Pediatrics Flashcards
(43 cards)
1
Q
Neonatal period:
age
PGA calculation
What is considered low birth rate?
Extremely low gestational age?
A
- Neonate is birth to 30 days old
- PGA =(# weeks gestation at birth) + (current age in weeks)
- post-op admission for pts <60 weeks PGA
- Pre-term <37 weeks
- Low birth rate <2500 grams
- ELGAN = 23-27 weeks
2
Q
All pre-term patients have potential for what problems?
(8)
A
- respiratory distress
- apnea
- hypoglycemia
- electrolyte disturbances (low mg and Ca)
- infection
- hyperbilirubinemia
- polycythemia
- thrombocytopenia
3
Q
What are the risks for babies of normal gestation?
postmature?
former premature up to 60 weeks PGA?
A
- Normal gestation: 37-40 weeks
- congenital anomalies
- viral infections
- perinatal depression
- fetal alcohol
- thrombocytopenia
- Postmature: >42 weeks (the above risks +…)
- meconium aspiration
- birth trauma if LGA
- hypoglycemia (esp if mother is diabetic)
- hyperbilirubinemia
- Up to 60 weeks PGA
- post-op apnea and bradycardia (often require 12 hour admission)
4
Q
Describe fetal circulation
A
- oxygenated blood leaves placenta via umbilical vein
- blood bypasses the liver via the ductus venosus to go straight to the IVC
- Portion of this blood “Jet streams” straight across Right atrium through Foramen ovale into left atrium to then be pumped through ventricle and aorta
- *Remaining blood goes normal route to right ventricle and PA. High pulmonary vascular resistance forces most of this blood through the Ductus arteriosus from PA to Aorta
5
Q
What are the primary changes that occur to fetal circulation at birth?
(6)
A
- ductus venosus closes
- blood is now oxygenated via lungs
- ductus arteriosus closes (d/t increased arterial O2 concentration)
- pulmonary vascular resistance decreases
- peripheral vascular resistance increases
- foramen ovale closes
- true closure is weeks later and 25-30% of adults have patent foramen ovale
6
Q
What is transitional circulation and what causes it?
How can it be prevented?
A
- occurs at birth and first several weeks of life
- hypoxia, hypercapnia, or hypothermia can lead to increased pulmonary artery pressure, reversal of flow through the foramen ovale, re-opening of ductus arteriosus and shunting
- hypoxia is #1 cause
- Prevention with optimal oxygenation, correct acidosis, keep pt warm
7
Q
How does the neonatal cardiovascular system differ?
A
- Heart:
- structurally immature
- fewer myofibrils
- sarcoplasmic reticulum immature
- cardiac calcium stores reduced
- Ventricles less compliant
- CO is HR dependent
- increased preload does not increase SV as much as in an older child
- Baroreceptor reflex immature in the neonate causing inability to compensate for hypotension with reflex tachycardia
- Parasympathetic dominance- tendency to brady
8
Q
What is the resting CO for a neonate at birth?
infant?
adolescent?
A
- neonate at birth: 400 ml/kg/min
- infant: 200 ml/kg/min
- adolescent:100 ml/kg/min
9
Q
Neonates are vulnerable to problems caused by citrated blood products because __________.
__________ is the preferred treatment of badycardia and decreased cardiac output in pediatric patients.
A
they are dependent on ionized calcium
Epi
10
Q
How does the neonatal pulmonary system differ?
A
- Fewer and smaller alveoli- they increase in number and size up until 8 yo
- Infants have a small airway diameter and increased resistance
- Highly compliant airway and chest wall - easy to see retractions
- Closing capacity is greater than FRC in very young and very old
- airway closure can occure before end exhalation–leads to shunting and dead space
- Early fatigue and diaphragmatic and intercostal muscles until age 2 b/c type 1 muscle fibers are not mature
- neonates have 10%, 2 yr and greater have 55%
- O2 consumption is 2-3x an adult
11
Q
Describe the airway anatomy of an infant
(10)
A
- larger tongue in smaller submental space
- higher larynx (C2-C4)
- short stubby (omega shaped) epiglottis
- angles vocal cords (caudal slant)
- funnel shaped larynx with narrowest region @ cricoid ring
- obligate nasal breathers
- large occiputs that affect sniffing position (use shoulder roll)
- edentulous
- short trachea (4-5 cm)
- angulation of right mainstem bronchus
12
Q
Airway differences comparing infant to adult
(table)
A
13
Q
Compare between an adult and neonate: (table)
Oxygen consumption
alveolar ventilation
respiratory rate
TV
A
14
Q
How does the pediatric airway affect gas flow?
