Pediatric Anesthesia Quiz #4

Question 1

How does lethal dose and sensitivity to pharmacological agents compare between neonates and infants with adults?

Answer 1

• Laboratory data have demonstrated the lethal dose in 50% of animals for many medications to be significantly less in neonatal animals than adult animals.
• The sensitivity of human neonates to most sedatives, hypnotics and narcotics is clinically well known and may in part be related to increased brain permeability(immature BBB) for some meds
• Incomplete myelination in infants may make it easier for drugs that are not particular lipid soluble to enter the brain at a greater rate than if the BBB were intact.

Question 2

What are three characteristics of inhaled pharmacokinetics of children versus adults?

Answer 2

VOLATILE [] INCREASES MORE RAPIDLY IN THE ALVEOLI IN CHILDREN THAN ADULTS. THIS RESULTS IN:

1. high level alveolar ventilation in relation to FRC
2. higher proportion of vessel-rich tissues that rapidly equilibrate with blood levels
3. lower blood-gas partitions coefficients of volatile anesthetic in infants

excretion/recovery of inhaled anesthetics is also faster in children than adults(QUICK ON-QUICK OFF)

Question 3

N2O speeds up induction and recovery(second gas effect), might cause analgesia for “difficult IV sticks”. Any gas-filled cavities within the body are vulnerable for expansion if nitrous is administered including…..

Answer 3

obstructed bowel, pneumothorax, cuff of ETT, LMA, bubbles in veins…..

Theoretically nitrous oxide should be avoided during lap surgery to avoid expanding CO2 bubbles that reach venous circulation

Question 4

Hyperoxia is considered one of many factors causing retinopathy of prematurity(ROP) in infants……(2 things)?

Answer 4

1. infants weighing less than 1500 grams

2. less than 28 weeks gestation

Question 5

It is recommended to blend air with oxygen to maintain SpO2 of ______.

Answer 5

90-95%

However, hypoxia is life threatening whereas Hyperoxia is not

Question 6

What is the “rule” in hcg testing for female pediatric patients?

Answer 6

12 years old or older OR post menesis if younger than 12 years old

Question 7

Do neonates have a greater or a less sensitivity to nondepolarizing NMB and why?

Answer 7

• Neonates have a greater sensitivity to NDNMB agents than adults and would require a smaller amount of drug. NDNMB agents act as competitive ACh antagonists a the immature neonatal NMJ
• Neonates/infants have GREATER VOLUME OF DISTRIBUTION FOR MUSCLE RELAXANTS and would require a greater amount of drug.
• The increased volume of distribution(normally requiring a greater amount of drug) is offset by the increased sensitivity of ND muscle relaxants at the NMJ
• NEONATES/INFANTS AND CHILDREN REQUIRE THE SAME DOSE OF NDNMB AS ADULTS ON A WEIGHT BASIS

Question 8

How does Halothane potentially affect the CV system/hemodynamics of pediatric patients?

Answer 8

• cardiac arrhythmias may occur
• depresses CO/BP/HR—>frequently causes bradycardia
• sensitizes the myocardium to exogenous catecholamines(arrhythmias with sub injection of LA with Epi

Question 9

When using Halothane in the pediatric population, LA administration of epinephrine should be limited to ____ to decrease the incidence of arrhythmias.

Answer 9

Limit epi to

Question 10

Is Isoflurane appropriate for inhalation induction?

Answer 10

no due to its pungent odor which irritates airway reflects and causes laryngospasm, breath-holding, coughing and ect.

Question 11

How does Isoflurane rapid increases of Isoflurane concentration affect the pediatric population?

Answer 11

-decreases BP/HR and RR—->especially in hypovolemia

ISOFLURANE IS A PROFOUND RESPIRATORY DEPRESSANT

Question 12

Isoflurane like Desflurane reacts with desiccated soda lime or Baralyme to release ___ ___ into the breathing circuit.

Answer 12

-carbon monoxide

Question 13

Desflurane has a very ____ blood solubility and the CV effects are ____ to ISO. Why is Desflurane not suited for inhalation inductions? Emergence from DES is very ___ and may result in ___. DES interacts with desiccated soda lime or Baralyme and may produce potentially toxic {} of ___ ___.

Answer 13

• low
• similar
• DES not suited for inhalation induction because its very pungent odor it is an airway irritant, causing laryngospasm, coughing and breath-holding.
• rapid
• delirium
• carbon monoxide

Question 14

Due to the rapid emergence of DES because of its very low blood solubility, what can occur in the pediatric population?

Answer 14

Emergence delirium

Question 15

Sevoflurane is excellent for inhalation induction. It has a somewhat excellent pleasant odor and does not cause airway irritation. What are the CV/Resp effects of ISO? Emergence from SEVO is smooth and rapid. Is there a risk of emergence delirium with SEVO and if so when?

