Hypoxia and Hypoxemia - Overview Hypoxia - insufficient oxygen delivered to tissues to meet demands Hypoxemia - low oxygen in the blood (most common type of hypoxia) PIO2 - atmospheric oxygen (how much O2 is inspired) PAO2 - alveolar oxygen (how much O2 reaches the alveoli) PaO2 - oxygen dissolved in arterial blood (measured on ABG) SaO2 - percent saturation of hemoglobin in arterial blood CaO2 - oxygen content of arterial blood (dissolved & Hb bound) HYPOXEMIC HYPOXIA - Insufficient oxygen in the blood (the most common type of hypoxia) - Low PaO2 ISCHEMIC HYPOXIA - Insufficient blood flow to tissues, also called stagnant hypoxia (e.g low cardiac output) - Low SvO2 → Low PaO2 ANEMIC HYPOXIA - Insufficient O2 carrying capacity (e.g. severe blood loss) or abnormal hemoglobin (e.g. COHb, MetHb) - Low CaO2 → Low SvO2 → Low PaO2 CYTOPATHIC HYPOXIA - Cells cannot use oxygen (e.g. cyanide toxicity, maybe sepsis) - High PaO2, High SvO2 Dr. Nick Mark MD @nickmmark #Hypoxia #Hypoxemia #summary #pulmonary #differential #diagnosis #causes #pathophysiology
