Neonatal Respiratory Adaptation Quiz

Neonatal Assessment and Care (Part 1-3)

• Learning Outcomes: Students will be able to:
  • Describe physiological and behavioral adaptations during the transition from intrauterine to extrauterine life.
  • Explain the mechanism of thermoregulation in newborns and discuss the impact of hypo- and hyperthermia.
  • Describe the process and rationale for assessing a neonate from "head to toes."
  • Recognize newborn reflexes (including differential abnormal responses).
  • Describe the nutritional needs of a neonate.
  • Discuss immunization and screening programs in Hong Kong.
  • Identify and manage neonatal jaundice.
  • Discuss the care of neonates at health risk (e.g., infection) and relevant management strategies.

Outline of NN Lectures

• Major neonatal adaptations: Physiological and neurological/behavioral adaptations.
• Nursing assessments and care: Immediately after delivery (delivery ward) and subsequent assessment (postnatal ward).
• Neonatal needs: Nutritional needs, neonatal screening, and neonatal jaundice.

Newborn Adaptation to Extra-uterine Life

• Neonatal period: from birth through the 28th day of life.
• Major adaptations during neonatal transition: The first 6-8 hours after birth.
• Physiological adaptations:
  • Establishing and maintaining respirations.
  • Adjusting to circulatory changes.
  • Regulating body temperature.
  • Endocrine adaptations.
  • Hepatic adaptations.
  • Immunologic adaptation.
  • Taking in, retaining, and digesting nutrients.
  • Eliminating waste.
  • Regulating body weight.
  • Sensory/neurological system.
• Behavioral development:
  • Period of reactivity.
  • State of organization.
  • Sleep-wake pattern.

Physiological Adaptations

• To survive the extrauterine life, a neonate needs to breathe on its own.
• This starts with initiating the first breath.

Respiratory Adaptation

• Chemical factors: Uterine contractions and umbilical cord clamping decrease the level of oxygen and increase the level of carbon dioxide, thus stimulating chemoreceptors in the aorta and carotid arteries to activate the respiratory center in the medulla oblongata.
• Mechanical factors: The compression of the chest during vaginal birth expels about one-third of the fluid from the fetal lungs. Re-expansion of the chest leads to negative pressure, drawing air into the airways and further replacing the fluid in the lungs. Crying expands the alveoli and further increases air distribution.
• Thermal factor: The extrauterine temperature is lower from 37°C to 21-23.9°C. This sudden chilling in the newborn stimulates temperature receptors in the skin, which in turn signals the respiratory centre in the medulla to sustain respirations.
• Sensory factor: Handling, suctioning, and stimulation during birth—such as, pain, light, noises, and scents—activate the respiratory centre to sustain respirations.
• Lung functions: Surfactant production, lung compliance, and airway resistance.

Lung Functions

• Surfactant production: A protein manufactured in type II lung cells that decreases alveolar surface tension, prevents alveoli from collapsing, and helps with lung compliance. Low surfactant levels are decreased in infants born before 32 weeks.
• Lung compliance: The ease with which the lungs can expand and fill with air. Surfactant helps increase compliance.
• Airway resistance: Fluid-filled lungs initially require pressure (~30-40 cm H2O) to open.

Successful Respiratory Adaptation

• Reabsorption of lung fluid: occurs by inspiration and expiration, distributes air in alveoli, and establishes functional residual capacity.
• Increased fluid flow across the alveolar membrane into pulmonary interstitial tissue.
• Increase fluid absorption by capillary and lymphatic circulation.
• Suction (only when indicated) from the newborn's mouth, throat, and nose assists in the absorption process.
• Catecholamines promote fluid clearance from the lungs (a fight-or-flight hormone).

Normal Newborn Respiration

• Approximate respiratory rate (RR): 30–60 breaths per minute (bpm).
• Initially, shallow and irregular breathing (count for one full minute).
• Diaphragmatic breathing, with synchronous abdominal movement.
• Nose breathers.

Abnormal Newborn Respiration

• RR < 30 or > 60 bpm.
• Apnea (>20 seconds).
• Tachypnea (inadequate clearance of lung fluid).
• Retractions of ribs.
• Cyanosis.
• Nasal flaring.
• Expiratory grunting.
• Stridor or gasping (airway obstruction).
• Seek immediate medical help if noted.

