What would cause a 2 y.o to take deep breaths every 20 seconds when relaxed watching tv. no other symptoms.. started after cold/virus a month ago..

Atelectasis: A big "sigh" breath is the body's mechanism from trying to prop open parts of the lung that have become under-filled or deflated. The other possibility is bronchospasm. Usually we think of wheezing and shortness of breath, but I have seen younger kids "cope" with chest tightness by yawning or deep sigh'ing. See your pediatrician for evaluation to rule out either of the above possibilities.

Reactive airway: Viruses can cause reactive airway and wheezing in susceptible individuals.i would make an appointment with the Pediatrician to make sure there is no bronchi spasm or wheezing.

Hyperreactive airway: This is a fairly common presentation for a new onset asthma or hyper reactive airways disease. Have your pediatrician take a careful evaluation and see if he is having some prolonged expiration, cough or wheeze. Good Luck :)