Pediatrics

Background and Physiological Rationale

At birth, a newborn must accomplish, within seconds, what took nine months in utero: establish independent gas exchange, clear fetal lung fluid, and transition the entire circulatory system from a parallel, placenta-dependent circuit to a series, lung-dependent circuit. The overwhelming majority (~90%) of newborns achieve this transition without any assistance. Roughly 10% require some assistance to begin breathing, and less than 1% require extensive resuscitative measures (chest compressions and/or medications). The NRP algorithm exists to identify, in real time, which infants fall into which category and to apply an evidence-graded, stepwise escalation of intervention — because both under-treatment (allowing ongoing hypoxia-ischemia) and over-treatment (unnecessary intubation, hyperoxia, aggressive suctioning) carry measurable harm.

Antenatal Preparation and Team Briefing

Before every delivery, a standardized pre-birth risk assessment is performed, addressing four questions: gestational age, amniotic fluid clarity, additional risk factors, and the umbilical cord management plan. At least one person capable of performing complete resuscitation, including endotracheal intubation and umbilical vein catheterization, must be immediately available for every birth, with additional personnel added proportionate to anticipated risk. Equipment checks (radiant warmer pre-warmed, blender/oxygen source functional, PPV device and correctly sized masks available, suction functional, laryngoscope with working bulb, ET tubes of multiple sizes, umbilical catheterization tray, and epinephrine pre-drawn or readily available for high-risk deliveries) are mandatory.

The Initial Rapid Assessment

Immediately after birth, three questions are asked simultaneously: Is the infant term gestation? Does the infant have good tone? Is the infant breathing or crying? If the answer to all three is “yes,” the infant can generally remain with the mother for delayed cord clamping and routine care (drying, skin-to-skin, ongoing observation). If the answer to any is “no,” the infant is moved to the radiant warmer for further evaluation and stepwise support.

Umbilical Cord Management

Current guidance favors delayed cord clamping for at least 30–60 seconds in both term and preterm infants who do not require immediate resuscitation, given evidence of improved iron stores, reduced transfusion requirement, and reduced IVH risk in preterm infants. For infants requiring resuscitation who cannot have the cord clamping delayed safely, umbilical cord milking is generally NOT recommended, particularly in extremely preterm infants (<28–29 weeks), given signal from trials (the PREMOD2 trial and subsequent data) suggesting increased severe IVH risk with milking in this specific population — an important, frequently tested “recent change” point.

Initial Steps — “The Golden Minute”

Within the first 30–60 seconds of life, four actions are performed in rapid sequence:

1. Provide warmth. The infant is placed under a pre-warmed radiant warmer. For infants <32 weeks gestation, additional measures prevent hypothermia (an independent predictor of mortality and IVH): the infant (without drying the body, though the head is dried and capped) is placed in a food-grade polyethylene wrap/bag up to the neck, an exothermic (chemical) thermal mattress is placed beneath, and delivery room temperature is increased to at least 23–25°C. Target admission temperature is 36.5–37.5°C — both hypothermia and iatrogenic hyperthermia are associated with worse outcomes.
2. Position the airway. The infant is placed supine or on their side with the neck in a neutral or slightly extended “sniffing” position, avoiding hyperextension or flexion, both of which can cause airway obstruction.
3. Clear secretions if needed. Routine oro/nasopharyngeal suctioning is no longer performed routinely, even for meconium-stained fluid, given lack of demonstrated benefit and potential for vagally-mediated bradycardia. Suction is reserved for infants with visible obstruction or those requiring PPV who are not responding adequately.
4. Dry and stimulate. Drying (for infants ≥32 weeks) provides both thermal benefit and tactile stimulation; further gentle stimulation (rubbing the back, flicking the soles) may be provided if the infant is not vigorously breathing.

Assessment of Heart Rate and Breathing

Following the initial steps, heart rate and respiratory effort are reassessed simultaneously. Heart rate assessment via 3-lead ECG is now preferred over auscultation or pulse oximetry during active resuscitation, given evidence that ECG provides a faster, more accurate reading than palpation/auscultation (which can under- or over-estimate heart rate, particularly in the critical first minute) — this is a key updated-guideline point that examiners specifically probe. Pulse oximetry (placed on the right hand/wrist for pre-ductal saturation) is applied simultaneously to guide oxygen titration.

