7 Flashcards
Rf for neonatal respiratory distress - 6
Signs
Details of the delivery are always important to know when assessing a newborn. The following perinatal information can provide important clues in determining the etiology of respiratory distress:
Maternal diabetes A risk factor for respiratory distress syndrome (RDS), among other difficulties
Prematurity
Predisposes to RDS caused by lung immaturity and lack of surfactant
Most infants born at 36 weeks’ gestational age do not have RDS
Maternal group B strep infection A risk factor for neonatal sepsis (a cause of respiratory distress)
C-section delivery Predisposes to transient tachypnea of the newborn (TTN)
Premature rupture of membranes ≥ 18 hours (prolonged PROM)
A risk factor for neonatal sepsis
Meconium in the amniotic fluid A risk factor for meconium aspiration syndrome
Signs of Respiratory Distress
The findings of tachypnea, retractions, and grunting are classic symptoms of respiratory distress from any cause.
Intercostal and subcostal retractions reflect the increased work of breathing due to decreased lung compliance, either due to primary lung pathology or edema.
Grunting occurs at the end of expiration, and is the audible sound of air being expelled through a partially closed glottis as the infant attempts to increase transpulmonary pressures, increase lung volumes, and improve gas exchange.
Diff dx for tachypnea -abnormally rapid breathing, in an infant
11
Respiratory distress syndrome (RDS)
Caused by a deficiency of lung surfactant and delayed lung maturation
Can occur as late as 37 weeks’ gestation, but normally at 28-30 weeks
Most common cause of respiratory distress in premature infants
Remember that there may be surfactant deficiency and delayed lung maturation in infants of diabetic mothers
Transient tachypnea of the newborn (TTN)
Result of delayed clearance of fluid from the lungs following birth
Much more common in infants born to diabetic mothers and in infants born by c-section bc no uterine contraction to help get rid of fluid
While generally considered a disorder of term infants, TTN does occur in premature infants
Pneumothorax
Caused by a collection of gas in the pleural space with resultant collapse of lung tissue
Common risk factors are mechanical ventilation or underlying lung disease (especially meconium aspiration or severe infant respiratory distress syndrome).
While relatively uncommon, always an important consideration in an infant with respiratory distress
More likely in a premature infant with RDS
Hypoglycemia
May be seen in infants of diabetic mothers due to the chronic hyperinsulinemic state that occurred during gestation
Can be more pronounced in premature infants
Tachypnea is a non-specific response to this metabolic derangement
Congestive heart failure (CHF)
In an infant, most often caused by a congenital heart defect
May present with early cardiac failure and tachypnea
Increased risk of heart defects in IDM infants, and therefore an increased risk of CHF
Neonatal sepsis
Can present initially with tachypnea and progress to more severe illness rapidly
Often due to infection with Group B Streptococcus (GBS), usually transmitted from the mother during labor
Prolonged PROM is associated with an increased incidence of neonatal sepsis
Congenital diaphragmatic hernia
Malformation resulting from a defect in the development of the diaphragm
Allows the passage of organs from the abdomen into the chest cavity and severely impairs lung development
Most defects occur on the left side
Occurs in 1 out of every 2,200 to 5,000 live births
Most common type (accounting for > 95% of cases) is the Bochdalek hernia, which is located posterolaterally
Absent breath sounds or presence of bowel sounds on one side of the chest are important diagnostic clues
Severe coarctation of the aorta
May cause respiratory distress if there is severe left ventricular outflow tract obstruction
Meconium aspiration
Infants who aspirate meconium in utero or at the time of delivery often present with symptoms of respiratory distress, including tachypnea
Maternal drug exposure
Maternal medication use may lead to tachypnea in the newborn
Hypothermia
Low core temperature can lead to tachypnea
Premature newborns are more at risk to become hypothermic because of their small body size
Transition to extrauterine life
Oxygenation changes dramatically at birth from a passive, placenta-provided source to an active respiration-based process. In utero, oxygenated blood from the placenta is transported to the fetus by the umbilical vein. A portion of this blood perfuses the liver. The remainder bypasses the liver through the ductus venosus and enters the inferior vena cava. One-third of this vena caval blood crosses the patent foramen ovale (PFO) to the left atrium and is pumped to the coronary, cerebral and upper body circulations. The remaining two-thirds combines with venous blood from the upper body in the right atrium, and is directed to the right ventricle and out the pulmonary artery. In utero, vasoconstriction of the pulmonary arterioles produces high pulmonary vascular resistance, allowing only 8-10% of the blood from the right ventricle to flow through the pulmonary vasculature. The remainder, 90-92%, is shunted through the patent ductus arteriosus (PDA) to the descending aorta.
