Respiratory Acidosis Risk in Infants Following BRUE
In an infant presenting after a brief resolved unexplained event (BRUE), you would NOT expect respiratory acidosis to be present, and routine blood gas measurement is specifically not recommended. 1
Evidence Against Routine Blood Gas Testing
The American Academy of Pediatrics provides a Grade B moderate recommendation that clinicians should NOT obtain measurement of venous or arterial blood gases in infants presenting with a lower-risk BRUE. 1
The rationale for this recommendation includes:
- Blood gas measurements have not been shown to add significant clinical information in otherwise well-appearing infants presenting with an ALTE (apparent life-threatening event, the former term for BRUE) 1
- The benefits of reducing unnecessary testing, pain, risk of thrombosis, and caregiver/infant anxiety outweigh the rare missed diagnostic opportunity for hypercapnia and acid-base imbalances 1
- May rarely miss instances of hypercapnia and acid-base imbalances, but this risk is outweighed by avoiding false-positive results and unnecessary interventions 1
When Respiratory Acidosis Would Be Expected
Respiratory acidosis in infants typically develops in distinctly different clinical scenarios than a resolved BRUE:
- Acute respiratory failure with ongoing respiratory distress, not a resolved event 2, 3
- Septic shock where patients progress from initial respiratory alkalosis to metabolic acidosis, and are at high risk to develop respiratory acidosis secondary to parenchymal lung disease and/or inadequate respiratory effort due to altered mental status 1
- Respiratory distress syndrome in premature infants with ongoing tachypnea (>60 breaths/minute), grunting, retractions, nasal flaring, and cyanosis 4, 5
- Alveolar hypoventilation from chest wall abnormalities, neuromuscular disorders, or central nervous system depression 2, 6
Clinical Monitoring Recommendations
Instead of blood gas measurement, the AAP recommends:
- Brief monitoring with continuous pulse oximetry and serial observations may be considered (Grade D, weak recommendation) 1
- Careful follow-up within 24 hours is important to identify infants who will ultimately have a lower respiratory tract infection diagnosed 1
- Risk factors for extreme events include prematurity, postconceptional age <43 weeks, and upper respiratory infection symptoms 1
Key Clinical Distinction
A BRUE is by definition a resolved event - the infant has returned to baseline and appears well at presentation. 1 This is fundamentally different from ongoing respiratory distress where respiratory acidosis would be a concern. If the infant has persistent respiratory symptoms, altered mental status, or ongoing cardiorespiratory compromise, the event would not meet criteria for a lower-risk BRUE and more extensive evaluation including possible blood gas measurement would be warranted. 1