Over half of the procedures were peripherally inserted central catheter (PICC). When results for the different procedures were analysed separately, the results were only statistically significant for this (18.8 ± 25.6 mm vs 12.2 ± 18.2 mm; P=0.02); however analyses of the other groups are likely to have been underpowered. The authors note that the observed difference did not meet the minimally clinically important difference in VAS score (10mm); however as there were low VAS scores in the control group, achievement of this would have required the scores for the intervention to be in single digits.
They say their findings suggest incremental benefit for the intervention over established procedural analgesia, and hypothesize that the temperature of the solution (cooler than body temperature) generates sensory nerve traffic within the spinal cord dorsal horn that can “gate” or inhibit the noxious signal from the lidocaine injection.