If the heart rate is ≥100/min and the infant is breathing well, routine post-birth care continues. If the heart rate is <100/min, or the infant is apneic or gasping, Positive Pressure Ventilation is initiated immediately — this is the single most important intervention in neonatal resuscitation.

Positive Pressure Ventilation

• Rate: 40–60 breaths per minute
• Initial inspiratory pressure: approximately 20–25 cmH₂O for the first few breaths (up to 30–40 cmH₂O may be needed for the very first breaths); PEEP of 5 cmH₂O with T-piece resuscitators
• Initial FiO₂: room air (21%) for term/late preterm infants; 21–30% for preterm infants <35 weeks, titrated using the target pre-ductal SpO₂ table (~60–65% at 1 minute, ~80–85% at 5 minutes, ~85–95% at 10 minutes)

Assessment of ventilation effectiveness is by rising heart rate as the primary indicator (chest rise is supportive but heart rate response is the definitive marker of adequate ventilation). If heart rate does not rise within 15 seconds, the MR SOPA corrective sequence is applied:

1. Mask adjustment (ensure a good seal)
2. Reposition the airway
3. Suction mouth and nose
4. Open the mouth (jaw thrust, consider an oral airway)
5. Pressure increase (in increments)
6. Alternative airway (laryngeal mask airway or endotracheal intubation)

Escalation to Chest Compressions

If, despite 30 seconds of effective PPV (ideally via ET tube or laryngeal mask), the heart rate remains <60/min, chest compressions are begun.

• Technique: two-thumb encircling hands technique, preferred over the two-finger technique
• Location: lower third of the sternum, depth approximately one-third of the anteroposterior chest diameter
• Ratio: 3:1 (compressions:ventilation) — 90 compressions and 30 breaths per minute (“1-2-3-breathe” cycle)
• FiO₂ increased to 100% once compressions begin
• Heart rate reassessed via ECG approximately every 60 seconds, without interrupting compressions/ventilation for longer than necessary

Epinephrine

If the heart rate remains <60/min despite 60 seconds of coordinated chest compressions and ventilation with 100% oxygen via a secured airway, epinephrine is administered.

• Preferred route: IV, via an emergently placed umbilical venous catheter — dose 0.01–0.03 mg/kg (0.1–0.3 mL/kg of 1:10,000 [0.1 mg/mL])
• Endotracheal route only as a temporizing measure while IV access is obtained, at a higher dose (0.05–0.1 mg/kg)
• Repeated every 3–5 minutes if heart rate remains <60/min, with reassessment of ventilation and compression quality between doses

Volume expansion (normal saline or O-negative packed cells, 10 mL/kg over 5–10 minutes) is considered if there is history suggestive of blood loss or signs of hypovolemic shock.

Post-Resuscitation Care

• Continuous monitoring: heart rate, SpO₂, blood pressure, temperature, blood glucose
• Avoid hyperoxia and hypocapnia/hypercapnia extremes
• Screen for HIE and therapeutic hypothermia eligibility (see Q2); ideally cooling initiated within 6 hours of birth
• Debriefing of the resuscitation team, and thorough documentation of the timeline

Special Situations

• Extreme prematurity (<25 weeks): decisions ideally discussed antenatally with the family
• Congenital anomalies incompatible with life or with a pre-established comfort care plan: resuscitation not initiated
• Meconium-stained fluid with a non-vigorous infant: intubation and tracheal suctioning may be considered if airway obstruction is evident, but must not delay PPV

Definition and Epidemiology

HIE refers to brain injury resulting from a hypoxic-ischemic insult occurring in the peripartum period, sufficient to produce a clinically recognizable neonatal encephalopathy. It remains a leading cause of neonatal mortality and long-term neurodevelopmental disability (cerebral palsy, epilepsy, cognitive impairment) worldwide, with a disproportionate burden in low- and middle-income countries.

Pathophysiology — The Two-Phase Injury Model

Phase 1 — Primary Energy Failure (during the insult): interruption of cerebral oxygen/glucose delivery rapidly depletes ATP and phosphocreatine. Failure of the Na⁺/K⁺-ATPase pump causes cytotoxic edema, membrane depolarization, and massive glutamate release. Glutamate excess causes excessive calcium influx via NMDA receptors, activating destructive proteases, lipases, endonucleases, and generating reactive oxygen species.

