Ex 2 Peds 1 Flashcards
1
Q
Neonatal period
A
first 28 days outside uterus (“extrauterine life”)
2
Q
Neonatal anesthesia
A
anesthesia only in this timeframe if urgent or life threatening
3
Q
Which is more resistant: full term or preterm infants?
A
More resistant: full term
4
Q
highest rate of adverse events intraop/postop
A
Neonates + infants < 12 months old
5
Q
Preterm infants are more prone to developing
A
respiratory complications
6
Q
Neonate - Age
A
0-1 month (28 days)
7
Q
Infant - Age
A
1-12 months
8
Q
Toddler - Age
A
1-3 years
9
Q
Child - Age
A
4-12 years
10
Q
Adolescent - Age
A
13-19 years
11
Q
Highest mortality in pediatric anesthesia is associated with
A
cardiac arrest, medication related, CVS
12
Q
Over half of all anesthesia related cardiac arrests were among what age group
A
infants < 1 y/o
*1/3 of arrests were ASA I-II
13
Q
What occurs 2x as often in pediatric anesthesia (vs adults)?
A
Bronchospasm
Laryngospasm
Aspiration
14
Q
Bradycardia is associated with
A
inadequate ventilation or impending catastrophe
15
Q
Organogenesis takes place within
A
8 weeks of conception
16
Q
Preterm infant
A
born before 37 weeks gestation
17
Q
Postmature infant
A
born after 42 weeks gestation
18
Q
Low birth weight infant
A
born weighing < 2500 g
19
Q
What may indicate potential anesthetic implications/problems during perinatal history eval?
A
Problems during pregnancy: maternal drug abuse, infxn, eclampsia, diabetes
or during/after delivery: fetal distress, meconium aspiration, prematurity, postdelivery intubation
20
Q
functional unit of placenta
A
chorionic villus
21
Q
Fetal circulation is characterized by
A
high PVR + low systemic circulatory resistance
22
Q
Why does fetal circulation have high PVR?
A
uninflated atelectatic lungs + hypoxic vasoconstriction
23
Q
Why does fetal circulation have low systemic circulatory resistance?
A
High flow + low impedence of the placental vessels
24
Q
Intracardiac shunts
A
Foramen ovale (atrial septum; RA to LA)
25
Extra cardiac shunts
Ductus arteriosus (RV-pulm artery to aorta) + ductus venosus (liver to inf. Vena cava)
26
Highest rates of AEs intra/postop
Neonates + infants (< 12m)
27
Risk of pediatric anesthesia most often d/t
Inadequate ventilation + unexplained CVS events
28
Occurs 2x as frequently in peds vs adults
Bronchospasm, laryngospasm, aspiration
29
Bradycardia in pediatrics
Sentinel sign of inadequate ventilation or impending catastrophe
10x as often in infants vs 4 year old
30
Organogenesis
Within 8 weeks of conception
| 1st trimester stress may cause abnormal organogenesis
31
Stress during 2nd trimester may result in
Abnormal functional development of organs
32
Stress during 3rd trimester may result in
Smaller organs or reduced muscle/fat mass
33
Thin layer of cells that separate maternal + fetal blood in placenta
Syncytial trophocytes
34
Cord blood is comprised of
2 umbilical arteries + 1 umbilical vein
35
What is getting bypassed in fetal circulation + how?
Lungs bypassed d/t Increased PVR via:
- Foramen ovale (RA to LA)
- Ductus Arteriosus (PA to Aorta)
36
Route of blood returning to mom from fetus
LV --> aorta --> common iliac artery --> umbilical arteries
37
PDA connects
aorta + PA
38
PFO connects
RA + LA
39
Ductus Venosus connects
sinusoids of liver to inferior vena cava
40
Fetal circulation of blood through the lungs is limited by
hypoxic pulmonary vasoconstriction (increased resistance in lungs d/t decreased O2)
41
Fetal circulation is characterized by
3 shunts: DV, DA, FO
High PVR
Low SVR
42
During birth, the first breath (while placenta still attached) causes what to occur?