A 50% reduction in radius increases the pressure ___-fold
A
- young children have elevated airway resistance at baseline
- swelling can have huge impact by increasing resistance
- Turbulant airflow is present to 5th bronchial division
- 32-fold
15
Q
How does the pediatric neurological system differ?
O2 consumption
CBF
growth
other things…
A
- Oxygen consumption and CBF is about 50% greatr in children than adults
- adults: 3.5 ml blood flow/100 g brain mass
- neonates: 5.5 ml/100g
- Myelinization and synaptic connections not complete until age 3-4 years
- Rapid brain growth in first 2 years
- Conus medullaris at L3 at birth, migrates to L1 or L2 by 3 yo
- Fontanels: anterior closed by 18 months, posterior closed by 2 mo
16
Q
What does recent research say about anesthesia-induced developmental neurotoxicity?
A
- Increased and accelerated neuroapoptosis occurs with virtually all anesthetics
- Single exposures of short duration are usually of no consequence
- Repeated and/or prolonged exposures at a young age (<3-4 years) may be associated with later behavioral and learning difficulties
- ***evidence is inconclusive
17
Q
What are differences you should consider with neuraxial in pediatrics?
A
- The conus medullaris ends at L1 in adults and at the L2-L3 in neonates and infants
- Iliac crest is even with L4-L5 or L5-S1 interspace (similar to adults) so it is still well below the conus medullaris
- Dural sac terminates more caudally (S3) in neonates and infants than in adults (S1)
- Infants have less lumbar lordosis leading to increased risk of high spinal with changes in positioning
18
Q
How does the renal system change from infancy through childhood?
A
- GFR is signifincantly impaired at birth but improves throughout the 1st year
- premature infants will take longer to reach renal maturation
- Renal tubular concentrating abilities do not achieve full capacity until about 2 yr
- Half-life of medications excreted by glomerular filtration are prolonged in the very young
- During childhood, renal clearance rate may be higher than adult clearance rates
- drug half life is shorter that adults for kids >2yr
19
Q
How is liver function different in pediatrics?
A
- Enzyme systems are still developing up until 1 yr
- At birth Phase I Cytochrome P450 system is 50% of adult values and Phase II (conjugation reactions) are impaired in neonates
- Causes longer half life on BZD and morphine
- deceased bilrubin breakdown d/t reduction in glucuronyl transferase (also affects tylenol metabolism)
- Hepatic synthesis of clotting factors reach adult levels withing one week of birth
- Lower levels of albumin and other proteins for drug binding in newborns–> causes larger proportion of unbound drug and increased effects
- Minimal glycogen stores- prone to hypoglycemia
20
Q
How does the GI system differ in pediatrics?
A
- Coordination of swallowing with respiration is not mature until 4-5 months of age
- causes high incidence of reflux
- Gastric juices are less acidic up to about 3 years
- Absorption of oral medications is slower compared to adults
- GI tract is slower (slower emptying time)
21
Q
What is the significance of thermoregulation in pediatric patients?
< 3 months old?
factors that contribute?
A
- They have large body surface area to weight ratio
- lack subq tissue for an insulator
- < 3 months:
- inability to shiver
- metabolize brown fat to increase heat production
- can lead to metabolic acidosis and increased O2 consumption
- Factors that contribute:
- cold OR
- anesthetic-induced vasodilation
- room temp IV fluids
- evaporative heat loss from surgical site
- cold irrigating solutions
- cold anesthetic gases
22
Q
What are the ways heat is lost in the OR?
(pic)
A
- conduction
- evaporation
- convection
- radiation
23
Q
How can you actively warm a pediatric patient?
