Neonatology Flashcards
Why do you get ishcaemia in HIE?
Hypoxia- causes blood vessles to contrict - ischaemia
What metabolic changes do you get in HIE?
Hypoxia- reduced aerobic respiration - increase anaerobic respiration - rise in latctae- metabolic acidosis
Why do you need respiratory support in HIE?
HIE management - theraputic hypothermia
Cooled infants are at risk of PPHN
So keep oxyegn sats between 92 and 98%
What anticonvulsants are used in HIE?
Phenobarbital remains the standard first-line pharmacotherapy for neonatal seizures resulting from HIE
Phenytoin
Midazolam
Why should you do a CXR of there is a history of meconium aspiration?
Meconium aspiration - can cause chemical injury - can result in pneumothorax
What is TTN?
Transient tachypnoea of the newborn (TTN)
Caused by delayed clearance/absorption of lung fluid after birth. Presents within 4h of birth. Common after elective CS.
- CXR: shows streaky perihilar changes and fluid in lung horizontal fissures.
- Treatment: supplemental O2. Consider nasal CPAP/high flow and antibiotics.
- Prognosis: spontaneously resolves within 24h.
What is RDS?
RDS is a lung disease caused by surfactant deficiency. It is largely seen in preterm infants, being less common after 32wk gestation.
Management of RDS
- Good delivery room resuscitation: this care may involve ETT intubation and administration of surfactant (extremely preterm) or nasal CPAP/high flow.
- Respiratory support will depend on the severity: may need O2, nasal CPAP/high flow (see graphic Neonatal respiratory support, pp. 140–141), or MV (see graphic Conventional positive pressure ventilation, pp. 142–143).
- Surfactant (Curosurf® or Survanta®): requires ETT intubation and MV and should be considered in all extremely preterm (<27/40) infants and when FiO2 >0.3–0.4.
- Antibiotics (e.g. penicillin and gentamicin): until congenital pneumonia has been excluded, as it can mimic or coexist with RDS.
- Nutrition: use IV fluids until the baby is stable. Then start gastric tube feeds with minimal volumes and slowly increase as tolerated. If unstable, start TPN.
What is old and new Bronchopulmonary dysplasia?
- ‘Old’ BPD was a disease of scarring and repair, and was associated with long periods of MV, often with high PIP and high FiO2.
- ‘New’ BPD is a condition of impaired alveolar development, with less destruction and scarring. Mechanical, oxidative, and inflammatory factors contribute to lung injury. The CXRs are less dramatic (see Fig. 4.7), but impairment in lung function continue through childhood and is associated with other disorders.
What is the defintion of BPD?
‘O2 requirement at 36/40 corrected gestational age (CGA)’
What is the severity classification of BPD?
- Mild: need for supplemental O2 at 28 days, but not at 36/40 CGA.
- Moderate: need for supplemental O2 <30% at 28 days and 36/40 CGA.
- Severe: MV or requiring O2 >30% at ≥36/40 CGA.
Risk factors for BPD?
- Gestational immaturity.
- LBW.
- ♂.
- Caucasian heritage.
- IUGR.
- Family history of asthma.
- History of chorioamnionitis.
Prevention of BPD
Caffeine citrate for apnoea of prematurity in infants <1250g.
Vitamin A supplementation for infants <1000g.
Management of establish BPD
No therapies are known to improve outcome in BPD. However:
* O2 is the most commonly used treatment, and the suggested dose is that needed for SpO2 90–95%
* Other treatments are: diuretics, corticosteroids, sildenafil, and optimizing nutrition.
* Immunization for at-risk infants with monoclonal respiratory syncytial virus (RSV) antibody
What is meconium aspiration syndrome?
Aspiration of meconium stained amniotic fluid (MSAF), which can happen either antenatally or during birth
Results in varying degrees of respiratory distress
Why do you get MSAF?
** after-effect of in-utero peristalsis**
In term or post term infants, where gastrointestinal maturation is appropriate, this movement leads to meconium passage.
The peristalsis usually is the result of:
- foetal hypoxic stress
- vagal stimulation due to cord compression
- There is also some evidence that chronic hypoxia may lead to it as well.
- These factors can also lead to fetal gasping which results in MAS.
What happens after aspirating the meconium?
Stimulate the release of many vasoactive and cytokine substances thatL:
- activate inflammatory pathways
- triggering vasculature changes
- inhibits the effect of surfactant in the lungs.
Common features seen with MAS-related respiratory distress of the newborn:
Partial or Total Airway Obstruction
Foetal Hypoxia
Pulmonary Inflammation
Infection: The inflammation process predisposes the foetal lung to an increased risk of infection and can cause a chemical pneumonitis
Surfactant Inactivation
Persistent Pulmonary Hypertension (PPHN)
RF for MAS
Conditions leading to foetal hypoxia and foetal gasping increase the risk of aspirating meconium in a term or post-term baby, they are as follows;
- Gestational Age > 42 weeks
- Foetal distress (tachycardia / bradycardia)
- Intrapartum hypoxia secondary to placental insufficiency
- Thick meconium particles
- Apgar Score <7
- Chorioamnionitis +/- Prolonged pre-rupture
- Oligohydramnios
- In utero growth restriction (IUGR)
- Maternal hypertension, diabetes, pre-eclampsia or eclampsia, smoking and drug abuse
Clinical features of MAS
clinical diagnosis. A full history of the risk factors, confirmed presence of meconium in the amniotic fluid and aspirated meconium (clinical signs of post-maturity and MSAF staining) are necessary to diagnose MAS in an infant presenting with respiratory distress where no other diagnosis can be confirmed ie. MAS is a diagnosis of exclusion.
On examination the newborn infant will show signs of respiratory distress:
- Tachypnoea – a respiratory rate of >60 breaths per minute
- Tachycardia – a heart rate of >160 beats per minute
- Cyanosis – this requires immediate management
- Grunting
- Nasal flaring
- Recessions – intercostal, supraclavicular, tracheal tug
- Hypotension – systolic blood pressure of <70 mmHg
Ix for MAS
- CXR
- Infection markers:
FBC
CRP
Blood cultures
Other neonatal ix:
* Arterial Blood Gas
* Dual Pulse Oximetry – (pre- and post-ductal) to determine hypoxia and assess any potential right-to-left shunts that may be present. A difference of 5-10% between the limbs is clinically significant of neonatal pathology.
* Echocardiography – Used to exclude any congenital heart abnormalities causing pulmonary hypertension e.g. PDA, PFO, tricuspid valve regurgitation
* Cranial Ultrasound – Used to assess for results of any hypoxic damage to the brain
