A 67-year-old male patient with chronic respiratory acidosis from end-stage chronic obstructive pulmonary disease (COPD) is receiving oxygen at 1 L/min per nasal cannula. Which statement by the nurse best explains to the patient’s daughter how this therapy prevents respiratory depression?

The therapy of providing oxygen at 1 L/min per nasal cannula helps to keep the patient's blood oxygen levels within a suitable range, which is critical for someone with COPD. People with end-stage COPD often have chronically high levels of carbon dioxide (CO2) in their blood, a condition known as hypercapnia, which their bodies have gradually adjusted to. Because of this adjustment, their respiratory drive is less responsive to CO2 levels and more responsive to oxygen levels. When too much oxygen is administered to these patients, it can suppress their already weakened drive to breathe.

The nurse might say, "For someone with COPD, their body is used to a higher level of CO2 in the blood, and the brain's signal to breathe is triggered more by low oxygen than high CO2 as in healthy individuals. Giving oxygen at a low flow rate, like 1 L/min, provides enough oxygen to maintain sufficient levels without lowering the CO2 too rapidly, which can sometimes cause their breathing to slow down or even stop — this is what is often referred to as 'respiratory depression'."

Extra: Chronic obstructive pulmonary disease (COPD) is a group of lung diseases that block airflow and make it difficult to breathe. In the late stages of COPD, patients often develop respiratory acidosis, which is a buildup of carbon dioxide in the blood due to poor gas exchange in the damaged lungs. In healthy individuals, the primary driver of breathing (respiratory drive) is the level of carbon dioxide in the blood. However, in COPD patients with long-standing high CO2 levels, their bodies adapt to this state and their respiratory drive becomes more sensitive to low levels of oxygen rather than high levels of CO2. This is why oxygen therapy must be carefully managed in these patients. Giving too much oxygen can further suppress the drive to breathe and lead to a dangerous condition where the blood has too little oxygen (hypoxemia) and too much carbon dioxide (hypercapnia), which can cause respiratory failure. The goal with oxygen therapy in COPD patients is to increase the oxygen level without drastically changing the CO2 levels to prevent additional respiratory complications.