* pulmonary alveoli open up*
- Decreased pressure in pulmonary tissue
- Decreased pressure in RH (blood rushes to fill alveolar capillaries)
- LH pressure increases (increased blood from Pulm veins)
43
Transitional Circulation
Occurs at birth d/t cessation of placental blood flow
* decreases PVR
* increases SVR
44
Transitional circulation: PVR decreases d/t
asphyxia, lung expansion, pulmonary vasodilation d/t presence of oxygen (+ no longer receiving prostaglandins from placenta - which keeps DA open)
45
When placenta is cut off, what significant events occur?
2 events:
1. fetal asphyxia (decreased PVR)
2. increased pressure in aorta + SVR
46
Why does the foramen ovale close?
LA > RA
d/t pulmonary vascular dilation
47
When does foramen ovale close?
At birth
| *permenantly closes 2-3 months
48
Why does the ductus arteriosus close?
OXYGEN
*exposure to oxygenated blood
+ SVR > PVR
49
When does the ductus arteriosus close?
1-8 days
* anatomic closure 1-4 months
* premies: may take longer to close
50
When does the ductus venosus close?
1-3 after birth
* mechanism unknown; muscular constriction
- portal venous pressure increases
* results in all vena cava blood = deoxygenated
51
Risk factors for prolonged transitional circulation
```
Prematurity
Acidosis
Infection
Pulmonary Disease
Hypothermia
Hypercarbia
```
52
Flip Flop
Revert back to fetal circulation
53
Flip Flop is d/t
Hypoxia, Hypercapnia, anesthesia induced changes in peripheral or pulmonary vascular tone
54
Mechanism of flip flop
Hypoxia (via any mechanism) causes pulmonary vasoconstriction (increased PVR) = R to L shunt (PDA or PFO)
55
Tx: Flip flop
Hyperventilation
| *increased PA pressure will return to normal d/t decreased PaCO2
56
When would RA > LA in a baby?
pHTN
57
Anesthetic goals of baby at risk for transitional circulation/flip flop
- keep infant warm
- maintain normal arterial O2 + CO2 tensions
- minimal anesthetic induced myocardial depression
58
PPHN
Persistent Pulmonary HTN of the Newborn
59
Persistent fetal circulation
PPHN
60
PPHN: characteristics
```
Sustained elevation of PVR
R to L shunt (PFO/PDA)
*vicious cycle*
RV + CO decreased
May be d/t Bronchopulmonary Dysplasia or CV disease
```
61
Risk of PPHN
RV dysfunction + RV hypertrophy (cor pulmonale)
62
PPHN Tx
```
Pulmonary Vasodilators
- NO
-Sildenafil
-Milrinone
-Bonsentan
-Prostanoids
Ventilation strategies: high frequency ventilation or exogenous surfactant administration
Avoidance of Hypoxemia, acidosis
Normal Hematocrit
```
63
Prostanoids
Iloprost, Prostacyclin, or treprostinil
64
Why does a normal hematocrit help treat PPHN?
To ensure adequate oxygen carrying capacity while avoiding polycythemia (hyperviscosity can increase PVR)
65
CV System: immature components
- myocardium
- contractile components
- baroreceptor reflex
- sympathetic NS
66
Cardiac output is solely dependent on
heart rate
67
Autonomic innervation is predominately controlled by the
parasympathetic nervous system
68
What may occur with suctioning + laryngoscopy?
