Severe MAS & APHN: The Advanced Management Protocol

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Severe MAS & APHN:

The Advanced Management Protocol

Evidence-based pathways for Meconium Aspiration Syndrome and Acute Pulmonary Hypertension of the Newborn.

The Pathophysiological Cascade

Airway Obstruction & Surfactant Inactivation — (Mechanical blockage and chemical pneumonitis)
Hypoxia & Acidosis — (Failure of normal postnatal pulmonary transition)
Failure of PVR Drop — (Pulmonary Vascular Resistance remains at fetal levels)
Right-to-Left Shunting — (Blood bypasses lungs via PFO/PDA; aPHN established)
Systemic Hypoperfusion — (Right Ventricular failure starves the Left Ventricle)

Delivery Room Protocol Updates

Obsolete Practices	Current Standard
~~NO routine suctioning on the perineum.~~	Intubate ONLY for suspected tracheal obstruction.
~~NO routine immediate laryngoscopy for non-vigorous infants.~~	Prioritize early CPAP (5 cm H2O) via face mask.

The Diagnostic Anchors for aPHN

Pre/Post-Ductal Gradient: >10% SpO2 difference between right hand (pre-ductal) and feet (post-ductal) confirms right-to-left shunting.

Clinical Presentation: Hypoxia disproportionate to hypercapnia; Tricuspid regurgitant murmur; Systemic hypotension.

Mimics Cyanotic Heart Disease. Always start Prostin if a duct-dependent cardiac lesion cannot be clinically excluded.

Pre-ductal (right hand)
>10% SpO2 difference
Post-ductal

The Critical Role of TnECHO

Exclude — Rule out Cyanotic Congenital Heart Disease (CHD) and structural anomalies.
Measure — Assess Pulmonary Artery Pressure utilizing Tricuspid Regurgitation (TR) jet velocity.
Evaluate — Assess Right and Left Ventricular dysfunction and determine the direction of shunting across the PFO and PDA.

Foundation of Care: The Systemic Milieu

Optimize the baseline physiological state before escalating vasoactive drugs.

Ionized Calcium: > 1.0 mmol/L (Essential for myocardial contractility).
Magnesium: >= 1.0 mmol/L (Natural pulmonary vasodilator).
Hemoglobin: >= 120 g/L (Optimize oxygen carrying capacity).
Environment: Minimal handling, rigid normothermia, and optimal sedation to minimize PVR spikes.

Respiratory Strategy: Gentle Ventilation

SpO2 (Pre-ductal): 91–95% — Do not attempt to close the pre/post-ductal gap if post-ductal SpO2 remains >70%. Avoid hyperoxia.
PaO2: 7.3–10.6 kPa — Tolerable hypoxaemia to prevent oxidative stress.
PaCO2: 6–8 kPa — Avoid hypocapnia—hyperventilation lungs and impairs cerebral perfusion.

Note: Consider surfactant therapy for underlying parenchymal disease (MAS, Pneumonia).

App screenshot (Neofast Medicines): Alfaporactant (Curosurf®) – surfactant; search field “surfa”; options: Alfaporactant (Curosurf®) – surfactant, Beractanto (Survanta®) – surfactant, Calfactant (Infasurf®) – surfactant, Lucinactant (Surfaxin®) – surfactant.

Route: TOT
Formulation: 80mg/mL Suspension
Weight (kg): 3
Desired dose (mL/kg/dose): 2.5
Initial dose: 2.5 mL/kg/dose
Dose: 7.5mL
Interval: AMD

Disclaimer: Please note: the information presented in this application is taken from bibliographical references and is for information purposes only. The doctor is solely responsible for prescribing, administering and making the necessary adjustments. This app does not replace medical guidelines or clinical judgment.

Tracking the Oxygenation Index (OI)

Airway/Blue — Vascular/Red spectrum

OI Formula: OI = [MAP (cm H2O) x FiO2 x 100] / [Post-ductal PaO2 (kPa) x 7.5]

OI > 20 — Trigger for inhaled Nitric Oxide (iNO) and transition to HFOV.
OI > 40 — Trigger for Time-Critical ECLS/ECMO referral.

Alternative: If arterial lines are unavailable, utilize the Oxygen Saturation Index (OSI = MAP x FiO2 x SpO2 / 100).

