First-aid procedure for pulmonary embolism: 1.absolutely lie down and give oxygen. 2.If there is difficulty in breathing, shallow and slow breathing, etc., tracheal intubation and ventilator should be given to control breathing. If there is respiratory and cardiac arrest, cardiopulmonary resuscitation, epinephrine and other resuscitation drugs should be given immediately. 3.In the case of stabilization of vital signs, thrombolytic treatment with urokinase and other drugs should be given immediately, or vascular intervention should be used to open the embolized blood vessels as soon as possible. 4.Symptomatic treatment. In case of shock, blood volume expansion should be given, followed by anti-inflammatory and anti-shock treatment with glucocorticoids and other drugs. If there is respiratory acidosis, sodium bicarbonate should be given to correct the acidosis.