bradycardia
69
Immature baroreceptor reflex may lead to _____ ; Tx =
inability to compensate for HOTN
| Tx: atropine or epi if refractory
70
ventilation with high peak pressures in neonate may result in
LV dysfunction + overload of RV
71
Neonates have a poor sensitivity to
volume loading
| -may develop CHF d/t stiff LV compressing RV (decreasing CO)
72
Preterm Neonate: Vital Signs
HR: 120-180
SBP: 45-60
DBP: 30
73
Term Neonate: Vital Signs
HR: 100-180
SBP: 55-70
DBP: 40
74
1 Year old: Vital Signs
HR: 100-140
SBP: 70-100
DBP: 60
75
2 Year old: Vital Signs
HR: 84-115
SBP: 75-110
DBP: 70
76
5 Year old: Vital Signs
HR: 80-100
SBP: 80-120
DBP: 70
77
HOTN in anesthetized newborn
SBP < 60 mmHg
78
EBV: Premature
90-100 mL/kg
79
EBV: Neonate (< 1 month)
80-90 mL/kg
80
EBV: Infant (3 months-3 years)
75-80 mL/kg
81
EBV: Children > 6 y/o
65-70 mL/kg
82
Newborns blood volume is dependent on
time of cord clamping (transfusion from placenta)
83
Intravascular volume of newborn changes how
- Decreases 25% in immediate postnatal period (loss of intravascular fluid)
- blood volume increases over next 2 months, peaks at 2 months old
84
HOTN in anesthetized 1 year old
SBP < 70 mmHg
85
HOTN in anesthetized older child
SBP 70 mmHg + (age x 2)
86
Why is the cardiac output of a neonate higher than that of an adult?
Necessary to meet higher metabolic oxygen consumption demands
87
Newborn cardiac output
180-240 mL/kg
| 2-3x adults CO: 70mL/kg
88
Predominant hemoglobin in babies
fetal hemoglobin
89
Normal Hemoglobin at birth
18-20 g/dL
90
Normal Hct: Full term baby
55%
91
Normal Hct: 3 months old
30%
92
Normal Hct: 6 months old
35%
93
At what age in babies does the Hgb hit lowest point?
3 months old - decline in Hgb reaches nadir
| "physiological anemia"
94
Type of cell that secretes surfactant
Type II pneumocytes
95
When does fetus begin to produce surfactant? Peak surfactant production?
Begins: 22-26 weeks gestation
Peaks: 35-36 weeks gestation
96
Why would a baby not have enough surfactant?
Premature neonate: absence of surfactant = stiff, noncompliant alveoli
97
What mechanism describes surfactant effect on lungs?
Law of Laplace
P=2T/R
Surfactant decreases surface tension within the alveoli to decrease alveolar collapse
98
Treatment for infantile respiratory distress syndrome
Synthetic surfactant
Continuous positive airway pressure
Mechanical ventilation
*steroids if preterm labor before 26w
99
Narrowest portion of neonate airway
Cricoid Cartilage
| beyond vocal cords aka glottis
100
Which law explains why pediatric airway anatomy is at higher risk for problems?
Poiseuilles Law
- small changes in radius can significantly increase resistance to airflow
- resistance is inversely proportional to radius^4 (laminar) or radius^5 (turbulent)
101
Biggest difference between adult + pediatric airway anatomy
- Shallow vallecula
- larynx directed towards nasopharynx (nasal breathing); C2-C4
- large arytenoids, tongue, occiput
- Subglottic regon = small, conical shaped
- cricoid lumen = ellipsoid, not round
- Cricoid cartilage lined w/ pseudostratified epithelium (easily injured = edema, stridor)
- should roll = best
102
Best position for infant intubation
Headrest + shoulder roll
1. glabella + chin plane horizontally aligned
2. neck: wide/open
3. external auditory meatus + substernal notch plane horizontally aligned
103
Best position for toddler intubation
Simple head extension
104
Infants are obligate nose breathers until
3 months
105
Airway obstruction risks in infants
choanal atresia, nasal secretions
106
failure of development of the posterior opening between nasal cavity + nasopharynx
choanal atresia
107
Alveoli increase in size and number until
child is 8 years old
108
Breathing mechanics in children
- pliable chest wall = paradoxical breathing
- horizontal rib orientation
- decreased FRC
- belly breathing
109
Muscle fibers involved in respiratory mechanics + their importance
Type I - resistant to fatigue, slow twitch
Type II - susceptible to fatigue, fast twitch
**neonates have more Type II, not enough Type I. At risk for respiratory failure d/t reduced reserve
110
FRC in infant vs adult
25mL/kg in infant
45mL/kg in adult
*less effective reserve d/t increased metabolism + O2 consumption rates
111
Postop monitoring required for
infants < 45-55 weeks postconception
| *24h observation in hospital
112
over-inflation of lung
Hering breur reflex
-pulmonary stretch receptors present in smooth muscle of airways respond to excessive stretching of lung during large inspiration
113
Maturation of Nervous system in infant
PNS: myelination begins in motor roots then sensory
CNS: myelination in sensory system precedes that of motor systems
*incomplete myelination
114
incomplete myelination can be seen in which CNS responses in infants?