Answer 15

Emergence from sevoflurane is smooth and rapid. Risk of emergence delirium is increased if pains not well controlled and high levels of sevo were given throughout the case.

Question 16

What is emergence delirium, what age has the highest incidence of ED and what often attenuates it?

Answer 16

• a dissociated state of consciousness in which children are inconsolable, irritable, uncompromising and/or uncooperative.
• The highest incidence of ED occurs in children 1-5 years of age.
• Appropriate pain relief often attenuates emergence delirium.

THE INCIDENCE OF ED AFTER INHALATIONAL ANESTHESIA IN CHILDREN RANGES FROM 2-80% WITH SIMILAR PREVALENCE WITH SEVO, DES AND ISO—>LESS WITH HALO

Question 17

List seven risk factors for emergence delirium in children.

Answer 17

1. age(INADEQUATE AMOUNTS OF PAIN RELIEF INCREASES EMERGENCE DELIRIUM

Question 18

Sevoflurane is hydrolyzed in the presence of soda lime/baralyme to………..?

Answer 18

-potentially nephrotoxic Compound A

Studies with primates suggests that SEVO may be administered in a closed circuit for up to 25 MAC-hrs before nephrotoxicity is a serious risk.—>keep flows at 2 L/M

Question 19

What are potential triggers for malignant hyperthermia?

Answer 19

All potent inhalational anesthetics and succinylcholine trigger MH reactions in susceptible adults and children.

Question 20

Why did the FDA issue a black box warning about succinylcholine?

Answer 20

several case reports of hyperkalemia cardiac arrests primarily in children with undiagnosed Duchenne MD—>almost all of these cases occurred in males 8 years old and younger

Question 21

Succinylcholine should be reserved for in the pediatric population.

Answer 21

-emergency intubations in which immediate securing of the AW is necessary—>i.e. laryngospasm, difficult AW, full stomach or for intramuscular route when a suitable vein is inaccessible.

Question 22

In the presence of hypoxemia with partial or complete upper airway obstruction what is the dosage of IV Succ?

Answer 22

-o.1 mg/kg or up to 4 mg/kg IM and positive pressure ventilation

Question 23

Succinylcholine is infrequently associated with ___________ and is among the volatile agents one of the _____________ agents.

Answer 23

• an increase in master muscle tone—>”Trismus”

- MH triggering agents

Question 24

In what pediatric cases should Succinylcholine be avoided(5)?

Answer 24

-avoid in eye trauma(increases IOP), children with burns(>24 hrs old), massive trauma, major neurologic disease(NM disease) or renal failure compounded by neuropathy

Question 25

The serum K+ {} increases _______ after IV Succ in normal children, however ____________ can occur after a single IV dose of Succ.

Answer 25

• 1 mEq/L or less

- life threatening hyperkalemia

Question 26

What is given to prevent bradycardia and asystole in children with Succ?

Answer 26

-Atropine 10-20 mcg/kg IV or 20-40 mcg/kg IM

Question 27

What are the primary triggers for MH?

Answer 27

all inhalational anesthetics and succinylcholine

Question 28

What is the pathophysiology of MH?

Answer 28

The primary triggers may induce in susceptible individuals an UNCONTROLLABLE RELEASE OF INTRAMYOPLASMIC CA2+ that results in sustained muscle contractures, which, in turn produce a hyper metabolic response.(increased oxygen consumption and CO2 production, elevated VS).

Also may cause master muscle spasm(“Jaws of Steel”) which refers to the inability to insert a laryngoscope blade between the teeth in the mouth.

Question 29

What are the clinical findings associated with MH and the laboratory findings associated with them?

Answer 29

• tachycardia, tachypnea, HTN(early)—>increased PaCO2
• hypercarbia(ETCO2—>early)—>acidosis(resp/metab)
• great increase in mV—>hypoxia, increased alveolar to arterial partial pressure gradient for oxygen
• generalized muscle rigidity(unresponsive to NDMR—>hypercalcemia
• Skin mottling—>elevated plasma lactate
• Hyperthermia(late sign)—>increased aerobic/anaerobic metabolic activity
• Cardiac arrhythmias(hyperkalemia induced:PVC,VT,VF)—>myoglobinuria, myoglobinemia
• Coca colored urine(late sign)—>increased CPK(late sign)
• DIC(late)—>abnormal coagulation studies(late sign)

Question 30

There is a black box warning for using Succinylcholine in pediatrics due to what specific category of undiagnosed patient who are especially susceptible to the diletarous affects of the agent?

Answer 30

male children

Question 31

Can MH be predicted?

