CCP S3 shit Flashcards
Define fetal macrosomia
Larger than average newborn torso size. Commonly size with diabetic mothers. These newborns are considered LGA
what percentage of newborns require resuscitation?
10% require some degree
<1% require extensive resus
when does bronchopulmonary epithelium begin producing fetal lung fluid
bronchopulmonary epithelium beings producing liquids as early as the 6th week of gestation. The volume and rate at which liquid is secreted are calibrated to maintain lung volume at the desired FRC.
- Issues such as congenital diaphragmatic hernia compress the lung in utero, preventing lung development in utero
- Reduction of amniotic fluid (sucks as in prolonged ROM) results in hypoplasia of the lungs from reduction of volumes available for inhalation
What is the “one-third rule”
The fetal lungs secrete Na and fluid to cause the lungs to expand and promote growth during development
During birth: before and during birth the bronchopulmonary epithelium Na channels changes from secretion to absorption of Na and fluid. This is upregulated with glucocorticoids and epinephrine during delivery. The “squeeze” from the birth cannel aids in compressing the chest and dispersing more fluid
1/3 from Na channel changes from secretion to absorption of Na and fluid. Upregulated with catecholamines.
1/3 squeezed in vaginal delivery
1/3 from initial cry
Infants born preterm have not yet facilitated the initial 1/3 of fluid clearance.
what is the role of glucocorticoids in the antenatal preterm pregnancy
glucocorticoids accelerate the production of type 1 and type 2 alveolar cells. Type 2 alveolar cells produce surfactant. They also enhance the exposure of Na-K-ATPase which assist in fetal lung fluid clearance.
Steroids also provide neuroprotection and maturation of skin
Why is 24 weeks GA typically the cutoff for extrauterine fetal survival?
Alveoli aren’t developed at this GA, the majority of the lung is composed of terminal bronchi. Alveoli develop in the 3rd trimester and dramatically increase up to age of 2 then gradually to age 8
Betamethasone and dexamethasone dosages for antenatal corticosteroid
Betamethasone = 12mg x 2 q 24 hours apart
Dexamethasone = 6mg x 4 doses 12 hours apart
When are antenatal corticosteroids indicated?
<34 weeks
What 4 questions should be asked of the mother during imminent birth?
GA
ROM
Clear amniotic fluid
Complications
Explain chest wall physiology of an infant
Increased chest wall compliance results in the in-drawing of the chest wall during negative pressure inspiration. This is why see-saw repirations are normal for infants.
Infant respiration relies almost solely on the strength of the diaphragm
what is normal FRC of an infant
30ml/kg
how long is induction/ceaserian typically delayed once antenatal corticosteroids are administered?
One week
Benefits are seen as of 4 hours post-initiation of therapy but greatest after one week
What are the contributing factors to the fall of PVR
- increase in alveolar and arterial oxygen tension. Fetal pulmonary circulation becomes more responsive to the vasodilator effect of oxygen after 31 weeks.
- Increase in production of vasodilators
- rhythmic distension of the lungs
When does the ductus arterioles normally close?
Within 12 hours of birth. Closure is primarily caused by redirection of BF to the pulmonary vasculature
What medication is used to maintain PDA patency
Prostaglandin. Alprostadil exerts direct vasodilatory effects on venous and ductus arterioles smooth muscle
Explain regulation of pulmonary vasculature tone
NO is produced by the endothelium and is metabolized into cGMP which produces vasodilation.
cGMP is degraded into GMP by the enzymes PDE5. cGMP degradation can be reduced by PDE5 by PDE5 inhibitors such as sildenafil
where are pre and post ductal measurements obtained from?
Pre-ductal is always from the right hand
Post-ductal should be from the feet because the left hand be pre-ductal in some circulation anomalies
Pre-ductal measurements identify the oxygenation of blood leaving the left ventricle before deoxygenated blood mixing from the RVA through patent PDA
What is the most effective way to determine GA?
