Warming Prior to Heel Stick: Blood Sample Quality and Infant Comfort-A Randomized Controlled Trial.
Ulla List Toennesen, Helene Kierkegaard, Poul-Erik Kofoed and 4 others
PMID 37824830WHAT IT FOUND
Warming the heel with a glove, gel pack, or blanket made no difference to blood flow, sample quality, or infant comfort.
However, warming an already warm heel (above 37.0°C) was linked to more bruising and swelling. Skip warming if the heel is already warm.
Key findings
01There was no significant difference between the three warming methods (glove, gel pack, blanket) for the primary outcome of blood flow velocity, nor for hemolysis index or COMFORTneo pain scores.
02Heel skin injuries (bruising or swelling) increased as the baseline heel skin temperature before warming increased, with most injuries occurring when the heel was already above 37.0°C.
03The glove method resulted in the highest heel skin temperature after warming, while the blanket resulted in the lowest, but this temperature difference did not translate to better procedure quality.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The study did not include a control group that received no warming, so it cannot determine if warming itself is beneficial compared to no warming. Heel appearance was only documented for 154 of the 173 procedures due to high nursing workloads, which reduced the statistical power for the injury outcome. Infants received multiple concurrent pain-relieving interventions (sucrose/milk, holding, swaddling), making it difficult to isolate the specific effect of warming on comfort.
Declared interests
The authors declare no conflicts of interest.
The easy way to misread this
Do not conclude that heel warming is ineffective or harmful. The study only compared three warming methods against each other; it did not test warming against no warming. The null result means the methods are equivalent, not that the practice lacks value.