Comparison of Prophylactic Effects of Polyurethane Cylindrical or Tapered Cuff and Polyvinyl Chloride Cuff Endotracheal Tubes on Ventilator-Associated Pneumonia - Mahmoodpoor, Ata; Peyrovi-far, Ali; Hamishehkar, Hadi; Bakhtyiari, Zhaleh; Mirinezhad, Mir Mousa; Hamidi, Masoud; Golzari, Samad Eslam Jamal (Acta Medica Iranica)