Vascular air embolism after contrast administration on 64 row multiple detector computed tomography: A prospective analysis

Venous air emboli during esophagoscopy confirmed by computed tomographic pulmonary angiography -a case report

BACKGROUND

Esophagogastroduodenoscopy (EGD) is vital for the diagnosis and treatment of various gastrointestinal conditions but carries a low risk of venous air embolism (VAE). We report a case of VAE during EGD, confirmed by computed tomographic pulmonary angiography (CTPA).

CASE

A 56-year-old male with a history of hypopharyngeal cancer underwent EGD for dysphagia-related esophageal dilation. Signs of VAE were noted, prompting swift interventions, including oxygen therapy, positional changes, and CTPA. CTPA revealed the Mercedes-Benz sign, pneumomediastinum, and a minimal pneumothorax. The patient's oxygen saturation improved within 30 min before undergoing CTPA, and he was discharged on postoperative day 4.

CONCLUSIONS

Timely recognition of VAE, resulting in appropriate interventions supported by CTPA, resulted in favorable patient outcomes.

Reduction of venous air embolism in coronary computed tomography angiography using a modified method of saline test injection

OBJECTIVES

This paper analyzed the feasibility of reducing venous air emboli introduced during tube connection in computed tomography angiography (CTA) through a modified method of saline test injection.

METHODS

A total of 386 cases of patients undergoing coronary CTA examination were randomly arranged into a control group (199 patients underwent conventional saline injection before the CTA examination) and a case group (187 patients underwent modified saline injection before the CTA examination). The two groups were compared for the location (Fisher's exact test), number (χ² test), and diameter (Mann-Whitney rank sum test) of the air emboli along the inflow direction of contrast agent within the scan.

RESULTS

The occurrence rate was 10.55% in the control group and 3.74% in the case group respectively, with a statistically different significance (P = 0.010). In the case group, there were 7 cases of small-grade venous air emboli. In the control group, there were 15 cases of small-grade venous air emboli and 6 cases of moderate-grade venous air emboli. No cases of large-grade venous air emboli were found in both groups.

CONCLUSIONS

The use of this modified method of saline test injection before CTA examination is able to effectively decrease the occurrence of venous air emboli introduced during tube connection, which has some certain practical significance.

An Unexpected Complication: Obstructive Shock Secondary to Venous Air Embolism

Air embolism is a rare but possibly life-threatening situation. Gas embolism can be arterial, occurring as a complication of a lung biopsy, arterial catheterization, or extracorporeal circulation in the context of cardiopulmonary bypass, or venous, as in cases of venous catheter manipulation (especially with a central venous catheter in a spontaneously breathing patient), pressurized venous infusions, or in a neurosurgical context. Various clinical manifestations are described in the literature, ranging from asymptomatic cases to obstructive shock. Clinical manifestations may include chest pain, dyspnea, nausea and vomiting, altered consciousness, focal neurological deficits, seizures, vertigo, and amaurosis. Physical examination findings may include hypotension and “mill wheel murmur” on chest auscultation. Early diagnosis and treatment are essential to improve the outcome of these patients. Approach and management include placing the patient in the left lateral decubitus and/or Trendelenburg position and on high-flow oxygen. Hyperbaric oxygen therapy is the definitive treatment for arterial gas embolism, which may reduce air emboli size, improve tissue oxygenation, and reduce ischemic lesion. Here, we report the case of a 62-year-old female patient with obesity, hypertension, dyslipidemia, and recovering from coronavirus disease 2019 (COVID-19) with obstructive shock due to venous gas embolism.

Venous Air Microembolism in Chest CT Angiography: Evidence of Normalization of Deviance Phenomenon

Purpose  This article provides evidence that detection of venous air microbubbles (VAMB) in chest computed tomography angiography (CTA) can be an indicator for “normalization of deviance” phenomenon in CT.

Method and Materials  Institutional review board-approved retrospective study, with waiver for informed consent. Contrast-enhanced chest CT performed during 6 months were reviewed for presence of VAMB in venous segments visible in chest CT (subclavian, brachiocephalic vein, superior vena cava) and cardiac chambers. VAMB volumes were quantified through a semiautomatic method (MIAlite plugin for OsiriX), using a region of interest (ROI) covering the bubble. With basal results, protocols for correct injection technique were reinforced, and VAMB were estimated again at 1 and 3 months. Six months later, questionnaires were sent to the CT technologists to inquire about their perception of VAMB. Descriptive measures with central distribution and dispersion were performed; statistical significance was considered at p  < 0.05.

Results  A total of 602 chest CTA were analyzed, 332 were women (55.14%), with a median age of 58 (interquartile range [IQR] 44–72) years. Among those, 16.11% (100 cases) presented VAMB. Most were emergency department patients (51.6%), male (50.3%), with a median age of 54 (IQR 26) years. There was no difference on detection of VAMB regarding sex ( p  = 0.19), age ( p  = 0.46), or referral diagnosis ( p  = 0.35). Mean air bubbles volume was 0.2 mL (range 0.01–3.4 mL). After intervention, the number of exams with VAMB dropped to 3.29 % (3/91) ( p  < 0.001). On the 6-month query, 50% of the technicians still considered that VMAB is inevitable, and 60% thought that the occurrence is not associated to risk, and therefore, not actionable.

