Introduction: blue was activated. Patient was intubated and

Introduction:

 

Transthoracic lung biopsy is a
common diagnostic procedure that is known to be associated with various
complications. Most commonly encountered complications are such as pneumothorax
and hemorrhage. Systemic air embolism however is a known but rare occurrence.

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We report a fatal case of air embolism to the left ventricle of the heart and
the aorta, confirmed by a CT thorax, followed by a review of the different
mechanisms that may have lead to the event.

 

 

Case Report:

 

A 72 year old man  was
admitted to the hospital for bilateral chronic limb ischaemia. His medical
history was also significant for right sided heart failure with Type 2
respiratory failure. His workup included a chest radiograph and a CT scan which
incidentally revealed a solitary left lung nodule at the apicoposterior segment
of the left upper lobe measuring 1.2 x 1.8cm. 
It was then decided for a CT guided biopsy to establish a diagnosis.

 

Patient was placed in prone position and an 18G biopsy
needle, 15c in length was inserted into the nodule under CT guidance. As the
needle was passing through, patient coughed slightly. Despite this shortcoming,
an adequate tissue sample was obtained. Immediately afterward, a CT scan was performed.

 

A review of the CT scan demonstrated air
entering the left pulmonary vein and advancing to the left ventricle and
eventually leaving the aorta. Following
this, the patient became unresponsive and pulseless. Resuscitative efforts were
commenced immediately and code blue was activated.

Patient was intubated and after 15 mins of
cardiopulmonary resuscitation, cardiac monitor showed sinus rhythm.

Subsequently patient was transferred to ICU and placed on high FiO2  setting
in order to facilitate reabsorption of the embolised air.

 

Hyperbaric
oxygen therapy was contemplated. However due to the patient’s hemodynamically
unstable condition, he was deemed not safe for transfer. Patient died shortly
after.

 

 

 

Transthoracic lung biopsy is a frequently performed
procedure that has been has been widely accepted as a standard method for the
diagnosis of pulmonary lesions.  Of
note,  Bou-Assaly et al stated that the most frequent complications are
pneumothorax (27%), pulmonary bleeding (11%) and hemoptysis (7%).

 Systemic air emboli are extremely rare with a published incidence of
0.02% from a lung biopsy survey in the United Kingdom.

However it is to be noted that the incidence rate
and mortality of air embolism is believed to have been underestimated due to
undiagnosed asymptomatic cases

The risk of
complications appears to be greatest in smokers, older patients (>60 years),
patients with chronic obstructive pulmonary disease or emphysema, and possibly
in those with ground glass nodules. 

 

Reportedly, there are three
likely manners air can be introduced in the systemic circulation during
needle biopsy of the lung. First, when the needle tip is placed within the
pulmonary vein and the stylet has been removed, it can create a direct
communication between the atmosphere and the pulmonary vein. Second, a
communicating fistula can be created between the pulmonary vein and lung
parenchyma as the needle passes through the lung parenchyma. Intra-alveolar, intrabronchial
, cavity or air cyst, and a nearby pulmonary vein
air can get introduced into the pulmonary venous circulation through the
fistula. A Valsalva maneuver, coughing, or positive-pressure ventilation may
increase air introduction by causing an elevation in the intra-alveolar
pressures. Finally, air may be introduced in the pulmonary arterial circulation
and later reach the pulmonary venous circulation by traversing the pulmonary
microvasculature.

 

In
this case, we are to believe that as patient coughed after the passing of the
core biopsy needle, it is likely that a fleeting communication between the
pulmonary vein and the biopsy tract may have been present at that time,
resulting in alveolar or bronchial air passing into the pulmonary vein, which
resulted from an increased intrapulmonary pressure induced by the coughing. The
air thereafter passed into the left atrium and then into the left ventricle.

The subsequent clinical events arose as a result of antegrade propulsion of the
air bubbles into the major branches of the aorta.

 

The immediate response to an air embolism is the
administration of 100% oxygen and placing the patient in the left lateral
decubitus position with lowering of the head.

Hyperbaric oxygen therapy is considered the
first-line therapy for systemic air embolism by reducing bubble volume and
improving tissue oxygenation. The size of a gas bubble is inversely
proportional to ambient pressure at constant temperature. Breathing
100% oxygen at a pressure above that of the atmosphere decreases the size. Hyperoxia produces diffusion of oxygen
into the bubble and nitrogen out and also allows a large quantity of oxygen to
dissolve in the plasma and increases oxygen diffusion in tissues.

 

Although immediate treatment is
recommended, delayed hyperbaric oxygen therapy may also increase survival and
decrease the neurologic deficit, even many hours after the incidence because
air bubbles have been demonstrated at 48 h after initial events. In
our case, hyperbaric oxygen was considered to be ineffective, as patient was
not fit for transfer.

 

Several
considerations have been recommended to reduce the risk of air embolism.  One of it being avoiding biopsy through a
cystic, cavitating lesion or bullous lung parenchyma. The use of a stylet and
keeping an occluded hollow at all times may also be considered.  We should also request the patient to hold
their breath when manipulating the biopsy kit and to restrain from coughing and
straining. Lastly, we should be sure to penetrate the least amount of
parenchyma to reach the lesion to avoid entrapment of air within the
vasculature.

 

Despite
the rarity of this dangerous and possible fatal complication, interventional
radiologists should be aware of the complication that is systemic air embolism
after lung biopsy and should be ready to provide emergent management for the
treatment of the patient. Although several recommendations and precautions have
been proposed to reduce the risk of this complication, it may be inevitable and
can occur despite long experience and meticulous care.

 

 

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