Module 4: Austin Flashcards
SGA
infant is below the 10th percentile on a standard growth chart
IUGR
refers to the deviation and reduction in expected fetal growth pattern
here are two types of IUGR:
symmetrical and asymmetrical
symmetrical
- the type of growth restriction occurs early in pregnancy and is associated with a decreased number of fetal cells
- inadequate growth of the head, body and extremities
- infants are born with fewer brain cells and tend to have poorer outcomes
- etiologies include genetic or chromosomal causes, early gestational intrauterine infections (TORCH) and maternal alcohol use
asymmetrical
- usually occurs early in the third trimester and is associated with impaired growth of the body, with normal growth of the head and extremities
- is the result of failure of the cells to increase in size resulting in less fat and smaller abdominal organs
- due to extrinsic influences that affect the fetus later in gestation, such as preeclampsia, chronic hypertension, and uterine anomalies
Causes of Intrauterine Growth Restriction.
asymmetric
Placental insufficiency Pre-eclampsia Hypertension Renal disease Long-standing diabetes Smoking Altitude Multiple pregnancy
Causes of Intrauterine Growth Restriction.
symmetric
Congenital infections Chromosomal abnormalities Skeletal abnormalities Fetal alcohol syndrome Constitutional short stature Low socio-economic status
Steps in Resuscitation of the Infant with Perinatal Asphyxia.
A – airway B – breathing C – circulation D – drugs E – environment F – family
Assessment, clear Airway, Apgar score
ensure Breathing, positive pressure until HR > 100/min support Circulation if HR < 100/min, Cardiac massage HR < 60/min - give Drugs - epinephrine
Environment – keep warm
keep Family informed of progress and prognosis
Using the growth chart provided, plot Austin’s percentiles for his weight.
Weight 900 grams — below 10th percentile
Using the growth chart provided, plot Austin’s percentiles for his length.
Length 40 cm — below 50th percentile (approximately 30th percentile)
Using the growth chart provided, plot Austin’s percentiles for his head circumference.
Head circumference 29 cm — 50th percentile
What type of SGA infant is Austin?
Austin is an asymmetrical IUGR baby.
This means that while his body, particularly in terms of weight, is underdeveloped, his head is not. This combination suggests that the antenatal problems causing Austin’s decreased growth were not severe enough to affect brain growth. This is good news for Austin.
What are some problems that Austin is at risk for by being IUGR/SGA?
Austin is at risk for:
hypoxia – due to placenta insufficiency
hypothermia – due to small size and reduced brown fat stores
hypoglycemia – reduced hepatic glycogen stores
polycythemia – due to increased erythropoiesis
Based on what you know about fetal growth and development, and specifically the vulnerability associated with prematurity and SGA, suggest a plan for assessing Austin. What will you plan to assess and monitor (pulmonary, cardio, neuro, GI, renal, immune, and metabolic systems)?
At 31 weeks gestation, all of the organ systems are anatomically well developed. However, physiologically, their functional abilities are quite immature. This means that all of Austin’s organ systems are vulnerable and at risk for problems, and, because of this, require close monitoring. This is an overview of the assessment and monitoring Austin requires:
pulmonary, cardio, neuro, GI, renal, immune and metabolic system
pulmonary
- assess RR and HR by monitor and auscultation
- assess air entry, indrawing, color, perfusion
- monitor blood gases
- pulse oximetry
cardiovascular
- assess HR by monitor and auscultation
- assess for murmurs
- assess perfusion, blood pressure, pulses, color
neurologic
-assess tone, movement, state, fontanelle, level of alertness
gastrointestinal
-assess stools, bowel sounds, abdominal girth, abdominal tenderness
renal
-assess urine output, weight, tissue turgor, serum electrolytes
immune
- observe for infection/sepsis
- monitor temperature, vital signs, CBC
metabolic
- assess temperature
- assess serum glucose
Apnea
Apnea is defined as a as cessation of breathing that lasts for more than 20 seconds and/or is accompanied by hypoxia (↓ O2 sats) or bradycardia (↓ HR) (Walsh, 2010).
Apnea in infants differs from that of adults in that infants respond to hypoxemia with only a brief increase in respiratory rate followed by hypoventilation or apnea.
There are two types of apnea:
primary apnea – is apnea that is not associated with any other diseases (eg: Apnea of Prematurity)
secondary apnea – may be associated with a particular disease or in response to a procedure
When referring to apnea in the context of neonatal resuscitation, primary apnea responds to the initial steps of NRP, whereas secondary apnea does not respond to stimulation, drying or suctioning and requires initiation of IPPV.
Note that in Canada two differing practices occur than what is stated in the article:
When doing bag and mask ventilation on an infant who is experiencing apnea, your oxygen concentration to start should be approximately 10% higher than what the infant is already receiving (e.g., if they are on room air, 21%, then you should give them approximately 30% oxygen to start and titrate up if needed).
Caffeine citrate is the drug of choice to treat apneas.
Apnea of Prematurity
The exact causes of apnea of prematurity are still not known. Immaturity and/or depression of the central respiratory drive to the muscles of respiration have been accepted as key factors in the pathogenesis of apnea of prematurity.
