Oxygen in the ICU: Too Much of a Good Thing?

Oxygen gas was discovered and described in the 1770s by Scheele, Priestley, and Lavoisier and shortly thereafter its therapeutic potential for patients with respiratory illness was appreciated.¹ Oxygen has become a mainstay of treatment for acutely ill patients, with emphasis frequently placed on the importance of avoiding hypoxemia.² Modern clinical practice guidelines for critically ill patients³ generally target the normal levels for the partial pressure of arterial oxygen (Pao₂) and the oxyhemoglobin saturation in arterial blood (Sao₂), which range from 89 through 100 mm Hg and 95% through 97%, respectively, depending on patient age.⁴