Keywords
Cardiac tamponade - pneumomediastinum - pneumopericardium - respiratory distress syndrome
- ultrasound guided drain of pneumopericardium
Introduction
Ultrasonographic guided procedures have a wide range of application in the abdomen
and pelvis, however their role is somewhat limited in the chest due to complete reflection
of the ultrasound beam, preventing the direct imaging of the tissues deep to the air-sound
interface.[[1]] Most of the chest procedures, other than thoracentesis, rely on the use of computerized
tomography (CT) scan. The disadvantages of using CT scan are the cost, lack of portability,
and most importantly, the radiation involved, particularly in case of infants and
children, whose tissues are more radiosensitive than adults. Identification of air
by ultrasonography can help direct needles and wires, to accomplish procedures which
may otherwise need CT.
Case Report
A 36-year-old [Gravida 5 and Living 3] mother, gave birth to a 35-36 week baby boy.
This was a high risk pregnancy associated with advanced maternal age, chronic hypertension
and superimposed pre-eclampsia. The new born experienced excessive grunting and severe
retractions which prompted endotracheal intubation shortly after birth. The baby received
surfactant and was monitored by serial chest radiographs. Initial radiograph showed
bilateral diffuse hazy granular opacities suggesting respiratory distress syndrome
(RDS) [[Figure 1]]. Due to increasing FiO2 demands and hypercapnia, the ventilator was adjusted several
times. Subsequently the serial radiographs showed enlarging pneumopericardium/pneumomediastinum
[[Figure 2]]A and [[Figure 2]]B. The patient also developed hypotension, suggesting some component of cardiac
tamponade. An echocardiogram was performed, which confirmed presence of pneumopericardium/pneumomediastinum.
[[Figure 3]]A and [[Figure 3]]]. Since the baby was not responding to conservative management, interventional
radiology was consulted to aspirate the air and place a drain in the pneumopericardium/pneumomediastinum.
A drain placement was preferred over simple aspiration to prevent re-accumulation
of air. At our institution, procedures to drain pneumothorax and pneumomediastinum
are typically performed under CT guidance, and hence, we asked the team to move the
patient to CT. However, the patient was very unstable at that time and after discussion
with the pediatric surgeon and neonatologist, we decided to perform the procedure
at the patient’s bedside using ultrasound imaging and radiography.
Figure 1: Anteroposterior radiograph of the chest showing granular opacities in both lungs
consistent with Respiratory distress syndrome
Figure 2 (A and B): (A) Anteroposterior radiograph of the chest, 2 hours after birth shows development
of pneumopericardium/ pneumomediastinum (black arrows). (B) Anteroposterior radiograph
one hour following the radiograph in Figure 2A, shows enlargement of the pneumopericardium/pneumomediastinum
Figure 3 (A and B): (A) Suprasternal notch imaging plane. Echobright imaging artifact consistent with
air in the superior mediastinum (arrows). INN; innominate vein, I; first branch of
aortic arch, II; second branch of aortic arch and III; third branch of aortic arch.
(B) Subcostal imaging plane demonstrating echobright artifact consistent with air
along the left ventricular free wall (arrows). RV; right ventricle, IVS; interventricular
septum, LV; left ventricle
Ultrasonographic guided drain placement for pneumopericardium/pneumomediastinum was
performed as follows; with the patient in the supine position, a hockey stick transducer
(15 MHz) was placed on the right anterior chest wall along the long axis of the ribs
in the expected location of the pneumopericardium/pneumomediastinum [[Figure 4]], as correlated with the radiograph. The right side was chosen as the pocket of
pneumomediastinum was wider on that side and also to stay away from the heart. A micro
puncture needle was then advanced under ultrasonographic guidance, using an in-plane
approach along the long axis of the ribs, making sure the needle approached the air
pocket. Once the needle was seated in the air pocket, the ability to visualize the
tip was lost and at this point, no further advancement was made. After this, a 0.018”
microwire was advanced through the needle without resistance. Once enough wire purchase
was achieved, the 5F micro puncture sheath was advanced over the wire into the pericardial/mediastinal
space. A 0.035” Benston wire was advanced through the micro puncture sheath. At this
point portable anteroposterior and lateral radiographs were obtained at the patient’s
bed side to confirm wire localization [[Figure 5]]A and [[Figure 5]]B. Once we were satisfied with the wire localization, we advanced a 6.5 French drain
into the mediastinum and aspirated the air. Another radiograph was obtained to confirm
the position [[Figure 6]]. Near complete resolution of the pneumopericardium/pneumomediastinum was seen.
