CCP 340 Neonatal Anatomy and Physiology 👶🏻 Flashcards
Neonatal airway anatomical features
aka from an ANATOMICAL perspective why do neonates suck to intubate
- VERY Small, compressible airway
2. Relatively large tongue and occipital area
Neonatal airway physiologic features
aka from an PHYSIOLOGIC perspective why do neonates suck to intubate
- Low Functional Residual Capacity
2. High metabolic rate and oxygen consumption (desaturate FAST)
Emergency evaluation of the newborn should be framed by three questions
- Was it a term birth? (37 weeks)
- Does the neonate have good tone?
- Is the neonate breathing or crying effectively?
Negative responses to any of the above questions should prompt further evaluation and likely initiation of resuscitation procedures.
Positive responses to all questions and no additional provider concerns indicate that resuscitation is likely not needed and the infant can stay with the mother.
main aetiologies for Neonatal distress and arrest
common: respiratory
rare: severe anemia or congenital/cardiac
location for PRE-ductal pulse oximetry
right upper extremity
what percent of term infants require drying and stimulation to trigger breathing reflex
10%
what percent of term infants will breathe spontaneously within the first 30 s of life and require no additional management
85%
what percent of term infants require positive pressure ventilation to trigger breathing reflex
3%
what percent of term infants require intubation for respiratory support
2%
what percent of full-term infants require chest compressions and epinephrine to achieve transition
0.1%
detail of the pathophysiology related to rapid shift in fetal circulation upon delivery
aka, how does CVS/respiratory shit change for baby once it gets outta mom
- Clamping of the umbilical cord ↑ the baby’s SVR
- Blood flow through the ductus venosus ↓ and gradually closes over the first 3-7 d, thereby ↑ blood flow to the IVC
- Lung expansion causes a ↓ in pulmonary vascular pressure, which ↑ right atrial flow
- The ↑ in right atrial flow ceases the flow through the foramen ovale, which then closes almost immediately.
- These alterations in blood flow through the ductus arteriosus → its closure within the first week of life
- obtaining an SpO2 on the right hand (preductal) gives the most accurate assessment of central oxygen levels.
- This process also explains the gradual shift in appropriate O2 levels from <65% at birth to 85%-95% at 10 min of age
maternal risk factors which increase prenatal stress on the fetus leading to higher rates of neonatal resuscitations
AKA, in what cases should you anticipate an NRP resus
Active infection Gestational diabetes Gestational hypertension Illicit drug use Lack of prenatal care Pre-eclampsia/eclampsia Prescription or hospital-administered drug use (including general anesthesia or magnesium therapy)
The normal neonatal respiratory rate
40-60 breaths per minute
The normal neonatal heart rate
120-160 beats per minute
how does PPV help a neonate “transition”
- The initiation of respiration is the first task in neonates.
- positive-pressure respiratory support aids in fluid absorption in the lungs and expands the lung volume → a decrease in PVR → an increase in right atrial flow → improved CVS/pulmonary dynamics/oxygenation
Pregnancy complications and fetal factors which play a role in an increased likelihood of NRP resuscitation requirements
Multiple gestation (particularly <35 wk) Oligo- or polyhydramnios Hydrops fetalis Fetal congenital malformations Premature rupture of membranes (rupture before labor begins) or prolonged rupture (>18 h) Preterm delivery (<36 wk) Non-reassuring fetal heart rate or bradycardia Meconium-stained amniotic fluid Breech presentation Shoulder dystocia Nuchal cord Emergency cesarean section
define gestational age
Gestational age is loosely defined as the number of weeks between the first day of the mother’s last normal menstrual period (LMP) and the day of delivery
APGAR: “Appearance”
Blue, pale (0)
Centrally pink (1)
Pink (2)
APGAR: “Pulse”
Absent (0)
<100 bpm (1)
>100 bpm (2)
APGAR: “Grimace”
Floppy (0)
Minimal responsiveness (1 )
Responds to stimulation (2)
APGAR: “Activity (tone)”
Absent (0)
Flexed (1 )
Active (2)
APGAR: “Respirations”
Absent (0 )
Slow (1)
Vigorous (2)
neonatal hypoglycaemia definitions
- Hypoglycemia in the first 1-4 h of life is considered at levels <2.2 mmol/L
- From 4-24 h of life, glucose should be >2.5 mmol/L
when does a fetus become viable?
