What is hypercapnia and how does it affect patient intervention?

By Cristiano Antonino On Feb 28, 2023

Hypercapnia is an accumulation of carbon dioxide in the blood. It affects people with chronic obstructive pulmonary disease (COPD)

COPD sufferers cannot breathe as easily as other people

The inflamed airways and damaged lung tissue make it more difficult to inhale the necessary oxygen and exhale the carbon dioxide that the body wants to get rid of.

Hypercapnia is not a problem for everyone with COPD and may not occur

Your doctor has probably suggested medication to facilitate breathing.

You may also use supplemental oxygen.

Oxygen is breathed in through a mask or nose plug connected by tubes to a device called a concentrator, which acts like a pump to filter and provide a clean, constant flow of air.

What happens in case of hypercapnia?

Hypercapnia alters the pH balance of the blood, making it too acidic.

This phenomenon can occur slowly or suddenly.

If it happens slowly, the body may be able to keep up by making the kidneys work harder.

The kidneys release and reabsorb bicarbonate, a form of carbon dioxide that helps keep the body’s pH level balanced.

A sudden increase in carbon dioxide, called acute hypercapnia, is more dangerous because the kidneys cannot handle the spike.

This is more likely to happen if you suffer from a severe form of COPD or have a flare-up.

In any case, it is possible that breathing is too slow, which means that air is not being sucked in and carbon dioxide is not being expelled at a healthy rate.

Acute hypercapnia can also occur if one starts taking a drug that gives drowsiness, such as a narcotic painkiller, after an injury or surgery.

These drugs, known as sedatives, can slow down the respiratory rate.

Acute hypercapnia is a life-threatening emergency.

If it is not treated promptly, one can stop breathing, have a seizure or go into a coma.

Symptoms of hypercapnia

The signs generally depend on the severity of hypercapnia.

Mild to moderate hypercapnia that develops slowly usually causes:

Anxiety
Shortness of breath
Daytime sluggishness
Headaches
Daytime sleepiness even if one has slept a lot at night (the doctor might call it hypersomnolence)

Acute hypercapnia can cause

Delirium
paranoia
Depression
confusion

If left untreated, it can lead to coma.

Severe hypercapnia can lead to

Tremors in the hands (asterixis)
sudden, brief muscle jerks (myoclonus)
epileptic seizures

Pressure in the brain (papilledema) that causes enlargement of the optic nerve and can lead to

headaches
nausea
Vision problems

Varicose veins (the doctor may call them dilated superficial veins).

If you notice any of these symptoms, call your doctor immediately. It may be necessary to go to hospital.

Causes of hypercapnia

They can be many, including:

Diseases of the brainstem
Encephalitis
Hypothermia
Metabolic disorders, including hypothyroidism and hyperthyroidism
Nervous system disorders, such as congenital central alveolar hypoventilation
Obesity
Sedative overdose
Sleep apnoea
Spinal cord injuries or disorders such as Guillain-Barré syndrome, myasthenia gravis and muscular dystrophy
Starvation
Stroke
Thoracic cage disorders such as flail chest and ankylosing spondylitis
Toxins, poisoning and drugs such as botulism and tetanus
Upper airway disorders
Diagnosis of hypercapnia

The doctor

take a medical history and examine the body for causes.
He or she will check your breathing. If you need help, you may receive supplementary oxygen. Or you may need a tube that enters the airway and connects to a machine that helps you breathe (ventilation).

You will order blood tests:

Arterial blood gas test: This test measures the levels of oxygen and carbon dioxide in your blood. The doctor takes some blood from an artery, usually from the wrist. The sample is sent to a laboratory where oxygen and carbon dioxide levels are measured.
Chemical analysis: Checks the level of salts (electrolytes and bicarbonates) that are formed when the body processes carbon dioxide.
Complete blood count: Low oxygen levels in the blood due to lung disease can be linked to an elevated red blood cell count. These other tests can be performed to search for causes:
Toxicological test
Thyroid function test
Creatine phosphokinase test
Diagnostic imaging tests to check that there is no physical problem in the lungs, brain or spinal cord.

Treatment

Do not attempt to treat hypercapnia on your own.

You must receive instructions from your doctor.

If you normally use supplemental oxygen, taking more could make the problem worse.

In the case of COPD, an excessive amount of oxygen could make people lose the ability to breathe.

If hypercapnia occurs, but is not too severe, your doctor may treat it by asking you to wear a mask that blows air into your lungs.

You may have to go to hospital to undergo this treatment, but your doctor may allow you to do so at home with the same type of device used for sleep apnoea, a CPAP or BiPAP machine.

If the hypercapnia is severe and you lose consciousness, a ventilator is necessary.

How to reduce the risk of hypercapnia

It is not always possible to prevent hypercapnia, but you can reduce its likelihood if you follow your doctor’s instructions for managing COPD.

Always take the suggested medication and use supplemental oxygen as directed by your doctor.

In addition, you should not use drugs that help you relax or sleep too often (your doctor will call them sedatives).

These include narcotics for pain relief and benzodiazepines, such as Xanax and Valium, for anxiety or insomnia.

If you need one of these drugs, review the dose with your doctor and watch out for side effects.

If you take supplementary oxygen and your doctor says you are at high risk of hypercapnia, it is advisable to keep a device called a finger pulse oximeter at home.

With this device you can check that your oxygen levels are not too high, which increases the likelihood of hypercapnia.

Pay attention to the warning signs of hypercapnia.

If you feel unusually short of breath, very sleepy or easily confused, contact your doctor immediately.

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