The severity of apnea attacks in premature infants correlates with gestational age. The more premature an infant is, the more likely he or she is to have frequent, severe apneic spells.
Studies have shown that apnea occurs most frequently during the sleep state and is especially prevalent during active sleep. Active sleep, or REM sleep, is the predominant sleep state of premature infants, and infants less than 32 weeks spend 80% of their time asleep. These two characteristics of the sleep states of premature infants puts them at significantly higher risk for developing apnea.
Premature infants have a decreased amount of peripheral catecholamines (epinephrine and norepinephrine) and this has also been implicated as a cause of apnea. When infection is present, catecholamines stores are further depleted, putting infected premature infants at a very high risk for developing apnea.
Respiratory muscle fatigue may also be a contributing factor in apnea of prematurity. Premature infants have very compliant chest cages and less compliant lungs than full-term infants and this means increased work of breathing for premature infants (Walsh, 2010).
Secondary Apnea
Rather than being due to prematurity, apnea may be the first sign of an underlying disorder.
When an infant suddenly starts having apneic spells, it is important to investigate for possible underlying disorders before jumping to the diagnosis of apnea of prematurity and initiating drug therapy.
Apnea seldom occurs in first 24 hours of life, even in premature infants. Therefore, the appearance of apneic spells in the first 24 hours is usually a sign of an underlying disorder. Apnea is rare in infants of greater than 34 weeks gestation and needs to be promptly investigated.
Causes of Apnea
Infection- Pneumonia, sepsis, meningitis
Resp distress-immaturity of resp development, RDS, airway obstruction, CPAP application, postextubation, congenital anomalies of the upper airways
Cardiovascular disorders- PDA, CHF
GI disorders- NEC, vomitting, deglutition syncope
CNS- depressant drugs, IVH, seizure, increased bill levels, bili encephalopathy/kernicterus, infection, tutors/ischemia
metabolic- hypoglycemia, hypocalcemia, hyponatremia/hypernatremia
environmental-rapid increase of environmental temp, hypothermia, vigorous suctioning, feeding, storing, stretching/movement; fatigue/stress, prenatal exposure to maternal cigarette smoking, position, sleep state, pain, first immunizations (increase apnea, bradycardia and desalts within 72 hrs of immunizations
hematopoietic-polycythemia,anemia
Respiratory Support
Assessment and intervention should proceed in an orderly sequence:
LOOK AT THE INFANT
CHECK BREATHING
CHECK HEART RATE
CHECK COLOR
Look
When the monitor alarm rings, it is important to first look at the infant. The infant may be fine: breathing, with a normal heart rate, and satisfactory color. The problem may be the monitor, the leads, etc. If the infant is not fine, proceed with assessment and intervention, following the sequence: breathing, heart rate, and color.
Breathing
If an infant is apneic, provide gentle stimulation by rubbing the infant’s back or moving his or her foot. Often, this stimulation is all that is required for the infant to resume breathing.
Check the infant’s airway and position the infant to ensure a patent airway. This position is called the “sniffing position” and is achieved by gently lifting the chin to slightly extend the neck.
If stimulation and positioning do not solve the problem, provide intermittent positive pressure ventilation (IPPV) with a bag and mask.
Heart Rate
Once the infant is breathing continue your assessment and check the heart rate. If the infant is on a cardiorespiratory monitor, you have likely been noting the heart rate all along. Nevertheless, at this point, turn your attention specifically to heart rate. If it is below 100 beats per minute, continue with or start positive pressure ventilation with a bag and mask.
The majority of bradycardia in infants is pulmonary in origin. Therefore, the provision of ventilation will usually improve the heart rate.
Color
Once the infant is breathing and the heart rate is above 100, turn your attention to the infant’s color. If pale or cyanosed, provide oxygen (~10% higher than what the infant is receiving). As long as the heart rate is greater than 100 and the infant is breathing, bag and mask ventilation is no longer required.
We have given you an overview of the sequence of events for responding to an infant’s apnea and/or bradycardia. Most often, gentle stimulation is all that is required.
Develop a list of potential reasons for Austin’s apnea and bradycardia
Some potential reasons for Austin’s apnea and bradycardia include:
prematurity — CNS immaturity, sleep patterns, catecholamine deficiency, fatigue
positioning — sometimes infants obstruct their airways when their chin falls to their chest or when their necks are hyperextended
hypoxia —depresses the respiratory center
anemia — insufficient oxygen carrying capacity
sepsis — all premature infants have the potential to develop infections because of the immaturity of their immune systems
neurologic — depressed respiratory center
hypothermia — Austin is very small with very little ability to self-regulate his temperature
hypoglycemia — Austin will have low glycogen stores because of prematurity and because of his SGA
gastro-esophageal reflux — causes bronchospasm
I chose these because they are the most likely causes. However, you must look at all aspects of Austin’s history to rule out the cause of Austin’s apnea and bradycardia.
What would you assess further about Austin in order to determine the cause of his apnea?
oxygen — pulse oximetry, Hgb, and Hct
check Austin’s position
complete set of vital signs, especially temperature
blood work: blood cultures, CBC/differential, electrolytes, glucose
tone, level of alertness