23 weeks +/- 1wk
SGA definition
small for gestational age
AGA definition
appropriate for gestational age
LGA definition
large for gestational age
IUGR definition
intrauterine growth restriction
extreme preterm definition
💵💵💵 MONEY SLIDE 💵💵💵
<30 wks
preterm definition
<37 wks
late preterm definition
35-37 wks
term definition (gestational age)
37-42 wks
at what week in embryonic development does the neonate start producing surfactant?
24 wks
at what week in embryonic development does the neonate form alveolar sacs?
36 wks
fluid choice for first 24hr in a neonate
D10W (no electrolytes, because kidneys aren’t working until post 24h)
goal sats preterm infant
88-92%
goal sats term infant
90-95%
ml/kg/min for a neonate minute ventilation
👊👊👊CORE CONTENT👊👊👊
200-300 ml/kg/min
side effects of prostinaglandin
- apnea
- hypotension
- fever
discuss the approach to oxygenation as part of the initial neonatal resuscitation
- Oxygenation should not be aggressive. Hyperoxia is associated with ↑ morbidity and mortality.
- Room air (21% oxygen) is sufficient during the initial stages of resuscitation.
- Preductal (right hand) goal SpO2 at 1 min of life is 65%-70% and ↑ by ~5% per min.
- The target SpO2 at 10 min of life is 85%-95%.
- If the HR is <60 after 90 s of resuscitation at lower oxygen concentration, the oxygen concentration may be ↑ to 100% until the heart rate recovers
describe the “MR SOPA” mnemonic
- Most neonates respond to positive pressure ventilation.
- If positive pressure ventilation is ineffective, the “MR SOPA” mnemonic may be used to improve ventilation
M = mask (adjust mask for good seal) R = reposition the airway S = suction the mouth then nose O = open the mouth with a jaw thrust P = increase pressure until there is chest rise A = airway control (ie, endotracheal tube)
primary reflexes in baby
suck, moro, grasp
side effect of pyridoxine (vitamin B6)
apnea
phenobarbital dosing for neonatal seizures
20mg/kg
then 10mg/kg x2
persistent projectile vomiting in a previously well baby (usually presents at 3-12 weeks of age)
typically pyloric stenosis
ml/kg/min for a paediatric minute ventilation
100-200mL/kg/min
neonate lung protective tidal volume
4-6mL/kg
peds lung protective tidal volume
6-8mL/kg
VITAMINS mnemonic for peds altered mental status
Vasculitis Infection Toxins Accidental Injury Metabolic intussusception Neoplasm Seizures
calculating Maintenance fluids in Neonates
- the 4-2-1 rule is not used in neonates as it overestimates the fluid requirements in the first few days and underestimates fluid requirements after day 4
- In Neonates we order as total fluid intake (TFI) per day:
For full term infants: Day 1: 60 cc/kg/day Day 2: 80 cc/kg/day Day 3: 100 cc/kg/day Day 4: 120 cc/kg/day Day 5: 140 cc/kg/day Beyond: 150 cc/kg/day
“intake” for fluid balance includes…
Intake includes:
- IV fluids
- Medications (IV, NG/GT)
- Oral Solids & Fluids
- NG/GT feeds
- All flushes (NG, GT etc.)
- Blood Products
- TPN & Lipids
initial fluid choice for first 24hr of life in a neonate
- D10W
- maintenance electrolytes generally are not given before 24 hours of life because of the relatively volume-expanded state and normal isotonic losses during the first days of life
discuss the use of electrolyte containing fluids in the first 24 of life in a neonate
- For infants receiving parenteral fluids, maintenance electrolytes generally are not given before 24 hours of life because of the relatively volume-expanded state and normal isotonic losses during the first days of life
- Use D10W
Major Objectives of Maintenance Fluid Therapy include:
Provide WATER to meet physiologic needs/losses
Provide essential ELECTROLYTES (Na, K, Ca)
Provide minimum CALORIC needs
Maintenance Fluid Therapy definition
Represents the fluid and electrolyte requirements needed by the average individual with normal intracellular(ICF)and extracellular(ECF) fluid volumes OVER a 24-hr PERIOD.
why do Infants have HIGHER fluid requirements?
