After placing the tip of the needle in the ligamentum flavum, a syringe containing 2 to 3 mL of saline and an air bubble is attached. The dominant hand maintains constant pressure on the syringe plunger while the nondominant hand rests against the patient's back and is used to slowly advance the needle. If the needle is properly placed in the ligamentum flavum, it will be possible to compress the air bubble without injecting the saline. As the needle tip enters the epidural space, there will be a sudden loss of resistance, and the saline will be easily ejected from the syringe.