Cyanosis may seen in: March 2013
Correct Answer: Stagnant hypoxia
Description: Ans. C i.e. Stagnant hypoxia Central cyanosis Often due to a circulatory or ventilatory problem that leads to poor blood oxygenatio in the lungs. It develops when aerial saturation drops to 85% or 75% (in dark-skinned individuals). Central cyanosis may be due to the following causes Central Nervous System (impairing normal ventilation): Intracranial hemorrhage, Drug overdose (Heroin) - Respiratory System: Pneumonia, Bronchilitis, Pulmonary hypeension - Cardiac Disorders: Congenital hea disease: TOF, Right to left shunts Blood: Methemoglobinemia, Polycythemia Others: High altitude Peripheral cyanosis Peripheral cyanosis is the blue tint in fingers or extremities, due to inadequate circulation. The blood reaching the extremities is not oxygen rich and when viewed through the skin a combination of factors can lead to the appearance of a blue colour. All factors contributing to central cyanosis can also cause peripheral symptoms to appear, however peripheral cyanosis can be observed without there being hea or lung failures. Peripheral cyanosis may be due to the following causes: - All common causes of central cyanosis Reduced cardiac output (e.g. hea failure, hypovolemia) - Cold exposure - Aerial obstruction (e.g. peripheral vascular disease, Raynaud phenomenon) - Venous obstruction (e.g. DVT) Differential cyanosis Differential cyanosis is the bluish coloration of the lower but not the upper extremity and the head. This is seen in patients with a patent ductus aeriosus . Patients with a large ductus develop progressive pulmonary vascular disease, and pressure overload of the right ventricle occurs. As soon as pulmonary pressure exceeds aoic pressure, shunt reversal (right-to-left shunt) occurs. The upper extremity remains pink because the brachiocephalic trunk, left common carotid trunk and the left subclan trunk is given off proximal to the PDA.
Category:
Physiology
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