Ele tem pulmões e eles foram feridos por Mace Windu nas Guerras Clônicas (Capítulo 25)
As he fled, Jedi Master Mace Windu Force crushed the plates covering Grievous's internal organ sac, injuring his lungs and aggravating the General's already irritating wheezing and coughing problems; a result of his organic form not taking well to his cyborg implants. This crippling blow injured Grievous for the rest of his life