Fetal Circulation

• Umbilical vein carries oxygenated blood to the Ductus venosus to heart sooner; bypassing the liver.
• Foramen ovale: >50% of the blood in the right atrium to cross to the left atrium, bypassing the pulmonary circulation
• Ductus arteriosus connects pulmonary artery with the descending aorta: bypassing pulmonary circulation.
• Umbilical arteries: Return deoxygenated blood to the placenta by the internal iliac arteries.

Cardiovascular Adaptations

• Placenta removed (↓ prostaglandins) & lungs begin to intake air (↑ pO2 in pulmonary P. & in systemic P.).
• Umbilical vein closes & becomes ligament
• Closure of ductus venosus becomes ligament.
• Closure of ductus arteriosus becomes ligaments in 1-3 months.
• Closure of foramen ovale leads to permanent closure in a few months or years.
• Closure of umbilical arteries takes ~2-3 months (fibrous proliferation, distal portion becomes lateral vesico-umbilical ligaments, proximal portions remaining open as superior vesicle arteries).

Cardiovascular Adaptations (continued)

• Heart rate: Initially ~110-180 bpm, but can be irregular. Stabilizes to 100-160 bpm in the first week and ~80-100 bpm in deep sleep.
• Heart murmurs are common in newborns (often due to incomplete closure of ductus arteriosus or foramen ovale); they usually resolve by 6 months.
• Blood pressure varies with gestational age, higher in extremities in some conditions, and warrants appropriate assessment to rule out vascular disease for accurate monitoring.
• Blood volume: ~80–100 ml/kg initially (~100 ml increase in blood volume from placenta immediately after birth).
• Hemoglobin: starts high at ~14–24 g/dL but decreases to ~12–20 g/dL in about two weeks.
• Hematocrit: (~43%-63%) decreases to (~39%-59%) during the first 8 weeks.
• RBC: high initial count (~4.6–5.2 million/mm³) lowers more rapidly to ~12,000/mm³ for the first neonatal period (life span: 80-100 days)
• Platelets (150,000-300,000/mm³) do not change significantly during the initial neonatal period.
• Vitamin K-dependent clotting factors increase slowly and reach adult levels by 6 months of life.
• Fetal hemoglobin (~70% at birth) gradually decreases, with only traces remaining by 6–12 months of life.

Cord Management Strategies

• Immediate cord clamping: no benefit for mother & newborn
• Delayed cord clamping: decrease hospital mortality, lower APGAR score at 1 minute, decrease blood transfusion in infants, and improves motor function at 18–22 months in corrected age. Increase in incidence of polycythemia, hyperbilirubinemia (must monitor for such complications when performing this type of procedure).

Thermal Regulation

• Normal axilla temperature: 36.4–37.2°C.
• Neonatal hypothermia: axillary T <36.5°C.
• Body temperature control: hypothalamus, brown adipose tissue (Brown fat) rich in vascular and nerve supply, and able to provide heat; increases in the fetus between 25–26 weeks of gestation and continues, to peak at 3–5 weeks after birth.
• Well-insulated, larger newborns tend to cope with lower environmental temperatures, while preterm or SGA newborns are at higher risk of losing heat due to inadequate adipose tissues and hypoflexed state.

Heat Production

• Increased muscle activity (respiration, restlessness, flexed posture).
• Increased cellular metabolic activity (in brain, heart, and liver requiring oxidative metabolism of glucose, protein, and fat).
• Peripheral vasoconstriction (decrease blood flow to skin, skin feels cool to touch and acrocyanosis - bluish discoloration of fingers and toes).

Heat Loss

• Convection: Loss of heat to cooler air currents
• Radiation: Loss of heat to cooler surfaces not in direct contact.
• Conduction: Loss of heat to cooler surfaces in direct physical contact.
• Evaporation: Loss of heat as moisture converts to vapor.

Practice in Hong Kong

• Newborn assessment practices vary.

Predisposing Factors for Heat Loss

• Thin subcutaneous fatty layer.
• Blood vessels close to skin surface.
• Lack of shivering.
• Large body surface area compared to body weight.
• Inability to get external "help" (clothing or change in posture).
• Immature thermal regulatory mechanisms.
• Cold room temperature (21°C) compared to intrauterine temperature (36.5-37.5°C).

