Increased CO 2 Production In several physiologic/pathologic states, the body can produce excessive carbon dioxide, resulting in hypercapnia under anesthesia. Exhausted absorbent agents and faulty expiratory check valves are the most common causes in modern anesthesia machines. Rebreathing When under general anesthesia, faulty breathing circuits or inadequate fresh gas flow in some circuit types, can lead to an increase in the inspired CO 2 and consequently and increase in the expired CO 2. propofol), and halogenated inhalational agents. Common causative agents are opioids, benzodiazepines, other sedative hypnotics (i.e. In spontaneously breathing patients, this is typically due to drug-induced depression of the ventilatory response to CO 2. In mechanically ventilated patients this is typically iatrogenic and the result of inadequate tidal volumes and/or respiratory rate contributing to a low minute ventilation. Hypoventilation Inadequate ventilation is the most common cause of hypercapnia. When assessing a patient with known or suspected hypercapnia, one should assess for a number of potential causes: however, this monitor is not always available outside of the operative environment. In the operating room, hypercapnia is typically detected with capnography. Hypercapnia, or high PaCO 2, can occur in numerous scenarios during anesthetic and post-anesthetic care.

Dead space in lungs hypercapnia