Device shown: INOmax DSIR nitric oxide delivery system with INOblender, displaying Q2 50, NO2 0.4, NO 20 settings.

Escalation to HFOV

Optimal Lung Volume Strategy

Initiation: Set MAP 2-4 cm H2O above the conventional MAP.
Frequency: Set strictly to 10 Hz.
Target: Titrate MAP in 1-2 cm increments to achieve 8 ribs of expansion on CXR.

Troubleshooting Low PaO2

Increase MAP (Assess for sub-optimal recruitment vs. over-inflation).
Check ETT patency and ensure in-line suction is utilized to maintain PEEP.

Targeted Pulmonary Vasodilation: iNO Protocol

Initiate iNO at 20 ppm
Assess at 60 minutes

Full Response:

SpO2 increases >20%
PaO2 increases >3 kPa
FiO2 decreases >0.2

Action: Wean slowly per standard guidelines.

Partial / No Response:

Action: Optimize lung recruitment (HFOV), re-evaluate hemodynamics, consider alternative vasodilators (Magnesium, Milrinone).

The RV/LV Interdependence Challenge

High PVR (Right Ventricle) — High PVR (Left Ventricle pathway)

aPHN is a systemic hemodynamic crisis. Elevated Pulmonary Vascular Resistance (PVR) creates a severe afterload on the Right Ventricle.

The failing Right Ventricle is unable to pump blood through the lungs, resulting in severe Left Ventricular preload starvation and profound systemic hypotension.

Echo-Guided Inotrope Selection Matrix

Blood Pressure	RV Dysfunction	Biventricular Dysfunction
Normal BP	Milrinone (0.25 mcg/kg/min) If PDA is closing/restrictive, add Prostin to offload the RV.	Milrinone (0.25 mcg/kg/min)
Low BP	Noradrenaline (0.05-0.4 mcg/kg/min) +/- Vasopressin. Wide Pulse Pressure profile.	Dobutamine (5-10 mcg/kg/min) + Adrenaline (0.05-0.2 mcg/kg/min) Narrow Pulse Pressure profile.

Refractory Modifier: Add Hydrocortisone (2.5 mg/kg 6-hrly) if unresponsive to first-line inotropes.

NeoFast App Screenshot 1: Continuous medication – Milrinona, IV continuous, concentrations 1mg/mL or 0.2mg/mL, options for Loading or Maintenance, fields for Weight (kg) and Desired dose (mcg/kg).
NeoFast App Screenshot 2: Continuous medication – Norepinephrine, IV continuous, concentration 1mg/mL, fields for Weight (kg), Desired dose (mcg/kg/min), Intended drip (mL/h).
NeoFast App Screenshot 3: Continuous medication – Dobutamine, IV – central access or IV – peripheral access, concentration 12.5mg/mL, fields for Weight (kg), Desired dose (mcg/kg/min), Intended drip (mL/h).

Refractory aPHN: ECLS (ECMO) Criteria

$A clinical algorithm outlining baseline criteria and absolute triggers for ECLS/ECMO in refractory acute pulmonary hypertension of the newborn, along with a three-track management algorithm (Milieu, Respiratory, Hemodynamic) leading to an escalation point for ECMO transfer.$

Refractory aPHN: ECLS (ECMO) Criteria

Recognize failure early. Do not delay consultation with an ECLS center when conventional therapies plateau.

Baseline Criteria

Gestation >= 34 weeks OR Weight >= 2 kg.
Reversible underlying lung disease.

Absolute Triggers

Oxygenation Index (OI) > 40 on conventional ventilation.
Oxygenation Index (OI) > 40 on HFOV.
Persistent hypotension despite escalating inotropic support.

The aPHN Algorithm

Milieu Track	Respiratory Track	Hemodynamic Track
Target SpO2 91-95%, Normalize Temp, Ca > 1.0, Mg >= 1.0.	Gentle Ventilation (PaCO2 6-8) → OI > 20 → Start iNO 20 ppm & escalate to HFOV.	Echo Assessment → Normal BP → Milrinone → Low BP → Dobutamine + Noradrenaline/Adrenaline → Hydrocortisone for refractory shock.

Escalation Point: OI > 40 OR Refractory Shock -> ECLS/ECMO Transfer

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