Pediatric Pharm & Fluids Flashcards
Water-Soluble Medications
Children ↑H2O body composition
↑Vd
Examples: Succinylcholine, Bupivacaine, & antibiotics
Fat-Soluble Medications
Children ↓fat & muscle mass
↓Vd
↑DOA (less tissue mass to distribute)
Examples: Fentanyl & Thiopental
Hepatic/Renal Function
IMMATURE
Longer drug half-lives
Blood-Brain Barrier
IMMATURE
Improved by 2yo
Pediatric 50th Percentile Weight
Age (yrs) x 2 + 9 = kg
Weight Formula < 1yo
Mos/2 +4
Neonates Physiological Differences
↑H2O content 70-75% (adults 50-60%)
↓fat % → reduced lean muscle mass
↑ECF Vd as compared to adults
Protein Binding
↓total serum protein ↑free drug available
↓barbiturates & LA dosages
Hepatic Metabolism
Normal adult hepatic enzymes convert medications from lipid-soluble (non-polar) to more polar water-soluble compound
Impaired metabolism improves w/ age
↑enzyme activity ↑drug delivery to the liver
Renal Excretion
Less efficient
- Incomplete glomerular development
- Low perfusion pressure
- Inadequate osmotic load
GFR & tubular function develop rapidly in 1st few months of life
Careful fluid administration to prevent fluid overload
Neonatal kidneys unable to excrete ↑amounts excess H2O or electrolytes
What medications have a prolonged elimination half-life in neonates due to impaired renal excretion?
Aminoglycosides & cephalosporins
Inhalational Agents
More rapid inhalation anesthetics concentration increase in the alveoli
Infants > children > adults
჻ more rapid inhalation induction
Excretion & recovery also more rapid
Potentiates NDMR actions
*Overdose occurs quickly & potentially leads to serious complications
Respiratory Physiological Differences
↑RR (higher minute ventilation)
↓FRC
Cardiovascular Physiological Differences
↑CO to vessel-rich groups Immature cardiac development Lack compensatory mechanisms Immature myocardium ↓Ca2+ stores
What age does MAC peak?
3 months old
Stage 1
Analgesia or disorientation
From beginning general anesthesia induction to loss of consciousness
Stage 2
Excitement or delirium
From loss of consciousness to onset automatic breathing
Eyelash reflex disappears, but other reflexes remain intact
Coughing, vomiting, & struggle may occur
Respirations irregular w/ breath-holding
Stage 3
Surgical anesthesia
From onset automatic respiration to respiratory paralysis
Divided into 4 planes
Plane 1
Stage 3
From onset automatic respiration to cessation eyeball movements
Eyelid reflex lost
Swallowing reflex disappears
Marked eyeball movement may occur, but conjunctival reflex lost at the bottom of the plane
Plane 2
Stage 3
From cessation of eyeball movements to beginning of intercostal muscles paralysis
Laryngeal reflex lost although upper airway tract inflammation ↑reflex irritability
Corneal reflex disappears
Plane 3
Stage 3
From beginning to completion intercostal muscle paralysis
Diaphragmatic respiration persists, but there’s progressive intercostal paralysis
Pupils dilated & light reflex abolished
Laryngeal reflex lost in plane 2 still able to be initiated w/ painful stimuli
Desired plane for surgery when muscle relaxants were not used
Plane 4
Stage 3
From complete intercostal paralysis to diaphragmatic paralysis
Stage 4
Anesthetic overdose causing medullary paralysis & vasomotor collapse
N2O
Nitrous oxide 2nd gas effect Analgesia & amnesia Odorless PIV placement on older children
N2O Contraindications
Pneumothorax - N2O 70% doubles pneumo w/in 12min
NEC
Bowel obstructions
contributes to PONV
What gas law explains the 2nd gas effect?
Dalton’s law
Total pressure = P1 + P2 + P3 + … + P#
What’s the choice inhalational anesthesia for pediatrics? Why?
