8.1b Physiologic Adpatations Flashcards
1
Q
Respiratory System
A
- Establishment of effective respirations is critical once baby is born
- Most newborns breathe spontaneously and are able to maintain adequate oxygenation.
- Preterm infants may have respiratory difficulty due to immature lungs
2
Q
Initiation of Breathing
A
- As a fetus, oxygen was shunted away from the lungs but during birth lungs must be used
- Clamping the umbilical cord causes a rise in BP which increases circulation and lung perfusion
- Initiation of respirations caused by chemical, mechanical, thermal and sensory factors
3
Q
Chemical Factors
A
- Chemoreceptors in carotid arteries and aorta activate due to hypoxia associated with labor
- Each labor contraction has decrease in uterine blood flow which causes the hypoxia and hypercarbia
- This causes decrease in pO2 and increase in pCO2 which lowers blood pH
- This stimulates the respiratory center in the medulla to initiate the first breath
- Clamping the cord can cause a drop in prostaglandin levels which can inhibit respiration
4
Q
Mechanical Factors
A
- Respirations stimulated by changes in intrathoracic pressure, resulting from compression of chest during vaginal birth
- After birth the pressure is relieved off the chest. The negative pressure from pressure being relieved helps draw air into the lungs
- Crying promotes expansion of alveoli
5
Q
Thermal Factors
A
- Low temperature of extrauterine life stimulates respirations
6
Q
Sensory Factors
A
- OB doctors suction a newborns mouth and nose
- Baby is dried by the nurses
- Lights/Sounds/Smells
- These all stimulate respirations
7
Q
Establishing Respirations
A
- At birth lungs hold about 20 mL of fluid per kg
- Days preceding labor there is reduced production of fetal lung fluid
- Shortly before labor, catecholamine surge promotes fluid clearance of lungs
- Lung fluid is brought into interstitial spaces via active transport and drainage goes into pulmonary/lymphatic system
- Retention of lung fluid interferes with infants ability to maintain adequate oxygenation
- This is especially important if baby has aspirated meconium, congenital diaphragmatic hernia, esophageal atresia with fistula, choanal atresia, congenital cardiac disease, and immature alveoli
8
Q
C-Section
A
- Babies can experience lung fluid retention (typically clears without harm)
- More likely to develop transient tachypnea
9
Q
Surfactant
A
- Lung expansion depends largely on chest wall contraction and adequate surfactant secretion
- Surfactant lowers surface tension which decreases pressure required for alveoli to open with inspiration. It also prevents collapse of alveoli on exhalation.
- Absent or decreased surfactant causes more pressure required during inspiration which can in turn tire or exhaust preterm/sick infants.
10
Q
Once Respirations are Established
A
- Breaths are shallow and irregular (30-60 breaths/min)
- There can be periods of paused breathing lasting less than 20 seconds
- Periodic breathing occurs most often during active REM sleep and decreases with age
- Apneic episodes longer than 20 seconds is abnormal
- Infants are nose breathers to help coordinate sucking/swallowing/breathing
- If there is a nasal obstruction, infants will open their mouths to breathe
11
Q
Breathing
A
- Before 3 weeks of age cyanosis and asphyxia (deprivation of oxygen) can occur with nasal blockage
- Breathing is usually noted as diaphragmatic contraction and abdominal breathing
- Abdomen and chest rise simultaneously with breathing
12
Q
Respiratory Distress
A
- Nasal Flaring
- Intercostal/Subcostal retractions (in drawing of tissue between ribs)
- Grunting
- Stridor/Gasping represents upper airway obstruction
- Seesaw/Paradoxical Respirations (exaggerated rise in abdomen with respirations as chest falls) should be reported
- Respirations outside normal range of 30-60 should be evaluated
- Analgesic/Anesthetics during labor can effect newborn breathing
13
Q
Apneic Episode
A
Caused by
- Rapid increase in body temperature
- Hypothermia
- Hypoglycemia
- Sepsis
14
Q
Tachypnea
A
- Results from inadequate clearance of lung fluids which can indicate respiratory distress syndrome (RDS)
