Pharmacology Pediatric Anesthesia Flashcards
Do pediatric patients have larger or smaller volume of distribution for water soluble drugs?
higher TBW
How are the half-lives of drugs different for pediatric patients?
longer due to immature hepatic/renal function
How is pediatric dosing done?
per kg
How can weight be roughly estimated?
50th percentile weight (kg) = (age x 2) + 9
How is the ECF volume of distribution different in pediatrics?
ECF volume of distribution proportionately higher than that of adult
What does it mean for certain drugs given if pediatric patients have an increased volume of distribution?
larger initial doses of water soluble drugs are required
delayed excretion
Do pediatric patients have increased or decreased volume of distribution for fat soluble drugs?
decreased due to decreased fat and muscle mass
How is protein binding different in pediatric patients?
reduced total serum protein concentrations so more of the administered drug is free in the plasma to exert a clinical effect
Which drugs may need decreased dosing due to decreased serum protein concentrations?
barbituates and local anesthetics
How is the concentration of volatile agents different in pediatric patients?
concentration of inhaled anesthetics in the alveoli increase more rapidly with decreasing age: infants > children > adults, more rapid inhalation induction
What are some benefits and disadvantages of inhalation agents in pediatric patients?
more rapid inhalation induction
excretion and recovery of inhaled anesthetics is also more rapid
overdose can occur quickly and leading cause of serious complications
What factors allow pediatric patients to have a rapid rise in alveolar anesthetic concentration that rapidly equilibrates with blood concentrations?
- Increased respiratory rate (higher minute ventilation)
- Decreased FRC
- Increased cardiac index/high blood flow to vessel rich organs
Besides increased RR, decreased FRC, and increased CI/high blood flow, what other possible explanations are there to explain the fast rise of alveolar anesthetic conentration?
- age-related differences in blood-gas partition coefficient
- state of hydration/dehydration
- type of anesthesia circuit
- vaporizer design
Why are pediatric patients at increased risk of overdose from inhalation anesthetics?
faster induction & immature cardiac development
Why is blood pressure very sensitive to volatiles?
- lack of compensatory mechanisms
- immature myocardium
- reduced calcium stores
How does MAC change with age?
infants have a higher MAC than older children or adults and peaks around 3 months of age
What are the approximate MAC value of Sevo for infants?
3.2
What is the approximate MAC value of Iso for infants?
1.8
What is the approximate MAC value of Des for infants?
10
Why is N2O contraindicated in patients with a pneumothorax?
Can double the size of a pneumothorax in about 12 minutes
What is the agent of choice for inhalation inductions?
Sevo because least irritating to the airway
What is the blood gas solubility of Sevo?
0.68
What are some side effects of Sevo?
dose-related depression in RR and TV
What can increase your production of compound A when using Sevo?
FGF
What is the blood gas coefficient of Iso?
1.43
What is a major disadvantage of Iso?
slower onset and more pungent
When is it appropriate to use Iso in pediatrics?
after inhalation induction
What is the blood gas coefficient of Des?
0.42
What are some disadvantages of Des?
most pungent, causes airway irritation
What is the percent incidence of laryngospasm if using Des during induction?
50%, why it is controversial to use with LMAs
What is an advantage of Des?
rapid emergence
Why do pediatric patients need a larger induction dose of Propofol?
increased volume of distribution and decreased fat/muscle
How does the elimination half life of propofol differ in pediatric patients?
elimination half life is shorter, higher rates of plasma clearance
What is a disadvantage of Propofol?
high risk for infection, discard after 6 hours
What are the IV induction doses of Propofol?
2-3 mg/kg
What is the infusion rate for propofol?
25-200 mcg/kg/min
What is the infusion dose for Propofol if you are doing intraoperative nerve monitoring?