Latent Phase (~1–6 hours post-insult): with restoration of oxygen/perfusion, cerebral oxidative metabolism partially recovers — a deceptive period of relative stability. This latent phase is the therapeutic window during which cooling can meaningfully alter outcome — the rationale for initiating therapeutic hypothermia within 6 hours of birth.

Phase 2 — Secondary Energy Failure (typically 6–48 hours after the insult): a delayed decline in cerebral energy status driven by mitochondrial dysfunction, ongoing excitotoxicity, oxidative/nitrosative stress, and neuroinflammation (activated microglia, IL-1, IL-6, TNF-alpha). Magnitude/duration of secondary energy failure correlates directly with eventual neurodevelopmental impairment — the principal target of neuroprotective therapy. A tertiary phase (weeks to months later) is increasingly recognized as the focus of adjunctive research.

Clinical Staging — Sarnat and Sarnat

Cooling Eligibility Criteria (must satisfy ALL categories)

• A. Gestational age: ≥36 completed weeks
• B. Biochemical/clinical evidence of asphyxia (any ONE): cord/postnatal (within 1 hr) arterial pH ≤7.0 OR base deficit ≥16 mmol/L; OR pH 7.01–7.15 or base deficit 10–15.9 mmol/L PLUS an acute perinatal event AND either a 10-min Apgar ≤5 or continued need for ventilatory resuscitation at 10 minutes
• C. Moderate or severe encephalopathy — Sarnat Stage II or III (seizures alone do not independently qualify in most protocols)

Cooling Protocol — Exact Parameters

• Initiation window: within 6 hours of birth
• Target core (rectal/esophageal) temperature: 33.5°C (range 33–34°C)
• Duration: 72 hours
• Method: whole-body cooling (servo-controlled blanket/mattress), preferred over selective head cooling
• Rewarming: ~0.5°C per hour, over 6–12 hours to normothermia

Monitoring During Cooling

• Continuous aEEG or conventional video-EEG for seizure detection and background pattern assessment
• Cardiorespiratory monitoring: mild bradycardia (HR 80–100) and mild hypotension are expected and do not by themselves require rewarming
• Coagulation profile: cooling mildly impairs platelet function/coagulation
• Electrolytes, renal function, blood glucose, liver function
• MRI brain ideally after rewarming, day 4–14 of life — basal ganglia/thalamic pattern (severe insults, dyskinetic CP) vs watershed/parasagittal pattern (prolonged partial insults, cognitive impairment)

Adjunctive/Emerging Therapies

Erythropoietin, melatonin, xenon, and allopurinol have been trialed as adjuncts to hypothermia, but none has yet demonstrated clear additive benefit in large RCTs; therapeutic hypothermia remains the sole evidence-based standard of care.

Long-Term Neurodevelopmental Outcomes

Pooled data from major RCTs (TOBY, CoolCap, NICHD NRN, and others) show therapeutic hypothermia reduces death or moderate-severe disability at 18 months (NNT ~6–7), with benefit persisting into mid-childhood (6–8 years) follow-up. Outcome correlates strongly with Sarnat stage, aEEG background recovery time, and MRI injury pattern/severity.

Pathophysiology

Pulmonary surfactant — a phospholipid-protein complex (dipalmitoylphosphatidylcholine being the principal phospholipid, along with surfactant proteins A, B, C, and D) — is synthesized and secreted by type II pneumocytes, functionally adequate typically only after ~34–36 weeks gestation. Surfactant reduces alveolar surface tension in proportion to alveolar radius (LaPlace's law), preventing smaller alveoli from collapsing into larger ones. Its absence causes progressive atelectasis, reduced FRC, reduced compliance, and increased work of breathing, with resulting hypoxemia/hypercapnia causing pulmonary vasoconstriction and acidosis — a self-perpetuating cycle worsening over the first 24–72 hours.

Clinical Features

Onset within minutes to hours of birth in a preterm infant: tachypnea, expiratory grunting (auto-PEEP mechanism), nasal flaring, and intercostal/subcostal/sternal retractions. Cyanosis develops as hypoxemia worsens.