Sevoflurane (previously Halothane)
Least irritating to the airway
Sevoflurane Considerations
Dose-related depression in RR and Vt
CO2 absorbents w/ barium hydroxide or soda lime ↑compound A production
Isoflurane
Slowest & pungent
Potentiates NDMR > Sevo or Des
Least costly inhalational agent
Desflurane
MOST pungent Causes airway irritation 50% laryngospasm incidence w/ induction Better utilized as maintenance Use w/ LMA controversial RAPID emergence α emergence delirium
Propofol
↑induction dose d/t ↑Vd Profound hypotension in critically-ill infants (consider Ketamine) Shorter elimination 1/2 life ↑plasma clearance rates Discard after 6 hours ↓SVR/BP → profound hypotension Dose-dependent ventilation depression Infection risk especially infants or children w/ immature/impaired immune systems
Ketamine
Cerebral cortex dissociation Analgesia & amnesia Side effects include ↑secretions, vomiting, & hallucinations Admin w/ Glycopyrrolate 0.01 mg/kg Nystagmus gaze Preserves spontaneous respirations ↑SNS response ↑HR/CO/BP ↑pulmonary pressures Bronchodilation (ideal in asthmatics)
PO 6-10mg/kg Sedation IM 2-5mg/kg Induction IV 1-2mg/kg (5-10mg/kg) Pain IV 0.5mg/kg bolus Infusion 4mcg/kg/min
Etomidate
Pain on injection, myoclonus, anaphylactic reactions, adrenal suppression
+ CV stability in hypovolemic patients
- adrenocortical suppression not well-tolerated in critically ill
Dose-dependent ventilation depression
0.2-0.3mg/kg
Opioids
More potent effects d/t immature blood-brain barrier
↑respiratory centers sensitivity (especially infants)
Morphine
0.025-0.05 mg/kg IV
Histamine release → erythema & pruritis
Reduced hepatic conjugation
↓renal clearance
Fentanyl
Synthetic opioid agonist - analgesia & blunts circulatory response to direct laryngoscopy
0.25-1 mcg/kg IV
Infusion 0.5-2 mcg/kg/hr
IV onset almost immediate
Max analgesic & respiratory depression effect w/in several minutes
↑DOA 30-60min w/ high doses d/t ↓fat & muscle
Neonates & preterm infants slower metabolism
Dependence w/in 7 days
Off-label FDA use
Hydromorphone
Semi-synthetic opioid agonist Morphine derivative 5x more potent IV or epidural Onset 5min DOA 2-3hrs Patients w/ renal toxicity ↑risk metabolite accumulation & neuroexcitatory S/S → tremors, agitation, & cognitive dysfunction
Naloxone
Antagonizes opioids - reduces respiratory depression, N/V, pruritis, & urinary retention
0.25-0.5 mcg/kg repeat dose until effect
Max 2 mg
Onset 30sec-1min
Elimination 1/2 life 1.5-3hrs
Overdose → systemic HTN, cardiac arrhythmias, & pulmonary edema
Midazolam
Premedication:
*PO 0.5 mg/kg (onset 20min)
Intranasal 0.2-0.3mg/kg
IV 0.05 mg/kg (onset 5min)
PICU sedation infusion 0.4-2mcg/kg/min
DOA 1-6hrs variable
Flumazenil
Benzodiazepine reversal agent GABA receptor competitive antagonist Onset 5-10min IV 10mcg/kg Elimination 1/2 life ≈ 1hr
Clonidine
Pre-synaptic α agonist ↓Ca2+ levels → inhibits NE release Oral premed 4 mcg/kg (onset 60-90min) Difficult to time premed Regional anesthesia adjunct Epidural/caudal 1-2 mcg/kg prolongs analgesia approximately 3hrs Residual sedation postop
Dexmedetomidine
α2 adrenergic receptor agonist Anxiolysis, sedation, & analgesic properties Sedation w/o respiratory depression Elimination 1/2 life ≈ 2hrs Oral or intranasal 1 mcg/kg IV 0.25-1 mcg/kg over 10-15min Infusion 0.2-2 mcg/kg/hr
NDMRs
↑variability w/ dose & response
↑sensitivity ↓ACh release (immature neuromuscular junction) & reduced muscle mass
Fetal receptors have longer opening time → Na+ enters the cell
Shorter onset up to 50% d/t ↑circulation times
Prolonged DOA w/ immature hepatic system (Roc, Vec, & Panc)
Difficult to monitor effect w/ peripheral nerve stimulator
Muscle Relaxants Doses
Rocuronium 0.6 OR 1.2 mg/kg IV (low dose 0.3 mg/kg intubating conditions in 3min)
Cisatracurium 0.15 mg/kg IV (liver transplants)
Vecuronium 0.1 mg/kg IV
Muscle Relaxant Reversal
Glycopyrrolate 0.01 mg/kg IV
Neostigmine 0.05 mg/kg IV
*Adolescent females avoid Sugammadex to prevent birth control inactivation
Succinylcholine
Infants require ↑dose d/t ↑ECF Vd
