Open Journal of Pediatrics, 2011, 1, 37-38 OJPed
doi:10.4236/ojped.2011.13010 Published Online September 2011 (
Published Online September 2011 in SciR es.
Spontaneous neonatal pneumomediastinum
Kiran Kumar Balegar V.1, Nadia Badawi1, Arieta Fa’asalele2, Kathryn Carmo1,2
1Department of Neonatology, Royal Alexandra Hospital for Children, Westmead, Australia;
2Newborn & Paediatric Emergency Transport Service, Westmead, Australia.
Received 18 June 2011; revised 26 July 2011; accepted 26 August 2011.
Radiolucency in the superior mediastinum may be
caused by a congenital cystic mass or pneumomedi-
astinum. Most cases of pneumomediastinum occur in
preterm newborns with surfactant deficiency receiv-
ing treatment with positive pressure ventilation. Sp-
ontaneous pneumomediastinum in term neonates is
also rarely reported. We report the outcome for a
term neonate with respiratory distress who was tran-
sferred for surgical evaluation of a cystic superior
mediastinal mass.
Keywords: Spontaneous Pneumomediastinum; Superior
Mediastinal Mass; Neonate
A male infant of 38 weeks gestation and birth weight of
3520g was referred to The Children’s Hospital at West-
mead, Australia for the surgical management of a radio-
lucent superior mediastinal mass. The infant was born by
elective caesarean section to a primiparous woman after
an uncomplicated pregnancy, in a regional hospital. Ap-
gar scores were 7 and 9 at one and five minutes, resp ec-
tively. Shortly after birth he developed mild respiratory
distress requiring treatment with head box oxygen. The
respiratory distress worsened over the next 24 hours and
oxygen requirement increased to 50% although blood
gas analysis and haemodynamics remained stable. Chest
x ray at this stage revealed a radiolucent superior medi-
astinal shadow. He was commenced on CPAP and the
state Newborn Emergency Transport Service (NETS)
team was contacted regarding advice and transfer. Re-
view of an x-ray film through telemedicine and multid-
isciplinary discussion with the receiving neonatologist,
transport team and cardiothoracic surgeon indicated the
possibility of pneumomediastinum. It was agreed to dis-
continue the CPAP and transfer the baby by road in crib
oxygen, rather than by air, despite the longer travel time.
The follow-up chest x-ray at the tertiary centre revealed
a classical Spinnaker sail sign of a pneumomediastinum
(Figure 1) with an otherwise normal appearance of the
lung fields. Conservative management in head box oxy-
gen resulted in complete resolution of the pneumomedi-
astinum over the subsequent 72 hours (Figure 2).
Figure 1. Chest x-ray on admission showing cys-
tic appearance and Spinnaker sail sign of pneu-
Figure 2. Chest x-ray after 72 hours showing
complete resolution of pneumomediastinum.
K. K. Balegar V. et al. / Open Journal of Pediatrics, 2011, 1, 37-38
Although most reported cases of neonatal pneumomedi-
astinum ensue exposure to positive pressure in the set-
ting of premature or diseased lungs [1-3], spontaneous
pneumomediastinum that occurs in the absence of clear-
ly defined precipitating factors, has rarely been reported
[4,5]. Pathogenesis of pneumomediastinum was first
demonstrated experimentally by Macklin in 1939 [6].
Exposure to an increased pressure gradient between the
alveoli and the pu lmonary interstitium results in alveolar
rupture into the perivascular space, at the junctional area
between compliant bronchial airway and poorly compli-
ant alveoli. Air dissects along the perivascular sheaths
towards the hilum and leaks into loose connective tissue
spaces of the mediastinum. The usual triggering agent is
positive pressure ventilation in combination with an un-
derlying abnormality such as surfactant deficiency or
meconium aspiration syndrome that renders the alveoli
more fragile and prone to rupture [7]. In spontaneous
pneumomediastinum the pressure gradient is thought to
be generated by excessive negative intrapleural pressure
during vigorous respiratory efforts in term infants, cou-
pled with an uneven inflation o f alveoli at birth [8]. This
is the most plausible explanation in our infant.
