Pain from IV Cannula Insertion: Does Size Matter?

It is widely believed that "smaller is better" when it comes to pain from IV catheter insertion, but no formal comparison has been conducted. This author, from the U.K., randomized 25 blindfolded volunteers to insertion of 20- and 22-gauge catheters, one in each hand. The choice of hands and order of catheter sizes were random. No local anesthesia or alcohol-containing skin preparation was used.

Twelve subjects found the 22-gauge catheter more painful, and the remaining 13 found the 20-gauge catheter more painful, a nonsignificant difference. There was no effect of which hand was used first or which size catheter was inserted first.