💵💵💵 MONEY SLIDE 💵💵💵
- ↑ Rates of Metabolism and Growth
- ↑ Caloric Expenditure translates into ↑ Fluid Requirements
- ↑ Insensible Fluid and Electrolyte losses d/t an ↑ BSA to Weight Ratio (almost 3x)
- Lower Tubular Concentrating Ability, → higher obligatory fluid loss.
- ↑ Respiratory Rates result in ↑ insensible losses
factors to consider in terms of Choice of Intravenous Fluids
- Age of the patient
- Nutritional status and Mandatory Glucose Energy Requirements
- Level of cellular injury and trauma
- Type and volume of ongoing fluid losses and/or fluid shifts
discuss Glucose Requirements for Neonates and Infants
- Glucose is the predominant fuel for the newborn brain and it depends on it exclusively.
- Hypoglycemia (especially in the early neonatal period) predisposes to long-term neurological damage.
- Normal adaptive mechanisms like gluconeogenesis and glycogenolysis are immature in neonates and infants. Hypoglycemia is particularly of concern in the premature and sick infant.
- Therefore, it is important to consider maintenance glucose administration in these infants
discuss maintenance fluids in the first 24hr of a neonates life (assume healthy, normal term birth)
- Neonates have ↑ total body water at birth, which must be redistributed and excreted.
- Physiologic diuresis is observed during the first few days of life which leads to a decrease of 5-15% in body weight by the end of week 1
- Therefore, no electrolytes are added to hourly maintenance fluids on DOL1 and sometimes up to DOL2.
- D10W remains the primary hourly maintenance fluid on DOL-1. Thereafter as UO ↑, maintenance rates are ↑ and electrolytes (Na, K, Ca) added to the maintenance fluid mix (D10½NS or D10NS w/ K+)
- Neonates and Infants who present for transfer should have their dextrose containing maintenance fluids continue during the transfer (except for brief interruptions). This will prevent intra-transfer hypoglycemia
name the Two right-to-left shunts occur in the fetus
- Foramen ovale − Blood shunted from the right to left atrium
- Ductus arteriosus − Blood shunted from the pulmonary artery to the aorta
umbilical vein carries oxygenated or deoxygenated blood?
oxygenated blood
umbilical artery carries oxygenated or deoxygenated blood?
deoxygenated
discuss the changes that exist in fetal hemoglobin vs normal hemoglobin
💵💵💵 MONEY SLIDE 💵💵💵
- Fetal HgB has ↑ O2 affinity compared with adult hemoglobin, which facilitates ↑ O2 transport across the placenta.
- The ↑ affinity of fetal HgB → high (~80%) O2 saturation, a level that promotes sufficient oxygen transport across the placenta to meet the metabolic needs of the fetus.
why does the fetus have low O2 tension in its circulating blood?
(average PaO2 in the fetus is between 25-55mmHg)
- The low fetal O2 tension → pulmonary vascular constriction, which maintains PVR at a high level, thereby promoting right-to-left shunting through the foramen ovale and ductus arteriosus
- basically, the fetus doesn’t need as much O2 to survive, and by keeping O2 levels low it preferentially shunts blood past the non-working lungs, keeping the baby alive
so S M R T
even though the fetus has low O2 tension, why is there still adequate tissue oxygenation ?
💵💵💵 MONEY SLIDE 💵💵💵
- Fetal HgB (↑ O2 affinity of fetal HgB)
- Decreased fetal oxygen consumption (baby is chilling inside mom, doesn’t need as much O2 to warm itself etc)
- Differential blood flow − In the fetus, the blood flow is structured so that vital organs (eg, liver, heart, and brain) receive blood with a relatively high degree of oxygen saturation.
All the “best” blood goes to heart/liver/brain
three hallmark features of “successful transition” from intrauterine to extrauterine life
- Alveolar fluid clearance
- Lung expansion
- Circulatory changes with ↑ in pulmonary perfusion and systemic pressure, and closure of the right-to-left shunts of the fetal circulation
factors contributing to Alveolar fluid clearance during transition from intrauterine to extrauterine life
labor, initial breaths, and thoracic squeeze
describe the Circulatory changes that occur at birth as part of the “transition” process from intrauterine to extrauterine life
💵💵💵 MONEY SLIDE 💵💵💵
🥼🥼🥼MEGA PIMPABLE🥼🥼🥼
- umbilical cord clamped → rise in neonatal systemic BP.
