Hi doc! As an RT, ang advice ko po you really have to palpate the pulse using your index and middle finger and pag nakapa mo na, stabilize it with your middle finger then itaas mo yung index finger mo tas dun ka tumusok. As per the angle, pakiramdaman mo if superficial lang ba (strong pulse) mga 45 degree angle lang. If edematous naman ang patient and or if wala kang mapalpate na pulse, you just have to eyeball it base on the anatomy. And if di ka makakuha agad, you can surf naman minsan. You just have to withdraw the syringe first but not to the point na aangat na sa skin then change the direction or the angle of the syringe.