2 Case StemA female infant is born in a community hospital by assisted breech delivery at 34 weeks to a 16 year old single primigravida. There had been no antenatal care. Her birth weight is 1.8 kg, and Apgar scores mins later, the baby’s breathing is laboured and there is apparent cyanosis.
3 ObjectivesReview the basic principles of newborn care and neonatal resuscitation and discuss use and significance of Apgar scoresUnderstand the fetal circulation and the changes that occur at birthReview lung development in utero, the pathophysiology of respiratory distress syndrome and its managementExplore the most common causes of distress in the newborn and its managementDescribe 3 commonly measured growth parameters and understand the concepts of low birth weight, prematurity, psychosocial issues, and their implications/significance
5 Changes at Birth Alveolar fluid clearance Lung expansion Circulatory changesIncreased O2 tension at birth enhances epithelial resorption of sodium and fluidsInitial breaths generate high transpulmonary pressure which drives fluid from air spaces to interstitiumThoracic squeeze during deliveryIncreasing inspiratory pressure expands alveolar air spaces and establishes FRC + stimulates surfactant releaseClamping of cord removes the low resistance placenta causing a rise in neonatal systemic BP, and lung expansion reduces pulmonary vascular resistance and pulmonary artery pressureDecreased right-to-left shunt at DA and increased left-to-right shuntIncreased lung perfusion increased O2 saturation closure of DALA pressure rises and RA pressure falls, until LA pressure exceeds RA FO closes
6 Lung Development in Utero Early Embryonic Phase(3-7 weeks)Pseudoglandular Phase (5-17 weeks)Canalicular Phase (16-26 weeks)Saccular Phase (24-36 weeks)Alveolar Phase (36 weeks to 8 years)1. Lung buds form2. Bronchial tree and acinar tubes develop, few terminal buds3. Completion of branching, terminal airways developing into alveoli, differentiation of Type I and II pneumocytes. May be possible to have limited gas exchange towards end of stage4. Development of true alveoli, production of surfactant5. True alveolar ducts and alveoli form
7 Surfactant LaPlace’s Law: P = 2T/R T is surface tension P is pressure necessary to keep the sphere openT is surface tensionR is radius of the sphereWith surfactant reducing the surface tension, even at low volumes, less pressure is needed to maintain open alveoli maintains alveolar volume and stabilityPressure is proportional to surface tension and inversely proportional to radiusLipoprotein complexHydrophilic groups at the air-water interface of alveoliHydrophobic tails (DPPC) face the air, reducing surface tension
8 APGAR Score Quick evaluation of newborn at 1 and 5 mins 10 point score with > 7 being normal, 4-6 requiring assistance, and < 4 requiring resuscitationApgar Sign21Appearance (skin colour)Normal colour all over (hands & feet pink)Normal colour but hands & feet are bluishBluish-gray or palePulse (HR)Normal (>100 bpm)< 100 bpmAbsent pulseGrimace (“reflex irritability”)Pulls away, sneezes, coughs, or cries with stimulationFacial movement only (grimaces with stimulation)Absent (no response to stimulation)Activity (muscle tone)Active, spontaneous movementArms and legs flexed with little movementNo movement, floppy toneRespiration (RR and effort)Normal rate and effort, good crySlow or irregular breathing, weak cryAbsent (no breathing)
9 Basic Principles of Newborn Care Rapid assessment: if “yes” to all 3 questions dry the baby, place skin-to-skin with mother, covered with dry linen to maintain TTerm gestation?Crying or breathing?Good muscle tone?If “no” to any baby should receive one or more of the 4 categories of action (in sequence)Initial stabilization – provide warmth, clear airway if necessary, dry, stimulateVentilationChest compressionsAdministration of epi and/or volume expansion
11 Case 1Male newborn baby weighing 2.62 kg born to 35 yo mother by c-section at 35+4 weeks GA because of oligohydramnios. APGAR scores at 51 and 95. The baby develops tachypnea soon after birth.
12 Transient Tachypnea of the Newborn PresentationTachypnea within 2 hrs of birth, other signs of respiratory distress. Often no hypoxia or cyanosisPathophysResidual pulmonary fluid in lung after deliveryRisk FactorsMaternal asthma, male, macrosomia, maternal DM, c-sectionCXR Findings“Wet silhouette” around heart, intralobar fluid accumulation, diffuse paranchymal infiltratesManagementSelf-limited, symptoms last up to 2 days, provide supp O2 via hood or nasal cannula to maintain SpO2 > 90%, tube feeding, IV fluids if neededPrognosisExcellentIf doesn’t improve after 4-6 hrs or initial CBC abnormal, obtain blood culture, begin antibiotics (amp + gent)
13 Case 2A baby is born by spontaneous vaginal delivery at 30 weeks to a 25 yo primigravida. Her birth weight is 2.05 kg, and Apgar score is 81. RR 40 and poor air entry bilaterally, no adv. sounds. Within a few mins, she becomes cyanosed and cry is feeble. With suction and supp O2, RR becomes irregular and grunting is heard.