Ultrasound. Accuracy worsens as the fetus develops
What is the most common organism to cause neonatal sepsis
Group B strep
E.Coli is the 2nd most common cause
What does blood in the amniotic fluid typically indicate ?
placental abruption
What are the two most common causes of premature fetal delivery
infection
cervical incompetence
What are the three most common causes of PTD without labour?
HTN
Fetal distress
Polyhydramnios
Why do we give Magnesium to preeclamptic mothers?
Prevent seizure of the mother (thought to be from NMDA receptor action, increasing the threshold for seizure)
Fetal neuroprotection (unknown mechanism)
What is lanugo
Newborn body hair. More prominent in early pregnancy
What is considered term?
> 37 weeks
what is considered preterm
23-36+6
what is considered post term
> 41
Define asymmetric IUGR
Hypotrophic growth restriction that is head sparing. The undernourished fetus directs energy to maintain vital organs (brain/heart)
Related to maternal issues. The baby usually catches up in growth
Define symmetric IUGR
Entire growth is restricted, considered SGA with a head that is appropriate for the body size.
Related to maternal issues. The baby doesn’t usually catch up with growth
Explain why IUGR babies are at risk of hypoglycaemia and hypothermia
IUGR babies have reduced body fat comparative to high body surface area. They also have hypo plastic livers
What is colostrum
the first breast milk produced by the mammary glands that are rich with immunologic factors
What is the Fenton chart
it is used by BCCH to track and assess a newborns growth
whats the percentage of body water in a newborn
Up to 85%
What is the difference between distribution of fluid between a preterm and a term infant?
term = 50% intravascular and 50% ECF
Preterm= primarily intravascular
What is normal UO of an infant
2-4 ml/kg/hr
new borns have very low UO for the first 24 hours then diurese
Three disabilities of preterm kidneys
- decreased GFR
- decreased reabsorption of Na and HCO3
- Decreased ability to dilute or concentrate urine
Six factors contributing to increased insensible water losses
- Lower gestation (due to high body surface area and immature water permeability skin)
- skin defects (gastrochisis)
- high body or ambient temperature (3% per degree)
- radiant light (50% increase IWL)
- increased motor activity
- pathogenic (chest tube etc)
5 Ways we can reduce insensible water losses:
- double walled incubator or plastic heat shield
- increase ambient humidity
- plastic bags
- humidified cpap/vent
- antenatal corticosteroids to promote maturation of skin and kidneys
over what time do newborns typically lose weight and gain it again
lose the first 2-3 days then gain by 7-10 days
what are two causes of hyponatremia in a newborn
SIADH
Excessive maternal free water intake
Two causes of hypernatremia in new borns
excessive sodium intake
dehydration
causes of hypokalemia in neonates
excessive GI losses
dilution
What weight should we use for medication dosing in the newly born infant?
birthweight until weight losses are regained
What is a repogle tube
A double lumen tube that allows for suctioning co-comittantly with feeding
what does APGAR stand for
activity pulse grimace appearance respiration
When does the cough reflex become more evident
At one or two months of age.
this is when we begin seeing coughing with respiratory infections
Until what age are infants obligate nose breathers?
6 months
What age is bronchiolitis most common in?