Radiological Features

Diffuse, fine reticulogranular (“ground-glass”) opacification, symmetric, with air bronchograms, and reduced lung volumes; severe untreated cases show complete “white-out.”

Antenatal Prevention

Antenatal corticosteroids (betamethasone or dexamethasone) given between ~24 and 34 weeks accelerate fetal lung maturation, significantly reducing RDS incidence/severity.

Surfactant Replacement Therapy

Types: Natural surfactants — beractant (bovine) and poractant alfa (porcine) — preferred over synthetic, protein-free surfactants. Poractant alfa at higher dosing may offer modestly superior outcomes vs beractant.

Indications/timing: Contemporary practice favors selective, early-rescue dosing (guided by FiO₂ requirement, commonly >0.3 despite adequate CPAP) rather than universal prophylactic dosing.

Administration Techniques

• INSURE (INtubate–SURfactant–Extubate): brief intubation for instillation, then prompt extubation back to CPAP/NIPPV, minimizing invasive ventilation duration
• LISA/MIST (Less Invasive Surfactant Administration/Minimally Invasive Surfactant Therapy): surfactant instilled via a thin flexible catheter through the vocal cords under laryngoscopic visualization into a spontaneously breathing infant on CPAP, without PPV/intubation. Evidence (OPTIMIST-A trial) suggests LISA reduces death/BPD compared to INSURE/traditional intubation

Non-Invasive Ventilation Strategies

The overarching philosophy is “CPAP first” from delivery room stabilization onward, reserving intubation for infants failing non-invasive support (COIN, SUPPORT trials). NIPPV is used as an escalation step before intubation; high-flow nasal cannula is used in select less-severe cases or during weaning.

Bilirubin Metabolism — Brief Physiological Basis

Senescent fetal/neonatal red cells are broken down in the reticuloendothelial system, releasing heme, converted via heme oxygenase to biliverdin then unconjugated bilirubin. This lipid-soluble bilirubin, bound to albumin, is transported to the liver where it is conjugated by UDP-glucuronosyltransferase (UGT1A1) — physiologically reduced in neonates, particularly preterm infants. Increased enterohepatic circulation (from higher intestinal beta-glucuronidase activity) further contributes to physiological hyperbilirubinemia, particularly with delayed feeding.

Approach to Term and Preterm Neonatal Jaundice

• Physiological jaundice: appears after 24 hours, peaks day 3–5 (term; day 5–7 preterm), resolves within ~2 weeks (term) or 3 weeks (preterm)
• Jaundice within the first 24 hours is, by definition, pathological — mandates urgent evaluation (leading concern: hemolytic disease)

Systematic evaluation includes history (onset, family history, maternal blood group, ethnicity, feeding/weight loss, birth trauma, gestational age), examination (cephalocaudal progression, hepatosplenomegaly, pallor, petechiae, sepsis signs), and investigations (total/direct serum bilirubin — direct fraction >20% of total or >1–1.5 mg/dL indicates cholestasis and mandates a separate workup for biliary atresia; maternal/infant blood group and direct Coombs test; peripheral smear; reticulocyte count; G6PD screening; sepsis workup if indicated).

AAP 2022 Updated Guidelines — Key Changes

• Revised hour-specific nomograms stratified by gestational age (35 to ≥38 weeks) and neurotoxicity risk factors
• Neurotoxicity risk factors explicitly incorporated: isoimmune/other hemolytic disease, G6PD deficiency, sepsis, significant clinical instability, albumin <3.0 g/dL, and (for exchange thresholds) signs of acute bilirubin encephalopathy
• Phototherapy thresholds modestly higher for well infants without risk factors, reflecting reassuring long-term safety data
• Greater emphasis on universal pre-discharge bilirubin screening combined with the hour-specific nomogram
• Escalation urgency: repeat measurement sooner if trajectory is rising rapidly or nearing the exchange threshold

Phototherapy mechanism: blue-green light (~460–490 nm) converts unconjugated bilirubin to water-soluble photoisomers (lumirubin and configurational isomers) excretable in bile/urine without hepatic conjugation.