At birth, successful transition to extrauterine life involves:
Removal of the low-resistance placental circulation by cutting the umbilical cord.
Initiation of air breathing by the newborn infant.
Reduction of the pulmonary arterial resistance.
Closure of the PFO and PDA.
First Breath
At delivery, the infant’s first breath results in the replacement of the lung fluid by air. This fluid is thought to leave the lungs by a combination of being squeezed out during uterine contractions with vaginal delivery, and absorption by the pulmonary lymphatics. Delayed absorption of pulmonary fluid results in a condition known as Transient Tachypnea of the Newborn (TTN), also referred to as persistent postnatal pulmonary edema.The first physical examination of the neonate provides a good indication of the infant’s successful transition to extrauterine life.
First Hour
In the first hour of life, as transition occurs, the respiratory and heart rates are often elevated:
Heart rate is often 160–180 per minute, and the respiratory rate is often 60–80 per minute.
Second Hour
In an infant with a successful transition, by the age of 2 hours:
Heart rate is usually 120–160 per minute, and the respiratory rate is usually 40–60 per minute.
Vital signs are most accurate if obtained when the infant is quiet and at rest. If the infant is crying, the heart rate and the respiratory rate may be falsely elevated. (See the following for more information about vital signs in the newborn: Thureen PJ, Deacon J, et al.: Assessment and Care of the Well Newborn. WB Saunders, 1999: 188–192.)
Abnormal Transition
Clinical evidence of abnormal transition from to extrauterine life is seen in infants with TTN and persistent pulmonary hypertension of the newborn (PPHN), also known as persistence of the fetal circulation.
Persistent pulmonary htn of the newborn
Result from -4
Symptoms - 5
PPHN is the result of elevated pulmonary vascular resistance to the point that venous blood is diverted to various degrees through fetal channels (the ductus arteriosus and foramen ovale) into the systemic circulation and bypasses the lungs, resulting in systemic arterial hypoxemia.
PPHN can result from several conditions, including meconium aspiration syndrome, diaphragmatic hernia, hypoplastic lungs, and in utero asphyxia. The following findings may indicate that an infant has PPHN:
Tachypnea
Tachycardia
Respiratory distress, with findings such as expiratory grunting and nasal flaring
Generalized cyanosis
Low oxygen levels, even while receiving 100% oxygen
Fetal effects of maternal hyperglycemia
High levels of maternal serum glucose during pregnancy result in hyperglycemia in the fetus. This stimulates the fetal pancreatic beta cells and the development of hyperinsulinemia. (Maternal insulin does not cross the placenta.)
Insulin is the primary anabolic hormone for fetal growth.
High levels in the third trimester result in increased growth of the insulin-sensitive organ systems (heart, liver and muscle) and a general increase in fat synthesis and deposition.
This combination of increased body fat, muscle mass, and organomegaly produces a macrosomic (LGA) infant.
Insulin-insensitive organs, such as the brain and kidneys, are not affected by the elevated insulin levels, and have appropriate size for gestational age.
Control of diabetes during pregnancy is an important predictor of fetal outcome, especially with regard to the risk of birth defects. The incidence of major malformations is directly related to the first-trimester HbA1c level:
Infants born to women with HbA1c levels > 12% have at least a 12-fold increase in major malformations.
Symptoms of hypoglycemia 5
Testing
Treatment
Monitoring
Jitteriness, lethargy, high pitched cry, hypotonia, weak suck
Testing
The glucometer test is a screening test only, and must not be used to confirm hypoglycemia. Glucose oxidase reagent strips are read by meter (glucometer) or by eye (Dextrostix, Chemstrip) and measure whole blood glucose, which is 10-15% lower than plasma glucose levels. These reagent strips are widely used as screening tools for hypoglycemia and may also be used for ongoing monitoring of glucose levels.
Any reagent-strip reading of whole blood glucose < 40 mg/dL must be confirmed by laboratory analysis of serum or plasma glucose. Treatment should be started immediately, not delayed until laboratory results are available.
Treatment
The choice of intervention depends on presence or absence of symptoms of hypoglycemia and any additional problems such as tachypnea. Breastfeeding or bottle feeding of pumped breast milk or formula depends on the ability of the infant to take feedings orally. Tachypnea may prevent adequate intake of glucose via oral feeds. In this situation, placement of a nasogastric tube and administration of either breast milk or formula would be appropriate, with resumption of breast or bottle-feeding as soon as the respiratory rate allows.
