Top Highlights

• Hypoxia refers to inadequate delivery of oxygen to tissues or ineffective cellular utilization of oxygen, leading to anaerobic metabolism.
• Tachypnea and labored respirations with a normal PaCO2 usually indicates increased dead space and a relative alveolar hypoventilation. This is one of the earliest signs of impending respiratory failure. It is nearly impossible to determine the PaCO2 with any kind of accuracy by clinical exam, so arterial blood gas measurements are essential.
• The SpO2 also becomes less accurate during significant hypoxemia (SaO2 < 80%), especially with darkly pigmented skin.