Paradoxical air embolism following contrast material injection through power injectors in patients with a patent foramen ovale

Embolic Events After Computed Tomography Contrast Injection in Patients With Interatrial Shunts: A Cohort Study

BACKGROUND

Patients with interatrial shunts (patient foramen ovale/atrial septal defect) are potentially at increased risk for paradoxical air embolism following computed tomography (CT) scans with intravenous (IV) contrast media injection. IV in-line filters aim to prevent such embolisms but are not compatible with power injection required for diagnostic CT.

PURPOSE

The purpose of this study was to determine whether the incidence of paradoxical embolism to the heart and brain in patients with an interatrial shunt is higher compared with controls within 48 hours following injection of IV contrast media without IV in-line filter.

METHODS

This is a retrospective cohort study conducted at a large tertiary academic center, which included a total of 2929 consecutive patients who underwent 8983 CT scans with IV contrast media injection between July 1, 2000 and April 30, 2018. Diagnosis of an interatrial shunt was confirmed by transthoracic or transesophageal echocardiography. Incidence and risk of cardiac embolic events (new troponin elevation, >0.1 ng/mL) and neurological embolic events (new diagnosis of stroke/transient ischemic attacks) were evaluated.

RESULTS

Among the 2929 patients analyzed (mean±SD age, 61±14 y), 475/2929 (16.2%) patients had an interatrial shunt. After applying the exclusion criteria, new elevated troponin was found in 8/329 (2.4%; 95% confidence interval [CI]: 1.1-4.7) patients with an interatrial shunt compared with 25/1687 (1.5%; 95% CI: 0.9-2.2) patients without an interatrial shunt. New diagnosis of stroke occurred in 2/169 (1%; 95% CI: 0.3-4.2) of patients with an interatrial shunt compared with 7/870 (0.8%; 95% CI: 0.4-1.7) without interatrial shunt.

CONCLUSION

Among patients with echocardiographic evidence of an interatrial shunt, IV CT contrast administration without an in-line filter does not increase the incidence of cardiac or neurological events.

Proactive Air Management in CT Power Injections: A Comprehensive Approach to Reducing Air Embolization

OBJECTIVE

Venous air embolism as a complication of contrast media administration from power injection systems in CT is found to occur in 7%-55% of patients, impacting patient safety, diagnostic image quality, workflow efficiency, and patient and radiographer satisfaction. This study reviews the challenges associated with reactive air management approaches employed on contemporary systems, proposes a novel air management approach using proactive methods, and compares the impact of reactive and proactive approaches on injected air volumes under simulated clinical use.

METHODS

Injected air volumes from three power injection systems were measured under simulated clinical use via custom air trap fixture. Two of the systems employed reactive air management approaches, while a new system implemented the proposed proactive air management approach.

RESULTS

The proactive system injected significantly less air (average of 0.005 mL ± 0.006 mL with a maximum of 0.017 mL) when compared to two systems with reactive approaches (averages of 0.130 mL ± 0.082 mL and 0.106 mL ± 0.094 mL with maximums of 0.259 mL and 0.311 mL, respectively) (p < 0.05). CT images were taken of static and dynamic 0.1 mL air bubbles inside of a vascular phantom, both of which were clearly visible. Additionally, the dynamic bubble was shown to introduce image artifacts similar to those observed clinically.

CONCLUSION

Comparison of the injected air volumes show that a system with a proactive air management approach injected significantly less air compared to tested systems employing reactive approaches.

SIGNIFICANCE

The results indicate that the use of a proactive approach could significantly reduce the prevalence of observable, and potentially artifact-inducing, venous air embolism in contrast-enhanced CT procedures.

Reducing the incidence of venous air embolism in contrast-enhanced CT angiography using preflushing of the power injector

AIM

To evaluate whether preflushing before connecting a power injector to a patient's catheter reduces the incidence of venous air embolism (VAE) in contrast-enhanced computed tomography (CT) angiography (CTA).

