If a patient is fast asleep and suddenly wakes up with suffocation, the condition may be due to the presence of sleep apnea syndrome, or to the presence of heart failure. It is suggested that the patient can combine BNP and cardiac ultrasound to rule out the presence of organic lesions. If necessary, an ENT consultation can be requested to clarify the presence of a deviated nasal septum, or a node and polysomnogram to clarify the presence of sleep apnea syndrome. Other patients may have similar abnormalities due to the presence of chronic obstructive pulmonary disease, or the presence of pulmonary heart disease. Patients may also be advised to combine pulmonary function tests with lung CT and arterial blood gas analysis to help better clarify the diagnosis.