Systemic Absorption of Lidocaine After Hematoma Block
Status:
Recruiting
Trial end date:
2021-05-01
Target enrollment:
Participant gender:
Summary
This study will measure in children how much numbing medicine, lidocaine, is absorbed into
the bloodstream after it is injected into a blood clot (hematoma) around a forearm fracture
for pain control when the broken bone is moved back into place (fracture reduction). This is
called a hematoma block and is commonly used in the Emergency Unit. To help with anxiety and
to add additional pain control, nitrous oxide (laughing gas) is given while the lidocaine
hematoma block is placed and continued during the fracture reduction. Advantages of using
this technique for pain control instead of an intravenous anesthetic such as ketamine include
faster recovery and discharge home, and longer pain control.
Of concern, if too much lidocaine is absorbed into the bloodstream, seizures and irregular
heart beating may occur. Bloodstream concentrations of lidocaine after a hematoma block have
been measured in only one study of 8 adults and found to be at significant but safe levels.
No study has been published in children to measure bloodstream lidocaine levels when a
hematoma block is used. Because children's bones are still growing and more metabolically
active than adult bones, the investigators believe it is important to determine whether
lidocaine blood levels in children are also at safe levels when using a standard lidocaine
hematoma block for reduction of fractures. The investigators also want to determine whether
bloodstream lidocaine levels correlate with type of fracture, size of the fracture hematoma
and effectiveness of pain control during fracture reduction.
The investigators also aim to determine if there is a difference in absorption pattern
between different types of distal radius fractures, if there is a correlation between
fracture type and systemic lidocaine absorption, if there this a correlation between fracture
type and fracture hematoma size, and if there is a correlation between fracture type and
ability to provide adequate pain and sedation control with lidocaine hematoma block/inhaled
nitrous combination. The investigators believe blood lidocaine levels after hematoma block in
children will peak at safe levels, but will be higher than those observed in adults. They
believe that a more displaced fracture will have a larger hematoma, that a larger hematoma
will be associated with a higher peak blood lidocaine level, and that a higher peak blood
lidocaine level will be associated with more successful pain control scores and satisfaction
with the procedure.