A
- warming mattress
- incubator
- cover with blankets
- head coverings
- transport in isolette
- humidify gases
- use plastic wrap on the skin
- warm prep and irrigation solutions
- change wet diapers and remove wet clothing
- Forced air warming **most effective strategy for childre >1 yr**
24
Q
How should you monitor temp?
How should you not?
What are some problems that hypothermia can cause?
A
- Core temp is best (esophageal)
- Axillary temp can recognize MH earlier
- NO Forehead temp! 10 MH episodes unrecognized w/forehead temp
- Hypothermia:
- delayed emergence
- reduced degradation of drugs
- increased infection
25
How does body composition vary over the age spectrum?
(table)
\*know trends, not actual numbers
26
How does the difference in body composition affect anesthesia?
* Higher total body water:
* Water sluble drugs have a larger volume of distribution
* need a larger initial dose (sch, abx)
* larger distribution can delay excretion
* Neonates have less fat and muscle
* drugs that depend on redistribution to fat for termination of action will have prolonged effects
* Protein binding: \<6 mo have less albumin and alpha-1 acid glycoprotein (AAG)
* higher free-fraction of protein bound drugs
* free fraction of local anesthetics will be higher (bind to AAG)
27
In general, most medications will have a _______ elimination half-life in pre-term and term infants, a _______ half-life in children older than 2 yrs up to early teen years, and a ________ of half-life in those approaching adulthood.
In general, most medications will have a **prolonged** elimination half-life in pre-term and term infants, a **shortened** half-life in children older than 2 yrs up to early teen years, and a **lengthening** of half-life in those approaching adulthood.
28
How do you calculate maximum allowable blood loss (MABL)?
29
How does fetal hgb differ from adult hgb?
Target hct for neonates?
* Fetal Hgb has a lower P50 at 19 mmhg compared to 26 mmHg in adults
* **LEFT shift**
* Target HCT is higher in neonates d/t L shift and decreased CV reserve
* minimum HCT of 40% instead of 30%
30
What is the expected hgb and hct for: (table)
newborn
3 mo\*\*\*
6-12 mo
adult female
adult male
\*\*\* physiologic anemia at 2-3 mo
31
\_\_-\_\_ ml/kg of PRBC will increase hgb about \_\_\_\_g/dL
EBV table
premature neonate
term neonate
infant
\>1 yr
**4-5** ml/kg of PRBC will increase hgb about **1**g/dL
32
How is blood administration done for pediatrics?
ratio
threshold
When would you consider blood sooner?
* Blood loss replaced at 3:1 with crystalloid
* Threshold: **24-30%**, determined on individual basis
* infants \<3 mo may have higher threshold d/t left shift and physiologic anemia
* Consider blood sooner when:
* preterm infants
* term newborns
* cyanotic congenital heart disease
* respiratory failure needing higher O2 carrying capacity
* \*\*Incidence of apnea is high in neonates and preterm infants who have hct \<30
33
When do you transfuse FFP?
What do you need to watch for with FFP?
When do you replace platelets?
How do you calculate how much blood should be transfused?
* FFP if \> one blood volume is being replaced
* FFP has the highest levels of citrate, so need to watch for ionized hypocalcemia and CV depression
* especially in neonates and children with liver failure
* Platelets replacement depends on starting plt cound and if there is oozing on the field
* a child with a nml plt count usually does not need plt until EBL is \> 2 blood volumes
34
What kind of fluid is used in children?
What are signs of dehydration in children?
* LR for maintenancy in healthy children
* glucose containing IVF may be needed in infants \< 6 mo or other risk of hypoglycemia (mitochondrial disease)
* use smaller bags or buretrol
* eliminate ALL air from line
* TPN should not be stopped suddenly, either continue in OR or ramp it down and bridge with glucose containing fluid
* Signs of dehydration:
* mild: (~50 ml/kg deficit) dry mouth, poor skin turgur
* moderate (~100ml/kg): mild sx plus sunkin fontanel, oliguria, tachycardia
* severe (~150 ml/kg): mod sx plus sunken eyes, hypotension, and anuria
35
How do pediatrics differ regarding inhaled anesthetics?