Conclusion  VAMB are a frequent finding in chest CTA, and being independent from patient-related variables, it is likely due to technical issues such as intravenous access manipulation during the exam. Reduction after reinforcement of proper performance, and certification of a low concern from CT technicians for any risk associated, provides evidence that there is normalization of deviance in this everyday procedure.

Venous air embolism in CT coronary angiography

INTRODUCTION

Venous air embolization (VAE) from IV lines is a risk with IV contrast administration. The incidence of VAE ranges from 7% to 23%. While life-threatening VAE is rare, there is the potential risk of serious cerebrovascular events from paradoxical systemic air embolization (SAE) in patients with congenital intracardiac shunts. CT coronary angiogram (CTCA) hypothetically carries a higher risk of VAE as it requires dual injections as compared to single bolus dose contrast used in CT chest (CTC). The aim of this study was to assess the risk of VAE using CTCA as compared to conventional CTC. The incidence of cardiac shunts and their association with paradoxical SAE were also investigated.

METHODS

A retrospective study was conducted at a tertiary hospital. Adult patients undergoing CTCA and CTC over a 6-month period in 2017 were included. Images were reviewed on PACS for the presence of VAE. Electronic medical records were interrogated for evidence of neurological sequelae or requiring neurological imaging (CTB/MRIB) within 1 month of the initial imaging.

RESULTS

508 patients were included, 408 underwent CTCA and 100 underwent CTC. The VAE incidence in CTCA was 24% (94 patients) and 10% in the CTC (10 patients). This was statistically significant. Among the CTCA group, 36% (108 patients) had an intracardiac shunt. No statistically significant difference in VAE incidence was identified in CTCA patients with shunts vs without shunts. There was no incidence of SAE in both groups.

CONCLUSION

VAE is more common with CTCA than conventional CTC. There were no cases of paradoxical SAE found.

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.

Pulmonary Air embolism Associated with Pneumocephalus: A Case Report

Iatrogenic air embolism is associated with significant morbidity and mortality. Retrograde cerebral venous air embolism is most frequently associated with manipulation of venous access most commonly from central venous catheters. The ascension of air to the cerebral circulation is possibly due to the low specific gravity of air compared to blood and the performance of procedures in the sitting position. Increased right ventricular pressures in the setting of pulmonary thromboembolism may also contribute to the retrograde flow of air. We present the case of a 61-year-old woman who developed a massive pulmonary embolism and pneumocephalus, which was evident during contrast enhanced CT pulmonary angiography. Neurological deficits were not apparent and air resorption occurred after 48 hours of high flow oxygen therapy.

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.

Multiple asymptomatic vascular air embolisms following contrast-enhanced CT scan

Vascular air embolism (VAE) is a known complication of contrast-enhanced CT (CECT) scan occurring in venous or arterial circulation with a wide spectrum of presentations. We report a case of a 44-year-old woman with endometrial adenocarcinoma stage IVB complicated with liver abscess and pulmonary embolism who developed VAE following a routine CECT scan after the sixth cycle of chemotherapy. This was an incidental finding and the patient remained asymptomatic throughout. As such, she was treated conservatively and gradually recovered. This case report serves as a reminder that VAE should be considered in patients presenting with unexplained symptoms following this procedure.

Air embolism: diagnosis and management

Air embolism is an uncommon, but potentially life-threatening event for which prompt diagnosis and management can result in significantly improved patient outcomes. Most air emboli are iatrogenic. Arterial air emboli may occur as a complication from lung biopsy, arterial catheterization or cardiopulmonary bypass. Immediate management includes placing the patient on high-flow oxygen and in the right lateral decubitus position. Venous air emboli may occur during pressurized venous infusions, or catheter manipulation. Immediate management includes placement of the patient on high-flow oxygen and in the left lateral decubitus and/or Trendelenburg position. Hyperbaric oxygen therapy is the definitive treatment which may decrease the size of air emboli by facilitating gas reabsorption, while also improving tissue oxygenation and reducing ischemic reperfusion injury.

Iatrogenic peripheral pulmonary air embolism following intravenous contrast administration for CT pulmonary angiography: proposal of the “double bronchus sign”

We present a case of iatrogenic extensive air embolism in the peripheral pulmonary arterial tree following intravenous contrast injection for a CT pulmonary angiogram performed to investigate chest pain in a 25-year-old female patient. Small volumes of iatrogenic air embolism following contrast injection are not infrequently encountered incidentally in the central vasculature (brachiocephalic veins, superior vena cava, right cardiac chambers and main pulmonary arteries). To our knowledge, however, this is the only case of extensive peripheral pulmonary arterial air embolism on CT that has been reported in the literature. Despite the extent of peripheral air, this potentially clinically significant complication was relatively inconspicuous at CT interpretation. A new radiological sign, the “double bronchus sign”, is proposed as a useful diagnostic tool. In addition to discussing the imaging features, important safety considerations and principles of immediate management, relevant to all radiologists, are addressed.