14 Respiratory Distress Syndrome (Hyaline Membrane Disease) PresentationImmediately after birth, tachypnea, grunting, retractions, hypoxia, cyanosisPathophysImmature type II alveolar cells less surfactant, increased alveolar surface tension, decreased compliance pulmonary vascular constriction, hypoperfusion, lung tissue ischemia formation of hyaline membranes bronchopulmonary dysplasiaRisk FactorsPrematurity (1/3 of infants born at wks), male, maternal DMCXR FindingsHomogenous opaque infiltrates, diffuse atelectasis, air bronchogramsManagementPrevention – give antenatal corticosteroids to pregnant women at <34 wks if high risk of preterm delivery within 7 days.Nasal CPAP. If respiratory failure, intubate. Indicated if persistent resp. acidosis on CPAP, hypoxemia on CPAP, severe apnea.Surfactant therapy via ETT– exogenous surfactant replacement most effective if given within first mins of life.Supportive care – prophylactic abx, maintain temperature, tube feedsPrognosisAcute complications – alveolar rupture, infection, IVH, PDA, pulmonary hemorrhage, NEC, GI perforation, apnea of prematurityChronic – BPD, retinopathy of prematurity, neurologic impairmentHyaline membranes = combination of sloughed epithelium, protein, edemaACS enhances maturational changes in fetal lung architecture and biochem, with increased synthesis and release of surfactant.Mechanical ventilation is a risk factor for BPD – try to avoid it with CPAP.Bronchopulmonary dysplasia – chronic lung disease, requiring O2 at corrected GA of 36 weeks. it’s directly related to high volume/pressure from mechanical ventilation. Highest risk at youngest GAs.
15 Case 3A female baby is delivered at 42+6 wks GA by emergency c-section because of fetal distress and thick MSAF. Birth weight is 3 kg. Apgar is 3 at 1 min. The baby is grunting with moderate retractions.
16 Meconium Aspiration Syndrome PresentationRespiratory distress immediately after delivery, with hypoxia. Baby born through meconium stained amniotic fluid, or evidence of meconium staining on exam.PathophysFetal passage of meconium in utero aspiration of mec irritation, obstruction, medium for bacterial cultureRisk FactorsPost-term neonates, small for GA, fetal hypoxiaCXR FindingsPatchy atelectasis or consolidation, hyperinflationManagementif MSAF – use minimal stimulation and keep baby head down to prevent breathing in meconioumNo evidence for routine amnioinfusion or suctioning (if HR>100, spont. respitation, reasonable tone).Supportive care, supp. O2. Prophylactic abx until cultures neg.PrognosisPulmonary sequelae – reactive airway disease commonNeurodevelopmental impairment – possibly due to underlying intrauterine hypoxia and chronic infectionMec composed of desquamated cells, secretions, lanugo, water, bile pigments, pancreatic enzymes, amniotic fluidNormal – passage of mec occurs early in first trimester, then slows after 16 wks and becomes infrequent by 20 wks, as anal sphincter is innervated. Passage may be caused by increased peristalsis and relaxation of anal sphincter due to increased vagal outflow with cord compression or increased sympathetic inflow during hypoxia.
17 Less Common Causes Infection Pneumothorax Presents as respiratory distress, temperature instability hours to days after birthRFs: prolonged rupture of membranes, prematurity, maternal feverBilateral infiltrates on CXR ± pleural effusions, serial blood culturesPneumothoraxCan occur spontaneously, or secondary to infection, MAS, lung deformityPersistent pulmonary hypertension of the newbornPulmonary vascular resistance fails to decrease after birthCan occur spontaneously, or secondary to MAS, infection, TTN
18 Differential Diagnosis of Respiratory Distress in the Newborn Most common (in order of incidence)Transient tachypnea of the newborn (TTN)Respiratory distress syndrome (RDS), aka hyaline membrane diseaseMeconium aspiration syndromeLess common, but significantDelayed transitionInfection (pneumonia, sepsis)Persistent pulmonary hypertension of the newborn (PPHN)PneumothoraxNon-pulmonary causes, e.g. anemia, congenital heart disease, congenital malformation, medications, neurologic or metabolic abnormalities, polycythemia, upper airway obstruction
20 Growth ParametersGrowth is a reflection of overall health and nutritional statusPattern of growth, not just absolute numberHeightWeightNormal birth weight is 2.5 – 4.5 kg (5.5 to 10 lbs)Head circumference
21 Prematurity Definitions: any birth occurring before 27 weeks GA Late preterm = GA weeksVery preterm = GA < 32 weeksExtremely preterm = GA < 28 weeksAssociated with 1/3 of all infant deaths, 50% mortality rate if born at or before 25 weeksShort term complications – respiratory distress, retinopathy, PDA, bronchopulmonary dysplasia, late-onset sepsis, necrotizing enterocolitis, IVHLong term complications – neurodevelopmental disabilities, e.g. CP, respiratory disorders, gastrointestinal problems, vision and hearing impairment
23 Low Birth Weight Premature infants can be classified by birth weight Low BW if < 2500 gVery Low BW if < 1500 gExtremely BW if < 1000 gAssess birth weight by percentile for GABoth low birth weight premature infants and small for gestation age (at term) infants have increased mortality and morbidity