The course Objectives are

• Analyze physiology related to oxygen transport and metabolism.
• Analyze physiology related to oxygen transport and metabolism.
• Identify the AHA’s guidelines on oxygen therapy in post-cardiac arrest, acute coronary syndrome, and stroke patients. And,
• Discuss the role of free radicals related to oxygen therapy.

An expert from the chapter Paramedic Recert EMS Care | 23-MCIT-F3-4103 | Oxygenation

In healthy individuals, there is a balance in the blood oxygen and carbon dioxide levels. When oxygen levels decrease, or carbon dioxide levels increase, the respiratory centers in the brain are stimulated, leading to an increase in the respiratory rate and depth of breathing.

In patients with COPD, their narrowed airways make it difficult to exhale fully, and they may be unable to eliminate enough carbon dioxide from their lungs. Carbon dioxide is a respiratory stimulant, so in healthy individuals, an increase in CO2 triggers the urge to breathe. However, in CO2 retainers, the respiratory drive is blunted or diminished, so they may not experience the same dyspnea (shortness of breath) expected in response to high CO2 levels. CO2 retainers often have chronically elevated carbon dioxide levels, and their bodies adapt to higher CO2 levels over time. This results in respiratory drive primarily triggered by low oxygen levels (hypoxemia) rather than high CO2 levels. Consequently, supplemental oxygen therapy must be carefully managed in CO2 retainers because excessive oxygen administration can suppress their respiratory drive, leading to further CO2 retention.

The traditional theory is that oxygen administration in patients with COPD induces hypercapnia through the ‘hypoxic drive’ mechanism, which can be dangerous. It is believed that oxygen administration to CO2 retainers causes:

1. Loss of hypoxic drive, resulting in hypoventilation and type 2 respiratory failure.
2. V/Q mismatching. And,
3. Changes the chemistry of the patient’s blood through the Haldane effect.