An underlying respiratory condition may undermine the prospect of recovery, but this is not always easy to predict .A patient with mild emphysema may suffer a bad bout of flu and recover unscathed after a few days, while others might end up condemned to the ventilator for ever. Co-morbidities, previously existing or newly acquired, will weigh in when deciding whether to go ahead or not. Constant progress and a team daring to challenge current clinical wisdom keep pushing the boundaries of what will be successful.