Exchange transfusion: reserved for bilirubin approaching/exceeding the exchange threshold despite intensive phototherapy, or any clinical sign of acute bilirubin encephalopathy regardless of numerical value.

Pathophysiology of Kernicterus

Kernicterus results when unconjugated bilirubin, in excess of albumin binding capacity, crosses the blood-brain barrier and deposits in the brain. Risk is increased by factors raising the free bilirubin fraction (hypoalbuminemia, competitive displacement, acidosis) or increasing BBB permeability (sepsis, hyperosmolality, prematurity). Neurotoxicity mechanisms include mitochondrial dysfunction, membrane disruption, and interference with neurotransmission.

Classic sites of injury: basal ganglia (globus pallidus), subthalamic nucleus, hippocampal CA2/CA3, cranial nerve nuclei (especially cochlear/auditory), and cerebellum (dentate nucleus, Purkinje cells).

MRI Findings

• Acute phase (neonatal): bilateral, symmetric T1-weighted hyperintensity in the globus pallidus
• Chronic phase (from several months): T1 hyperintensity resolves, same regions show T2-weighted hyperintensity
• This T1-to-T2 evolution is considered a diagnostic imaging signature essentially unique to kernicterus

Chronic Bilirubin Encephalopathy — Clinical Tetrad

1. Choreoathetoid (extrapyramidal/dyskinetic) cerebral palsy
2. Sensorineural hearing loss/auditory neuropathy spectrum disorder
3. Oculomotor abnormalities — classically upward gaze palsy (“setting sun”)
4. Dental enamel dysplasia (green-staining of primary teeth)

Notably, cognitive function is often relatively preserved in classic kernicterus — a distinguishing exam point versus diffuse HIE.

Prevention

Universal pre-discharge risk assessment (bilirubin + hour-specific nomogram + clinical risk factors), adequate feeding support, timely follow-up scheduling, and parental education — kernicterus is considered a largely preventable adverse outcome.

Epidemiology and Significance

NEC remains one of the most significant causes of morbidity/mortality in preterm, very low birth weight infants, occurring in roughly 5–10% of infants born <1500g. Mortality remains substantial (10–30% overall, higher with surgical NEC), and survivors face short bowel syndrome, strictures, and impaired neurodevelopmental outcomes.

Pathogenesis — A Multifactorial Model

1. Intestinal immaturity: immature mucosal barrier, immature motility (stasis, bacterial overgrowth), and a dysregulated mucosal immune system with excessive TLR4 signaling in response to Gram-negative LPS
2. Abnormal microbial colonization (dysbiosis): altered, less diverse gut microbiome dominated by Proteobacteria vs the protective Bifidobacterium/Lactobacillus flora of breast milk feeding
3. Ischemia-reperfusion injury: from perinatal asphyxia, hypotension, PDA-associated diastolic steal, umbilical catheter vasospasm, or polycythemia
4. Enteral feeding as substrate: rapid feed advancement provides fermentable substrate; NEC is rare in entirely unfed infants

Bell's Staging Criteria — Detailed

Radiological Correlates — Mechanistic Explanation

• Pneumatosis intestinalis — gas within the bowel wall from gas-forming bacteria fermenting damaged, hypoperfused bowel; the hallmark sign confirming “definite” NEC
• Portal venous gas — gas tracked from diseased bowel into the portal venous system; signals more extensive disease and higher likelihood of surgery, but not an absolute indication
• Pneumoperitoneum (best seen on left lateral decubitus/cross-table lateral film) — indicates full-thickness perforation; the single clearest, universally agreed absolute indication for emergency surgery
• A “fixed, dilated loop” persisting unchanged on serial films suggests necrotic, non-viable bowel and warrants close surgical surveillance

Medical Management (Stage I through IIB)

• Complete bowel rest (NPO), typically 7–14 days, with NG decompression
• Broad-spectrum IV antibiotics (e.g., ampicillin, gentamicin, and metronidazole) for 7–14 days
• Parenteral nutrition during bowel rest
• Serial exams and abdominal radiographs (every 6–8 hours during the acute phase)
• Correction of coagulopathy/thrombocytopenia; hemodynamic/respiratory support
• Discontinuation/review of umbilical catheters

Surgical Management

Absolute indication: pneumoperitoneum.