Hepatic Adaptations

• Liver function:
  • Iron storage: sufficient for 4–6 months.
  • Carbohydrate metabolism: lowest blood glucose levels ~30-90 mins after birth (newborns of mothers with diabetes are at risk for hypoglycemia).
  • Coagulation: coagulation factors rise slowly but don't reach adult levels until 9 months, requiring prophylactic vitamin K injection upon birth.
• Conjugation of bilirubin: Immature liver function, with decreased enzyme activity (glycuronyl transferase), leads to bilirubin accumulation. Factors that can increase bilirubin include: shorter red blood cell lifespan, delayed cord clamping, insufficient caloric intake, or insufficient albumin levels.

Measures to Decrease High Bilirubin

• Maintain skin temperature at ≥36.5°C.
• Monitor stool for amount and characteristics.
• Encourage early breastfeeding (colostrum effect).
• Encourage early feedings (caloric & protein intake).

Endocrine Adaptations

• Cortisol: A regular hormone for fetal maturation and neonatal adaptation is progressively increasing starting at 30 weeks' gestation, peaking during labor and several hours after delivery and contributing to normal fetal to newborn transition.
• Lung maturation (surfactant): Cortisol activates the sodium pump, promoting clearance of fetal lung fluid
• Gut functional maturation.
• Maturation of thyroid hormones: Cortisol plays a role in energy metabolism.
• Catecholamines: Large amount released as a normal response to birth, responsible for increased BP, energy metabolism, and initiating thermogenesis from brown fat
• Thyroid hormones: Released after detachment from placenta and environmental temperature change, essential for brain growth during infancy.

Immunologic Adaptations

• Defense against infections: skin and mucosa membranes, neutrophils, monocytes, eosinophils, and lymphocytes.
• IgG: The only immunoglobulin crossing the placenta (passive acquired immunity during the third trimester and through breast milk).
• IgM: Normally produced by fetus in utero (starts at 10–15 weeks' gestation).
• IgA: Protection of the respiratory and GI tracts, produced by the fetus or newborn.

Ingesting, Retaining, and Digesting Nutrients

• Suckling and swallowing coordinated well after 32–33 weeks; normally establish early in the first week, helping to sustain the function of the intestines.
• Normal colonic bacteria established early, crucial for synthesis of Vit K, folate, and biotin.
• Small stomach capacity (50-60 ml) and bowel sounds present 30-60 minutes after birth.
• Gastric emptying time (intermittent) about 2–4 hours after feeding.
• Immature cardiac sphincter can cause regurgitation during the first 1-2 days post-birth, hence proper positioning and avoidance of overfeeding are important.

Eliminating Wastes

• Meconium: First stool, tarry and black, typically passed within 8–24 hours.
• Transitional stools: D2-3, brown to greenish, thin, and less sticky than meconium
• Milk stool: Loose, yellow (mustard-yellow), soft, and inoffensive in breastfeeding newborns; pale yellow, formed, and slightly sharp smelling for formula-fed newborns.
• Frequency of bowel movement varies.

Urinary Tract Adaptation

• Kidneys fully developed by 34–36 weeks' gestation.
• Glomerular filtration rate (GFR) is low, unable to effectively dispose of water quickly; tubules are short and narrow. This leads to less concentration of urine.
• Initial bladder volume: 6–44 ml at term.
• Urine: usually diluted and pale yellow, able to concentrate urine by 3 months of age.

Body Weight

• Weight: 2.5-4kg (37-41 weeks).
• About 70–75% water and a 5-10% weight loss is normal in the first 3-4 days. It should regain weight by 10-14 days.
• Increase about 7 oz/week after the first week and until 6 months.
• Potential distress signs if birth weight is outside 10th or 90th percentile range.

Gestational Age & Birth Weight

• Small for gestational age (SGA): Weight below 10th percentile on intrauterine growth curve
• Appropriate for gestational age (AGA): Weight between 10th and 90th percentiles
• Large for gestational age (LGA): Weight above 90th percentile on intrauterine growth curve
• Low birth weight (LBW): Weight < 2500 g.

Regulating Body Weight

• Weighing newborn after immediate stabilization or before they leave the delivery room.
• In the first 3-4 days, 5–10% weight loss is considered normal. Possible causes for loss include small fluid intake, large meconium stool volume, and fluid shifts.
• Growth expectations for newborns, with gains between birth and 12 months.

