Meconium aspiration Flashcards
What is meconium aspiration?
Spectrum of respiratory distress in neonates born through meconium stained liquor
What severity can meconium aspiration be
Mild respiratory distress to severe repiratory failure
What can meconium cause in resp tract?
Inflammatory response through cytokine release
What is meconium release into amnitoic fluid related to?
Increased vaginal outflow - umbilical cord compression or hypoxia
Risk factors for meconium asporation
2-10% neonates born in meconium stained liquor
MAS risk increases with postdates gestation and small for gestational age
What are the clinical features of MAS?
Meconium-stained liquor
Respiratory distress at or shortly following birth
Typical radiographic features on CXR, hyperinflation, patchy opacification and consolidation
Increased O2 requirements - mechanical ventilation may be required for severe cases
Different ways meconium can affect repiratory system
Respiratory distress
Pneumonitis
Bacterial pneumonia
Pneumothorax
How is respiratory distress caused by medonium?
Damages surfactant and metabolism
Severe effects due to reduced surfactant ef increased surface tension, reduced lung volume, compliance and oxygenation
How does meconium cause pneumonitis?
-> irritation and local inflammation -> exudatice and inflammatory pneumonitis
How does meconium cause bacterial pneumonia?
Meconium stained liquor - bacterial infection in utero - E.coli esp -> increased morbidity
How does meconium cuase pneumothorax?
Thich meconium -> AW obstruction in distal small AWs
Plugging and distal gas trapping can lead to distention of dital lung and pneumothorax
What does meconium in AW mechanisms cause ?
Hypoxic and repiratory distress
Differntial diagnosis for meconium aspiration
Transient tachypnoea of newborn
Delayed transition form foetal circulation
Sepsis
Congenital oneumonia
Persistent pulmonary HPTN of newborn
Pneumothorax
Hypovolaemia
TTN vs MAS
Infants with TTN present initially similar but recover quickly
Why treat infants iwth MAS withantibiotics?
Presents v similarly to pneumonia - treat until blood cultures return
How differentiate MAS with penumothorax
Transillumination of chest wall and CXR
Bedside investigations for MAS
Pre and post ductal saturations
Capillary gas or venous gas
Pre and post ductal sats why do it with MAS?
assess resp involvement and detect congenital cardiac lesions
Why do capillary gas or venous gas in MAS?
Assess degree of respiratory compromise and assist in decisions regarding respiratory support and systemic involvement
Lab investigations for MAS
FBC - raised WCC
CRP
Blood cultures - bactaraemia suggestive of sepsis and pneumonia
What imaging should be done with MAS?
CXR - local guidelines
Why would you wait 4 hours to do a CXR in sus MAS? When would you not?
TTN will resolve after this time, eliminating the need for X ray
Acutely unwell or mechanically ventialted CNAT DELAY
CXR findings in MAS
Hyperinflated lungs from distal air trapping, patchy pulmonary changes and may show pneumothorax or pneumomediastinum due to raised alveolar tension
Intrapartum measures prevent MAS
Foetal hypoxia
Prevent postdates gestation
Vigorous vs non vigorous infant management
Vigorous infant - no oropharyngeal suctioning despite meconium-stained liquor (doesnt reduce risk)
Non-vigorous infant - May need oropharyngeal suctioning if meconium obstructing AW - rapidly initiate intervention
No routine endotracheal suction
What APGAR score infants do not require additional monitoring (except for sepsis)
> 9
What should be done with infants with respiratory distress after birth?
4-6 hours in neonatal unit to ensure successful transition
Management for MAS
Supportive - avoid morbidity and mortality ass with MAS
Oxygen therapy needed
Assisted ventialtion if required
Why is CPAP used with caution in MAS?
May exacerbate air trapping
What does surfactnat use reduce the need for in MAS?
Extracorpereal mebrane oxygenation in ventilated infants
Short term complications form MAS
Ongoing O2 requirements
Seizures
Necrotising enterocolitis
Increased reactive airwyas disease
Good long term prognosis
