Abstract
Following an uncomplicated CT-guided transthoracic biopsy, a patient becomes unconscious and subsequently dies despite immediate cardiac resuscitation. The patient felt well during the procedure but started complaining about dizziness and chest pain when he sat up. When he again was put in a supine position, cardiac arrest was noted. A CT scan performed when the symptoms initiated was afterwards rigorously reviewed by the team and revealed air located in the left ventricle, aorta and right coronary artery.
We present a rare but potentially lethal complication following CT-guided transthoracic needle biopsy—systemic vascular air embolus. Knowledge and evidence about the complication are sparse because of low incidence and varying presentation. However, immediate initiation of treatment can save a life, and awareness of the complication is therefore crucial.
Keywords: cancer intervention, radiology (diagnostics), lung cancer (oncology)
Background
Computed Tomography (CT)-guided transthoracic needle biopsy is a leading part of the diagnostic workup of pulmonary nodules not possible to reach using endobronchial procedures.
Because of the increased focus, debate and presumably implementation of lung cancer screening programmes, we expect to identify even more pulmonary nodules that need to be assessed to rule in or rule out malignancy.1
Non-interventional methods for risk-stratification of patients with a positive screening finding are being explored, for example, the value blood or breath biomarkers; however, until solid evidence is presented, endoscopic or CT-guided transthoracic needle biopsies are needed. An increased number of procedures also lead to an increasing number of complications.2
The overall complication rates vary depending on whether core needle or fine-needle technique is used (38.8% (95% CI 34.3% to 43.5%) and 24.0% (95% CI 18.2% to 30.8%), respectively).3
The most frequent complications following CT-guided transthoracic needle biopsy are pneumothorax and pulmonary haemorrhage where a majority of these do not require intervention or treatment.3 4 Another rare but significant complication is systemic vascular air embolism. The reported incidence is 0.02%–0.07% but, maybe due to the low incidence, very few studies explore and investigate the true incidence.5 6 Although often self-limiting, systemic vascular air embolism can entail severe and even fatal complications if the air embolus reaches the coronary or cerebral arteries.
We report a case of a fatal systemic air embolus following a CT-guided transthoracic needle biopsy and discuss the strategies for the management and treatment of these patients.
Case presentation
An 80-year-old man was seen every sixth month in the pulmonology department due to three spiculated nodules in the lungs discovered 2 years ago. The nodules were located in the right upper lobe (5 mm), right lower lobe (8 mm) and left lower lobe (10 mm) (figure 1). During the follow-up period so far, the nodules had not changed in size, appearance or character. The measurements and follow-up strategy were based on CT scans and there was not found any additional or suspicious masses or enlarged lymph nodes.
Figure 1.
CT scan showing the three nodules in the right upper lobe, right lower lobe and left lower lobe (prior to growth).
The patient suffered from mild to moderate Chronic obstructive pulmonary disease (COPD), which was well treated with no exacerbations in the last 2 years. At the time of referral, spirometry showed Forced expiratory volume in 1 second (FEV1) =2.23 L (73%), Forced vital capacity (FVC) =3.42 L (84%), entailing an index of 65%, and the patient did not present any new or worsened respiratory symptoms. The patient also had a history of hypertension and atrial fibrillation and was a previous smoker but stopped 30 years ago (approximately 40 pack-years).
At the time of referral, the most recent thoracic CT scan revealed that the nodule in the left lower lobe has grown to 30 mm and newly developed left-sided pleural effusion appeared (figure 2).
Figure 2.
CT scan of the nodule in the left lower lobe; at the time of referral, the nodule size was 30 mm.
Investigations
Previously, malignancy was not suspected but due to the growth of the nodules and spiculated format, a Positron Emission Tomography (PET)-CT was done revealing increased Fluorodeoxyglucose (FDG) uptake in 10 of the 30 mm in the nodules located in the left lower lobe (figure 3).
Figure 3.
Positron Emission Tomography (PET)-CT shows increased Fluorodeoxyglucose (FDG) uptake in the nodule; the area is approximately 10 mm.
The patient and patient’s family were informed about the findings and it was decided to perform a CT-guided transthoracic needle biopsy to explore if the growing nodule in the left lower lobe was malignant.
At the beginning of the procedure, the patient was placed in an oblique prone position in the CT scanner. Local anaesthesia was injected, and a core needle was used to biopsy the most cranial part of the nodule corresponding to the area with increased FDG uptake on PET-CT.
