CO2Retention

CO2 retention refers to the accumulation of carbon dioxide in a system when removal is insufficient or production is increased. In medical contexts, it describes hypercapnia, a rise in arterial carbon dioxide levels due to inadequate ventilation or gas exchange. In environmental discussions, the phrase may be used to describe the persistence of CO2 in the atmosphere or in storage reservoirs after emissions.

In human physiology, the primary mechanism is alveolar hypoventilation, where ventilation fails to eliminate CO2 produced by metabolism. Conditions that contribute include chronic obstructive pulmonary disease, obesity hypoventilation syndrome, neuromuscular disorders, chest wall abnormalities, sedative or opioid use, and central respiratory depression. Less common causes include diffusion impairment and certain metabolic or endocrine factors that alter acid-base balance.

Clinically, CO2 retention can present with headaches, confusion, dizziness, shortness of breath, or sleepiness, and at higher levels may progress to severe acidosis, altered mental status, or coma. Diagnosis typically relies on arterial blood gas measurements showing elevated PaCO2 and decreased pH, supported by capnography or transcutaneous CO2 monitoring for real-time assessment.

Management aims to correct the underlying cause and restore appropriate ventilation. This may involve optimizing airway clearance, bronchodilator or anti-inflammatory therapy for obstructive diseases, noninvasive ventilation or invasive mechanical ventilation in acute or severe cases, and addressing contributing factors such as obesity, infection, or sedative use. Monitoring of oxygenation is essential to avoid hypoxemia during correction.

In environmental contexts, CO2 retention can refer to the long residence time of atmospheric CO2 and its sequestration in geological, marine, or terrestrial reservoirs as part of climate-change mitigation and carbon management strategies.