Paeds - Neonatology Flashcards
Define Jaundice and describe the simplified physiology?
Jaundice describes the condition of abnormally high levels of bilirubin in the blood.
Red blood cells contain unconjugated bilirubin. When red blood cells break down, they release unconjugated bilirubin into the blood. Unconjugated bilirubin is conjugated in the liver.Conjugated bilirubin is excreted in two ways:
- via the biliary system into the gastrointestinal tract
- via the urine - ME: gut bacteria convert billirubin to urobilinogen (10% reabsorbed and goes to the kidneys, 90% processed to stercobilin in the GI faeces)
What is physiological jaundice in newborns and what causes it?
What time period of neonatal jaundice is concerning? Why?
A mild yellowing of skin and sclera from 2 – 7 days of age. This usually resolves completely by 10 days.
There is a high concentration of red blood cells in the fetus and neonate. These red blood cells are more fragile than normal red blood cells. The fetus and neonate also have less developed liver function.
Fetal red blood cells break down more rapidly than normal red blood cells, releasing lots of bilirubin. Normally this bilirubin is excreted via the placenta, however at birth the foetus no longer has access to a placenta to excrete bilirubin. This leads to a normal rise in bilirubin shortly after birth, causing a mild yellowing of skin and sclera from 2 – 7 days of age. This usually resolves completely by 10 days. Most babies remain otherwise healthy and well.
TOM TIP: Jaundice in the first 24 hours of life is pathological. This needs urgent investigations and management. Neonatal sepsis is a common cause - me inflammation impairs liver function. Babies with jaundice within 24 hours of birth need treatment for sepsis if they have any other clinical features or risk factors.
When is neonatal jaundice pathological and what is the top differnetial?
Other causes of Neonatal jaundice - just name a few for each category?
TOM TIP: Jaundice in the first 24 hours of life is pathological. This needs urgent investigations and management. Neonatal sepsis is a common cause. Babies with jaundice within 24 hours of birth need treatment for sepsis if they have any other clinical features or risk factors.
The causes of neonatal jaundice can be split into increased production or decreased clearance - see below..
Prematurity: In premature babies, the process of physiological jaundice is exaggerated due to the immature liver. This increases the risk of complications, particularly kernicterus. Kernicterus is brain damage due to high bilirubin levels. Bilirubin levels need to be carefully monitored in premature babies, as they may require treatment.
Breast milk juandice: Babies that are breastfed are more likely to have neonatal jaundice. There are several potential reasons for this. **Components of breast milk inhibit the ability of the liver to process the bilirubin. **Breastfed babies are more likely to become dehydrated if not feeding adequately. Inadequate breastfeeding may lead to slow passage of stools, increasing absorption of bilirubin in the intestines.
Haemolytic disease of the newborn: When there is rhesus incompatibility between the maternal and neonatal red blood cell surface antigens. The most important is the rhesus D antigen. When the mother is Resus D negative, and her child is rhesus D positive, if blood from the babie crosses into the mother’s bload stream the mother’s immune system will produce antibodies to the rhesus D antigen. Thus doesn’t usually cause issues in the first pregnancy, but during subsequent pregnancies the mothers antibodies can cross into the fetus, causes haemolysis of the red blood cells and aneamia, with high billirubin.
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Others - dont test these!!!
Increased production of bilirubin:
Haemolytic disease of the newborn
ABO incompatibility
Haemorrhage
Intraventricular haemorrhage
Cephalo-haematoma
Polycythaemia
Sepsis and disseminated intravascular coagulation
G6PD deficiency
Decreased clearance of bilirubin:
Prematurity
Breast milk jaundice
Neonatal cholestasis
Extrahepatic biliary atresia
Endocrine disorders (hypothyroid and hypopituitary)
Gilbert syndrome
When is neontal jaundice classed as prolongued and what needs to be done about it?