<2 years of age (but especially below 6 months)
Bronchiolitis is unresponsive to bronchodilators
Some of the neurological differences seen in children
- suture and fontanelles (which close around 6 months)
- spinal cord ends at L3 (L1-L2 in adults)
List some CVS differences seen in children
- stroke volume is fixed, HR is the only way to increase CO
- SVT is more common in the first few weeks of life because of the immaturity of the AV septum
List some of the respiratory differences seen in children
- cone shape narrow trachea
- larger tongue
- softer pallate
- lower FRC (contributing to quicker desaturations, along with increase basal metabolic rate
- immature sinuses
- toothless but at risk of tooth bud injury
- obligate nose breathers
- compliant chest wall
List some of the dermatological differences seen in children
- thin skin and higher body surface area contribute to hypothermia
- brown fat is utilized for thermogenesis, rather than shivering
- sweating and vasodilation is less effective in infants and toddlers
Why is SCIWORA more common in infants
- the fulcrum is located at C1/C2 rather than C5-C6 in adults
- Atlantoaxial dissociation is more frequent and is fatal
Three components of paediatric triangle
apperance
breathing
circulation
What is the equation for average MAP in children
age x 1.5 +40
A HR of up to ___ is useful to increase CO in children. Beyond this rate, diastolic filling is impaired
180 HR
what are the two most troublesome side effects of Dexmedetomidine (precedex)
Bradycardia and hypotension
Why is propofol not used beyond 24 hrs in the sedation of pediatrics
-childreen are at higher risk of PRIS due to fat distribution and dosage requirements for effects
outline the drug profile of Milrinone
classified : Phosphodiesterase inhibitor
MOA: increases intracellular cAMP, increasing cardiac isotropy, and chronotropy, dromotropy
Why does epinephrine cause hyperlacataemia
thought to be caused by peripheral vasoconstriction of distal capillaries with some degree of distal limb ischemia
What is a histogram
a graph that is used to determine time at a specific oxygen saturations
List the fetal channels
umbilical veins ductus venosus foramen ovale ductus arteriosus umbilical artery
Describe TTN
Respiratory distress associated with inadequate fetal lung clearance. Transient in nature, and generally resolves in 24 hours
Describe neonatal RDS
Respiratory distress caused by surfactant deficiency
Describe PPHN
Pulmonary HTN caused by abnormal presence of elevated PVR that leads to right-to-left shunting of deoxygenated blood though the PFO and PDA.
PPHN is often caused by underdevelopment of pulmonary vascular bed, and can also be caused by fetal distress, such as in MAS
Define meconium aspiration syndrome
- fetal distress results in meconium with subsequent aspiration. Meconium layers the respiratory tract, causing chemical irritation, inflammation, infection and surfactant inactivation
- MAS produces bilateral diffuse grossly patchy opacities. The areas of thee CXR are patchy because of areas of total atelectasis, as well as areas of air trapping within the alveoli
Why is meconium voided during fetal distress
increased vagal outflow from umbilical cord compression or increased sympathetic outflow from hypoxia causes peristalsis and relaxation of the anal sphincter
what is the equation for calculation ETT size in peds?
age/4 + 3 = cuffed
age/4 + 4 = uncuffed
What is the calculation for ETT depth
tube x 3
what is the neonatal/ped does for succinylcholine for RSI
2mg/kg
Why are babies born from diabetic mothers at higher risk of hypoglycaemia
The fetus is accustomed to receiving an abidance of glucose, meaning they have had to up regulate endogenous insulin production in order to maintain normoglycemia.
Once the placental delivery of glucose comes to a halt, the infant will be overproducing insulin for the amount of glucose being produced
what are three clinical features necessary for the dx of DKA
Hyperglyemia >11.1 mmol/L
pH <7.3
HCO3 <15
Ketones
Why does gluconeogenesis and glycogenolysis occur during DKA despite elevated BGL?
Astrocytes cannont detect glucose levels because of insulin deficiency. Without insulin to transport glucose into astrocytes, the brain registers hypoglycaemia, and promotes gluconeogenesis and glycogenolysis
What are the three ketones?