* uptake is more rapid d/t:
* increased RR and cardiac index
* large proportion of blood to VRG (heart, brain, GI, kidneys, endocrine)
* reduced tissue and blood solubility in infants
* alveolar ventilation to FRC ratio is 5:1 in infants vs 1.5:1 in adults
* Increased incidence of hypotension in neonates and infants
* Increased risk of **anesthetic overdose** in infants/toddlers
* when HR starts to go down, turn down the gas!
* MACS are generally higher in children
36
What is the inhaled agent of choice for pediatrics and why?
Why not the others?
* Sevo
* not very pungeant, does not irritate the airway
* Halothane was good as well but is no longer available; caused bradycardia
* Desflurane is too pungeant, can cause coughing, laryngospasm, salivation
* lower solubility makes it useful for maintenance during long procedures or obese children
37
Effects of volatile agents on...
respiratory
CV
emergence delirium
* Resp: all volatiles cause dose related resp depression and depressed response to CO2 and hypoxia
* apnea worsens with higher concentration
* CV: dose dep depression
* sevo usually maintains or increases HR during induction
* all cause prolonged QT
* halothane has greatest depression of contractility
* myocardial depression may be exaggerated in deonates
* Emergence delirium associated with all VA
* sevo \> des \> halothane
38
How is dosing of induction agents for pediatrics done?
* Neonates have immature BBB and slower metabolism so they require lower doses
* Older children and adolescents require higher doses
* Propofol
* **3 mg/kg** for infants \<2yr
* **2.5 mg/kg** for children 6-12 years
* Ketamine
* 2 mg/kg IV or 4-8 mg/kg IM
* plus atropine 0.02 mg/kg IM/IV (for secretions)
* Etomidate (not FDA approved \< 12yr)
* 0.25-0.3 mg/kg
* Thiopental
* neonates **3-4 mg/kg**
* infants **7-8 mg/kg**
* children **5-6 mg/kg**
39
Sedatives:
midaz oral dosing (18 mo-3 yr, 3-6 yr, and 6-10 yr)
Ketamine dart dose
* Oral midaz dosing- increases in younger pts; poor oral bioavailability and bitter taste
* 18 mo-3 yr: 0.75-1 mg/kg
* 3-6 yr: 0.6-0.75 mg/kg
* 6-10yr: 0.5 mg/kg
* Ketamine dart:
* 2-5 mg/kg
* onset 3-5 min and duration 30-40 min
40
Opioid dosing in peds:
morphine
dilaudid
fentanyl
remi
demeral
codeine
* Morphine: 50-100 mcg/kg
* Dilaudid: 10-20 mcg/kg
* Fentanyl: 0.5-3 mcg/kg
* Remi: 0.05-0.1 mcg/kg/min
* Demerol: 0.25-0.5 mg/kg
* Codeine: no longer prescribed as often d/t ultra rapid metabolizers having increased risk of OD--\>BLACK BOX
41
Non opioid pain dosing in pediatrics:
acetaminophen
ketorolac
* Acetaminophen
* PO: 10-15 mg/kg
* IV: 15 mg/kg q 6 hours (10 min onset)
* Ketorolac
* 0.5 mg/kg
* \*\*Caution with all NSAIDS in severe asthma
42
How are muscle relaxants different in peds?
* NMJ not fully mature until about 2 mo
* infants more sensitive to NDMB but have larger VD, so dose ends up the same as adults (except ROC)
* Roc dose is 0.3 mg/kg
* May see prolonged DOA d/t immature kidney and liver
* Higher sch dose needed in neonateds d/t larger VD
* Sch only used in RSI or laryngospasm (bradycardia, hyperkalemia, MH)
* Neostigmine dose 40% lower than adult (0.2-0.4 mcg/kg
43
How are LA different for pediatrics?
* LA absorption increased d/t increased CO and local blood flow (2-3x greater in infants than adults)
* Epi can still slow down uptake
* Plasma AAG is low at birth and does not reach adult levels before 1 yr
* Free fraction of all LA is increased in infants
