It can affect multiple body systems- Notably, oxygen toxicity can affect the central nervous system, resulting in seizures, the respiratory system, causing irritation, coughing, shortness of breath, and acute respiratory distress syndrome. Oxygen toxicity affects the eyes, causing bleeding, cataract formation, and fibrosis. Muscle twitching is common with the condition.
Of course sick patients may require oxygen, but the goal should be to decrease the amount of supplemental oxygen as quickly as possible and titrate the oxygen level to an spO2 of greater than/ equal to 96%.
Ventilation should ideally be tailored to an end tidal CO2 of 35-40. Titration of ventilation status to waste products is a good reminder of the need to decrease the fraction of inspired oxygen, and that hyper-oxygenation can be a classic example of "too much of a good thing." Optimization of oxygenation status is an absolute priority after a code, and decreasing the fraction of inspired O2 is a part of that optimization process.
Additionally, oxygen is a powerful vasoconstrictor. In a recent study of measured coronary blood flow, patients had a decrease of approximately 15% in their coronary blood flow after breathing 100% oxygen for just 5 minutes. The vascular resistance in the vessels increased 20%. It is important to keep the benefits and risks of oxygen in mind when working with post-code and acute coronary patients.
Moradkhan, R., & Sinoway, L. I. (2010, September 21). Revisiting the role of oxygen therapy in cardiac patients. Journal of the American College of Cardiology, 56(13), 1013-1016. http://dx.doi.org/10.1016/j.jacc.2010.04.052