Moro + Palmar Grasp Reflex
115
Myelination is not complete until what age?
3 years old
116
Moro Reflex
Response to sudden loss of support, when infant feels as if it is falling:
1. spreading out arms (abduction)
2. unspreading the arms (adduction)
3. Crying
* present in newborns until 3-4months
117
Palmar Grasp Reflex
Object placed in infants hand, palm of child stroked, fingers close reflexively
-object is grasped
118
Which muscles are more easily depolarized in infants?
Immature
d/t prolonged opening of ion channels.
*risk of diaphragm - susceptible (fewer Type I fibers)
119
Which NMBs are effective in infants? Why?
increased ECF + ____
(NMBS = highly H2O soluble)
1. increased sensitivity to NDMR
= normal dose
*Prolonged DOA (immature clearance)
2. normal sensitivity to Sux
= increased dose
120
Sux dose
2mg/kg IV
| 4mg/kg IM
121
Postop apnea Tx
Caffeine 10mg/kg IV
122
Risk of pain in neonate
HTN + immature cerebral autoregulatory response + fragile cerebral vasculature
=risk of intracerebral hemorrhage +pHTN
123
most damage from anesthesia occurs when?
during maturation periods when synaptogenesis rapidly occurs
*in utero: post 20 weeks
124
Infants/Kids: Conus medularis terminates between
L2 and L3
| Age 8: L1
125
Nerves within spinal cord mature until completion at age
6-7
126
Dural sac ends between _____ in kids?
Between S2-S3 until 6 years old
127
Brain size in infants
2x size by 6m old
| 3x size by 1y/o
128
Maturation of cerebral cortex + brainstem is nearly complete by what age
1 y/o
129
Anterior fontanelle closes by
2 y/o
130
Posterior fontanelle closes at
4 months
131
Blood brain barrier in infants
immature until 1 y/o
| Higher permeability
132
What should be avoided in neonates d/t their BBB immaturity?
Hypertonic solutions
-can damage cerebral vessels, prone to intracranial bleeding (+ hypoxia, hypercarbia, hypo- or hyperglycemia, swings in BP)
133
Primary fuel for brain
Glucose
134
major source of morbidity in infants
hypoglycemia
135
s/s hypoglycemia in infants
jitteriness, cyanosis, lethargy, hypotonia, apnea, HOTN, bradycardia, convulsions, brain injury
136
Why are neonates at higher risk for hypoglycemia?
Decreased stores of glycogen
137
CBF in premature infant
40mL/100g/minute
138
CBF in older children
adult level
| 100mL/100g/minute
139
Loss of cerebral autoregulation may occur in infants due to?
- hypoxia
- severe hypercapnia > 80 mmHg
- BBB disruption (head trauma, hemorrhage, cerebral ischemia)
- after admin of IAs or vasodilators (SNP)
140
Bradycarda in infant, Tx focuses on
1st hypoxia
| -treat laryngospasm, post-extubation croup, bronchospasm, aspiration, inadequate O2, pneumothorax
141
Drugs that may cause bradycardia in infants
Sux, anticholinesterases, IAs
142
Neurogenic causes of bradycardia in infants
Oculocardiac reflex
143
Metabolic causes of bradycardia in infants
Hypoglycemia, anemia, hypothermia, acidosis
144
Infancy: Autonomic Nervous System
PNS > SNS
145
SNS in infants develops when?
4-6 months old
146
Infants: renal system considerations
"obligate sodium losers"
- unable to conserve sodium
- cannot fully respond to aldosterone
* decreased GFR + concentration ability
147
When are infants kidneys developed?
70% mature by 1 month
| Adult level by 1 year old
148
Infants have low GFR due to?
