in four patients during insertion, in 14 patients during unintentional disconnection, and in eight patients after removal and other procedures. The total mortality rate was 23%. Two types of neurologic manifestations may be distinguished: group A (n = 14) presented with encephalopathic features leading to a high mortality rate (36%); and group B (n = 12) presented with focal cerebral lesions resulting in hemiparesis or hemianopia affecting mostly the right hemisphere, with a mortality rate as high as 8%. In 75% of patients, an early computed tomography indicated air bubbles, proving cerebral air embolism. Hyperbaric oxygen therapy was performed in only three patients (12%). A cardiac defect, such as a patent foramen ovale was considered the route of right to left shunting in 6 of 15 patients (40%). More often, a pulmonary shunt was assumed (9 of 15 patients; 60%). For the remainder, data were not available.

CONCLUSION

When caring for critically ill patients needing central venous catheterization, nursing staff and physicians should be aware of this potentially lethal complication.

Horseradish peroxidase as a histological indicator of mechanisms of porcine retinal vascular damage and protection with perfluorocarbons after massive air embolism

BACKGROUND AND PURPOSE

This laboratory has previously shown that a second-generation perfluorocarbon emulsion (PFE) reduces the severity of cerebral injury induced by air embolism during cardiopulmonary bypass (CPB). Horseradish peroxidase examines vascular permeability and was used in this study of the mechanisms of cellular protection afforded by the PFE.

METHODS

Twenty domestic pigs underwent CPB with a prime of standard crystalloid or PFE (5 mg/kg) and crystalloid. After 10 minutes on CPB, a 5-mL/kg bolus of room air or saline (control) was delivered via the right carotid artery. The air insult was delivered as either a single bolus or double bolus. After 1 hour of CPB and 1 hour of spontaneous reperfusion, horseradish peroxidase was injected intravenously and circulated for 15 minutes. After euthanasia, both eyes were removed, and the retinas were isolated for histological analysis.

RESULTS

Total length of retinal vessels exhibiting horseradish peroxidase extravasation was significantly less in PFE pigs (P < .05). Vascular spasm and red blood cell hemorrhages were unaffected by PFE. PFE pigs exhibited mild to moderate vascular nonperfusion and red blood cell sludging; crystalloid groups demonstrated severe nonperfusion and sludging.

CONCLUSIONS

Histological staining with horseradish peroxidase indicated that mechanisms of cerebral air embolism include vascular endothelial leakage, vascular nonperfusion, and red blood cell sludging and hemorrhage. Pretreatment with PFE prevented some sequelae associated with massive air embolism and CPB.

Recommendations for hyperbaric oxygen therapy of cerebral air embolism based on a mathematical model of bubble absorption

Transcranial doppler studies show that microscopic cerebral artery air emboli (CAAE) are present in virtually all patients undergoing cardiac surgery. Massive cerebral arterial air embolism is rare. If it occurs, hyperbaric oxygen therapy (HBO) is recommended as soon as surgery is completed. We used a mathematical model to predict the absorption time of CAAE, assuming that the volumes of clinically relevant CAAE vary from 10(-7) to at least 10(-1) mL. Absorption times are predicted to be at least 40 h during oxygenation using breathing gas mixtures of fraction of inspired oxygen approximately equal to 40%. When CAAE are large enough to be detected by computerized tomography, absorption times are calculated to be at least 15 h. Decreases in cerebral blood flow caused by the CAAE would make the absorption even slower. Our analysis suggests that if the diagnosis of massive CAAE is suspected, computerized tomography should be performed, and consideration should be given to HBO therapy if the CAAE are large enough to be visualized, even if patient transfer to a HBO facility will require several hours.

Gas Embolism: Part II. Arterial Gas Embolism and Decompression Sickness

Gas emboli syndromes are known to occur in many different settings, and they may result in life-threatening emergencies. Venous gas embolization was discussed previously in Part I of this review. Gas emboli that gain access to the arterial circulation or that result from exposures to decreased ambient pressures in the environment are discussed in Part II. The prevalence of arterial gas emboli and decompression sickness are likely not as high as for venous gas emboli. Most cases are preventable, and prompt treatment is frequently effective. Once present, gas bubbles generally distribute themselves throughout the body based on the relative blood flow at the time, thus making the nervous system, heart, lung, and skin the primary organ systems involved. Both mechanical and biophysical effects lead to intravascular and extracellular alterations that result in tissue injury. The clinical manifestations of these disorders are varied, and a high index of suspicion in the appropriate settings will aid health care providers in prompt recognition of these problems and allow timely intervention with specific therapy. Management of arterial gas emboli and decompression sickness is similar, with a focus on hyberbaric chamber therapy and intermittent hyperoxygenation. Recompression schedules in current use have withstood the test of time. Research continues to refine our understanding of these diseases and to optimize the treatment regimens available.

Kinetics of elimination and acute consequences of cerebral air embolism

The pathophysiology of arterial air embolism inducing brain injuries remains unclear. Previous experiments demonstrated the usefulness of computed tomography (CT) in the detection of air emboli in canine brain. This canine study investigates CT's ability to detect small air bubbles and to determine the kinetics of air elimination from cerebral arteries and its relationship with clinical, electroencephalographic (EEG), and histological manifestations. CT detects small air embolism, and intracerebral air volume strongly correlates with injected air dose (r2 = 0.86, p = 2 x 10(-3)). Air clearance time significantly depends on intracerebral air volume (r2 = 0.86, p = 0.04) and on the number of bubbles (r2 = 0.71, p = 0.03), whereas half-life of air elimination does not. No relationship was found between injected air dose, air clearance time, intracerebral volume of air, and clinical, EEG, and histological findings. The data indicate that CT accurately detects small air bubbles in the early course of cerebral air embolism, that air elimination from cerebral arteries follows a first-order compartment model, and that early CT findings do not correlate with clinical, EEG, and histological manifestations.

Massive cerebral air embolism following cardiopulmonary resuscitation. Report of two cases

Cerebral air embolism can occur in a number of situations. We report two cases of massive cerebral arterial air embolism following cardiopulmonary resuscitation, and its mechanism is discussed.

A case of intracerebral air embolism secondary to the insertion of a Hickman line

Complications following the insertion of intravenous catheters are relatively uncommon. We report a potentially serious, hitherto unrecognized complication of Hickman line insertion, and discuss the condition.

CT diagnosis of delayed cerebral air embolism following intraaortic balloon pump catheter insertion

Air embolism to the brain occurred several days after insertion of an intraaortic balloon pump. CT demonstrated diffuse hemispheric edema along with two small collections of air in the cerebral hemispheres. Early diagnosis of air embolism to the brain allows early institution of proper therapy in this life-threatening condition.