Give major differential diagnoses for central cyanosis?

1. Pulmonary embolism: A blood clot in the lungs can cause a decrease in oxygen levels in the blood, leading to central cyanosis.

2. Congenital heart defects: Certain heart conditions, such as tetralogy of Fallot or transposition of the great arteries, can cause cyanosis due to mixing of oxygenated and deoxygenated blood.

3. Chronic obstructive pulmonary disease (COPD): Conditions like emphysema or chronic bronchitis can lead to impaired gas exchange in the lungs, resulting in central cyanosis.

4. Pneumonia: Infections in the lungs can cause inflammation and fluid buildup, leading to decreased oxygen levels in the blood and central cyanosis.

5. Pulmonary edema: Fluid accumulation in the lungs, often due to heart failure, can impair oxygen exchange and cause central cyanosis.

6. Asthma: Severe asthma attacks can lead to airway constriction and decreased oxygen intake, resulting in central cyanosis.

7. Carbon monoxide poisoning: Inhaling carbon monoxide can interfere with the body's ability to transport oxygen, leading to central cyanosis.

8. High altitude sickness: Lack of oxygen at high altitudes can cause central cyanosis in individuals who are not acclimated to the lower oxygen levels.

9. Methemoglobinemia: A condition in which the blood contains high levels of methemoglobin, a form of hemoglobin that cannot carry oxygen effectively, leading to central cyanosis.

10. Sepsis: Severe infections can cause systemic inflammation and organ dysfunction, including impaired oxygenation of the blood and central cyanosis.