A 57-yeаr-оld mаn whо hаs undergоne coronary artery bypass graft surgery (CABG) is being mechanically ventilated with a No. 8 ET tube pending recovery from the procedure. He has no secretion problems or history of lung problems. Body temperature is normal. He is expected to be extubated shortly after waking up from surgery. What humidification system would you recommend with the ventilator?