MATERIALS AND METHODS

With the approval from the local ethics committee, consecutive patients were divided randomly into a control group and a preflushing group and underwent CTA from June to November 2017. The control group underwent the conventional injection procedure. In the preflushing group, the injector tubes were flushed at high speed (10 ml/s) with saline before being connected to the patients' indwelling catheters. The locations, number, and sizes of VAE were analysed. The difference in the incidence of VAE between the two groups was compared.

RESULTS

A total of 4,900 adults (control/preflushing, 2,190/2,710) were included and 228 (4.65%) patients were found to have 318 VAEs (285 bubbles and 33 gas-liquid plane VAEs). The incidence of VAE in the preflushing group (3.21%) was lower than that in the control group (6.44%); a similar trend was observed for multiple VAEs (p<0.05). VAEs occurred in the following locations from high to low frequency: right atrium>pulmonary artery trunk>superior vena cava>right ventricle>left brachial vein>right brachial vein. There was no significant difference in the location, shape, or diameters (p=0.19) of VAEs between the two groups.

CONCLUSIONS

The proposed preflushing procedure is simple yet effective in reducing the incidence of VAE by 50.16% in patients with CTA, thus improving safety during power injection.

Association of the incidence of venous air embolism on coronary computed tomography angiography with the intravenous access route preparation process

Venous air embolism (VAE) can be observed in the right heart system on contrast-enhanced computed tomography (CT), following injection of contrast media with a power injector system. Although most VAEs are mostly asymptomatic, they may result in paradoxical air embolism (PAE).To evaluate whether the incidence of VAE on coronary CT angiography is associated with the process of preparation of the intravenous access route.We retrospectively evaluated 692 coronary CT examinations at 3 institutions. Trained CT nurses placed an intravenous cannula in the forearm. Tubes connected to the cannula were prepared in the following ways: A, using an interposed three-way cock and a 20-mL syringe filled with normal saline to collect air contamination in the tube; B, through direct connection to the power injector system without the interposed 3-way cock; and C, using an interposed three-way cock and a 100-mL normal saline drip infusion bottle system to keep the tube patent. The incidence and location of VAE and preparation of intravenous injection were assessed.The overall incidence of VAE was 55.3% (383/692), most frequently observed in the right atrium (81.5%, 312/383). Its incidence varied significantly across the 3 techniques (A: 21.6% (35/162), B: 63.2% (237/375) and C: 71.6% (111/155); P < .001). No patient demonstrated any symptom associated with VAE.Using a 3-way cock with syringe demonstrated the lowest incidence of VAE on coronary CT angiography. It is thus recommended to reduce potential complication risks related to intravenous contrast media injection.

A case of iatrogenic air bubbles in the left ventricle by coronary computed tomographic angiography

We report a case of asymptomatic iatrogenic air bubbles in the left ventricle observed by coronary computed tomographic angiography. Air bubbles are rarely found in the left ventricle and could prove fatal should they migrate to the brain or coronary arteries. We believe that the cause is micro air bubbles in the tubing system between the intravenous catheter and power injector.

Vascular air embolism: A silent hazard to patient safety

PURPOSE

To narratively review published information on prevention, detection, pathophysiology, and appropriate treatment of vascular air embolism (VAE).

MATERIALS AND METHODS

MEDLINE, SCOPUS, Cochrane Central Register and Google Scholar databases were searched for data published through October 2016. The Manufacturer and User Facility Device Experience (MAUDE) database was queried for "air embolism" reports (years 2011-2016).

RESULTS

VAE may be introduced through disruption in the integrity of the venous circulation that occurs during insertion, maintenance, or removal of intravenous or central venous catheters. VAE impacts pulmonary circulation, respiratory and cardiac function, systemic inflammation and coagulation, often with serious or fatal consequences. When VAE enters arterial circulation, air emboli affect cerebral blood flow and the central nervous system. New medical devices remove air from intravenous infusions. Early recognition and treatment reduce the clinical sequelae of VAE. An organized team approach to treatment including clinical simulation can facilitate preparedness for VAE. The MAUDE database included 416 injuries and 95 fatalities from VAE. Data from the American Society of Anesthesiologists Closed Claims Project showed 100% of claims for VAE resulted in a median payment of $325,000.

CONCLUSIONS

VAE is an important and underappreciated complication of surgery, anesthesia and medical procedures.