The effect of fentanyl addition to bupivacaine on shivering and vomiting nausea in patients undergoing femoral fracture surgery by spinal anesthesia: A double-blind randomized clin... oleh javad vagharfard, ahmad rastgarian, Mohammad Rahmanian, masomeh pourmokhtari, mohammad hasan damshenas, samira taban, hasan zabetian, navid kalani, naser hatami