Late Signs of Hypoxia

Also commonly called “diaphoretic,” compensatory responses release catecholamines like epinephrine and norepinephrine into the bloodstream, which cause increased perspiration. This increased perspiration cools the skin. Unpleasantly wet skin is also termed “clammy.”

Accessory muscles are additional muscles that can help increase the amount of air that is inspired. These muscles are used to increase the volume and rate of respiration. Along with dyspnea at rest, patients may appear as if they are pausing for breath between words as the effort to breath becomes increasingly difficult.

Visualization of muscles pulling into the body cavity in the neck and intercostals can be seen during inspiration. This occurs as patients attempt to increase the force, rate and volume of inspired air. Retractions are more easily visible in thin patients and children.

In the early stages of hypoxia, blood pressure is typically increased as a compensatory mechanism, but with sustained or severe hypoxia, the body can no longer meet the demands for oxygen and tissues are unable to compensate, resulting in low blood pressure. Blood pressure changes are not a good indicator of hypoxia.

The heart is very sensitive to low oxygen levels because it has a high extraction percentage of oxygen from the blood. When oxygenation decreases slightly, the cardiac muscle can be immediately affected. This can occur in early stages, as well as late stages. Sustained hypoxia can lead to lethal arrhythmias.