Valerie Hill - Newborn

The newborn Period

• Birth to 28 days of life.

• Intrauterine to extrauterine changes occur in the first 6-8 hours after birth.

First Period of Reactivity

• First 30 mins after birth. HR increases to 160-180 immediately after birth, but in the first 30 mins it will gradually fall to 100-160. Respirations may be irregular, and 60-80rpm is normal. Crackles, nasal flaring, and retractions can also occur for up to the first hour.

Period of Decreased Responsiveness

• Lasts from 60-100 mins. Newborn may sleep, or decrease motor activity. Rapid shallow respirations, up to 60rpm.

Second Period of Reactivity

 Occurs at 2-8 hours after birth. Brief periods of tachycardia and tachypnea occur. Increased muscle tone and mucus production. Muconium may be passed at this stage.

Chemical Factors for Initiation of Newborn Breathing

Chemoreceptors in the carotid arteries and aorta respond to the hypoxia associated with labor contractions. Interestingly, clamping the umbilical cord after birth results in dropped levels of prostaglandins which can inhibit respirations.

Mechanical Factors for Initiation of Breathing in Newborns

• Changes in intrathoracic pressure resulting from the compression of the chest during vaginal birth, which is relieved after birth, drawing air into the lungs. Also crying.

Thermal Factors for Initiation of Newborn Breathing

• Low temperature exposure stimulates the respiratory center in the medulla

Newborn Lung Fluid and Alveolar Cells

 In the days preceding birth, the fluid in the lungs is slowly drained from the lymphatic system so that the baby is prepared to fill their lungs with air after birth. A C section before “organic” labor can result in higher fluid volume in the lungs, resulting in transient tachypnea of the newborn. In addition, newborn lungs are 95% alveolar type I cells and 5% alveolar type II cells. Type II generates surfactant, which reduces the pressure needed to inhale. Lower levels of surfactant can thereby cause breathing issues as breathing is more difficult for these babies.

Breathing Findings for Newborn (4)

• A resp rate <30 or >60 in a resting newborn is abnormal.

• Apneic episodes are common but must not last >20secs.

• Acrocyanosis (hands and feet) is normal in the first 7-10 days after birth. Central cyanosis (lips, mucus membranes) is abnormal.

• Fine crackles may be auscultated for several hours after birth

Cardiac Closures in the Newborn Period

• Decreased pressure in the right side (from pulmonary capillary distension due to breathing), and increased pressure on the left side closes the foramen ovale. During the first few days, crying may temporarily open the foramen, leading to mild cyanosis.

• The ductus arteriosus functionally closes in the first 24hrs after birth, but permanent closure can take up to 3-4 weeks, at which point it becomes a ligament. A patent ductus arteriosus presents as a heart murmur. 

• The umbilical arteries, vein and ductus venosus functionally close instantly after cord clamping, but may take 2-3 months to become ligaments.

Newborn HR

• Newborn HR is 110-160. It can go as low as 80-100 in deep sleep, and 180+ during crying.

Newborn BP

Newborn BP is 60/40-80/50. The number of weeks of gestation is a rough estimate of the MAP (40 weeks = MAP of 40). The BP increases in the second day of life.

4 Mechanisms of Newborn Heat Loss

• Convection: Flow of heat from body surface to cooler air. The room temp for a newborn should be 22-26C

• Radiation: Loss of heat from the body surface to a cooler surface nearby such as windows

• Evaporation: Loss of heat from water evaporating off the skin. Newborns should be thoroughly dried

• Conduction: Heat loss from body to cooler surfaces touching the newborn such as a scale.

How do Newborns Deal with Cold

Because newborns can’t really shiver, they warm themselves by metabolizing brown fat, and increased metabolic activity in the brain, heart and liver. Cold stress can rapidly deplete the brown fat, which is supposed to be present for several weeks after birth.

How to Know What is Causing Newborn Hyperthermia

• Due to environmental factors: Newborn will appear flushed from vessel dilation, limbs will be warm, and newborn will be extended

• Due to sepsis: Newborn will be pale, with cold limbs. 

Newborn Renal System

• At 1 day of age, a minimum of one void is expected. This increases by one void a day till 5 days. 

• At 1 week of age, about 6-8 voids per day is indicative of adequate fluid intake.

• Newborns lose waterweight. 5-10% of birthweight is lost in the first 3-5 days of life, and regained by day 10-14.

What Enzymes are Present in Newborn GI Tract

• Newborns have all enzymes and digestive juices except pancreatic amylase and lipase. Salivary amylase is present after three months, and pancreatic after 6. Human breastmilk contains lipase so the infant can absorb the fats from our milk.

Meconium

Meconium is formed from amniotic fluid, intestinal secretions and cells. It is passed within the first 12-48 hours of birth.

Newborn Abdomen Assessment

• Fullness of the abdomen above the umbilicus indicates a serious disorder if present at birth. After birth it may be a result of overfeeding, constipation or GI disorders. 

• A scaphoid or sunken abdomen is a sign of a diaphragmatic hernia if accompanied with respiratory distress, or a sign of bladder distension if not.

How is Bilirubin stored, transferred and excreted

• When RBCs are broken down, they release Hgb, which breaks into heme and globin

• Heme is broken down by reticuloendothelial cells into bilirubin in its unconjugated form. 

