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Decreasing Venipuncture Pain: Should You Insist on This New Device for Blood Draws in Young Children? :

February 10, 2016

I'm not ready to jump on the bandwagon to recommend all pediatric providers use this device for blood draws, but the authors of this article provided one of the best descriptions of study limitations I've seen in a long time.


I'm not ready to jump on the bandwagon to recommend all pediatric providers use this device for blood draws, but the authors of this article provided one of the best descriptions of study limitations I've seen in a long time.

Source: Lunoe MM, Drendel AL, Levas MN, et al. A randomized clinical trial of jet-injected lidocaine to reduce venipuncture pain for young children. Ann Emerg Med. 2015;66(5):466-473; doi.org/10.1016/j.annemergmed.2015.04.003. See AAP Grand Rounds commentary by Dr. Pamela Okada (subscription required).

PICO Question: Among young children undergoing venipuncture, does jet-injected lidocaine reduce pain more effectively than vapocoolant spray or sham?

Question type: Intervention

Study Design: Randomized controlled

A group in 1 tertiary pediatric emergency department randomized 205 children ages 1 - 6 years who were about to undergo venipuncture. They were randomized into 3 groups: half went into the intervention group and received 0.2 mL of 1% buffered lidocaine, administered at the subsequent venipuncture site via a needle-free jet injection system, followed by a spray of normal saline at the site; 1/4 of the children entered into a control group, receiving only a vapocoolant spray; the final 1/4 was a sham group, where an empty jet device was deployed near the site, followed by vapocoolant spray. The authors stated they did not have a true placebo group because vapocoolant spray was the standard of care at their institution and they did not consider a placebo group to be ethical (more on this later). They found that the group receiving lidocaine via jet injection had less venipuncture pain than in the control and sham groups, but somewhat hidden in the results is the fact that the sham group (vapocoolant followed by saline spray) actually had lower pain scores at venipuncture than did the control (vapocoolant only) group, a finding in at least 1 other study. (This actually makes sense, as the authors state, by considering the gate theory of pain.)

 In terms of study design, the authors did about as well as possible given the complexities of the clinical question. With any study involving a commercial device, I look immediately to see if the company funded or influenced the study somehow. In this case, the company supplied the devices and supplies, but no funding or input on study design. Also, none of the authors received support from the company for the usual things that might cause conflict of interest, such as serving on speakers' bureaus or as paid "consultants."

 The main outcome of this study, pain, is a subjective measure, so I wanted to know how pain was measured, and how well the measurement was validated in this setting. Here, the authors used the FLACC (Face, Legs, Activity, Cry,  Consolability) Scale. I looked up the reference the authors used to state the scale is validated, and as expected this can be an exercise in circular reasoning, since we really have no gold standard for pain in young children. If you're interested in learning more, 1 article provides a good discussion of many of the issues. Also, it's difficult to ensure that outcome raters are truly blinded to group assignment. The authors expended considerable effort, since the patients and families might not have been completely blinded to group assignment, to blind the FLACC scorers.

 However, the real problem with this study is that the authors' "gold standard" for venipuncture pain control, the vapocoolant spray, actually may be no better than placebo. In their discussion, they mention a systematic review suggesting that vapocoolant spray was ineffective in this setting; the review was published after this jet injection study was performed, but these authors must have been aware that controversy existed at the time they were developing their randomized controlled trial. Even though they mention a standard of care at their institution, I suspect if they had wanted to include a true placebo group (i.e. a group receiving no vapocoolant spray), they could have made the case to their hospital ethics committee, but of course I don't know that to be the case.

 I'm all for reducing procedural pain in children, but as Dr. Okada stated in her AAP Grand Rounds commentary, we shouldn't discard the use of distraction or physical comfort techniques in these circumstances. She also mentioned a recent review on the su
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