- decreased systemic arterial pressure
- increased renal vascular resistance
- decreased permeability of the glomerular capillaries
149
infant PO requirement
150mL fluids/kg/day
150
Infants cannot reduce urine output below
1mL/kg/hr
151
What may occur if hypoglycemia in preterm neonates is not treated?
Neurologic damage
152
Increased risk of hypoglycemia if infants are
- premature
- SGA
- infants of diabetic mothers
153
Which other electrolyte may be off in babies?
Calcium
| *risk of hypocalcemia
154
Hypocalcemia is common in infants who are
- premature
- SGA
- asphyxiated
- offspring of diabetic moms
- offspring of mothers who received transfusions with citrated blood or FFP
155
Explain the process of glycogen synthesis in the infant
Fetal liver synthesizes glycogen
- w/in first 48h of life, 98% of stored glycogen is released from liver
- glycogen levels not restored until 3weeks old
* SGA/preterm = susceptible to hypoglycemia
156
Fetal hepatic system - effect on Rx
Immature Phase II liver enzymes
| -Rx metabolized by P450 = prolonged elimination half life
157
Fetal hepatic system - why is jaundice seen?
Decreased glucuronyl transferase activity
| enzyme responsible for breakdown of bilirubin
158
Fetal hepatic system - effect on protein and drugs
-lower total protein
*albumin + alpha-1-acid glycoprotein (binds Rx) decreased
= decreased protein binding of Rx
= higher free drug concentration
159
When does the ability to coordinate swallowing with breathing take place?
4-5 months old
160
Upper intestinal abnormalities in infants present as
vomiting + regurgitation
161
Lower intestinal abnormalities in infants present as
Distention + failure to pass meconium
162
Why are neonates/infants at higher risk for hypothermia?
- Large surface area
- poor insulation
- small mass
- inability to shiver
163
What does cold stress cause in neonates/infants?
Increased O2 consumption + metabolic acidosis
164
In infants who cannot shiver, how do they stay warm?
Non-shivering thermogenesis (NST)
- increases heat production by 100%
- brown fat metabolism: high density of mitochondria, activated by norepi: acts on brown fat to uncouple oxidative phosphorylation
165
Majority of heat loss in babies is due to
Radiant Heat Loss
| -transfer of heat to environment
166
Counteract radiant heat loss how?
- Preheat OR to 26 C
- Double shelled isolette during transport
- wrap neonate in warm blanket
- head = 60% total heat loss
167
What type of heat loss is due to a cold operating table?
Conductive
| *also warm irrigation, blankets, bair hugger
168
What type of heat loss is due to air currents?
convection
169
What type of heat loss is due to wet clothing, liquid from body cavities/resp tract?
Evaporative
| *vaporization of liquid from body to air
170
What is the most effective means of warming children?
Hot air blankets
171
Premature fluid compartment volumes: TBW, ECF, ICF
TBW: 80-90%
ECF: 50-60%
ICF: 60%
172
Infant fluid compartment volumes: TBW, ECF, ICF
TBW: 75%
ECF: 40%
ICF: 35%
173
Child fluid compartment volumes: TBW, ECF, ICF
TBW: 65-70%
ECF: 30%
ICF: 40%
174
Adult fluid compartment volumes: TBW, ECF, ICF
TBW: 55-60%
ECF: 20%
ICF: 40%
175
Volume of distribution equation
Dose of drug/plasma concentration
176
Lipid soluble drugs in infants = _____ plasma concentration
higher
177
Water soluble drugs in infants = ______ plasma concentration
lower
178
Pharmacokinetics - infants cardiac output effects this how?
Higher CO = faster drug delivery + removal
179
Albumin binds to ____ Rx
acidic
180
AAG binds to _____ Rx
Basic
181
Highly protein bound drug
Lidocaine
182
Highly protein bound drugs will have what effect in infants?
greater free fraction of drug, potentially greater pharmacological effect.... narrow therapeutic index (high risk of toxicity) --> reduce the dose!
183
Water soluble drugs
NMBDs
184
How is acetaminophen, chloramphenicol, and sulfonamides metabolized in neonates?