- lung expansion leads to ↓ PVR
- These two changes lead to ↓ fetal right-to-left shunt at the ductus arteriosus + foramen ovale
- These two changes also → increased blood flow through pulmonary arteries and lungs. This shift to left-to-right shunting → an increase in ventricular stroke volume, which is associated with an ↑ in cerebral oxygen saturation
- With ↑ lung perfusion and expansion, neonatal O2 saturation is ↑, which stimulates closure of the ductus arteriosus
- In addition, the ↑ pulmonary arterial blood flow raises pulmonary venous return to the LA and left atrial pressure
- As the LA pressure ↑ and the RA pressure ↓, right-to-left shunting across the foramen ovale decreases.
- Closure of the foramen ovale occurs when the LA pressure exceeds the RA pressure.
what % of neonates will experience “difficult transition” and require resuscitative efforts at birth
10% of newborns will need some intervention (usually just positioning, O2, suction, or BMV),
1% will require extensive resuscitative measures (full resus)
risk factors associated with “difficult transition” and requiring resuscitative efforts at birth
- Maternal conditions − Advanced maternal age, maternal diabetes mellitus or hypertension, maternal substance abuse, or previous history of stillbirth, fetal loss, or early neonatal death
- Fetal conditions − Prematurity, postmaturity, congenital anomalies, or multiple gestation
- Antepartum complications − Placental anomalies (eg, placenta previa), or either oligohydramnios or polyhydramnios
- Delivery complications − Transverse lie or breech presentation, chorioamnionitis, foul-smelling or meconium-stained amniotic fluid, antenatal asphyxia with abnormal fetal heart rate pattern, maternal administration of a narcotic within four hours of birth, or delivery that requires instrumentation (eg, forceps, vacuum, or cesarean delivery)
how does Lack of respiratory effort lead to “difficult transition”
a lack of vigorous, regular spontaneous respirations at birth interferes with alveolar fluid clearance, lung inflation, and the fall in PVR
how does Blockage of the airways lead to “difficult transition”
Mechanical blockage of the airway prevents the infant from making adequate initial breaths, interfering with alveolar fluid clearance, lung inflation, and the fall in PVR
define and describe Persistent pulmonary hypertension of the newborn (PPHN)
- term used when the PVR remains abnormally elevated after birth.
- It results from blood shunting right to left through fetal circulatory pathways via the ductus arteriosus and foramen ovale, and can result in severe life-threatening hypoxemia and hypercapnia that may not respond to conventional respiratory support.
- may be seen when adequate lung expansion and ventilation does not occur immediately after birth
describe why preterm infants are predisposed to Inadequate ventilation
- Immature lungs are deficient in surfactant (difficult to inflate and ventilate)
- Immature respiratory drive and weak respiratory muscles increase the likelihood of apnea and inadequate respiratory effort.
describe why preterm infants are predisposed to Hypothermia
- Large BSA to weight ratio, thin skin, and ↓ subcutaneous fat.
- The smaller the infant, the more difficult it is to prevent hypothermia
describe why preterm infants are predisposed to infection
- Preterm infants have immature immune systems, ↑ the risk of acquired postnatal infection
NRP initial assessment three questions to determine neonate’s clinical status
(If the answer to all three questions is yes, the newborn does not need resuscitation, should not be separated from the mother, and is managed by routine neonatal care)
- Is the infant full-term?
- Does the infant have good muscle tone?
- Is the infant breathing or crying?