After the first biopsy, a small asymptomatic pneumothorax was identified. The patient had no symptoms, it was therefore decided not to intervene and additionally two biopsies were performed. The patient described minor chest pain at the end of the procedure but was otherwise feeling well and the procedure was terminated as standard.
The patient sat up afterwards but started to complain about pain in the left arm and left side of the thorax. Subsequently, he sensed increasing dizziness and tingling in the arm. At that time, the blood pressure was 117/89, heart frequency was 59 times per minute and saturation was 89%.
The radiological staff helped the patient to lay down again because of the increasing dizziness, and the patient then became unconscious. Another CT scan was performed to identify the cause of the patient’s symptoms and subsequently cardiac arrest was noted.
Differential diagnosis
The patient underwent a CT-guided transthoracic needle biopsy, and the radiologist identified a minor pneumothorax after the first biopsy. Because of that, the most obvious differential diagnosis in the acute setting was a larger, symptomatic pneumothorax or tension pneumothorax. Immediately after the patient lost consciousness, he was scanned, and the radiologists inserted a pigtail catheter to relieve the potential symptomatic pneumothorax. Insertion of the catheter did not improve nor change the situation.
The cardiac arrest team, a cardiologist and a pulmonologist were called and arrived within minutes. The patient was treated according to guidelines for cardiac arrest and an echocardiography performed by the cardiologist ruled out cardiac tamponade and pulmonary embolism, which also are two potential and life-threatening differential diagnosis. A cardiothoracic surgeon was also called to put in a larger surgical chest tube if a tension pneumothorax or haemothorax, despite the inserted minor catheter, was identified as a cause of the symptoms and cardiac arrest. However, there was no blood or significant air in the pleural space. All reversible causes were discussed by the group and, unfortunately, the resuscitation was not successful.
The acute CT scan performed when the symptoms began after failed resuscitation was rigorously reviewed. On the scan, air was seen in the left ventricle, aorta and right coronary artery (figure 4).
Figure 4.
The CT scan performed immediately after the patient loses consciousness. The images reveal air in the left ventricle, aorta and right coronary artery.
Treatment
Treatment of a systemic arterial air embolus varies depending on the symptoms of the patient. However, management and initiation of correct handling and treatment require awareness of this rare but potentially life-threatening complication; prompt recognition is, therefore, crucial.7
Immediate supportive therapy consisting of supplemental oxygen therapy, intravenous volume expansion and medical vasopressor therapy are initial cornerstones for unstable and critical patients. Ventilatory support and/or intubation may be necessary if the situation is critical and the patient is not conscious; this is independent of whether a cerebral or cardiac systemic air embolus is suspected or confirmed.
According to the literature, the patient position is diverse depending on whether a venous or arterial air embolus is suspected or confirmed. In case of an arterial air embolus, which may enter through the pulmonary veins, the patient must be placed in right lateral decubitus.8 9 This position would potentially create an airlock in the left ventricle and prevent air from entering the systemic circulation.10
In our case, the patient’s neurological symptoms began when he sat up and worsened, causing unconsciousness when he was placed in a supine position. In a supine position, the aortic valve is the highest point in the left side of the heart and an arterial air embolus could depart the left side of the heart and enter the systemic vascular system. Since the patient lost consciousness at the time of change in position, an air embolus has probably left the heart into the arterial system. This is the hypothesis but can, for good reasons, not be definitely confirmed.
If a venous air embolism is suspected, the patient is to be placed in left lateral decubitus (Durant’s manoeuvre) to trap the air in the left atrium or in Trendelenburg position.11 However, because of the low incidence and the potential critical hyperacute setting, it is not well explored what the actual outcome and benefit are for the potential change in positions.12 13
Hyperbaric oxygen therapy plays a key role in the treatment of systemic vascular air embolism, especially if the patient suffers from neurological deficits.14 Most optimal, the patient should be placed in the hyperbaric chamber within 4–6 hours for the best result.15 16 The treatment is said to decrease the damage in the affected ischaemic tissue and reduce the dimension of the air bubbles in the vessels.8
Discussion
Systemic vascular air embolisms are rare but potentially lethal.14 Arterial, left-sided air embolisms are typically associated with severe decompression sickness during scuba diving, following barotrauma with related ruptured alveoli and a pre-existing cardiac right-to-left shunt, or iatrogenic.