Although chest roentgenography can be diagnostic in
most cases of pneumomediastinum, the appearance may
be confused with other surgical cystic mediastinal le-
sions such as congenital cystic adenomatoid malforma-
tion or congenital lobar emphysema, as illustrated in our
case. This is because of the unique anatomical feature of
the neonatal thymus characterized by a thick fascial
capsule which envelopes the thymus and merges with
the fibrous pericardium [8]. Air tends to loculate around
the thymus and sometimes can even dissect within the
interlobular and connective tissue septa of the thymic
capsule, giving rise to a cystic appearance. It is postu-
lated that this cystic appearance is uncommon in older
children and adults because the thymus and its fascia
undergo atrophy and are unable to contain a sudden air
leak [5,8].
Suspicion of pneumomediastinum prevented us from
using aggravating factors such as CPAP or positive
pressure ventilation. Between the 2 available options
namely, transporting the baby in pressurised air transport
vehicle at a lower altitude versus road transport - we
chose the latter so as to avoid the possible disastrous
effects from expansion of gases in the closed spaces at
lower ambient air pressure (as dictated by Boyle’s law).
A careful evaluation of the x-ray film in our case re-
vealed the crescentic configuration of the elevated
thymic lobes resembling a windblown Spinnaker sail.
Serial x-ray films showing evolution of the pneumome-
diastinum with this classic Spinnaker sail sign followed
by complete resolution avoided CT scan, which other-
wise is the investigation of choice to confirm the nature
of a mediastinal mass.
Most cases of spontaneous pneumomediastinum re-
solve spontaneously. Timely recognition and avoidance
of aggravating factors constitute th e crux of management
and prevent deterioration and haemodynamic instability
Neonatal pneumomediastinum can be confused with
surgical cystic radiolucent mass owing to the unique
anatomical feature of the neonatal thymus characterized
by a thick enveloping fascial capsule that contains air.
Awareness of spontaneous pneumomediastinum in
newborn babies with respiratory distress helps to direct
the nature of respiratory support and the mode of trans-
port. With timely recognition and avoidance of aggra-
vating factors, most cases resolve spontaneously.
[1] Lin, H.P., Johnson, R.O., Lam, K.L., Ong, T.H. and
Singh, J. (1979) Pneumomediastinum in the newborn pe-
riod and early childhood. Singapore Medical Journal, 20,
[2] Rosenfeld, D.L., Cordell, C.E. and Jadeja, N. (1990)
Retrocardiac pneumomediastinum: Radiographic finding
and clinical implications. Pediatrics, 85, 92-97.
[3] Mohamed, I.S., Lee, Y.H., Yamout, S.Z., Fakir, S. and
Reynolds, A.M. (2007) Ultrasound guided percutaneous
relief of tension pneumomediastinum in a 1-day-old new-
born. Archives of Disease in Childhood—Fetal and Neo-
natal Edition, 92, F458.
[4] Lawal, T.A., Glüer, S. and Reismann, M. (2009) Sponta-
neous neonatal pneumomediastinum: The “spinnaker sail”
sign. Eur opean Journal of Pediatric Surgery , 19, 50-52.
[5] Lee, C.T., Tsao, P.N. and Peng, S.S. (2008) Spontaneous
multiseptated cystic pneumomediastinum in a term new-
born. Pediatrics & Neonatology, 49, 197-200.
[6] Macklin, C. (1939) Transport of air along sheaths of
pulmonic blood vessels from alveoli to mediastinal me-
diastinum. Archives of Internal Medicine, 64, 913-926.
[7] Hauri-Hohl, A., Baenziger, O. and Frey, B. (2008) Pneu-
momediastinum in the neonatal and paediatric intensive
care unit. European Journal of Pediatrics, 167, 415-418.
[8] Low, A.S., Tan-Kendrick, A.P., Loh, M. and Chui, C.H.
(2003) Spontaneous multiloculated multiseptated pneu-
momediastinum in a newborn baby: The spi nnaker sail is
rigged—CT features with pathologic correlation. Pediat-
ric Radiology, 33, 712-715.
opyright © 2011 SciRes. OJPed