CAN BE THE FIRST SIGN OF - Cardiac/Respiratory/Metabolic/Infectious illness
15
Q
Baby Color
A
- Newborn should turn from blue to pink within the first 3-5 minutes
16
Q
Acrocyanosis
A
- Blue color in hands and feet
- Normal for first 24 hours of birth
- Duskiness while crying is also common immediately after birth
17
Q
Central Cyanosis
A
- Hypoxemia
18
Q
Circumoral Cyanosis
A
- Blue lips/mucous membranes RESULTS OF - Inadequate oxygen delivery to alveoli - Poor perfusion of lungs that inhibit gas exchange - Cardiac dysfunction
19
Q
Central Cyanosis
A
- Late sign of respiratory distress and significant hypoxemia
20
Q
Transient Tachypnea (TTN)
A
- Rates up to 100 breaths per minute can be present
- Happens with intermittent grunting, nasal flaring and retractions
- Supplemental oxygen may be needed
- Usually resolves within 48-72 hours
21
Q
Signs of Newborn Stress
A
- RR above `120 breaths/min
- Moderate-Severe retractions
- Grunting
- Pallor
- Central cyanosis
- Hypotension
- Temperature instability
- Hypoglycemia
- Acidosis
- Signs of cardiac problems
22
Q
Congenital Defects
A
- Anomalies of great vessels
- Diaphragmatic hernia
- Chest wall defects
- These can cause respiratory issues
23
Q
Hydrops Fetalis
A
- Fluid buildup causing edema
- Can be caused by blood incompatibilities
24
Q
Cardiovascular System
A
- Increased pulmonary blood flow from left side of heart increases pressure in the left atrium which closes the foramen ovale
- Crying can reverse flow through foramen ovale which leads to cyanosis
- CO doubles after birth increasing blood flow to lungs, heart, kidneys, and GI Tract
- Ductus Arteriosus constricts once PO2 levels reach 50 mmHg
25
Q
Ductus arteriosus
A
- Prostaglandins play an Important role in closing ductus arteriosus
- Functionally closed within first 24 hours (permanent closure in 2-3 months)
- Can re-open in response to low oxygen and heard as a heart murmur
26
Q
Heart Rate and Sounds
A
Term Newborn - 120-160 bpm
Term Newborn During Sleep - 80-100 bpm
Term Newborn When Crying - 180 bpm
- Out of range heart rates above 160 or less than 100 should be re-evaluated in 30-60 minutes or when activity changes
27
Q
Apical Impulse (Pericardial Activity)
A
- 4th intercostal space to the left of midclavicular line
28
Q
Heart Rate
A
- Irregular heart rate or sinus dysrhythmias are common in first few hours of life
- Most heart murmurs during neonatal period is not pathologic and disappear by 6 months of age
- Murmurs with poor feeding, apnea, cyanosis, pallor should be evaluated
29
Q
Blood Pressure
A
- Primary affected by gestational age, postconceptional age, birth weight
- BP rises when these factors rise
At birth - 75-95/37-55
12 hours - 50-70/25-45
96 hours - 60-90/20-60
30
Q
Blood Volume
A
- 80-100 mL/kg
- Preterm is 90-105 mL/kg
- Preterm has more blood volume than term because they have greater plasma volume (not RBC)
31
Q
Delayed Cord Clamping (DCC)
A
- Expands blood volume from “Placental Transfusion” by as much as 100 mL depending on length of time delayed
ASSOCIATED WITH - Increased blood volume
- Increase blood pressure
- Reduced risk of intraventricular hemorrhage and necrotizing enterocolitis
- Benefits are best for pre-term babies
- Polycythemia (blood cancer) that occurs with delayed clamping is not harmful
- Increased risk of hyperbilirubinemia must be treated with phototherapy
32
Q
CVD Problems
A
- Variation in VS can be indicative of Cardio Problems
- Persistent tachycardia can be signs of anemia, hypovolemia, hyperthermia and sepsis
- Persistent bradycardia can be signs of congenital heart block or hypoxemia
- CVD issues are seen as unequal/absent pulses, bounding pulses, decreased/elevated BP
33
Q
Skin Pallor
A
During immediate post-birth period can be caused by
- Anemia
- Marked peripheral vasoconstriction as a result of asphyxia or sepsis
- Cyanosis other than hands and feet
- Presence of jaundice can indicate ABO or rH factor incompatibility
34
Q
Congenital Heart Defects
A
- Most common congenital malformation
- Risk increases if mom has rubella, metabolic diseases (diabetes), and maternal drug ingestions
Serious defects can cause
- Cyanosis
- Dyspnea
- Hypoxia