Jaundice is “prolonged” when it lasts longer than would be expected in physiological jaundice. This is:
- More than 14 days in full term babies
- More than 21 days in premature babies
Prolonged jaundice should prompt further investigation to look for an underlying cause. These are particularly looking for conditions that will cause jaundice to persist after the initial neonatal period, such as:
- biliary atresia
- hypothyroidism
- G6PD deficiency.
THERE ARE LOADS OF CAUSES TEHY ARE ON THE CARD BEFORE THIS
Ix (7) and Management of neonatal jaundice
Investigations
- FBC + blood film for polycythaemia or anaemia
- Conjugated bilirubin: elevated levels indicate a hepatobiliary cause
- Blood type testing of mother and baby for ABO or rhesus incompatibility
- Direct Coombs Test (direct antiglobulin test) for haemolysis
- Thyroid function, particularly for hypothyroid
- Blood and urine cultures if infection is suspected. Suspected sepsis needs treatment with antibiotics.
- Glucose-6-phosphate-dehydrogenase (G6PD) levels for G6PD deficiency
Management
- monitoring of total billibrub on treatment threshold charts. Billrub against age (IN HOURS) - If the total billirubin reaches the threshold then they need to being treatment.
- Phototherapy is usually adequate to correct neonatal jaundice. Term threshold is 350
- Extremely high levels may require an exchange transfusion. Exchange transfusions involve removing blood from the neonate and replacing it with donor blood. Term threshold is 450
**Missed this in the Exam - exchange transfusion was needed. **
Background Phototherapy Mechanism: invovles shining blue light (not UV) on the babies skin, which converts unconjugated bilirubin into isomers than can be execreted in the bile and urine without requiring conjugation in the liver. Billirubin is closely montiored during treatment. Rebound billirubin needs to be measured 12 hours after treatment finnishes to make sure it doesn’t rise again.
Key Complication of neonatal jaundice?
Kernicterus is a type of brain damage caused by excessive bilirubin levels. It is the main reason we treat neonatal jaundice to keep bilirubin levels below certain thresholds.
Bilirubin can cross the blood-brain barrier. Excessive bilirubin causes direct damage to the central nervous system. Kernicterus presents with a less responsive, floppy, drowsy baby with poor feeding. The damage to the nervous system is permeant, causing cerebral palsy, learning disability and deafness. Kernicterus is now rare due to effective treatment of jaundice.
NIPE- How do you check the pre-ductal and post-ductal saturations and why is this important?
Babies should have their pre-ductal and post-ductal oxygen saturations checked. This measures the oxygen level before and after the ductus arteriosus. Normal saturations are 96% or above. There should not be more than a 2% difference between the pre-ductal and post-ductal saturations.
Pre-ductal saturations are measured in the baby’s right hand. The right hand receives blood from the right subclavian artery, a branch of the brachiocephalic artery, which branches from the aorta before the ductus arteriosus.
Post-ductal saturations are measured in either foot. The feet receive blood traveling from the descending aorta, which occurs after the ductus arteriosus.
Certain congenital heart conditions are duct-dependent, meaning they rely on the mixing of blood across the ductus arteriosus.
Me - actually this makes sense, if the post ductal sats are significantly higher then it shows there might be a congenital heart defect.
Common issues with the NIPE, how are the following abnormalities managed (just one line each)?
- Talipes
- undecended testes
- clicky hips
- skin findings
- haemangiomas near the eyes, mouth or affecting the airway
- port wine stanes
- cephalohaematomas
- boney-injuries (calvicles)
- cardiac murmurs
Talipes, also known as clubfoot, is where the ankles are in a supinated position, rolled inwards. It can be positional or structural. Positional talipes is where the muscles are slightly tight around the ankle but the bones are unaffected. The foot can still be moved into the normal position. This requires referral to a physiotherapist for some simple exercises and will resolve with time. Structural talipes involves the bones of the foot and ankle and requires referral to an orthopaedic surgeon.
Undescended testes require monitoring and referral to a urologist if not decended within 6 months
Skin findings generally do not require any action. Many will fade with time.
