What questions should I ask and physical examination findings should I look for in a 3-year-old female patient currently on High Flow Nasal Cannula (HFNC) at 1L/kg with 25% Fraction of Inspired Oxygen (FiO2)?

Assessment of a 3-Year-Old on HFNC at 1L/kg and 25% FiO2

You should focus on identifying signs of HFNC failure and respiratory deterioration, specifically monitoring respiratory rate, work of breathing, oxygen saturation trends, and mental status, as these predict the need for escalation to invasive ventilation. 1

Critical Questions to Ask

Respiratory Status Evolution

• What was the initial oxygen requirement and respiratory distress level? Knowing the trajectory helps determine if the child is improving or plateauing 1
• How long has the child been on HFNC? Failure to improve within 1-2 hours suggests need for escalation 1
• Is the child feeding adequately? Inability to feed indicates significant respiratory compromise 1
• Any episodes of apnea or irregular breathing? These are ominous signs requiring immediate ICU transfer 1

Underlying Etiology

• What is the diagnosis? Community-acquired pneumonia, bronchiolitis, or viral illness have different trajectories and risk profiles 1
• Any comorbidities? Immunocompromised states, cardiac disease, or chronic lung disease increase risk of deterioration 1

Family and Social Context

• Can the family recognize deterioration? This determines whether step-down from ICU monitoring is safe 1

Physical Examination Priorities

Respiratory Assessment (Most Critical)

• Respiratory rate: Normal for 3-year-old is 20-30 breaths/min; >50 breaths/min indicates severe distress and potential HFNC failure 1
• Work of breathing: Look specifically for:
  • Suprasternal, subcostal, and intercostal retractions 1
  • Nasal flaring 1
  • Use of accessory muscles (sternocleidomastoid) 1
  • Grunting: This is a sign of severe disease and impending respiratory failure requiring immediate escalation 1
  • Thoracoabdominal asynchrony (paradoxical breathing) indicates respiratory muscle fatigue 2

Oxygenation Monitoring

• Continuous pulse oximetry: Target SpO2 >92% 1
• At current settings (1L/kg, 25% FiO2): If SpO2 is <92%, this indicates inadequate support 1
• Trend over time: Declining SpO2 despite HFNC suggests failure 1, 3

Cardiovascular Assessment

• Heart rate: Sustained tachycardia (>120 bpm for age 3) suggests inadequate oxygen delivery or impending shock 1
• Perfusion: Check capillary refill, skin color, and blood pressure for signs of shock requiring ICU admission 1

Neurological Status

• Mental status: Agitation may indicate hypoxia; lethargy or altered consciousness suggests hypercarbia and impending respiratory failure requiring immediate intubation 1
• Activity level: Decreased activity is a concerning sign 1

Hydration Status

• Signs of dehydration: Dry mucous membranes, decreased urine output, sunken fontanelle (if still open) 1
• Ability to maintain oral intake: Critical for determining need for IV fluids 1

Abdominal Examination

• Distension or bloating: HFNC can cause aerophagia; significant distension may compromise diaphragmatic excursion 4, 5

Red Flags Requiring Immediate Escalation

Criteria for ICU Transfer

• SpO2 ≤92% despite FiO2 ≥0.50 (50%): Absolute indication for ICU admission 1
• Altered mental status: Whether from hypoxemia or hypercarbia 1
• Recurrent apnea or slow irregular breathing: Indicates impending respiratory arrest 1
• Grunting: Sign of severe disease 1
• Hemodynamic instability: Tachycardia with poor perfusion or need for vasopressor support 1

Signs of HFNC Failure (Consider Intubation)

• No improvement or worsening after 1-2 hours on HFNC 1
• Rising respiratory rate with increasing work of breathing 1
• Progressive hypoxemia despite increasing FiO2 1, 3
• Development of multiorgan dysfunction 1

Monitoring Strategy

Continuous Monitoring Required

• Pulse oximetry: Continuous 1
• Respiratory rate: Frequent assessment, should decrease with effective HFNC 1, 5
• Cardiorespiratory monitoring: If heart rate >120 bpm or any dysrhythmia 6

Reassessment Timing

• Within 1 hour of HFNC initiation: To identify early failure 1
• Every 30-60 minutes thereafter: Until stable improvement demonstrated 4

Common Pitfalls to Avoid

• Delayed escalation: Waiting too long to intubate a failing patient worsens outcomes and creates emergency intubation scenarios 1
• Inadequate flow rate: At 1L/kg for a 3-year-old (~15 kg), flow should be at least 15 L/min to qualify as true HFNC 5
• Missing subtle signs of deterioration: Grunting, decreased activity, or inability to feed are early warning signs 1
• Underestimating oxygen requirement: If needing >50% FiO2, this child requires ICU-level monitoring 1