35
Q
HEMATOLOGIC SYSTEM
A
36
Q
Red Blood Cells
A
- Fetus has more RBC’s for oxygen transport due to less efficient fetal circulation
- RBC, Hgb, Hct higher than adults at birth
- Capillary blood yields higher values than venous blood
- RBC slightly increase after birth than substantially drop
- Blood contains 70% hemoglobin at birth
- 6-12 months nearly no fetal hemoglobin left
- Iron stores from mom is usually enough to last 4 months (when transient anemia can occur)
37
Q
Leukocytes
A
- Leukocytosis (elevated WBC) range from 9000-30000 (normal)
- WBC count is initially very high at birth (24000) then drops rapidly to stable (12000)
- Leukocytes in newborns are limited in ability to recognize foreign protein and localize to fight infections
- Sepsis can cause rise in neutrophils
38
Q
Neutrophilia Causes
A
- Infection
- Prolonged crying
- Asymptomatic hypoglycemia
- Hemolytic disease
- Meconium aspiration syndrome
- Labor induced with oxytocin
- Surgery
- Difficult labor
- High altitude
- Maternal fever
39
Q
Platelets
A
- Range from 150,000 - 300,000
- Essentially same in newborns and adults
- Vitamin K reaches adult levels by 6 months
40
Q
Thermogenic System
A
Thermoregulation - Maintenance of balance between heat loss and production Important due to newborns - Thin subcutaneous fat - Blood vessels close to surface of skin - Larger surface to body weight ratios
41
Q
Heat loss
A
- Neutral Thermal Environment - Allows baby to maintain normal body temperature minimizing oxygen and glucose consumption.
Convection - Heat loss from wind
(wrap newborn and put hat on them)
Radiation - Heat loss from cooler surface in close proximity
(Place baby away from outside windows and avoid direct air drafts)
Evaporation - Loss of heat from evaporation
(Most significant cause of heat loss during first few days. Keep baby dry)
Conduction - Loss of heat from touch with a cold object
(Use pre-warmed bed and covers for scales)
42
Q
Methods to prevent heat loss
A
- Skin to skin contact
- Dry baby directly after birth
- Place baby under radiant warmer
43
Q
Thermogenesis
A
- Neonate generates heat via increased muscle activity
- Thermogenesis leads to increased cellular metabolic activity primarily in brain, heart, liver
- Flexion position helps guard baby against heat loss
- Peripheral blood vessels also constrict to conserve heat
44
Q
Heat Loss
A
- Babies cannot shiver to warm themselves
- Metabolism of brown fat is used to heat baby however baby has limited supply of brown fat
45
Q
Hypothermia/Cold Stress
A
- When temperature drops, vasoconstriction occurs
- Baby can look pale and mottled with cool skin
- Respiration rate increases
- If the infant does not maintain adequate oxygen, vasoconstriction jeopardizes pulmonary perfusion.
- When this happens o2 decreases as well as blood pH causing acidosis
- Decreased pulmonary perfusion and oxygen can re-open ductus arteriosus
46
Q
Cold Stress
A
- BMR increases
- Anaerobic Glycolysis
- Acidosis
- Hyperbilirubinemia
- Hypoglycemia
47
Q
Hyperthermia
A
- Temperature greater than 37.5 (99.5)
- Can result from inappropriate use of heating devices such as phototherapy, sunlight, excessive clothes
Signs
- Dilated skin vessels
- Flushed skin
- Extremities warm to touch
- Extension posture
If Sepsis is cause
- Vessels on skin are constricted
- Color is pale
- Hands and feet are cold
- Caused by immature sweat glands
- Can cause neurological injury, seizures, heatstroke and death
48
Q
Renal System
A
- Excretes 15-60 mL/kg/day
- 2-6 voiding a day for the fist 2 days and increase every 24 hours
- Pale straw color indicates adequate hydration
- If infant has not voided in 24 hours check for fluid intake, bladder distension, restlessness, signs of discomfort
- Uric crystals are normal to appear on diaper
- 5-10% loss of birth weight over 3-5 days
- Weight should be regained in 10-14 days
49
Q
Fluid Electrolyte balance
A
- 75% of weight is water
- Weight loss in first few days is extracellular fluid
Fluid Requirements
Days 1-2 = 60-80 mL/kg
Days 3-7 = 100-150 mL/kg
Days 8-13 = 120-180 mL/kg
- GFR rate is lower, fully mature by 2 years old
- Lack of steady stream can indicate renal issues