Haemangiomas near the eyes, mouth or affecting the airway may require referral for treatment with beta blockers (i.e. propranolol). Otherwise they can be monitored and usually resolve with time.
Port wine stains are pink patches of skin, often on the face, caused by abnormalities affecting the capillaries. They don’t fade with time and typically turn a darker red or purple colour. Rarely they can be related to a condition called Sturge-Weber syndrome, where there can be visual impairment, learning difficulties, headaches, epilepsy and glaucoma.
Clicky or clunky hips require referral for a hip ultrasound to rule out developmental dysplasia of the hips.
Cephalohaematomas require monitoring for jaundice and anaemia.
Boney injuries may require an xray to look for fractures (e.g. clavicular fracture).
Soft systolic murmurs of grade 2 or less in otherwise healthy well neonates may be monitored, as these often resolve after 24 – 48 hours. This may be caused by a patent foramen ovale that closes shortly after birth. Any suspicion of heart failure or congenital heart disease requires referral to cardiology for an ECG and echocardiogram. If they are unwell, they require admission to the neonatal unit and immediate management.
Neonatal Respiratory Physiology:
- Which cells produce surfactant and at what gestation?
- What is the function of surfactant?
Type II alveolar cells become mature enough to start producing surfactant between 24 and 34 weeks gestation. Therefore, pre-term babies have problems associated with reduced pulmonary surfactant.
Surfactant contains proteins and fats. It sits on top of the water in the lungs. It has a hydrophilic side, that faces the water, and a hydrophobic side, that faces the air. The surfactant reduces the surface tension of the fluid in the lungs, essentially providing a barrier that reduces the water molecules tendency to pull towards each other.
The result is that surfactant keeps the alveoli inflated and maximises the surface area of the alveoli. This reduces the force needed to expand the alveoli and therefore the lungs during inspiration. This is known as compliance. Therefore, surfactant increases lung compliance.
Additionally, as an alveolus expands, the surfactant becomes more thinly spread and therefore the surface tension increases, making it more difficult to expand that alveolus further. This stops one alveolus expanding massively whilst another alveolus only expands a little. Therefore, surfactant promotes equal expansion of all alveoli during inspiration.
Explanation:
Surface tension is the attraction of the molecules in a liquid to each other, pulling them together and minimising surface area. This is why, in zero gravity, water floats around in a ball rather than diffusing into a mist.
Alveoli are the small sacs where gas collects and diffuses into the blood during inhalation. These are lined with fluid. The molecules of this fluid pull together due to surface tension, in turn pulling the walls of the alveoli towards each-other, attempting to collapse the space in the alveoli.
Cardio-Respiratory Changes at Birth:
- stimulating the baby to breathe
- changes in the heart and lungs
- changes in the ductus arteriosus
- changes in the ductus venosus
During birth the thorax is squeezed as the body passes through the vagina, helping to clear fluid from the lungs. Birth, temperature change, sound and physical touch stimulate the baby to promote the first breath. A strong first breath is required to expand the previously collapsed alveoli for the first time. Adrenalin and cortisol are released in response to the stress of labour, stimulating respiratory effort.
The first breaths the baby takes expands the alveoli, decreasing the pulmonary vascular resistance. The decrease in pulmonary vascular resistance causes a fall in pressure in the right atrium. At this point the left atrial pressure is greater than the right atrial pressure, which squashes the atrial septum and causes functional closure of the foramen ovale. The foramen ovale then structurally closes and becomes the fossa ovalis.
Prostaglandins are required to keep the ductus arteriosus open. Increased blood oxygenation causes a drop in circulating prostaglandins. This causes closure of the ductus arteriosus, which becomes the ligamentum arteriosum.
Immediately after birth the ductus venosus stops functioning because the umbilical cord is clamped and there is no blood flow in the umbilical veins. The ductus venosus structurally closes a few days later and becomes the ligamentum venosum.
What are the 3 big issues in neonatal resuscitation (one main one)?