• Unconjugated bilirubin must be bound to albumin. If it is not, it is insoluble and will cause damage to nearby structures and the nervous system

• To excrete bilirubin, it is conjugated by glucuronic acid, which makes it soluble and able to be excreted as bile, which is carried into the duodenum. 

• Duodenal flora convert this bilirubin into urobilogen and stercobinogen. Both are excreted in the feces, but urobilogen can also be excreted in urine.

Enterohepatic Circulation

Beta glucuronidase converts conjugated bilirubin into its unconjugated form, which is reabsorbed by the intestines. Therefore, to reduce bilirubin levels, we need to make it travel fast through the intestine so this enzyme does this stuff less. This is done through proper feeding. Colostrum is a natural laxative.

Jaundice Biliruibin Levels

 Bilirubin > 85-102.

Physiological Jaundice

Occurs in over half of term newborns, and most pre-term newborns. Appears after 24 hours, and resolves without treatment. Bilirubin levels rise by 60-72 hours of life, decrease and plateau by the 5th day, and then decrease by days 12-14.

Breastfeeding Associated Jaundice

• Begins at 2-5 days of age, and is the result of ineffective feeding, which slows peristalsis, allowing more enterohepatic circulation

Breast Milk Jaundice

• Occurs at 5-10 days of age. Bilirubin peaks at the 2nd week, and persists until week 12. No hemolysis or liver dysfunction.

Newborn Immune System (antibodies, GI)

• Most of the antibodies in the newborn are IgG antibodies transferred via placenta. The fetus also produces low levels of IgM. 

• Stomach acid, pepsin and trypsin are not fully developed in the newborn, and can therefore contribute to reduced intestinal sterility. 

• Breast milk provides membrane protective IgA to the GI tract (but not to resp or urinary tracts). This IgA is useful in microbial protection, and reducing the risk of autoimmune disease. 

• While newborn WBC are slow to react, the immune response to vaccines in newborns is excellent.

• Newborns typically don’t present with fever. Hypothermia is a sign of infection.

Nevi Simplex

Small flat pink blanchable lesions that are symmetrical. Most common on the face and neck. Fade in the first year of life.

Nevi Flammeus

Red purple stain on face and neck.

Infantile Hemangioma

• Raised, sharply demarcated bright or dark red rough surfaced swelling. Appears at birth or shortly after. Max growth at 6 months, and then involution up to ten years.

Erythema Toxicum

Appears during the first 24-72 hours after birth. Appears suddenly. Thought to be an inflammatory response. No clinical significance.

Caput Succedaneum

Edematous area of the scalp, usually near the occiput, that is a result of the presenting part having lesser circulation because it is pressed against the cervix. As a result, it is swollen.

Subgaleal Hemorrhage

• Bleeding into the subgaleal compartment. Usually caused by vacuum assisted birth, that tears the scalp from the bony calvarium, resulting in tearing blood vessels. Boggy scalp, increasing head circumference and tachycardia are symptoms of this.

Hip Dysplasia

An easily dislocatable hip. Signs include asymmetrical gluteal and thigh skinfolds and uneven knee levels

Barlow and Ortalini Tests

• Barlow Test: Tries to dislocate the hip by flexing, adducting and pushing it basically. Test is positive for DDH if you dislocate the hip

• Ortalani Test: Tries to relocate the hip. Positive if you can relocate.

Club Foot

If the foot is turned inwards and plantar flexed, that is a sign of a congenital abnormality called club foot. If it can be moved into the normal position it is likely not congenital and instead positional, and will gradually resolve.

Sleep Wake States

Deep sleep, light sleep, drowsy, quiet alert, active alert and crying. Optimal state is quiet alert.

AOGAR Scores

• Assesses five signs of the newborn's physiological state

  • HR (auscultation or palpation of umbilical cord. Ausc is gold standard)

  • Resp rate

  • Muscle tone based on degree of flexion, and movement of the extremities

  • Reflex irritability

  • Generalized skin color.

• Evaluations at 1 and 5 mins. 

• Score of 0-3 indicates severe distress

• 4-6 indicates moderate difficulty

• 7-10 indicates minimal to no difficulty

• Reassessed at 10 and 20 mins if the score was <7 at 5 mins.

Opthalmia Neonatorum

Ophthalmia neonatorum is an inflammation of the eyes from gonorrhea or chlamydia contracted during vaginal birth. Erythromycin ointment in the eyes is therefore prophylactic. However the Canadian pediatric society does not recommend continuing this practice, and instead opts for rigorous screening.

Normal Birth weight, head circumfrence and length

• A normal birth weight is between the 10th - 90th percentile of a baby with the selected population

• Bigger babies grow faster and smaller babies grow slower regardless of gestational age

• Term newborns weigh around 2500-4000g

• The term newborn has a head circumference of 32-36.8cm above the brow.

• The term newborn is 45-55cm long.

Preterm, Late preterm, Early term, Full term, Late Ter, Post Term and Postmature

• Preterm/Premature: Before 37 weeks

• Late Preterm: Between 34-36+6

• Early Term: 37-38+6

• Full term: 39-40+6

• Late Term: 41 weeks

• Post Term: 42+

• Postmature: 42+ and showing the effects of progressive placental insufficiency.