Four main interventions in NRP
- Initial stabilization (provide warmth, clear Airway if necessary, dry, and stimulate)
- Breathing (ventilation and oxygenate)
- Chest compressions
- Administration of epinephrine and/or volume expansion
discuss delayed cord clamping in the term birth
- ACOG committee + AAP recommend a delay of at least 30 to 60 seconds; with some authors recommending a 2-5 minute delay
discuss delayed cord clamping in the preterm birth
- ACOG committee + AAP recommend a delay of at least 30 seconds
NRP initial steps of stabilization
- Dry the infant, keep warm and maintain body temperature, preferably with skin-to-skin contact with mother
- Position airway and clear secretions if needed
- Stimulation – Tactile stimulation of the newborn is initiated promptly after birth to facilitate respiratory effort. Efforts at stimulating the infant should not be prolonged and should be no more than 30 seconds before initiating next resuscitative steps
NRP intervention for Apnea/gasping and heart rate <100 bpm
Positive pressure ventilation (PPV) at a rate of 40 to 60 breaths per minute
NRP intervention for Apnea/gasping and heart rate <100 bpm after 30 seconds of PPV
M = mask (adjust mask for good seal) R = reposition the airway S = suction the mouth then nose O = open the mouth with a jaw thrust P = increase pressure until there is chest rise A = airway control (ie, endotracheal tube)
if this all fails, tube the kid or put in an iGel
NRP intervention for Labored breathing or persistent cyanosis and heart rate ≥100 bpm
- Position and clear airway
- Use pulse oximetry to monitor SpO2
- Provide supplemental O2 to targeted preductal SpO2
- Consider the use of CPAP
what is the danger associated with unnecessary suctioning in the neonate
AKA why did they change the guidelines to say no more routine suctioning in newborns ?
Unnecessary suctioning can produce a vagal response, → apnea and/or bradycardia
preductal location for the oximeter probe
right upper extremity, usually the wrist or medial surface of the palm
targeted preductal SpO2 levels for term infants born at sea level based on the time after delivery
minute 1-10
1 minute – 60 to 65 percent 2 minutes – 65 to 70 percent 3 minutes – 70 to 75 percent 4 minutes – 75 to 80 percent 5 minutes – 80 to 85 percent 10 minutes – 85 to 95 percent
conditions resulting from hyperoxemia, especially in preterm infants
- bronchopulmonary dysplasia
2. retinopathy of prematurity
preferred oxygen concentration For resuscitation of neonates born at <35 weeks gestation
- oxygen concentration between 21-30%
2. 100% oxygen should NOT be used initially as it is associated with ↑ mortality
when does one initiate chest compressions per NRP algorithm?
Chest compressions are initiated if the infant’s heart rate remains <60 bpm despite adequate ventilation for 30 seconds
compression to ventilation ratio per NRP
- compressions to ventilations at 3:1 @ 120 events/minute → 90 compressions + 30 breaths per minute
“One-and-Two-and-Three-and-Breathe”
IV epinephrine dosing and indications in NRP
- IV epi at a dose of 0.01 to 0.03 mg/kg (0.1 to 0.3 mL/kg of a 1:10,000 solution) is recommended when the HR <60 bpm despite adequate ventilation and CPR
- the ETT route may be used while IV access is being obtained, but is inferior to IV administration. If epi is given through an ETT, a dose of 0.05 to 0.1 mg/kg (0.5 to 1 mL/kg of a 1:10,000 solution) should be used
when should you suspect hypovolemia as a treatable cause in NRP
- ante- or intrapartum hemorrhage, (which may be d/t an umbilical cord accident, placenta previa, placental abruption, or trauma)
- if there are clinical signs of hypovolemia seen despite an adequate HR, such as pallor, poor perfusion, and weak pulses
- administer a 10 mL/kg bolus of NS (or O Rh-negative PRBC if severe blood loss and/or anemia is suspected)
reasons why neonates may fail to respond to PPV
- Mechanical blockage (eg, meconium, mucus, choanal atresia, congenital airway malformation)
- Impaired lung function (pneumothorax, pleural effusions, congenital diaphragmatic hernia, pulmonary hypoplasia, congenital pneumonia, or hyaline membrane disease)
main causes for persistent apnea in newborn
- Brain injury (hypoxic ischemic encephalopathy)
- congenital neuromuscular disorder
- respiratory depression from maternal medication
after how much time should you consider d/c’ing neonatal resuscitation (NRP)
- Resuscitation efforts may be d/c’d after 20 min of effective resuscitation including intubation and the use of epinephrine, if the neonate has demonstrated no signs of life (no heart beat or respiratory effort for >20 minutes)
basic initial care for the newborn infant
- providing warmth to the infant (preferably skin-to-skin contact with the mother)
- clearing his/her airway
- drying and stimulating the infant
ideal ETT placement in neonates
between T1-3, just above the carina.
most effective way to reduce lung injury in neonates
- Avoid mechanical ventilation using early CPAP with, or without, surfactant administration
criteria for neonatal respiratory failure (hint, values differ from older patients)
💵💵💵 MONEY SLIDE 💵💵💵
- Respiratory acidosis, documented by an arterial pH <7.2 and PaCO2 >60-65 mmHg.