Answer 31

• no, susceptible individuals may have a number of uneventful GA before an MH event is triggered.
• negative family history shout not be considered as evidence that a child is not MH susceptible.

Question 32

What are nine other disease states that may initially have a differential diagnosis of MH?

Answer 32

1. hyperthyroidism(minimal ABG/CPK abnormalities)
2. sepsis(early normal ABG/late met acidosis)
3. pheochromocytoma(sim to MH except marked BP lability)
4. metastatic carcinoid(flushing, diarrhea, hypotension)
5. cocaine intoxication(fever, rigidity, rhabdomyolysis)
6. heat stroke
7. Masseter Spasm(may progress to MH)
8. Neuroleptic malignant syndrome(associated with antipsychotics)
9. Serotonergic Toxicity(associated with SSRIs)

Question 33

What is the preferred temp prop location and why?

Answer 33

Axillary temp probe preferred: axillary region is surrounded by large muscle bulk in the pectoral shoulder girdle.

Question 34

What are some preparations of workstation for the MH-susceptable child?

Answer 34

1. succinylcholine should not be readily available for administration
2. all vaporizers should be either physically disengaged from the machine or taped so accidentally turned on
3. CO2 replaced and new anesthetic circuit installed
4. the anesthetic machine should be flushed with 10 LPM of oxygen for a period of time(30 minutes)

Question 35

What should one do if a child is suspected to be experiencing MH?

Answer 35

• turn off inhalation agents, 100% O2 with high fresh gas flow
• call for help
• inform surgeon so surgery can be aborted
• request new anesthesia machine with new circuit and soda lime
• request MH cart with Dantrolene
• cooling of patient
• baseline labs(CK)
• immediate tx of electrolyte imbalances, acidosis…

Question 36

What is the initial bolus of Dantalene, the concentration and how is it mixed?

Answer 36

• 2.5 mg/kg to 10 mg/kg
• 0.33 mg/ml {}
• 20 mg of Dantrolene needs to be resolved with 60 mls of sterile water—>shake well

DANTROLENE IS HIGHLY ALKALINE—> INFUSE RAPIDLY INTO A LARGE VEIN OR CENTRAL LINE WATCHING FOR THROMBOPHLEBITIS

Question 37

What is the {} of Ryanodex?

Answer 37

Reindex requires 5 ml of sterile water to reconstitute 250 mg of dantrolene and is easily mixed within 1 minute(50 mg/ml)

Question 38

How many vials of drug does a 70 kg patient require of the old formulation of Dantrolene as compared with the newer formulation of Ryanodex?

Answer 38

70 kg patient needs 9(2.5mg/kg) to 36(10mg/kg) vials of the old formulation and 1(2.5mg/kg) to 3(10mg/kg) vials of the new formulation called Ranodex.

old formulation {} = 0.33 mg/ml
new formulation {} = 50 mg/ml

Question 39

MHAUS recommends what Dantrolene regimen for a child experiencing MH?

Answer 39

1 mg/kg of Dantrolene by administered IV Q6 hrs for 24-48 hrs

Question 40

How do children exhibit different pharmacokinetics from adults?(4 ways)

Answer 40

1. Lower protein binding(more free drug=greater effect)
2. Larger volume of distribution(“jellyfish)-require larger loading dose of WATER SOLUBLE meds to achieve clinical effect
3. Smaller proportion of fat and muscle stores(less redistribution into muscle/fat mass=large initial blood concentration)
4. Immature renal and hepatic function(less metabolism & elimination)

Question 41

What drugs will have a larger volume of distribution in the infant compared with the adult?
What drugs will have a smaller volume of distribution in the infant compared with the adult?

Answer 41

• The infant’s extracellular body fluid compartment is large compared to the adult, so WATER-SOLUBLE DRUGS will have a LARGER VOLUME OF DISTRIBUTION IN THE INFANT compared with the adult
• Conversely, LIPID-SOLUBLE DRUGS will have a SMALLER VOLUME OF DISTRIBUTION IN THE INFANT compared with the adult

Question 42

Some medications may displace bilirubin from its protein binding sites and possibly predispose an infant to ______?

Answer 42

kernicterus

Question 43

Neonates require a higher dose of succinylcholine than adults because of these two reasons:

Answer 43

1. Neonates have a LARGER VOLUME OF DISTRIBUTION than adults(40-50% BW of neonates is extracellular fluid whereas in the adult extracellular fluid is only 20-25% BW—>Succ distributes in the EC volume so more drug is needed on a per kg basis
2. Neonates have immature neuromuscular junctions(they are less sensitive or more resistant to its neuromuscular effects)more Succ is needed to compete with the ACh at the NMJ(neonates require twice as much succ on a BW basis than older children or adults)