1) Hypocapnia 2) Physiological condition 3) Physiological state 
lack or deficiency of carbon dioxide
Less than the normal level of carbon dioxide in the blood. The opposite of hypercapnia. ... (12 Dec 1998) ... 
Medical condition in which there is a low concentration of carbon dioxide in the blood.
Type: Term Pronunciation: ă-kap′nē-ă Definitions: 1. Absence of carbon dioxide in the blood; sometimes used erroneously for hypocapnia.
Acapnia: Less than the normal level of carbon dioxide in the blood. The opposite of hypercapnia. The origin of the word 'acapnia' is curious. It comes from the Greek 'a-' meaning 'without' + 'kapnos' meaning 'smoke' so acapnia literally means 'smokeless' referring to carbon dioxide which is a principal part of smoke.
acapnia 1. A condition marked by the presence of less than the normal amount of carbon dioxide in the blood and tissues; sometimes used erroneously for hypocapnia.2. The total absence of carbon dioxide in the blood. Such an absolute absence does not occur in living organisms. Also, acarbia.3. From New Latin, Latin acapnos, without smoke, from Greek...
a deficiency of carbon dioxide in the blood and tissues.