Following the procedure the patient’s oxygen requirement decreased (improved) from
100% to 50%. The drain was clamped after 3 days of dwell time and removed 24 hours
later, as serial X-rays showed no re-accumulation of air. The baby was discharged
home in a stable condition 3 weeks after its birth.
Figure 4: Sagittal ultrasound of the chest in the region of the right lower chest, showing
dirty shadowing consistent with air echoes (white arrows)
Figure 5 (A and B): Anteroposterior (A) and lateral (B) radiographs of the chest, after advancing a Bentson
wire (black arrows), shows the wire in good position coursing through the pericardial/mediastinal
space
Figure 6: Anteroposterior radiograph with pericardial drain placement shows near complete evacuation
of the pneumopericardium/pneumomediastinum. The drain is located in the right side
of the heart/mediastinum (black arrow)
Discussion
Pneumopericardium in the neonatal period is a rare clinical condition which is usually
associated with other simultaneously-occurring air leaks. The majority of reported
cases are in preterm newborns with RDS who had required active positive pressure during
resuscitation and/or subsequent respiratory support.[[2]],[[3]]
The chest radiograph is the standard diagnostic method. The classic finding in pneumopericardium
is the “halo sign”: Air completely surrounding and outlining the heart, but not extending
beyond the reflection of the pericardium along the great vessels.[[4]] The exact pathophysiology of neonatal pneumopericardium is still unclear. Air is
thought to dissect from ruptured alveoli along the perivascular sheaths to the hilum
and mediastinum, with subsequent rupture into the thorax or mediastinum.[[5]] Rupture of this air into the pericardium has been postulated to occur in an area
of weakness at the reflection of the parietal and visceral pericardium, near the pulmonary
veins.[[5]]
There have been case reports of CT and fluoroscopic guided mediastinal drain placement
in neonates [[6]],[[7]] however, to our knowledge, there have been no case reports of sonographic guided
and X-ray assisted drain placement for a tension pneumopericardium/pneumomediastinum.
Most cases of pneumopericardium/pneumomediastinum can be managed conservatively.[[8]] If there is continuous leakage of air in the pericardium, tension pneumopericardium
may occur and result in compromised venous return to the heart, ultimately evolving
into a life-threatening condition.[[9]],[[10]]
Use of ultrasound for the detection and drainage of pleural and pericardial effusions
in patients of all ages is well established. Despite many advantages of ultrasound
in neonates, there is little information regarding the use of ultrasound for evaluation
of abnormal air in the mediastinum/pericardium. The unique anatomy of the pediatric
chest allows superior acoustic windows that can provide valuable information in children.
The bony structures in the neonatal thorax are mostly cartilaginous, allowing sound
beam transmission.[[11]],[[12]]
One has to be cognizant of possible injury to the adjacent lung while trying to intervene
in the mediastinum/pericardium. Several sonographic signs which help to identify the
normal pleural space and the underlying lung have been described. Some of the useful
signs include the “The Bat Sign”—where the periosteum of the ribs represents the wings
and the bright hyperechoic pleural line in between them represents the bat’s body.[[13]] “Pleural Sliding Sign” is another important sign to identify the normal aerated
lung. It relates to the to-and-fro movement of the visceral pleura on the parietal
pleura, which occurs with respiration.[[14]]
The subtle movement of the pleura can also be identified by M-Mode ultrasound. It
is beneficial in the elderly or patients with poor pulmonary reserve, who are not
capable of taking large breaths. M-mode cursor placed over the presumed pleural line
displays two different patterns on the screen: The motionless portion of the chest
above the pleural line creates horizontal lines –”Waves”, and the sliding below the
pleural line creates a granular pattern, the “Sand”. This is therefore called the
“seashore sign” and is present in normal aerated lung.[[15]],[[16]],[[17]]
Conclusion
Ultrasound can be used to evaluate the lung, pleural space, and to guide chest/mediastinal
procedures, as long as it is tailored to the clinical suspicion and the setting.
Acknowledgements
Authors would like to thank the Interventional radiology department at the University
of Missouri, Columbia for their exceptional care of this patient. We also thank Joanne
Cassani our Director of Research for coordinating and putting together the materials
needed to publish this case report.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
