Although pneumothorax is
the commonest presentation of pulmonary barotrauma unrelated to mechanical ventilation,
systemic air embolism and emphysema within the pulmonary interstitium, mediastinum,
retroperitoneum, pericardium, and subcutaneous tissues have all been described.(1) We
report a case of pulmonary barotrauma after inflation of party balloons.
Case report
A 24 year old previously healthy, non-smoker presented with a 48 hour history of a
sensation of crackling under the skin. His symptoms were initially confined to the neck but
within 24 hours had affected his chest wall, trunk, and legs. The next day he developed
retrosternal pleuritic chest pain and attended the accident and emergency department. He
reported that 24 hours before the onset of symptoms he had inflated about 20 party balloons
over one hour. He had not experienced chest pain or shortness of breath at the time or
immediately afterwards.
Fig 1 - Plain chest radiograph showing widespread subcutaneous and mediastinal emphysema
On presentation his temperature was 38 degrees centigrade, his heart rate was
140 beats/minute, he was normotensive, and his arterial oxygen saturation was 98% while
breathing room air. Subcutaneous emphysema was present over his shoulders, chest, abdominal
wall, and in the neck to the angle of the jaw, and it extended anteriorly into his legs and
the arms. Subcutaneous air was palpable over his whole back and buttocks. There was good air
entry into both lungs and a loud crunching sound audible over the precordium synchronous
with the heart sounds (Hamman's sign). Plain chest radiographs showed extensive subcutaneous
emphysema in the neck and chest wall pneumomediastinum and pneumopericardium (fig 1).
Computed tomography also showed large collections of air in the retroperitoneum and superior
mediastinum. Lung texture was normal, and there were no bullae. There was no leakage of
ingested contrast medium from the oesophagus during barium swallow examination. He was given
intravenous antibiotics, fluids, and analgesics, and radiographs showed complete resolution
of his emphysema after 10 days. Four weeks after admission respiratory symptoms had resolved
and lung function tests showed no underlying lung abnormalities.
Six balloons identical with those he had inflated were analysed in the lung function
laboratory. A mean pressure of 64 (SE 0.73) cm H2O was required to initiate
inflation, but thereafter a pressure of 40 cm H2O was required. Each balloon
comfortably held 6 litres of air before rupturing. In a demonstration of his technique the
patient inhaled to maximum inspiratory capacity and then rapidly exhaled into the balloons
to maximum expiratory capacity, inflating a balloon in two or three such manoeuvres.
Comment
Extra-alveolar air in subcutaneous tissues and mediastinum may accumulate
after damage to alveoli. Increases in intra-alveolar pressure or decreases in perivascular
interstitial pressure may rupture alveoli and result in interstitial emphysema in the lung
periphery. As mean interstitial pressure in the mediastinum is usually lower than in the
lung periphery air may dissect proximally along the bronchovascular sheath to the
mediastinum.(2)
Increased alveolar pressure caused by straining against a closed
glottis is associated with alveolar rupture when a strong expiratory effort is applied at
the maximum inspiratory capacity, as occurs in the Valsalva manoeuvre.(3) This may
explain the apparent ease with which extra-alveolar air may develop after voluntary Valsalva
manoeuvres during smoking of marijuana or cocaine.(4)
Similar pathophysiological
mechanisms may underly pulmonary barotrauma during mechanical ventilation. Subcutaneous
emphysema and pneumothorax occur in 5-15% of such patients.(5) Predisposing factors
include high peak inflation pressure, high tidal volume, and pre-existing lung disease.
Maximum inflation pressures of 30-80 cm H2Ocarry considerable risk of alveolar
rupture.(5) To initiate balloon inflation our patient generated airway pressures of 64
cm H2Oon each occasion. He probably sustained alveolar rupture during
expiration early in the course of inflation, with large quantities of extra-alveolar air
being forced into the pulmonary interstitium during subsequent inflations. This later became
clinically apparent as extensive subcutaneous, mediastinal, and retroperitoneal emphysema.
This case shows that significant pulmonary barotrauma can occur after seemingly innocuous
respiratory manoeuvres and is not confined to patients with pre-existing lung disease.
We thank Mr Michael Saunders, Pulmonary Function Unit, Llandough Hospital, for his
analysis of the balloons, and Professor L K Borysiewicz for permission to report this case.
Funding: None.
Conflict of interest: None.
Department of Medicine,
University Hospital of Wales,
Cardiff
CF4 4XN
Andrew D Mumford,
senior house officer
Keyoumars Ashkan,
house officer
Respiratory Investigation,
Level 11,
Belfast City Hospital,
Belfast BT9 7AB
Stuart Elborn,
consultant physician
Correspondence
to: Dr Elborn.
email: stuart.elborn@bch.n-i.nhs.uk
References:
1 Janz M A, Pierson D J.
Pneumothorax and barotrauma. Clinics in Chest Medicine 1994;15:75-91.
2
Maunder R J, Pierson D J, Hudson L D. Subcutaneous and mediastinal emphysema. Arch Intern
Med 1984;144:1447-53.
3 Varkey B, Kory R C. Mediastinal and subcutaneous
emphysema following pulmonary function tests. Am Rev Respir Dis 1973;108:1396.
4 Goldberg R E, Lipuma J P, Cohen A M. Pneumomediastinum associated with cocaine abuse: a
review of the literature. J Thorac Med 1987;2:88-9.
5 Parker J C,
Hernandez L A, Peevy K J. Mechanisms of ventilator-induced lung injury. Crit Care Med
1993;21:131-43.
