BDNF and respiratory failure: The relevance of neurotrophins in lung hyperactivity was found to be particularly important in children with an acute RSV infection in a study carried out in 2005 that found significantly more elevated levels of BDNF and NGF in the bronchoalveolar lavage (BAL) of mechanically ventilated infants positive to RSV, in comparison to mechanically ventilated infants with respiratory failure caused by adenoviral or parainfluenza infections [28, 29].