Hypoxia
When contractions happen, the placenta is unable to carry out normal gaseous exchange, leading to hypoxia. Extended hypoxia will lead to anaerobic respiration and a subsequent drop in the fetal heart rate (bradycardia). Further hypoxia will lead to reduced consciousness and a drop in respiratory effort, in turn worsening hypoxia. Extended hypoxia to the brain leads to hypoxic-ischaemic encephalopathy (HIE), with potentially life-long consequences in the form of cerebral palsy.
Hypothermia - babies have a large surface area to volume ratio and are born wet
Meconium, if present may block the mouth or airway
Steps to the Neonatal Resusitation algorithm?
What score is used?
Threshold for chest compressions?
warm the baby - dry them and keep them under a heat lamp, (plastic bag below 28 weeks)
Stimulate breathing - rubbing vigerously with a towel stimulates them to start breathing (often all that is required), keep head in a neutral position, aspirate any meconium that is visualisable
Assess - colour, tone, breathing, heart rate
Calculate the APGAR score are 1,5 and 10 minutes
Ensure an open airway
Inflation breaths (when baby is not breathing/gasping despite adequete inital stimulation) :
- 2x cycles of 5 inflations breaths (3 seconds each) to stimulate breathing and heart rate
- If there is no response and the heart rate is low, 30 seconds of ventilation breaths (1 second each) can be used
- If there is still no response, chest compressions can be used, coordinated with the ventilation breaths
Note - inflation breahes are about expanding the alveoli and pushing out the fluids
chest compressions - used if heart rate remains below 60bpm despite inflation breaths
- If there is no response and the heart rate is low, 30 seconds of ventilation breaths can be used
If there is still no response, chest compressions can be used, coordinated with ventilation breaths in a 3:1 ratio
Prolonged hypoxia increases the risk of hypoxic-ischaemic encephalopathy (HIE). In severe situations, IV drugs and intubation should be considered. Babies near or at term that have possible HIE may benefit from therapeutic hypothermia with active cooling.
Compents of an APGAR score for neonatal resusciation
Appearance - pink/ blue extremities/ blue centrally
Pulse - 100+/100-/absent
Grimmance (response to stimulation) - none/ little/ good repsonse
Activity (muscle tone ) - floppy/ flexed/ active
Respiration - abscent/ slow/ strong
each is scored 0-2, giving a maximum score of 10 for an unconcerning baby
Neonatal resucutation - what is the importance of delayed umbilical cord clamping
After birth there is still a significant volume of fetal blood in the placenta. Delayed clamping of the umbilical cord provides time for this blood to enter the circulation of the baby. This is known as placental transfusion. Recent evidence indicates that in healthy babies, delaying cord clamping leads to improved haemoglobin, iron stores and blood pressure and a reduction in intraventricular haemorrhage and necrotising enterocolitis. The only apparent negative effect is an increase in neonatal jaundice, potentially requiring more phototherapy.
Current guidelines from the resuscitation council UK state that uncompromised neonates should have a delay of at least one minute in the clamping of the umbilical cord following birth.
Neonates that require neonatal resuscitation should have their umbilical cord clamped sooner to prevent delays in getting the baby to the resuscitation team. The priority will be resuscitation rather than delayed clamping.
Why are newborns given an injection shortly after birth?
When should baby be fed?
Babies are born with a deficiency of vitamin K. Vitamin K is an important part of normal blood clotting. Standard practice is to give all babies an intramuscular injection of vitamin K in the thigh shortly after birth. This can have the helpful side effect of stimulating the baby to cry, which helps expand the lungs. Vitamin K helps to prevent bleeding, particularly intracranial, umbilical stump and gastrointestinal bleeding.
Alternatively, vitamin K can be given orally, however this takes longer to act and requires doses at birth, 7 days and 6 weeks.
Once out of the delivery room, initiate bottle feeding as soon as the baby is alert enough
The blood spot screening test is taken on day 5 of life
