What regular investigations are needed for a baby with birth asphyxia?

Regular Investigations for Infants with Birth Asphyxia

Infants with birth asphyxia require systematic monitoring for multi-organ dysfunction, with continuous cardiorespiratory surveillance, serial laboratory assessments for hepatic, renal, hematologic, and coagulation abnormalities, and neurologic evaluation including therapeutic hypothermia candidacy within the first 6 hours of life.

Immediate Assessment (First Hour of Life)

• Umbilical arterial blood gas should be obtained from a clamped section of cord when Apgar score is ≤5 at 5 minutes to document pH and base deficit 1
• Apgar scores at 1,5,10,15, and 20 minutes document the infant's physiologic condition and guide resuscitation intensity 1
• Continuous cardiorespiratory monitoring including heart rate, respiratory rate, blood pressure (preferably intra-arterial via umbilical or peripheral line), and continuous pulse oximetry (preductal and postductal) 1
• Temperature monitoring to maintain normothermia and assess for therapeutic hypothermia candidacy 1

Multi-Organ Dysfunction Screening (First 6-24 Hours)

Birth asphyxia causes extra-cranial organ dysfunction in 86% of affected infants, even without moderate-to-severe hypoxic-ischemic encephalopathy 2. The neonatal Sequential Organ Failure Assessment (nSOFA) score at ≤6 hours of life predicts mortality with 100% sensitivity and 83.9% specificity when ≥3.5 3.

Respiratory System (Most Common: 77%)

• Continuous pulse oximetry with preductal and postductal measurements; difference should be <5% 1
• Arterial blood gases to monitor pH, PaCO₂, and oxygenation 1
• Target oxygen saturation 92-94% to prevent hypoxia without causing additional lung injury 1, 4
• Serial chest radiographs if mechanical ventilation required 1

Hepatic Function (20%)

• Liver function tests including AST, ALT, bilirubin, and albumin 2
• Monitor for hepatomegaly on physical examination 1

Coagulation System (18.5%, Higher in Severe Acidosis)

• Platelet count (component of nSOFA score) 3
• Coagulation studies including PT, PTT, fibrinogen—particularly critical when pH <7.00 (32% incidence vs 10% with pH 7.00-7.10) 2

Renal Function (9.2%)

• Urine output monitoring with goal >1 mL/kg/hour 1
• Serum creatinine and BUN 2
• Electrolytes including sodium, potassium, calcium (ionized calcium should be normalized) 1

Cardiovascular System (3%)

• Echocardiogram to assess for myocardial depression, pulmonary hypertension, and rule out ductal-dependent congenital heart disease 1
• Any infant with hepatomegaly, cyanosis, cardiac murmur, or differential upper/lower extremity blood pressures requires immediate echocardiography 1
• Serial echocardiograms at 4-6 month intervals if pulmonary hypertension develops 1, 4

Hematologic System (7.7%)

• Complete blood count with differential 2
• Monitor for anemia and polycythemia

Metabolic Monitoring

• Glucose monitoring continuously; maintain normal glucose with D10%-containing isotonic IV solution at maintenance rate 1
• Ionized calcium levels; hypocalcemia is common 1

Neurologic Assessment

Hypoxic-Ischemic Encephalopathy Evaluation

• Clinical neurologic examination for encephalopathy grading within first 6 hours 1
• Therapeutic hypothermia candidacy assessment must occur within 6 hours of birth for infants ≥36 weeks gestation with evolving moderate-to-severe HIE 1
• Cooling protocol: 33-34°C for 72 hours, then rewarming over ≥4 hours 1

Ongoing Neurologic Monitoring

• Continuous observation for seizure activity 1
• Neurodevelopmental follow-up at regular intervals through 24 months corrected age 5

Continuous Monitoring Requirements

Critical pitfall: Brief spot-checks of oxygenation are insufficient 1, 4. Infants require:

• Continuous pulse oximetry during all sleep periods and periodic checks when awake 4
• End-tidal CO₂ monitoring if available, though not routinely recommended for all infants 1
• Trained nursing observation to detect subtle changes in perfusion, tone, color, and respiratory effort 1

Special Considerations for Persistent Oxygen Requirement

If oxygen dependence persists beyond initial stabilization:

• Sleep study to identify obstructive, central, or mixed causes of hypoxemia 1, 4
• Flexible bronchoscopy to diagnose structural airway abnormalities (tracheomalacia, subglottic stenosis, vocal cord paralysis) 1, 4
• Upper GI series, pH/impedance probe, swallow study to evaluate for gastroesophageal reflux and aspiration 1, 4
• 72-hour Holter monitoring if cardiac arrhythmias suspected 1

Frequency of Reassessment

• First 6 hours: Hourly vital signs, continuous monitoring, initial laboratory panel, nSOFA calculation 3
• First 24-72 hours: Every 4-6 hour vital signs, daily laboratory monitoring of affected organ systems 2
• Beyond 72 hours: Frequency based on clinical course and organ dysfunction severity 2
• Long-term: Serial echocardiograms every 4-6 months if pulmonary hypertension present 1, 4

The severity of initial acidosis (pH <7.00 vs 7.00-7.10) predicts higher rates of coagulation dysfunction and should trigger more intensive hematologic monitoring 2.