Reduced enzyme activity ...
Neonates lack the capacity to effectively conjugate bilirubin (decreased glucuronyl transferase activity)
*same enzyme needed to metabolize these Rx
185
Drugs with prolonged half lives in neonates/infants
```
bupivacaine (25 hrs)
mepivacaine (8.5 hrs)
diazepam (100 hours)
indomethacin (15-20 hours)
meperidine (22 hours)
phenytoin (21 hrs)
```
186
Which drugs may be effected in infants due to their immature enzyme activity?
LA, sux, atracurium, cisatracurium, esmolol
187
oral/rectal drug administration relies on ______ for absorption
passive diffusion
188
Rectal administration of drugs: superior rectal veins empties into
portal system
189
Rectal administration of drugs: middle/inferior rectal veins empties into
IVC (systemic circulation)
190
oral drugs degree of ionization depends on
gastric/intestinal pH levels
191
Oral drugs degree of ionization depends on gastric/intestinal pH levels. Acidic drugs are ____
- non-ionized
| - favored absorption in stomach
192
Oral drugs degree of ionization depends on gastric/intestinal pH levels. Basic drugs are ____
absorbed in the intestines
193
Upper 1/3 of rectum - superior rectal veins
| Which Rx avoid this area?
Avoid opioids + midazolam
| *acetaminophen okay to give there
194
Rapid equilibrium of IAs in infants d/t
- increased ventilation (relative to FRC)
- increased cardiac output
- decreased solubility of IA
195
Neonates have _____ MAC but ____ at ___ days
lower MAC but peaks at 30 days
196
intracardiac shunts will cause what during induction (inhaled)?
prolonged time (R to L shunt)
197
FA/FI ratio is affected by
delivered IA concentration, IA blood-gas coefficient, alveolar ventilation, cardiac output, distribution to vessel rich (heart, brain, liver, kidneys)
198
Why may IV agents have a prolonged DOA in infants?
decreased muscle/fat (therefore less redistribution)
199
Highly ionized, low lipophilicity, limited ability to cross BBB
Neuromuscular blocking drugs
200
Which NMBD are infants more resilient to?
Sux
| *only used in emergencies < 12 y/o d/t severe hyperkalemia risk in undx myopathies
201
Important rule of NMBD
ALWAYS reverse
202
Which system in infants is inhibited by anesthesia?
RAAS - renin angiotensin
203
Neonate maintain urine osmolality between
200-400 mOsm/L
204
Neonate specific gravity should be maintained
1.006-1.012
205
Neonate normal serum osmolality
270-280 mOsm/kg
206
Neonate on TPN - what fluids to give?
continue or infuse dextrose solution + monitor BG
207
NPO requirements - breast milk
4 hours
208
NPO requirements - clear liquids
2 hours
209
NPO requirements - formula
6 hours
210
Preterm + SGA neonates glucose requirement
8-10 mg/kg/min to prevent hypoglycemia
211
If preterm or SGA neonate becomes hypoglycemic intraop, Tx?
D5 or D10 solution followed by 10-15% Dextrose solution titrated to serum BG > 40 mg/dL
212
electrolyte abnormality d/t excess water loss in infants
hypernatremia
213
electrolyte abnormality d/t respiratory alkalosis/aggressive diuresis
hypokalemia
214
Hyperglycemia in neonate/infants intraop may lead to
intraventricular hemorrhage, osmotic diuresis, dehydration, release of insulin --> hypoglycemia
215
How to estimate blood loss from neonate/infant
1gm sponge weight = 1 mL blood loss
216
Which should be transfused at higher Hgb levels: neonate, infant, child?
Neonate
217
Most common cause of cardiac arrest in noncardiac procedures
hyperkalemia
218
What will reduce the risk of hyperkalemia d/t blood transfusion in neonate/infant?
Fresh ( < 1 week old)
Washed blood
Radiated
pRBC NOT whole blood
219
Which patient population should receive irradiated blood?
Immunocompromised patients
220
Electrolyte abnormality seen in blood transfusions
hypocalcemia
d/t citrate in blood
= CV instability