- Hypoxia documented by an arterial PaO2 <50 mmHg despite supplemental O2, or when FiO2 >40% on nasal CPAP
most common neonatal conditions to receive mechanical ventilation
- RDS
- Apnea due to prematurity or perinatal depression
- Infection – Sepsis and/or pneumonia
- Postoperative recovery
- PPHN
- MAS
- Congenital pulmonary and cardiac anomalies, such as congenital diaphragmatic hernia
- HIE
Initial tidal volumes for volume-controlled lung protective ventilation in pediatric patients with poor lung compliance
(straight outta UpToDate)
tidal volume 3 to 6 mL/kg of IBW for patients with poor lung compliance (eg. Peds ARDS)
Initial tidal volumes for volume-controlled lung protective ventilation in pediatric patients with normal lung compliance
(straight outta UpToDate)
tidal volume 5 to 8 mL/kg when compliance is preserved
Initial tidal volumes for volume-controlled lung protective ventilation in Infants (<1 year of age) patients with normal lung compliance
(straight outta UpToDate)
5 to 8 mL/kg (healthy lungs)
Initial tidal volumes for volume-controlled lung protective ventilation in Infants (<1 year of age) patients with poor lung compliance
(straight outta UpToDate)
3 to 6 mL/kg (lung protective strategy)
Gastroschisis
- birth defect of the abdominal wall. The baby’s intestines are found outside of the baby’s body, exiting through a hole beside the belly button
- due to failure of the intestines to return to the body during development.
- Normally “bad gut” but good baby
Omphalocele
- birth defect of the abdominal wall.
- The infant’s intestines, liver, or other organs stick outside of the belly through the belly button.
- The organs are covered in a thin, nearly transparent sac
- Good gut but bad baby. Usually many midline defects and genetic anomalies
causes of bilious vomiting
- Duodenal atresia/stenosis/webbing, malrotation, obstruction
- Bilious vomiting is likely to be of surgical in nature.
focused neonatal GI/GU physical exam
Birth Weight Color of material from gastric tube Dehydration Anterior wall defect Abdominal distention, signs of visible bowel loops, color, tender Increasing abdominal girth Other anomalies noted
why are babies at risk for temperature instability
surface area to body mass ratio is 4x that of an adult, but the ability to increase heat production is only 1/3 that of an adult.
focused Antepartum infectious disease history
Maternal Infection
history of previous baby with GBS infection or unexplained still birth
ROM at < 37 weeks gestation
positive GBS screen
focused Intrapartum infectious disease history
PTL
ROM > 18 hours
Maternal temperature > 38
Chorioamnionitis
suspected or proven bacterial infection from mother
risk of vertical transmission of viral infection: HIV, HSV, Hepatitis, COVID
focused Neonatal infectious disease history
Need for rescuscitation
prematurity or low birth weight
baby going to the NICU
nosocomial or community acquired infections
focused Neonatal infectious disease physical
Observation for sources of infections (wounds, skin break down)
investigate localized infections
Sepsis work up: Blood Culture (urine if over 3 days), CBC with white cell differentiation and Plt
NICU tidal volume targets
4 - 6 mL/kg
NICU respiratory rate targets
40 - 60
NICU inspiratory time (Ti) targets
0.35 - 0.55
NICU PEEP targets
5 - 8
NICU minute ventilation targets (mL/min/kg)
💵💵💵 MONEY SLIDE 💵💵💵
200-300 (mL/min/kg)
NICU pH targets
7.25 - 7.45
NICU pCO2 targets
40 - 55
NICU pO2 targets
50 - 80
NICU bicarb targets
22 - 26
Define fetal macrosomia
- Larger than average newborn torso size
- Commonly size with diabetic mothers.
- These newborns are considered LGA
Define newborn hypoglycaemia (specific value)
BGL < 2.6 mmol/L
What is the normal respiratory rate of a newborn?
40 to 60 breaths per minute
What percentage of newborns require resuscitation?
- 10% require some degree
2. < 1% require extensive resuscitation
When does bronchopulmonary epithelium begin producing fetal lung fluid?