Sensory Adaptations

• Visual: Respond to light, focus on close-up objects (~8-15 inches), prefer facial and eye features, prefer black-and-white patterns, and detect color by 2 months.
• Auditory: Developed at birth, turn eyes towards sound, well-developed at birth, discriminate between voices, and hearing as good as an adult.
• Olfactory: Highly developed, able to recognize smells and especially the mother's scent immediately after birth
• Taste and sucking: Distinguish sweet and sour tastes, frequently used for self-regulation.
• Tactile: Sensitive to touch, seeking contact.

Behavioural Phases of Term Newborns

• Crying at birth: Helps clear fluids and is a natural behavior.
• Relaxation: Occurs within a few minutes after birth, quiet and relaxed.
• Awakening: Opening eyes and beginning head movements.
• Activity (4-12 min of life): Increases activity.
• Resting (13-27 min of life): Becoming quiet and sleep.
• Crawling (18-54 min): Searching for the mother's nipple and using smell to locate the maternal breast.
• Familiarization (29-62 min): Licking areola and nipple in a specific and repeating manner.
• Suckling (44-90 Min): Nursing and suckling (without assistance) are common.
• Sleeping (by 70 min): Regularly rests and naps.

Transitional Period (0-30 min)

• First period of reactivity: quiet, awake, active, and appear hungry & exhibit strong sucking reflexes, which is a prime opportunity for parents to bond with their baby.
• Inactivity to sleep phase: the baby is often difficult to wake, sleeps for few minutes to 2-4 hours, and shows no interest in stimulation
• Second period of reactivity: awake, more alert, show stronger reactivity to stimuli, increase HR, and show sucking and swallowing reflexes.

State of Organization (state of consciousness)

• A group of characteristic behaviors and physiologic changes that recur consistently, impacting the newborn's response.
• This reflects central nervous system (CNS) maturity, and is important for growth, development, and learning.
• Divided into 2 sleep and 4 awake states.

Sleep-wake Pattern

• Sleep states typically include deep or quiet sleep (~35-45%) and active or light sleep (~45-50%).
• Alert states usually include drowsiness, quiet alert, active alert, and crying.

The Golden Hour

• The first hour after birth is critical for adaptation, and for establishing successful breastfeeding.
• Skin-to-skin contact (SSC) promotes regulating body temperature, and helps control respiration and reduce the risk of hypoglycemia and allows for optimal bonding.
• Healthcare teams must promote immediate and uninterrupted skin-to-skin contact (SSC) and support mothers to initiate breastfeeding as early as possible.

Subsequent Assessment (Nursery/Postnatal Ward)

• Objectives of complete newborn assessment: Assess danger signs, normal adaptations after birth, congenital malformations, and traumas.
• Assess growth and development; provide appropriate care and treatment; offer advice and counseling to the mother and family.
• Assessments to be conducted in a warm room (above 25 °C) within 15–20 minutes on a completely naked newborn, using good light, and completed by a doctor within 24 hours.

Assessments of the Newborn (Vital Signs)

• Pulse: 110–160 bpm; 80–100 bpm in deep sleep; > 180 bpm when crying.
• Respiration: 30–60 breaths per minute (bpm); predominantly diaphragm use should be observed.
• Blood pressure: Measured by accurately placed cuff of appropriate size to the newborn (facility policy should be followed for accurate assessment of vital signs), which varies by gestational age and birth weight.
• Temperature: Rectal (37–38°C) and axillary (36.5–37.5°C).

Characteristics of a Healthy Newborn

• Respiratory rate (RR) 30-60 breaths per minute (BPM) .
• Heart rate (HR) > 100BPM
• Skin color (mostly pink)
• Body temperature (BT) 36.5–37.5° C
• Posture (flexed arms and legs)
• Movement, active
• Cries && reacts to stimuli; moves legs and arms equally; able to suck & pass urine.

Head-to-toes Assessments

• General appearance: Proportional large head; short neck with chin resting on the chest; round chest with prominent abdomen; narrow hips; muscles in a flexed position with good muscle tone; short extremities, hands usually tightly clenched.

Newborn Measurements

• Weight: 2.5-4kg (born during week 37–41).
• Head circumference: Measure around the occiput (~32-37 cm), repeat measurement to assess molding.
• Chest circumference: Approximately 2 cm less than the head circumference (approximated across the nipple line).
• Length: Measure from crown to rump and from rump to heel (~46–56 cm).

Physical Assessment of the Newborn: Head Assessment

• Symmetry: large head (1/4 body size); HC :32-37 cm
• Asymmetry: Molding (overriding of cranial bones), caput, cephalohematoma, hydrocephalus, and microcephaly.
• Soft spots (fontanels): Anterior (1-4cm) closes by ~18 months; Posterior (≤1cm) closes by ~2–3 months.

