Observation should be the treatment of choice for primary spontaneous
small closed pneumothoraces without significant breathlessness,
in a spontaneously breathing patient. Inhalation of high
concentrations of oxygen may speed the resolution of a pneumothorax
by reducing the partial pressure of nitrogen in the pulmonary
capillaries. This should increase the pressure gradient
between the pleural cavity and pleural capillaries, so increasing the
absorption of air from the pleural cavity. The rate of re-absorption
of spontaneous pneumothoraces is 1.25–1.8% of the volume of
hemithorax every 24 h.11
Symptomatic patients should not be left without intervention
regardless of the size of the pneumothorax on a chest radiograph.
Other considerations include the need for positive pressure ventilation,
impending anaesthesia and surgery (nitrous oxide diffuses
into air collections and increases pressure/volume), transport in or
outside the hospital, and altitude changes (including air transport).