What is hypercapnia?

In November 22, 2015, a woman felt uncomfortable while she was driving through Highway No.3 in Nantou, Taiwan. Because her daughter was fainted in the same vehicle, she called the police.

When the police arrived, they found that she did not turn on the air-conditioning. She switched to circulation, which did not allow fresh air to come in.

I often found it curious why our car has a setting "circulation". Although it can prevent bad smell coming from outside to enter our car, but it also prevent fresh air from coming in. If we drive for a long time and leave the setting on "circulation" (like this woman did), you may suffer from hypercapnia.

What is hypercapnia?

The prefix hyper-, we is from Lesson 6-1, meaning above.

The prefix capn- is introduced in Lesson 17-1, meaning carbon dioxide. It can also be written as capno-, depending on what letter connecting to it.

The suffix -ia is introduced in Lesson 16-4, meaning condition.

Putting them together, hypercapnia is a condition of abnormally elevated carbon dioxide (CO₂) levels in the blood.

According to Wikipedia, hypercapnia normally triggers a reflex which increases breathing and access to oxygen, such as arousal and turning the head during sleep. A failure of this reflex can be fatal, for example as a contributory factor in sudden infant death syndrome.

Symptoms and signs of early hypercapnia include flushed skin, full pulse, tachypnea (abnormally rapid breathing), dyspnea (difficult in breathing), extrasystoles (a heartbeat outside the normal rhythm), muscle twitches, hand flaps, reduced neural activity, and possibly a raised blood pressure. According to other sources, symptoms of mild hypercapnia might include headache, confusion and lethargy. Hypercapnia can induce increased cardiac output, an elevation in arterial blood pressure, and a propensity toward arrhythmias.

Recently, a research paper suggested if the carbon dioxide in the ocean keeps rising, the fish will also suffered from hypercapnia too!

Source: Wikipedia

Hypercapnia is also called carbon dioxide toxicity. It will happen within 30 minutes when the concentration of carbon dioxide reach 6%.

Next time when you are going for a long ride with your family, please remember to check the air-conditioner's setting!

Reference :

民視新聞。2015/11/22。國道驚魂!車內只開循環 女副駕缺氧昏厥。

Wikipedia. Hypercapnia.

Ben I. McNeil & Tristan P. Sasse. 2016. Future ocean hypercapnia driven by anthropogenic amplification of the natural CO2 cycle. Nature. 529, 383–386