- Acetoacetate
- Beta-hydroxybutrate
- Acetone
Outline the mgmt of DKA in peds
- fluid 10-20ml/kg
- even rehydration over 24-36 hours, assuming 5-10% dehydration
- use 0.45 or 0.9 NaCl
- No insulin for the first 1-2 hours of treatment, due to increased risk of cerebral edema that is likely related to fluid channels in the brain
- target BGL 8-12mmol/L with continuous insulin infusion once initiated, using 2-bag method with glucose to match
- continue insulin therapy until anion gap or BOHB levels resolve
- Potassium correction in conjunction with insulin therapy
Explain the fluctuation of sodium in DKA
Hyponatremia is caused by water shift into the ECF, diluting serum sodium
Hypernatremia is superimposed from loss of water with glucosuria-induced osmotic diuresis, sparing sodium and potassium
describe mechanism that produce hyperkalemia in DKA
- solvent drag
- impaired K entry into cells from insulin deficiency
- intracellular protein and phosphate depletion
- buffering of hydrogen ions
Criteria for dx of HHS
BGL >33.3 mmol/
Hyperosmolarity >320 mOsm/kg
small or absent ketonuria
absence of significant acidosis
outline mgmt of HHS
fluids 20ml/kg NS
correct glucose, potassium and sodium levels
- glucose lowered by 3-5 mmol/Hr
- Sodium lowered by 0.5mmol/Hr
What is the marker of the correction of HHS
-osmolality and glucose back to normal ranges
what is the dose of d10w for neonatal hypoglycaemia
2ml/kg bolus followed by 4ml/kg/hr infusion
List four predisposing factors to PTD
Cervical shortening
Incompetent cervix
PPROM
Preterm labour
RF for PTD
Maternal - previous PTD, uterine abnormality
Fetal – IUGR, fetal anomaly, multiple gestation
Placental - poor implantation, antepartum hemorrhage
what is considered a short cervix
<2.5cm before 24 weeks
what is an incompetent cervix
it is essentially the opening of the cervix without labour. defined as painless cervical dilation, typically before 24 weeks GA
What are the components of the initial assessment of PTL?
- GA
- Palpation of contractions
- sterile speculum exam
- digital exam
What is fFN testing
-fetal fibronectin testing is a protein dectable during labour. it is produced when there is separation of the placenta from the uterine wall
The negative predictive value is very good at ruling out PTL
Goals of tocolytic therapy ?
allow for steroids to work
allow for abx to work
transport
what is a normal fetal HR
110-160
What are the consequences of PROM
PTD within 1 week in 50% of births,
Fetal pulmonary hypoplasia
Fetal skeletal maldevelopment
Ascending infection
What are the steps of delivery of a fetus with shoulder dystocia? (theres an acronym)
- Ask for help
- Legs back
- Anterior shoulder (push anterior shoulder downwards, just above pubic bone)
- rotate
- manual removal of posterior arm
ALARM
what medication reduces preeclampsia by ~50%
Aspirin
Define HTN in pregnancy
<140/90
Severe HTN in pregnancy
SBP or DBP >160/110
Define gestational HTN
non-preexisting hypertension that develops beyond 20 weeks GA
What are the criteria needed for dx of preeclampsia
Gestational HTN with 1 of the following:
- new proteinuria or associated symptoms
Define oligohydraminos
Deficiency of amniotic fluid
What are the benefits of delayed cord clamping?
- increased blood volume (20-40ml/kg)
- increased stem cell transfer
- increased iron volume
- increased oxygen carrying capacity
- decreased risk of NEC
- decreased risk of IVH (likely due to stabilized BP from additional blood volume)
When is delayed cord clamping contraindicated?
Absent blood flow to neonate
Multiple gestations that are sharing a placenta (though can be utilized on last baby)
define parturition
the active of giving birth to the young
define Braxton hick contractions
unorganized contractions of the uterus
List four factors that promote labour
- fetus
- myometrial activation
- hormones
- ROM
How does ROM induce labour
ROM produces an inflammatory cascade mediated by arachidonic acid that ultimately thins and dilates the cervix
What are tocolytics
a medications used to suppress premature labour
What are the commonly used tocolytics
Nifedipine (Adalat) – CCB. Blocks calcium influx to inhibit labour contractions
Indomethacin –> an NSAID and tocolytic that inhibits prostaglandin synthestase
Progesterone
Why is Nifedipine usually the first tocolytic agent used at BCCH
it has less adverse effects on thee DA and less risk of causing NEC
Explain the MOA of oxytocin
Oxytocin is classified as a uterotonic
Oxytocin stimulates uterine contraction by increasing intracellular calcium.