Caput Succedaneum v. Cephalohematoma

• Caput succedaneum: Fluid collection, edematous swelling of the scalp, caused by pressure on presenting part during birth, crosses suture lines, present within 12 hours of birth, and resolves within several days.
• Cephalohematoma: Blood collection between cranial bone and periosteum; caused by pressure over presenting part, instrumental delivery, or prolonged labor; does not cross suture lines, appears within 1–2 days, resolve in 2–5 weeks.

Facial, Eye, Ear, Mouth, Nose Assessment

• Face: Normal hairlines, symmetric movement of facial features, presence of eyebrows and eyelashes, no abnormal discharge (especially in the nasal region).
• Eyes: Symmetrical size and shape; spontaneous opening; no drooping; full movement in all directions; normal size and color.
• Ear: Symmetrical size, position, shape, and pliable; no abnormalities (low-set ears, preauricular skin tag).
• Mouth: Pink lips; symmetry in lip and tongue movement; complete and intact gum mucosa; no abnormalities (cleft lip/palate, nerve palsy), no thrush.
• Nose: Midline positioning; patent breathing when mouth is closed; ability to smell; no abnormalities (choanal atresia, flat or wide bridge).

Assessment of Extremities

• Generally flexible, symmetrical movement, good muscle tone (flexor type).
• Count number of fingers and toes; absence/extra digits (polydactyly), single line on palm (trisomy 21), webbing, clubfoot, or hip dislocation (abnormalities).
• Skin: Color consistent with ethnicity (pink with acrocyanosis); vernix caseosa, lanugo, milia, birthmarks (Mongolian spots).
• Back: Straight and flat when prone position; check for patency; abnormalities (spinal bifida, dimple, hair at the base of spine).
• Anus: Check for patency; absence of fissures, tears, or skin tags. Abnormalities (imperforate anus).

Assessment of Maturity

• Estimate gestational age: Evaluate neurological and musculoskeletal development, external physical characteristics (e.g., plantar creases, breast tissue, amount of lanugo), cartilaginous development of the ear, testicular/labial development (scrotal/labial development).

Physical Maturity Score

• A validated system that evaluates several physical characteristics to estimate gestational age.

Assessment of Neuromuscular Maturity

• Determine neurological function.
• Note presence, strength, and symmetry of reflexes.
• Assess common newborn reflexes (primitive reflexes).

Estimation of Gestational Age (Ballard Score)

• A validated neuromuscular assessment for estimating gestational age using physical characteristics (e.g., posture, arm recoil, popliteal angle, scarf sign and heel to ear).

Scarf Sign

• No resistance: score 1
• Presence of resistance/no resistance. The elbow at midline: score 2
• Beyond 40 weeks, the elbow won't reach the midline : score 4

Neurological Reflexes (Primitive Reflexes)

• Moro (startle): Sudden head extension, symmetrical abduction/extension, followed by flexion and adduction of the arms.
• Palmar/plantar grasp: Flexion of fingers/toes when an object is placed in the palm or on the ball of the foot.
• Rooting: Stroke the cheek, and the head turns towards the side stroked.
• Sucking: When the palate or nipple is touched, the newborn begins to suck.
• Tonic neck: When the head is turned to one side, the arm and leg on that side extends, while the arm and leg on the opposite side flex.
• Babinski: Stroke the sole of the foot, toes extend outward, the big toe moves upward.
• Stepping/placing: When held upright, lifted, foot touches a surface and then opposite foot, the baby displays stepping reflex.

Other Observations

• Airway: Evaluate patency of both nostrils.
• Chest wall: Assess chest wall movement during respiration and look for presence of abnormal retractions.
• Abdomen: Assess for soft, non-distended abdomen; presence of umbilical stump.
• Skin: Observe for acrocyanosis or central cyanosis, if present.
• Genitalia: Evaluate genitalia to determine sex, but do not force examination in this area.
• General: Evaluate for any birth-related injuries (e.g., nerve injuries, fractures).

Test your knowledge about the processes and factors influencing a neonate's first breath after birth. This quiz covers various aspects such as the role of crying, lung fluid dynamics, and the medulla oblongata in respiratory adaptation. Challenge yourself and enhance your understanding of neonatal physiology!