Chapter 34 Pediatric Postoperative Pain Flashcards
KEY POINTS 1. Anatomic and physiologic differences in neonates and young infants necessitate lower doses of epidural local anesthetics and intravenous opioids up to 4 to 6 months of life. 2. Behavioral or physiologic measures of pain intensity are available for infants and children unable to selfreport their pain. 3. Aspirin is not routinely used for postoperative pain control in children because of an association with Reyes syndrome, a potentially fatal hepatoencephalopathy. 4. Epidural ana
Total body water represents about what in full-term newborns
80% of body weight
Total body water represents about what in 2 years of age,
This drops to 60% of body weight by 2 years of age, with a large proportional decrease in extracellular fluid volume.
The larger extracellular and
total body water stores in infancy lead to
a greater volume
of distribution for water-soluble drugs.
Newborns have
smaller skeletal muscle mass and fat stores and have what effect on
decreasing the amount of drug bound to inactive sites in muscle and fat. These stores increase during infancy.
Immaturity of the blood–brain
barrier in early infancy allows
increased passage of more
water-soluble medications such as morphine
The combination of increased blood flow to the brain and increased drug passage through the blood–brain barrier can lead to
higher central nervous system drug concentrations and
more side effects at a lower plasma concentration.
Renal and hepatic blood flow in infants
Renal and hepatic blood flow is also increased in infants
relative to adults. As glomerular filtration, renal tubular function and hepatic enzyme systems mature, generally reaching adult values within the first year of life, increased blood flow to these organs leads to increased drug metabolism and excretion.
serum albumin and a-1 acid glycoprotein (AAG)
the quantity and binding ability of serum albumin and a-1 acid glycoprotein (AAG) are decreased in newborns
relative to adults. This may result in higher levels of
unbound drug, with greater drug effect and toxicity at
lower overall serum levels.
Effect of serum albumin and a-1 acid glycoprotein (AAG) in neonates on local anesthetic dosing
This has led to lower local
anesthetic dosing recommendations in neonates and young infants, although neonates have shown the ability
to acutely increase AAG levels while on continuous local
anesthetic infusions
spinal cord and dura mater in the newborn
The spinal cord and dura mater in the newborn and
infant extend to approximately the third lumbar (L3) and
third sacral (S3) vertebral level, respectively, and reach the
adult levels of approximately L1 and S1 to S2 by about
1 year of age.
The intercristal line connecting the posterior superior iliac crests, used as a surface landmark during needle insertion,
crosses the spinal column at the S1 level in neonates versus the L4 or L5 level in adults.
Children over approximately 8 to 10 years of age pain assessment
able to use the standard adult numeric rating
or visual analog scale to self-report their pain
Children under 8 years of age pain assessment
Behavioral or physiologic measures are available
for younger ages and for developmentally disabled
children
Acetaminophen (paracetamol)
very commonly used in
pediatric patients, alone or in combination with other analgesics. It is often administered rectally in the perioperative period in infants or children for whom oral intake is not an option
Acetaminophen (paracetamol) side effect
Dose-dependent hepatotoxicity is the most serious acute side effect of acetaminophen
administration.
intramuscular, and rectal NSAID administration in pediatric surgical patients demonstrate
reduced postoperative
pain scores and decreased supplemental analgesic requirements.
Adverse Effects of NSAID
Bleeding, renal damage, and gastritis are
more likely to occur with prolonged administration and in
the presence of coexisting disease.
Why are Acetaminophen and NSAIDs given in
combination?
they work by different mechanisms and
their toxicity does not appear to be additive.
