Hypercapnia

Hypercapnia occurs when there is too much carbon dioxide, the waste product of respiration, in the blood.

Why Does Hypercapnia Occur in COPD?

Generally speaking, when we breathe, we inhale oxygen and exhale carbon dioxide. These two respiratory gases are exchanged deep within the lungs, in tiny, grape-like clusters, or air sacs called alveoli.

In COPD, this process is impaired because the alveoli are destroyed, leaving less surface area for oxygen to get from the lungs into the bloodstream and for carbon dioxide to get from the blood into the lungs to be exhaled. This results in a low amount of oxygen in the blood, or hypoxemia, and high levels of carbon dioxide in the blood, or hypercapnia.

Causes of Hypercapnia

The following are a few examples of the types of conditions that may cause hypercapnia:

• seizures
• drug overdose
• brainstem lesions
• skeletal muscle weakness
• asthma
• COPD
• obstructive sleep apnea

Symptoms of Hypercapnia

Hypercapnia that develops slowly over time and is extremely mild may not reveal any symptoms at all. If symptoms do occur, they may initially be in the form of:

• headache
• inability to think straight
• drowsiness/sleepiness

Symptoms of severe hypercapnia may eventually lead to respiratory failure and possibly death, and may include:

• flushed skin
• dizziness
• rapid breathing
• increased blood pressure
• increased heart rate
• muscle twitches

Treatment for Hypercapnia

Treatment for hypercapnia depends upon its severity, and starts with addressing the underlying cause. If this is ineffective, additional treatment may include:

• non-invasive positive pressure ventilation (CPAP, BiPAP)
• intubation and mechanical ventilation

When to Call the Doctor

The fact that hypercapnia can be a potentially fatal condition leading to respiratory failure and death should alert COPD patients and their caregivers to be aware of the symptoms of hypercapnia, and to call their primary care provider for any change in condition as soon as possible.

_Sources:

_{Disorders of Gas Exchange: Hypercapnia and Hypoxia. Stanford University.}

_{Toxicity of Carbon Dioxide Gas Exposure, CO2 Poisoning Symptoms, Carbon Dioxide Exposure Limits, and Links to Toxic Gas Testing Procedures. http://www.inspectapedia.com/hazmat/CO2gashaz.htm}