The pathogenesis is complex and well debated, but most explanatory models reasonably conclude that air accesses the pulmonary vessels because of a pressure gradient.17–19 This gradient occurs either due to an increased intrabronchial or alveolar pressure or a decreased endovascular pressure. Several contributing factors are associated with these pressure changes or gradient, for example, needle tip next to or in conjunction with a pulmonary vein, a bronchial-venous fistula or air via the pulmonary capillary system.
The symptoms often occur within seconds to minutes after the air bubble has entered the artery and occluded the blood flow causing minor or major ischaemic organ damage. The symptoms are often catastrophic but vary depending on the location of the affected artery and affected organ, as well as the volume of the air bubble.
Occlusion of cardiac or cerebral arteries often causes more acute and prominent symptoms than in, for example, skin, kidneys or the gastrointestinal tract. Cerebral occlusion is described to cause symptoms like a cerebral stroke, changed mental status, hemiparesis, focal sensory or motoric deficits, seizures and loss of consciousness, whereas cardiac affection, with air entering the coronary arteries, causes arrhythmias, pain in the chest and arms, cardiogenic shock or even sudden cardiac arrest.
Altered mental status, newly emerged respiratory symptoms or affected general condition following a CT-guided transthoracic biopsy should always lead to a clinical evaluation and risk assessment of potential complications. Case reports, a limited number of case series and few retrospective studies have been published describing air embolisms.5 17–27 Despite these independent publications, the empirical evidence on possible risk factors and the effect of treatment are sparse.
Several reasons can explain this lack of evidence regarding systemic arterial air embolisms. Possible causes discussed are the low incidence, the potential hyperacute setting and the variating expression of symptoms; from systemic vascular air as an incidental finding on a control scan to diffuse neurological deficits and immediate cardiac arrest. Some air embolisms are asymptomatic or could present like a vasovagal reaction including short-term and limiting dizziness, sensory disturbance or heart palpitations. The incidence of systemic vascular air embolisms could be much higher and the total number under-reported—because the physicians performing the procedure do not interpret the symptoms of being a systemic vascular air embolism. Freund et al report that air embolisms could retrospectively be discovered in 3.8% of cases undergoing CT-guided transthoracic biopsy even though only 0.5% was reported symptomatic.5
In summary of the case reports, retrospective studies and reviews published, we aimed to merge a list of risk factors (with varying evidence) described to be associated with systemic vascular air embolism17 28:
-
Patient related:
Cough during the procedure.
Prone position.
Grade of emphysema or moderate to severe COPD (Global initiative for chronic Obstructive Lung Disease (GOLD)).29 30
Patient in general anaesthesia during the procedure.
-
Nodule or lesion related:
Nodules in the lower part and lobes of the lungs.
Long distance from skin to the lesion.
Cavitating lesions.
-
Procedure related:
Core needle biopsies (larger biopsy needle).
Parenchymal bleeding during the procedure.
Biopsy through interlobar fissures.
Open needle biopsy system.
Number of needle insertions.
To our knowledge, no controlled studies or series have been published to assign definitive risk factors, and the authors are aware that the evidence for the presented risk factors varies. The 1-year mortality rate is 21%, regardless of the cause of an iatrogenic systemic vascular air embolism,31 and since prompt recognition and management are crucial, physicians performing CT-guided transthoracic biopsies should be aware of these risk factors as well as symptoms.2
In conclusion, systemic vascular air embolisms are rare but can be fatal, such as the case presented in this paper. There is a need for prospective, structured studies to evaluate risk factors and management strategies to reduce death and disabilities as a complication of this diagnostic procedure. It is important to identify risk factors whether they are patient, equipment or disease related.
This is increasingly important since, as stated previously, the number of procedures is expected to increase in the coming years.
Learning points.
This is a rare but classic and non-predictable case of a systemic vascular air embolism following a CT-guided transthoracic needle biopsy of a pulmonary nodule.
Air embolisms are associated with high morbidity and mortality; therefore, it is of great importance to know the risk factors and symptoms.
Urgent termination of the procedure and 100% oxygen supply can potentially increase the survival and benefit the patient.
A majority of the cases reported in the literature are non-fatal and with full recovery.
Footnotes
Twitter: @PiaIben
Contributors: All three authors have made substantial contributions to the planning, conducting and reporting the work of the case report. All authors are guarantors and accept full responsibility for the work. The first and corresponding author, Dr PIP, has made the final revision and is in charge of submission with final approval from Ms GMJ and Mr AC.
Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests: None declared.
Provenance and peer review: Not commissioned; externally peer reviewed.
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