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Pediatric Pacing
Children
and infants can require noninvasive pacing
by Linda Del Monte,
BSN, clinical consultant, Physio-Control
It’s 10 a.m. and
relatively quiet in the ED when suddenly paramedics rush in with a
two-year-old, 28-pound child. The parents tell you their daughter
ingested an un-known amount of her grandfather’s propranolol tablets.
The child presents asymptotic, though somewhat fussy, but about five
minutes later becomes lethargic. A quick look at the monitor indicates
profound bradycardia with a heart rate of 55. Atropine is given with no
increase in heart rate. The physician orders noninvasive pacing at a
rate of 90 ppm.
Your mind races. You’ve
never paced a child so small before...you wonder what capture threshold
you should expect...what about electrode placement...electrode size...
anything different to be expected in a small child?
The answer is yes.
During the last decade
noninvasive pacing has been an increasingly accepted therapy for adults
and now thanks to the availability of pediatric pacing electrodes, this
therapy is feasible and practical for infants and small children as
well.
Bradycardia is the most
common dysrhythmia in children and is usually secondary to hypoxic
events. Although noninvasive
pacing may be attempted, typically bradycardias of hypoxic etiology do
not respond. First line therapy is prompt airway support, ventilation
and oxygenation.
Although less frequent
in occurrence, children and infants do experience heart blocks and
bradycardias where treatment with noninvasive pacing is indicated and
could be lifesaving.
Indications for
pediatric noninvasive pacing are: bradycardias from surgically acquired
AV blocks, congenital AV block, viral myocarditis, newborn complete
heart block due to maternal lupus, heart block secondary to toxin or
drug overdose, permanent pacemaker generator failure or lead wire
fracture, and epicardial pacing wire failure (post cardiac surgery).1
Stand-by noninvasive
pacing should be available during general anesthesia in patients with
complete heart block, during pacemaker reprogramming, in the cath lab
for potential AV block during anatomic study, and to treat bradycardia
post electrical cardioversion of tachyarrhythmias.
Noninvasive pacing
As with any procedure,
patient and family preparation is key for success. Before initiating the
procedure, sedation should always be considered. The skeletal muscle
contractions associated with noninvasive pacing, along with the
discomfort associated with the procedure, is quite frightening to
parents and child. Without sedation, patient cooperation can’t be
expected.
The landmarks for
pacing electrode placement are the same for adults and children, however
placement on a child is more challenging due to the limited size of the
torso. Anterior/posterior is the most common pacing electrode placement.
Anterior-lateral placement is also acceptable but will take up more
space on an already crowded chest. In order to obtain a clear tracing on
the monitor, ECG electrodes should be placed well away from the pacing
electrodes.
Pediatric pacing
electrodes should be used on children who weigh less than 33 pounds. The
larger "adult" size pacing electrodes should be used as soon
as they fit on a child’s chest without overlap of the sternum, spine
and diaphragm.
Capture thresholds in
children are similar to those in adults. This may seem odd, given the
much smaller size of children. Studies indicate no relationship between
body surface area, weight, and capture thresholds and although many
children will achieve capture between 50-100 mA,1 higher current
requirements are possible. The pacing rate must be set high enough to
perfuse the patient.
Potential
complications/interventions
Burns have been
reported in small children after noninvasive pacing.2 Newborn skin is
especially fragile and adult-like current passing through the smaller
electrode surface produces relatively high current densities. Frequent
inspections of the skin under the pacing electrodes should be done after
30 minutes of continuous pacing.
The skeletal muscle
contractions associated with noninvasive pacing can be quite intense in
the smaller child and can cause respiratory distress in infants and
younger children. Ventilatory support should be available. If possible,
position the electrode to avoid the diaphragm. The addition of
neuromuscular blockers will eliminate the contractions and may
considered in intubated children.1
Although noninvasive
pacing in adults has been well documented, the procedure has not been as
well studied in children. One incident of ventricular tachycardia
related to noninvasive pacing has been reported in the literature.3 It
involved a critically ill three year old boy in a state of
cardiovascular collapse.
Summary
Noninvasive pacing
offers a rapid and effective way to institute ventricular pacing in
children. It can be easily initiated by paramedics, nurses, and
physicians. The introduction of pediatric pacing electrodes makes pacing
of infants and small children possible. Although the effectiveness of
noninvasive pacing in children is variable and the need is infrequent,
the technique can be lifesaving in certain conditions.
Pediatric noninvasive
pacing follows the same principle as adult pacing but special attention
must be paid to the unique needs of infants and younger children.
References
1 Beland MJ.
"Noninvasive transcutaneous cardiac pacing in children." In
Noninvasive Transcutaneous Cardiac Pacing. 1993;91-98. Futura Publishing
Company, Inc., Mount Kisco, NY.
2 Pride HB, McKinley
DF. "Third-degree burns from the use of an external cardiac pacing
device." Crit Care Med. 1990;18:572-573.
3 Beland MJ, Hesslein
PS, Rowe RD. "Ventricular tachycardia related to transcutaneous
pacing." Ann Emerg Med. 1988;17:279-281.
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