Meconium aspiration syndrome — structured oral (viva)

Branch 1 — Immediate resuscitation (5 minutes)

Examiner: The infant is floppy, apnoeic, heart rate 70. The midwife asks whether you want to intubate and suction. Talk me through your immediate management. [1]

Expected:

• Confirm non-vigorous state (poor tone, apnoea, heart rate below 100).
• State clearly: the presence of meconium does not mandate tracheal suctioning; resuscitate per standard NRP — initiate positive-pressure ventilation [1].
• Routine intubation-suction abandoned (2015 NRP); intubation only if ventilation ineffective due to suspected obstruction.
• Intrapartum oronasal suctioning before shoulders abandoned (Vain 2004).
• Assess response at 30 to 60 seconds; escalate to intubation/ventilation and chest compressions per NRP if heart rate remains below 60.

Branch point (if candidate suggests intubating to suction): Probe — what evidence changed this practice? Expect Vain et al. 2004 and the 2015 NRP update [1].

Branch 2 — Establishing the diagnosis (5 minutes)

Examiner: He is now intubated and ventilated, FiO2 0.5, with coarse crackles and a hyperinflated chest. What is your working diagnosis, and how do you confirm it? [7]

Expected:

• Working diagnosis: MAS — triad of MSAF, early respiratory distress, characteristic CXR.
• Send chest radiograph: expect coarse infiltrates, hyperinflation +/- air leak; excludes congenital diaphragmatic hernia.
• Pre-/post-ductal oximetry; arterial blood gas; septic work-up with blood culture and CRP; empiric antibiotics (sepsis indistinguishable) [7].

Branch point: If candidate omits pre-/post-ductal probes — prompt for PPHN screening [6].

Branch 3 — Recognising PPHN and escalating (5 minutes)

Examiner: At 3 hours his FiO2 climbs to 0.9; pre-ductal SpO2 88 per cent, post-ductal 65 per cent. How do you interpret this and what next? [6]

Expected:

• Wide gradient plus disproportionate hypoxaemia points to PPHN.
• Urgent echocardiogram to confirm elevated pulmonary pressures with right-to-left shunt and exclude CHD.
• Calculate oxygenation index; commence inhaled nitric oxide 20 ppm if OI above 15 to 25 [6].
• Correct acidosis (pH above 7.25), normocarbia or permissive hypercapnia — avoid hyperventilation.
• Refer to tertiary NICU with iNO/ECMO capability.

Branch 4 — Refractory disease (5 minutes)

Examiner: Despite iNO at 20 ppm, OI is now 42 and rising. What is your plan? [6]

Expected:

• OI above 40 refractory to iNO triggers ECMO referral to an accredited centre [6].
• Consider surfactant if not already given (meconium inactivates surfactant; Cochrane-supported) [2].
• Maintain oxygenation and acid-base optimisation during transfer.
• Counsel family regarding severity, HIE coexistence (assess for therapeutic hypothermia window), and prognosis driven by brain injury.

Examiner notes — common pitfalls

• Intubating to suction a non-vigorous meconium infant (abandoned practice) [1].
• Missing PPHN by not placing pre-/post-ductal probes [6].
• Hyperventilating to drive down CO2 (impairs cerebral perfusion).
• Failing to cover sepsis empirically [7].