Hemoptysis may also indicate other, potentially fatal, medical conditions.A history of exposure to potential causes and evaluation of symptoms may help in revealing the cause the exacerbation, which helps in choosing the best treatment. A sputum culture can specify which strain is causing a bacterial AECB. An early morning sample is preferred.E-nose showed the ability to smell the cause of the exacerbation.The definition of a COPD exacerbation is commonly described as "lost in translation", meaning that there is no universally accepted standard with regard to defining an acute exacerbation of COPD. Many organizations consider it a priority to create such a standard, as it would be a major step forward in the diagnosis and quality of treatment of COPD. Prevention
Acute exacerbations can be partially prevented. Some infections can be prevented by vaccination against pathogens such as influenza and Streptococcus pneumoniae. Regular medication use can prevent some COPD exacerbations; long acting beta-adrenoceptor agonists (LABAs), long-acting anticholinergics, inhaled corticosteroids and low-dose theophylline have all been shown to reduce the frequency of  COPD exacerbations. Other methods of prevention include:

Smoking cessation and avoiding dust, passive smoking, and other inhaled irritants
Yearly influenza and 5-year pneumococcal vaccinations
Regular exercise, appropriate rest, and healthy nutrition
Avoiding people currently infected with e.g. cold and influenza
Maintaining good fluid intake and humidifying the home, in order to help reduce the formation of thick sputum and chest congestion. Treatment
Based on the severity different treatments may be used. Mild exacerbations are treated with short acting bronchodilators (SABDs).
Choice of antibiotics is also dependent on the severity of the symptoms:
"Simple" COPD is generally where a person 65 years or less, has fewer than four exacerbations per year, has minimal or moderate impairment in respiratory function and no comorbid disease. In patients with "simple" COPD, therapy should be targeted towards Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and possibly pathogens of atypical pneumonia. The first-line treatment is a beta-lactam antibiotic such as amoxicillin. The choice will depend on resistance patterns. In patients with penicillin allergy, doxycycline or trimethoprim are preferred. More complicated bronchitis may be when the patient is more than 65 years old, has four or more exacerbations per year, has an FEV1/FVC ratio of less than 50% on spirometry, has failed to respond to previous antibiotic treatment, and/or has comorbidity. In these cases, treatment should be aimed at Gram-negative bacteria and the possibility of high antibiotic resistance should be considered. Sputum culture results are of great value in determining antibiotic resistance. First-line treatment is cefuroxime or co-amoxiclav. Third-line treatment, as well as treatment in penicillin-allergic patients, is a fluoroquinolone such as ciprofloxacin. An agent active against Streptococcus pneumoniae may have to be added. Corticosteroids such as prednisolone reduce inflammation in the airways. According to a 2018 systematic review, a shorter, five-day course of systemic corticosteroids is likely comparable to longer (10–14 day) therapy for treatment of COPD exacerbation (Odds ratio (OR) 0.72, 95% confidence interval (CI) 0.36 to 1.46).