12-phase flow (12)

1. 1FRAME
   Frame by gestational age (iNO is for ≥ 34 wk PMA), postnatal age, and underlying driver (MAS, pneumonia, asphyxia, CDH, RDS, idiopathic). Pre-/post-ductal SpO₂ gradient + echo are the diagnostic anchor.
   inputs: gestational_age_weeks, birthweight_grams, postnatal_age_hours
   advance: GA + driver classified; iNO eligibility determined
2. 2ENTRY
   Identify trigger: pre-/post-ductal SpO₂ gradient > 10%, severe hypoxemia with clear CXR (pure PPHN), echo R→L shunt at PDA/PFO, OI ≥ 25.
   inputs: pre_ductal_spo2, post_ductal_spo2
   advance: PPHN suspected and entry trigger documented
3. 3CONTEXT
   Driver identification: meconium aspiration (meconium-stained fluid + asymmetric CXR), pneumonia (focal infiltrate + sepsis markers), asphyxia (HIE history), CDH (scaphoid abdomen + bowel-in-chest), late-preterm RDS (ground-glass CXR), idiopathic (none of the above).
   inputs: cxr_neonate
   advance: Driver phenotype documented
4. 4RED_FLAGS
   OI ≥ 40 on max therapy with reversible cause → ECMO consideration. Refractory shock despite vasoactive → ECMO + cardiac consult. Critical CHD (ductal-dependent — coarctation, HLHS) → DO NOT close PDA with hyperoxia → PGE1 + cardiology STAT. Hypotension worsens R→L shunt → vasoactive + IV fluids.
   inputs: sbp_neonate, oxygenation_index_calculated
   advance: Red flags addressed; ECMO referral discussed if OI ≥ 40
5. 5INITIAL_WORKUP
   Echo within first hours (rule out CHD!); ABG pre-/post-ductal; CXR; CBC + blood culture + glucose + lactate; intubation if SpO₂ < 90% on FiO₂ 1.0 with face mask; surfactant if RDS / MAS parenchymal driver; iNO at 20 ppm if OI ≥ 25 (Cochrane 2017 PMID 28056166).
   inputs: abg_pre_and_post_ductal, cbc_with_diff_neonate, blood_culture, lactate_neonate, cxr_neonate, echo_for_pphn_diagnosis_and_function
   actions: panel.cbc, panel.abg
   advance: Echo done (CHD excluded); iNO started if eligible; surfactant given if parenchymal driver
6. 6BRANCHING_WORKUP
   CDH — surgical consult + delayed repair after stabilization (iNO less effective in CDH per Cochrane 2017). Sepsis-driven PPHN — empiric antibiotics (route to neonatal.early-onset-sepsis.v1). Polycythemia (Hct > 65, hyperviscosity) — partial exchange transfusion. Meconium aspiration — surfactant + supportive. RDS-PPHN overlap — both surfactant + iNO.
   advance: Driver-directed branches resolved
7. 7DIFFERENTIAL
   PPHN vs cyanotic CHD (echo distinguishes; hyperoxia test traditional but echo definitive). PPHN vs RDS (parenchymal vs vascular — RDS has ground-glass CXR; pure PPHN has clear lungs). PPHN vs sepsis with shock (cultures + maternal risk; can co-occur). PPHN vs CDH (scaphoid abdomen + bowel-in-chest). PPHN secondary to congenital pulmonary anomalies (lobar emphysema, CCAM, sequestration — imaging).
   advance: Mimics excluded; PPHN phenotype confirmed
8. 8RISK_STRATIFICATION
   OI < 15 mild (supportive + oxygen). OI 15-25 moderate (intubation + surfactant if parenchymal). OI 25-40 severe (iNO indicated). OI ≥ 40 on max therapy critical (ECMO consideration if reversible cause + weight > 2 kg + GA > 34 wk). Calculator id `calc.oxygenation_index` not yet registered — rendered narratively.
   inputs: oxygenation_index_calculated
   advance: Severity tier set; ECMO referral threshold discussed
9. 9TREATMENT
   iNO 20 ppm titrated to response (composite non_pharm — medical gas; not a single RxCUI for inhalation route). Sildenafil 0.5-1 mg/kg PO q6h as adjunct or weaning aid (Steinhorn J Pediatr 2009 PMID 19836028). Milrinone 0.25-0.75 mcg/kg/min IV for LV dysfunction + PH. Dobutamine 5-20 mcg/kg/min IV for cardiac-output support. Surfactant if parenchymal driver (poractant alfa 200 mg/kg or beractant 100 mg/kg — same RxCUIs as RDS engine). HFOV for severe parenchymal disease. ECMO if OI ≥ 40 on max therapy + reversible cause. Avoid alkalosis-induction (older practice; superseded — narrative note).
   inputs: birthweight_grams, gestational_age_weeks
   advance: iNO + adjuncts + supportive care in place; ECMO referral if threshold met
10. 10DISPOSITION
    NICU (icu) primary. ECMO center if OI ≥ 40 on max therapy + GA ≥ 34 wk + BW ≥ 2 kg + reversible cause + no major CNS injury. Step-down when off iNO + SpO₂ stable on minimal support.
    inputs: oxygenation_index_calculated
    advance: Level of care assigned; ECMO referral if needed
11. 11MONITORING
    Continuous pre-/post-ductal SpO₂ + ECG + invasive BP + ETCO₂ if intubated. Serial ABG. OI calculated q4h initially. Echo daily during iNO. Serial CBC + platelets (iNO can cause methemoglobinemia; check MetHb level if cyanosis disproportionate to SpO₂). Cardiac output / lactate trend. Sildenafil response over 12-24 h.
    inputs: pre_ductal_spo2, post_ductal_spo2, abg_pre_and_post_ductal
    actions: panel.abg
    advance: iNO weaning successful; off vasoactive; stable on minimal support
12. 12FOLLOWUP
    High-risk follow-up clinic at 3-6-12-24 mo (Bayley III, neurodev). Hearing screen (AABR) before discharge + audiology surveillance (PPHN + iNO + ECMO survivors at risk for sensorineural hearing loss). Echo at 1-3-6 mo if persistent PH suspected (route to BPD-PH evaluation per Berkelhamer Steinhorn 2018 PMID 30384985). Pulmonology follow-up if BPD or chronic lung disease. RSV prophylaxis (nirsevimab) per AAP / ACIP.
    advance: Outpatient follow-up scheduled; hearing + echo surveillance plan documented