Optimal volume for the draw-and-return methods to enhance activated partial thromboplastin time ratio accuracy in hemodialysis patients with central venous catheters oleh Chitrada Thongdee, Lalita Lumkul, Pakpoom Wongyikul, Nantana Spilles, Boonruksa Laonapaporn, Jayanton Patumanond, Phichayut Phinyo