“…[ 6 ] Pneumothorax is often diagnosed in a patient with subcutaneous or mediastinal emphysema, oxygen desaturation, circulatory disturbance, or MV impairment with increase of peak pressure. [ 1 3 4 ] However, it is likely to go unnoticed post-operatively in a sedated, pain-free patient receiving supplemental oxygen, as in this case. Several risk factors were found in the reported patient including, heavy smoking, bullous emphysema, neck surgery, tracheotomy, MV and using of N 2 O.…”