Relative indications: worsening metabolic acidosis, persistent/worsening thrombocytopenia, refractory hemodynamic instability, abdominal wall erythema/fixed mass, persistently dilated fixed bowel loop.

• Exploratory laparotomy with resection of necrotic bowel — primary anastomosis or enterostomy with mucous fistula
• Primary peritoneal drainage — bedside drain placement under local anesthesia, used as definitive or bridging measure in extremely unstable ELBW infants

Long-Term Considerations

Short bowel syndrome, post-NEC strictures (requiring contrast surveillance), and long-term neurodevelopmental follow-up given NEC's independent association with worse outcomes.

Prevention Strategies

Human milk feeding is the single most consistently evidence-supported preventive strategy. Standardized feeding protocols, probiotic supplementation, and judicious antibiotic stewardship are additional recognized preventive measures.

Early-Onset Sepsis (EOS, within 72 hours of life)

Predominantly acquired via vertical transmission (transplacental or ascending/birth canal). Group B Streptococcus (GBS) and E. coli are the leading causes globally, with E. coli particularly prominent among VLBW infants. Listeria monocytogenes is a classically tested but less common cause (unpasteurized dairy/deli meat in pregnancy). Risk factors: maternal GBS colonization without adequate IAP, PROM >18 hours, maternal intrapartum fever/chorioamnionitis, prematurity, low birth weight.

Late-Onset Sepsis (LOS, beyond 72 hours of life)

Predominantly nosocomial — coagulase-negative staphylococci (CoNS) are the most common overall cause (biofilm formation on catheters); Staphylococcus aureus (including MRSA); Gram-negative organisms (Klebsiella, E. coli, Enterobacter, Pseudomonas), often more fulminant; and Candida species, particularly in ELBW infants with prolonged central line duration, broad-spectrum antibiotics, and TPN use.

Diagnostic Biomarkers — Utility and Limitations

Combining multiple biomarkers and trending them serially substantially improves diagnostic accuracy compared to any single time-point value.

Empirical Antibiotic Protocols

• EOS: Ampicillin plus Gentamicin — covers GBS, Listeria, and most common Gram-negatives; standard first-line pending cultures
• LOS: guided by the local NICU antibiogram — commonly Vancomycin (CoNS/MRSA) plus an aminoglycoside or 3rd/4th-generation cephalosporin; anti-pseudomonal and/or empirical antifungal coverage considered in critically ill infants

Antimicrobial Stewardship and Infection Prevention

• Timely de-escalation/discontinuation at 36–48 hours if cultures negative, low clinical suspicion, reassuring biomarker trends
• Central line care bundles to reduce CLABSI
• Hand hygiene compliance, minimizing line duration, promoting breast milk feeding
• Formal antimicrobial stewardship programs with audit/feedback and biomarker-guided discontinuation

Definition and Epidemiology

PPHN is characterized by failure of the normal postnatal fall in pulmonary vascular resistance (PVR), resulting in persistent right-to-left shunting across fetal channels (ductus arteriosus and/or foramen ovale) and severe, often labile hypoxemia disproportionate to underlying lung disease severity. Occurs in ~1–2 per 1000 live births, predominantly term/near-term infants; mortality historically 10–20%, improved with iNO and ECMO.

Pathophysiology and Classification

1. Maladaptation — structurally normal vasculature failing to undergo normal functional vasodilatory transition, secondary to an acute perinatal insult (asphyxia, MAS, sepsis/pneumonia)
2. Maldevelopment (abnormal remodeling) — structural remodeling in utero with increased smooth muscle extension into peripheral arterioles; seen in chronic intrauterine hypoxic stress and idiopathic (“black lung”) PPHN
3. Underdevelopment (hypoplasia) — reduced total number of pulmonary vascular/alveolar units; classic in congenital diaphragmatic hernia and severe oligohydramnios/Potter sequence

Clinical Presentation

Severe, labile hypoxemia with a striking pre-to-post-ductal SpO₂ gradient (>5–10% strongly suggests right-to-left ductal shunting), loud single S2, and possible tricuspid regurgitation murmur. Hypoxemia is frequently disproportionate to CXR appearance, particularly in idiopathic PPHN.

Clinical Management

Oxygenation goals: target pre-ductal SpO₂ 90–97% while avoiding hyperoxia, which adds oxidative stress without proportionate PVR reduction.