Aspirin is not used for postoperative pain management in
infants and children because
highly significant association
with Reye syndrome
Reye syndrome
acute, fulminant,and potentially fatal hepatoencephalopathy that
occurs in children with influenza-like illness or varicella
who ingest aspirin-containing medications
Acetaminophen*
oral
10–15 mg/kg
Acetaminophen*†
rectal
35-40 mg/kg loading dose;
20 mg/kg thereafter
Ibuprofen
6–10 mg/kg
Naproxen
5–6 mg/kg
Ketorolac
0.3–0.5 mg/kg IV
Tramadol
1–2 mg/kg
Codeine (Oral)
dose of 0.5 to 1 mg/kg and
often in combination with acetaminophen for mild to moderate
pain
Morphine
0.3 mg/kg
Hydrocodone
0.1–0.2mg/kg
Oxycodone
0.1–0.2mg/kg
Hydromorphone
0.04–0.08mg/kg
Methadone
0.1–0.2mg/kg
Patient-Controlled Analgesia
Morphine
Loading dose (over 1–5 min): 0.05–0.20 mg/kg
Demand dose: 0.01–0.02 mg/kg
Lockout time: 5–15 min
1-hr limit (optional): 0.10–0.20 mg/kg
Continuous infusion (optional): 0.01–0.02 mg/kg/hr
Patient-Controlled Analgesia
Hydromorphone
Loading dose (over 1–5 min): 1–4 mg/kg Demand dose: 2–3 mg/kg Lockout time: 5–15 min 1-hr limit (optional): 30–40 mg/kg Continuous infusion (optional):2–3 mg/kg/hr
Patient-Controlled Analgesia
Fentanyl
Loading dose (over 1–5 min): 0.5–2.0 mg/kg
Demand dose: 0.2–0.4 mg/kg
Lockout time: 5–15 min
1-hr limit (optional): 3–4 mg/kg
Continuous infusion (optional): 0.2–0.4 mg/kg/hr
parent- or nurse-assisted epidural analgesia
used to optimize dosing flexibility and pain
relief given via the epidural route.
Compared to adults given morphine, neonates and premature infants have
a longer elimination
half-life, lower plasma clearance, and marked interindividual variability in plasma morphine concentration. For a given dose, they will achieve a higher plasma concentration
for a longer duration.
“SINGLE-SHOT” CAUDALS indications
SSC is
used in infants and children up to approximately 10 to
12 years of age having surgery from lumbosacral to midthoracic
dermatome levels with anticipated moderate
postoperative pain.
“SINGLE-SHOT” CAUDALS medications
Bupivacaine in concentrations of 0.125% to 0.25% is the most commonly used and studied
local anesthetic for SSC. Injection volumes of 0.5 to
1.5 ml/kg will provide upper-lumbar to low-thoracic levels,
respectively. An upper volume limit of 20 ml is generally
used. The maximum recommended bupivacaine dose is 2.5 to 3.0 mg/kg, with an upper limit of 1.25 mg/kg
recommended in early infancy
“SINGLE-SHOT” CAUDALS
test dose
0.1 ml/kg (maximum 3 ml) of local anesthetic with 1:200,000 epinephrine (5 mg/kg) is used to ensure correct needle or catheter position. A 25% increase in T-wave amplitude, 10-beat/min increase in heart rate, or 10% increase in systolic blood pressure within 60 s of administration is
considered a positive test dose.
additives to prolong the duration and/
or density of analgesia
bupivacaine can be combined
epidurally with fentanyl, morphine, the a-2-adrenergic agonist clonidine
Pediatric Epidural Dosing
Bupivacaine
Initial Bolus: <0.4–0.5 mg/kg/hr
Pediatric Epidural Dosing
Ropivacaine
Initial Bolus < 0.4–0.5 mg/kg/hr
Pediatric Epidural Dosing
Fentanyl
Initial Bolus: 1–2 mcg/kg
Infusion Solution: 2–5 mcg/ml
Infusion Limits: 0.5–2 mg/kg/hr
Pediatric Epidural Dosing
Morphine
Initial Bolus: 10–30 mcg/kg
Infusion Solution: 5–10 mcg/ml
Infusion Limits: 1–5 mcg/kg/hr
Pediatric Epidural Dosing
Hydromorphone
Initial Bolus: 2–6 mcg/kg
Infusion Solution: 2–5 mcg/ml
Infusion Limits: 1–2.5 mcg/kg/hr
Pediatric Epidural Dosing
Clonidine
Initial Bolus: 1–2 mcg/kg
Infusion Solution: 0.5–1 mcg/ml
Infusion Limits: 0.1–0.5 mcg/kg/hr
Lower infusion
rates are generally recommended in neonates and infants
less than 3 to 6 months old because
lower protein binding and consequently higher free fractions of drug, and because of pharmacokinetic differences potentially resulting in higher plasma levels and prolonged drug
half-life.
As a rule, optimal analgesia is obtained with
the catheter tip positioned
at or near the dermatomes to
be blocked. It is possible in infants and smaller children to
thread caudally inserted catheters to lumbar or thoracic
levels
