Heat treatment will kill the bedbugs as long as the temperature is high enough and the entire couch is subjected to the treatment. All items in the bedbug-infested room should be treated for pest control, not just the couch.
Bedbugs cannot survive for more than 60 seconds in temperatures of at least 120 degrees Fahrenheit. Therefore, it is possible to kill bedbugs in a couch by heating the couch to at least 120 degrees Fahrenheit. This can be achieved by either manually heating the entire couch surface with a hair dryer or using a consumer product, such as a portable thermal chamber, to completely encase the couch (and subsequently heat the couch).