If the baby is symptomatic from hypoglycemia, an intravenous infusion of dextrose should be started immediately as it guarantees a stable source of glucose.
Most pediatricians would not give 5% glucose in water to a hypoglycemic infant, and if they did, the infant would be fed with breast milk or formula as soon as possible after the glucose.
Glucose water does raise the serum glucose level, but only transiently. Rebound hypoglycemia often develops 1-2 hours after feeding glucose water if the infant is hyperinsulimemic (i.e., the infant of a diabetic mother). Milk feeding (formula or breast) raises glucose levels, maintains stable levels, and avoids rebound hypoglycemia.
Monitoring
Once feeds have been initiated, glucose levels should be closely monitored until levels are stable (> 45 mg/dL). The frequency of monitoring will depend on the severity of the hypoglycemia and may range from every 30 minutes to every 3 hours prior to feeds.
TTN transient tachypnea of the newborn findings on x ray vs respiratory distress syndrome on x ray
Significant perihilar streaking: interstitial fluid and engorged lymphatics.
Coarse, fluffy densities that represent fluid-filled alveoli.
Fluid in the pleural space and a small amount of fluid in the fissures on the lateral view.
“wet” looking lungs, no consolidation, and no air bronchograms.
An infant with RDS would have radiographic findings that typically include a diffuse reticulogranular appearance of the lung fields (“ground glass appearance”) and air bronchogram
When should gestational age be checked on every infant
What confirms gestational age
3 types of gestational age
Gestational age assessment should be performed on every neonate within 12–24 hours of life.
Ballard score is good for confirming gestational age (tests physical and neuromuscular maturity)
Lga- birth weight greater than 90th percentile
SGA - birth weight below the 3rd or 10th percentile depending on the system used
Adam is a newborn male who was just born to a G2P1 mother at 36.2 weeks’ gestation via a vaginal delivery. The mother reports that she did not receive prenatal care because she did not have insurance. She says that she thinks her “water broke” about two days ago, but she did not have any contractions after that, so she decided not to come to the hospital. She did not start having contractions until 19 hours before she delivered. After delivery, Adam did not cry vigorously, was tachypneic, cyanotic, and febrile to 100.5 F. Amniotic fluid did not contain meconium. His chest x-ray is normal. Given Adam’s birth history, what is the most likely cause of his symptoms?
B. Prolonged rupture of membranes (PROM) is when the chorioamniotic membrane ruptures before the onset of labor. The main risks associated with PROM are preterm labor and delivery and neonatal sepsis. Adam’s mom said that her “water broke” two days ago, which indicates that she had PROM. Adam’s mother also did not receive prenatal care; therefore, she did not receive any of the prenatal screening tests that she should have, which increases the likelihood that she has an infection that could have potentially been transferred to Adam after the rupture of her membranes. Adam’s history of PROM along with his fever and respiratory distress make this answer choice the best choice.
Adam is a 2-hour-old infant born at 32 weeks’ gestational age via spontaneous vaginal delivery to a healthy mother with negative group B streptococcus status. There was no premature rupture of membranes and no meconium in the amniotic fluid. His Apgars were 8 at one minute and 9 at five minutes. Over the last two hours he has become progressively tachypneic. On physical examination he is large for gestational age. His vital signs are respiratory rate 75, temperature 36.5 C and heart rate is 130 beats per minute. His lung exam is remarkable for intercostal and subcostal retractions, grunting, and equal breath sounds. His heart exam reveals normal rhythm, normal S1 and S2, no murmurs, and normal peripheral pulses and capillary refill. Which of the following is the most likely cause of the patient’s condition?
D. Respiratory distress syndrome (RDS) causes tachypnea and is therefore an important consideration in this case. RDS is more common in premature infants. Given the lack of history of maternal diabetes, an NSVD birth, and few risk factors for sepsis other than prematurity, Adam is likely to have RDS.
Evaluation of a cyanotic newborn - 8
Arterial blood gas- knowing pco2 is helpful in understanding cause of cyanosis
Blood and csf- sepsis possible so identify organism
CBC with differential- neutropenia, thrombocytopenia- sign of sepsis
Chest x ray- view lungs and size and shape of the heart
Echo - congenital cardiac lesions and persistent pulmonary htn of newborn
Oxygen challenge- helps if lung issue, does not help if cardiac lesion PE
Pulse ox
Developmental dysplasia of the hip
RF - 3
Breech position , gender 9:1 f:m, fam Hx
Bronchopulmonary dysplasia
Rf - 2
Chronic lung disease (alveoli damaged) that affects newborns - mostly premature -and infants
Mechanical ventilator
Long term use of oxygen
