<P> In the case of altitude sickness, where hypoxia develops gradually, the symptoms include fatigue, numbness / tingling of extremities, nausea, and anoxia . These symptoms are often difficult to identify, but early detection of symptoms can be critical . </P> <P> In severe hypoxia, or hypoxia of very rapid onset, ataxia, confusion / disorientation / hallucinations / behavioral change, severe headaches / reduced level of consciousness, papilloedema, breathlessness, pallor, tachycardia, and pulmonary hypertension eventually leading to the late signs cyanosis, slow heart rate / cor pulmonale, and low blood pressure followed by death . </P> <P> Because hemoglobin is a darker red when it is not bound to oxygen (deoxyhemoglobin), as opposed to the rich red color that it has when bound to oxygen (oxyhemoglobin), when seen through the skin it has an increased tendency to reflect blue light back to the eye . In cases where the oxygen is displaced by another molecule, such as carbon monoxide, the skin may appear' cherry red' instead of cyanotic . Hypoxia can cause premature birth, and injure the liver, among other deleterious effects . </P> <P> If tissue is not being perfused properly, it may feel cold and appear pale; if severe, hypoxia can result in cyanosis, a blue discoloration of the skin . If hypoxia is very severe, a tissue may eventually become gangrenous . Extreme pain may also be felt at or around the site . </P>

What kind of systemic manifestations might be present if a person is experiencing hypoxia