Pediatric patients ↑risk to experience cardiac dysrhythmias, hyperkalemia, rhabdomyolysis, myoglobinuria, masseter muscle spasm, or malignant hyperthermia
Cardiac arrest → treat hyperkalemia
Often avoided in routine elective pediatric surgery
Succinylcholine Dose/Routes
IV (intubation) <10kg 2 mg/kg >10kg 1-2 mg/kg
IM 4mg/kg
IV (laryngospasm) 0.25-0.5mg/kg
Atropine 0.02 mg/kg IV or IM to prevent bradycardia
Sugammadex
Water-soluble sugar molecule encapsulates NDMRs
IV 2-4 mg/kg
16 mg/kg after RSI dose Rocuronium 1.2 mg/kg
Ketorolac
NSAID
0.5 mg/kg IV
Elimination 1/2 life ≈ 4hrs
Caution in impaired renal, ↑bleeding risk, & impaired bone healing
Reserve for children > 1yo (UNC 6mos) when renal function more mature
Glucose
Neonates - minimal glycogen stores & prone to hypoglycemia when NPO or stressed
Impaired renal glucose excretion
Hypoglycemia Treatment
10% dextrose 1-2 mL/kg
NEVER admin D50% bolus d/t vessel necrosis & high osmolarity (2mL D50 + 8mL NS = D10%)
Maintenance IV dextrose infusions
Minimize preop fasting
Dextrose 10% vs. 50%
Per cent = grams per 100mL
D50% = 50g dextrose per 100mL = 0.5g/mL D10% = 10g per 100mL = 0.1g/mL D5% = 5g per 100mL = 0.05g/mL
Dilution 1mL D50% in total 5mL → 0.1g/mL or D10%
1mL D50% dilute in 10mL → 0.05g/mL or D5%
MIVF
0-10kg → 4mL/kg/hr per kg
10-20kg → 40mL + 2mL/kg/hr per kg >10kg
>20kg → 60mL + 1mL/kg/hr per kg >20kg
What fluid type should be utilized for NPO fluid deficits & evaporative loses?
Balanced salt solutions such as NS or LR
What blood products always require a filter & warmer?
PRBCs
FFP
*Platelets only require blood filter tubing
EBV
Premature 100mL/kg Term infant 90mL/kg 6mos 80mL/kg Children < 1yo 75mL/kg Children > 1yo 70mL/kg Adults 55-65mL/kg
Volume PRBCs to be transfused FORMULA
[(desired Hct - current Hct) x EBV] / PRBCs Hct (≈ 60%)
OR
(desired Hct - current Hct) x EBV x 1.5
When to administer FFPs?
Replenish clotting factors lost during massive transfusion - often when EBL exceeds 1-1.5x the EBV
Observed coagulopathy
Prolonged PT, PTT, or ROTEM/TEG
Tolerated platelet counts in children w/ ITP or chemotherapy _____ mm^3
15,000mm^3
Tolerate lower platelet counts to limit donor exposures
Platelet transfusion required when _____
↓platelet count d/t dilution (massive blood transfusions)
< 50,000mm^3
Filter only
Warming → activated & sticky w/in warming device DO NOT WARM
Cell Saver
Salvages erythrocytes (RBCs) from suctioned blood ↑volumes washed cells → coagulopathy d/t coagulation factor dilution
What complications does citrate preservative cause?
PRBCs & FFP contain calcium citrate
Rapid/multiple transfusions → hypocalcemia
Neonates have impaired ability to mobilize Ca2+ & to metabolize citrate
What does serve ionized hypocalcemia lead to?
Cardiac depression w/ hypotension
Irradiated Blood Products
Indicated to prevent transfusion related graft vs. host disease
Cancer & immunocompromised patients
Filtered Blood Products
Effective way to eliminate CMV infection risk
Cancer & sickle cell patients
Washed Blood Products
Reserved for patients w/ life-threatening allergic reactions
Wash out WBCs
Significantly ↓RBC lifespan & effectiveness in circulation
Recommendations to prevent hyperkalemia cardiac arrest associated w/ blood transfusions:
- Transfuse before significant hemodynamic compromise
- Use large bore PIV catheters over central lines
- Fresh (w/in 5 days old) & washed RBCs
Hct goal ↑30%
Earlier transfusions
Hyperkalemia Treatment
Hyperventilation Ca2+ chloride 20mg/kg IV or Ca2+ gluconate 60mg/kg Dextrose 0.25-1g/kg + insulin 0.1units/kg IV Sodium bicarbonate 1-2mEq/kg IV Albuterol Furosemide 0.1mg/kg IV Cardiac arrest → CPR Activate ECMO (arrest > 6min)
PRBCs
Infants 30-40%
Child 25%
10-15mL/kg
↑Hgb 2-3g/dL
FFP
Massive blood transfusion
10-15mL/kg
↑factor levels 15-20%
Platelets
Count < 100,000mm^3
5-10mL/kg
↑platelets 50-100,000
Cryoprecipitate
Persistent bleeding
10-20mL/kg
↑fibrinogen 60-100mg/dL
Calcium Chloride
Hypocalcemia
10mg/kg
IV slow admin via central line
Calcium Gluconate
Hypocalcemia
30mg/kg
IV slow admin via peripheral line
