1) A newborn with cyanosis of the extremities alone is initially assessed for common causes like hypothermia, but peripheral cyanosis can also indicate serious conditions like sepsis and should not be ignored until ruled out.
2) Differential or harlequin cyanosis, where one half of the body is cyanotic while the other is pink, can indicate a PDA or vasomotor instability.
3) In an infant presenting with cyanosis, lethargy and cold extremities on day 4 of life, the physician would perform a full examination, order diagnostic tests like a chest x-ray and echocardiogram, and consider treatments for potential cardiac or pulmonary causes while closely monitoring the