Oxytocin is released from the posterior pituitary during active labour. It is useless when cervix is full constricted (as it essentially produces uterine contractions against a closed door)
What is the role of tocolytics in preterm labour
Tocolytic delay labour to allow prelabour growth. They also allow for administration of corticosteroids to allow fetal production of surfactant and to buy time for transport.
What are the four stages of labour?
stage 1 - onset of regular contractions to full dilation
stage 2 - full cervical dilation to delivery of the fetus
stage 3 - delivery of the placenta
stage 4 - post birth
When delivering the placenta, what are some important considerations?
- delivery occurs with maternal effort and gentle cord traction
- place a hand at the symphysis pubis to prevent uterine inversion
- a placenta will normally deliver with a gush of blood, with cord lengthening from the uterus contracting downwards. uterus contractions clamps the closure of the ruptured blood vessels from the uterus
What is the importance of immediate breast feeding after birth?
Oxytocin release, stimulating uterine contraction and reducing hemorrhage
Colostrum feeding for the infant
Conduction of heat from mother to infant
What is the MOA of ultraviolet lights in babies with hyperbilirubinemia
Ultraviolet light acts as a catalyst for the binding to albumin, promoting elimination
What are the most common cause of death in PTD
RDS. cerebral hemorrhage, NEC
Risk Factors of PTD
Maternal –> previous PTD, pre-excisting disease, uterine anomaly
Fetal –> IUGR, fetal anomaly, multiple gestation
Placental –> poor implantation, antepartum hemorrhage
What is considered a short cervix
<2.5 cm before 24 weeks
Define PTL
PTL is defined as regular contractions twice in 10 minutes, as well as changes in length or dilation of the cervix.
What are the components of the initial assessment of PTL
eGA
Palpitation of contractions
sterile speculum exam (cultures, rule out ROM, FFT)
VE
What is ferning?
Microscopic investigation into fluid obtained from speculum exam. Presence of ferning indicates PROM
Define gestational HTN
Non-preexisting hypertension that develops beyond 20 weeks GA
What are the criteria needed for the dx of preeclampsia
Gestational HTN with 1 or more following:
- new proteinuria
or
-associated symptoms
At what GA does preeclampsia/Eclampsia develop
> 20 weeks GA
What is the pathophysiology of preeclampsia
Poor placentation results in inadequate development of placental blood flow. This results in release of antiangiogenic factors from the placenta into the maternal circulation, which binds with vascular endothelium growth factor, resulting in widespread endothelial dysfunction.
Define HELLP syndrome
complication of preeclampsia involving hemolysis, elevated liver enzyme and low platelet count
What symptoms should promote investigation into HELLP syndrome
Nausea/vomiting
RUQ pain
Outline the mgmt of hypertensive disorders of pregnancy
Initial therapy –> Nifedipine and labetalol
Second line methyldopa and other BBs
Why should ACE-i and ARBs be avoided in the mgmt of hypertensive disorders of pregnancy?
they’re fetotoxic
Why does HTN often peak in the days following delivery
the return of volume from the uterus produces hypertension
eclampsia can occur up to 6 weeks post-partum
define oligohydramnios
deficiency in amniotic fluid
What is placenta accreta
Placental growth into the uterus. Placenta accreta is associated with massive mortality and hemorrhage
What are the benefits of delayed cord clamping?
increased blood volume (20-40ml/kg additional blood) increased stem cell transfer increased iron volume increased oxygen carrying capacity decreased risk of NEC Decreased risk of IVH
disadvantages of delayed cord clamping
higher risk of jaundice, though minimal
When is DCC contraindicated
Absent blood flow to neonate
multiple gestations that are sharing a placenta (though can be utilized on the last baby)
CVS changes in moms
increased preload from a rise in blood volume. decreased afterload from declining SVR. increased HR ~20 BPM. Left axis deviation
Resp changes in moms
progesterone stimulation produces an increased resp drive, reducing PaCO2 to 30-32 creating a respiratory alkalosis
PaO2 elevation to 104-108 as a result of increased CO and minimization of VQ mismatch. Upward displacement of diaphragm leading to 20% decrease in FRC. Oxygen consumption increases to 20%