Echocardiographic evaluation confirms shunting, estimates pulmonary artery pressure (from TR jet velocity via modified Bernoulli), assesses RV size/function/septal configuration, and critically excludes structural congenital heart disease (especially ductal-dependent lesions).

Therapeutic Ladder

1. Optimize ventilation and correct acidosis — appropriate lung recruitment avoiding under- and over-distension; HFOV often used with coexisting parenchymal disease (e.g. MAS); cautious pH correction (aggressive alkalinization no longer favored)
2. Inhaled Nitric Oxide (iNO) — a selective pulmonary vasodilator, diffusing locally into ventilated alveolar units, activating guanylate cyclase and raising cGMP, without significant systemic vasodilation (rapidly inactivated by hemoglobin). First-line specific pharmacotherapy; reduces need for ECMO
3. Sildenafil — PDE-5 inhibitor preventing cGMP breakdown; used as adjunct/bridging/weaning agent or alternative where iNO is unavailable
4. Other adjuncts — Milrinone (PDE-3 inhibitor, inotropic + vasodilator, useful with concurrent LV dysfunction); careful systemic hemodynamic support (volume, vasopressor-inotropes) to maintain the favorable systemic-over-pulmonary pressure gradient

ECMO Criteria

Reserved for severe, refractory hypoxemic respiratory failure not responding to maximal conventional therapy including iNO — classically guided by a sustained Oxygenation Index (OI = [FiO₂ × Mean Airway Pressure × 100] / PaO₂) >40, though institutional thresholds vary; other criteria include failure to respond to iNO, persistent severe acidosis, or hemodynamic instability.

Retinopathy of Prematurity (ROP)

Pathogenesis: retinal vascularization proceeds from the optic disc toward the periphery, completing near term. Preterm birth interrupts this; the relatively hyperoxic extrauterine environment suppresses further vascular growth (Phase 1), followed by a relatively hypoxic under-vascularized retina driving VEGF-mediated abnormal neovascularization (Phase 2) — fragile, hemorrhage-prone, and capable of progressing to fibrous scarring and tractional retinal detachment.

Screening criteria: infants born ≤30 weeks and/or birth weight ≤1500g should be screened; extended criteria for select larger/more mature infants with an unstable course. First examination typically at 4 weeks chronological age or 30–31 weeks postmenstrual age, whichever is later.

International Classification of ROP

• Zone (I, II, III) — location of the vascularized/avascular border relative to the disc; Zone I most posterior and highest risk
• Stage (1–5) — Stage 1 (flat demarcation line), Stage 2 (raised ridge), Stage 3 (extraretinal fibrovascular proliferation), Stage 4 (partial retinal detachment), Stage 5 (total retinal detachment)
• “Plus disease” — dilation/tortuosity of posterior retinal vessels, indicating significant disease activity

Treatment: Laser photocoagulation remains standard of care for Type 1 ROP (per ETROP criteria). Anti-VEGF intravitreal bevacizumab is increasingly used, particularly favored for Zone I disease (BEAT-ROP trial), though requiring more prolonged follow-up given late reactivation risk.

Intraventricular Hemorrhage (IVH)

Pathogenesis: originates from the germinal matrix, a highly cellular, immaturely vascularized subependymal structure (prominent at the head of the caudate nucleus), most prominent before ~32 weeks and involuting thereafter. Its fragile, thin-walled vessels are vulnerable to rupture with impaired cerebral autoregulation. Precipitants include hypotension/hypertension, rapid volume administration, mechanical ventilation, and rapid correction of hypercapnia.

Papile Staging

Prevention Strategies

• Antenatal corticosteroids — robustly evidence-supported, reduces IVH incidence/severity
• Delayed cord clamping — improves hemodynamic stability, associated with reduced IVH risk
• Antenatal maternal transfer to a tertiary NICU-equipped center rather than postnatal transfer
• Minimal handling protocols, avoidance of rapid volume boluses/rapid blood gas correction
• Careful, stable ventilation avoiding wide PaCO₂ swings
• Routine cranial ultrasound screening (infants <32 weeks/<1500g), enabling detection of progression to post-hemorrhagic ventricular dilation