Acute pulmonary embolism is a type of disease with very many and complex inducing factors.

Clinically, acute pulmonary embolism has a very sudden onset, and patients often present with unexplained symptoms such as pale complexion, chest tightness, chest pain, and difficulty breathing. During the acute phase of pulmonary embolism, immediate and effective anti-shock and other symptomatic resuscitation are essential upon arrival at the hospital. Generally, after timely and effective resuscitation, the patient's condition may be somewhat controlled. Usually, the first 1-3 days after the onset of pulmonary embolism are the most dangerous; therefore, continuous monitoring of the patient's vital signs is crucial during this time, followed by anti-shock and anticoagulation treatment as needed.

Therefore, acute pulmonary embolism will not improve by the second day, although some of the patient's clinical symptoms may slightly improve after treatment.