Testing is hardly necessary, and I often omit it. I use an alcohol wipe to test. I ask the patient if it feels cold on her arm. I then wipe it up the abdomen, starting from the inguinal region and heading up to the nipple in mid-clavicular line, and ask the patient to tell me when it feels cold. If it never feels cold, I try on the shoulder.
Most patients can say where the block has got to.
If it is above the umbilicus at five minutes, I position the patient slightly head up. The block comes on more rapidly than surgeons can scrub, prep, drape, and catheterise the patient. Most surgeons will test by pinching the site of incision with a clamp. Patients are not usually aware of this happening. Hypotension is a frequent problem.