RDS Flashcards
What causes RDS?
Deficiency of alveolar surfactant
This leads to atelectasis, re-inflation with each breath exhausts the baby and respiratory failure follows
Hypoxia leads to reduced cardiac output, hypotension, acidosis and renal failure
Blood gases show hypoxaemia and acidosis
What are signs of RDS?
Increased work of breathing shortly after birth (1st 4h) Tachypnoea (>60/min RR) Grunting Nasal flaring Intercostal recession Subclavicular recessions Tracheal tug Cyanosis Tachycardia >160 bpm Hypotension
What is seen on CXR in RDS?
Diffuse granular patterns (ground glass appearance)
Air bronchograms
How is RDS prevented?
Betamethasone or dexamethasone should be offered to all women at risk of preterm delivery from 23-35 weeks
Maternal steroids help maturation of fetal lungs
What is management for RDS?
Delay clamping of cord to promote placento-fetal transfusion
Give oxygen via oxygen-air bledner
Sats of 85% are normal in first 5-10 minutes of life
IF spontaneously breathing stabilise with CPAP
If <26wks gestation, intubate and give prophylactic surfactant via ET tube
Aim SaO2 85-93% to avoid retinopathy of prematurity and bronchopulmonary dysplasia
Wrap up warmly and take to NICU incubator
If blood gases worsen, intubate and support ventilation
If deterioration, check DOPE - displaced ET tube, obstructed, pneumothorax, equipment failure
Fluids - 10% glucose IV
Nutrition - inositol is an essential nutrient promoting surfactant maturation
What is bronchopulmonary dysplasia? Tests?
Persistent hypoxia ± difficult ventilatory weaning
Mainly from barotrauma and oxygen toxicity whereas surfactant related BPD is multifactorial with airway infections triggering inflammatory cascades
CXR:
Hyperinflation, rounded, radiolucent areas alternating with thin, denser lines
Histology:
Necrotising bronchiolitis with alveolar fibrosis
What is transient tachypnoea of the newborn? When is it more common? Investigation? Management?
Commonest cause of respiratory distress in the newborn period caused by delayed resorption of fluid in the lungs.
More common following Caesarean sections possibly due to lung fluid not being squeezed out during passage through the birth canal
No hypoxia or cyanosis usually seen
CXR: hyperinflation and fluid in the horizontal fissure, may show some perihilar markings
Blood gas normal
Settles within 1-2 days without intervention
What is meconium aspiration syndrome? Features?
Respiratory distress in the newborn as a result of meconium in the trachea. It occurs in the immediate neonatal period.
This follows the aspiration of meconium stained amniotic fluid.
Partial/total airway obstruction - thick sticky consistency - may lead to atelectasis
Foetal hypoxia - VQ mismatch, mechanical obstruction, airways oedema, surfactant inactivation
Pulmonary inflammation
Infection - due to inflammation
Surfactant inactivation - loss of surface tension in alveoli - reducing gas exchange
Remodelling of pulmonary vascular bed in response to hypoxia - persistent pulmonary hypertension
What is meconium?
Meconium is the dark green, sticky and lumpy faecal material produced during pregnancy. It is usually released from the bowels after birth.
What are risk factors for MAS?
Gestational age > 42 weeks Foetal distress Intrapartum hypoxia due to placental insufficiency Thick meconium paritcles Chorioamnionitis Apgar > 7 Oligohydramnios IUGR Maternal HTN, DM, pre-eclampsia, smoking
What investigations for MAS?
Bedside:
Dual Pulse Oximetry SaO2 - RUL and on either lower limb to determine hypoxia and assess potential right to left shunts
BP
Bloods:
FBC, CRP, Blood culture for infection
ABG - pH, PaO2, PaCO2, metabolic acidosis
Imaging: CXR: Increased lung volumes Asymmetrical patchy pulmonary opacities Pleural effusions Pneumothorax Multifocal consolidation due to chemical pneumonitis
Echocardiography for congenital heart abnormalities causing pulmonary hypertension - PDA, PFT, Tricuspid valve regurgitation
Cranial US - hypoxic brain injury
What is management for MAS?
Observation:
SaO2
Routine care: Placed under infant warmer SaO2 monitoring BM, U&E, FBC, CRP assessment Nutritional support - IV fluids - switch to NG and oral feed when permitting
Nasal cannula oxygen therapy
CPAP via nasal prongs (Can cause air trapping - regular CXRs)
Aim for SaOI2 of 92-97%
Wean if no respiratory distress
If ineffective, intubation and mechanical ventilation in NICU
Antibiotics if suspicion of infection - ampicillin IV, gentamicin IV
Surfactant bolus in newborns with moderate MAS or if a pneumothorax is present.
Inhaled nitric oxide to reduce pulmonary HTN (vasodilator)
What are complications of MAS?
Air leak - alveolar hyperdistension leading to penumothorax or pneumoperitoneum
- Needle aspiration
Persistent pulmonary hypertension of newborn
- ECHO for investigation of right to left shunt and iNO for treatment
Cerebral palsy - from cerebral hypoxia
Chronic lung disease