- at ~6th week of gestation
- Issues such as congenital diaphragmatic hernia compress the lung in utero, preventing development
- Reduction of amniotic fluid (such as in prolonged ROM) → hypoplasia of the lungs from ↓ of volumes available for inhalation.
What is the “one-third rule” (fetal lung fluid clearance)
- rule states that 1/3 of fetal lung fluid will be cleared by the infant before birth, the second 1/3 is squeezed out during vaginal delivery, and the final 1/3 is cleared by the infant following birth.
- Infants born preterm have not yet facilitated the initial 1/3 of fluid clearance
- C-section babies don’t get the birth canal squeeze
Explain chest wall physiology of an infant
- ↑ chest wall compliance → in-drawing of the chest wall during negative pressure inspiration. This is why see-saw respirations are normal in infants
- Infant respiration relies almost solely on the strength of the diaphragm
What is normal FRC of an infant?
30 mL/kg
What are ABDs? (term often used in the nicu when trending babies)
- Apneas, bradys, and desats.
2. >3 per hour should raise concern for badness
Explain the role of caffeine for newborns
Caffeine is given to newborns who have immature apnea centres. Caffeine stimulates the apnea centre to breath.
What is the percentage of total body water in a newborn vs child vs elderly
newborn: ~85%
Children: ~75%
Elderly: ~50%
What is the difference between the distribution of fluid between a preterm and term infant?
- Term = 50% intravascular, 50% extracellular
2. Preterm = Primarily intravascular
What is the normal U/O of an infant?
2 ml/kg/hr → This volume allows for excretion of normal solute load.
Newborns typically have very low U/O in the first 24 hours, then diurese
Explain the three disabilities of preterm kidneys
↓ GFR
↓ reabsorption of Na+ and HCO3-
↓ Decreased ability to dilute or concentrate urine
List 6 risk factors contributing to increased insensible water losses in neonates
- Lower gestation (due to high body surface area and immature water-permeable skin.
- Skin defects (ie. gastroschisis)
- High body or ambient temperature (30% per degree)
- Radiant light (50% increase IWL)
- ↑ motor activity
- Pathogenic fluid loss (ie. chest tube drainage)
List 5 things we can do to reduce insensible water losses in neonates
- Double-walled incubator or plastic heat shield (incubators reduce IWL by 1/3).
- ↑ ambient humidity
- Thin transparent plastic barriers (stuff em’ in a plastic bag)
- Humidification of inspired gas in CPAP or ventilator
- Antenatal corticosteroids to promote maturation of skin and kidneys.
Over what time do newborns typically lose weight?
When do they again achieve their birth weight?
- Weight loss over the first 2 to 3 days.
2. Birth weight achieved by 7 to 10 days.
When replacing fluids/electrolytes, what are the three goals to function by?
- Replace deficit
- Replace ongoing losses
- Maintenance fluids
What is the standard fluid bolus dose for infants? (replacement)
10 ml/kg
What weight should we use for medication dosing in a newly born infant? How about a two-day old infant?
Birth weight until weight losses are regained
what do pre ductal and post ductal sats measure exactly
Pre-ductal measurements identify the oxygenation of blood leaving the LV before deoxygenated blood mixes from the RV through a patent ductus arteriosus
Preductal SpO2 at 1 min of life is approximately _____ and increases by ___% per min until 5 min of life
65%-70%
increases by 5% per min until 5 min of life
Target SpO2 at 10 min of life is ______
85%-95%.
Emergency evaluation of the newborn should be framed by three questions:
Was it a term birth?
Does the neonate have good tone?
Is the neonate breathing or crying effectively?
The normal neonatal heart rate is ____ to ____ beats per minute
120-160
The normal neonatal respiratory rate is ____ to _____ breaths per minute.
40-60
Extremely preterm weeks
(≤27 6/7 wk)
Very preterm weeks
(28 0/7 to 31 6/7 wk)
Moderate to late preterm weeks
(32 0/7 to 36 6/7 wk)
Hypoglycemia in the first 1-4 h of life is considered at bG levels < ____
< 2.2 mmol/L
The preductal location
right upper extremity
“MR SOPA” mnemonic
may be used to improve ventilation in neonate
M = mask (adjust mask for good seal), R = reposition the airway, S = suction the mouth then nose, O = open the mouth with a jaw thrust, P = increase pressure until there is chest rise, A = airway control (ie, endotracheal tube)
