Agree with use of smaller gauge needle as suggested above, perhaps with ultrasound guidance if available
I do want to touch on the nitroglycerin suggestion as well because I think it's important; Nitroglycerin is a strong venodilator and health professionals are generally recommended to wear gloves when contacting this substance. Why is that? Dilating out veins quickly in this way can cause a drop in your arterial blood pressure, which could cause someone to pass out. As above, risks would be far outweighed by the benefits.