Talk to Pediatric Cardiologist on Persistent Pulmonary Hypertension Of The Newborn

Patient: 22-day-old female, history of birth asphyxia, MAS, HIE (controlled seizures), and resolved late-onset sepsis. Currently home on 0.5L $O_2$.Current Status: SpO2 95–99% on $O_2$; drops to 80–85% for 45 mins off. HR 125–150. Hb 8.8 (untreated). Feeding well.Echocardiograms (Day 7 & 21): Persistent severe PPHN (TR 52–53 mmHg) despite 2 weeks of oral Sildenafil (0.35ml BD). Moderate secundum ASD (L→R), small PDA. Good biventricular function preserved.Proposed Plan vs. Second Opinion Queries:Switching vs. Combination: Stop Sildenafil and start Bosentan. Query: Should Bosentan be added to Sildenafil instead of replacing it?Diuretics: Add Lasix. Query: Is Lasix indicated given good BV function and no clinical fluid overload?Weaning & Hypoxia: Aggressive $O_2$ weaning (5/10/15-min cycles). Query: Are drops to 80–85% safe given the HIE history? Is aggressive weaning safe at TR 53?Pathology: Doctor claims low-flow $O_2$ causes PH. Query: Does low-flow $O_2$ cause PH?Referral: Should tertiary care for iNO be considered?Anemia: Should iron be initiated for Hb 8.8?