First Things First (assess & treat for the following):

• Definition
  • Respiratory failure: inadequate oxygenation and/or ventilation OR failure to protect airway
  • Respiratory failure can be physiologic or mechanical
    • Physiologic: infection, mental status, systemic acid–base disturbance, acute coronary syndromes, etc.
    • Mechanical failure: anatomic obstruction or disruption preventing adequate gas exchange (eg, angioedema, tracheal transection, neck hematoma) OR failure of respiratory musculature (eg, neuromuscular disease, spinal trauma)
  • Oxygenation: measured by SaO₂ or PaO₂
  • Ventilation: measured by PaCO₂
  • ABG is test of choice; VBG correlates, but higher PCO₂ threshold value
  • Airway protection: gag reflex is not helpful—clinical assessment is paramount; gag reflex does not accurately predict ability to protect airway
  • Despite potential appearance otherwise, trauma patients with GCS < 8 should be considered to have impeding respiratory failure
• Treat hypoxemia aggressively and early
  • Rule out acute cardiac failure as cause
  • Rule out toxidrome by history
    • Toxicology-focused labs generally not helpful in identifying life-threatening toxidrome with respiratory failure
• Identification
  • Recognition of impending respiratory failure is a CLINICAL assessment
  • Not done on the basis of laboratory or radiographic findings
• Findings that mandate airway management
  • Significant hypoxia that does not improve with non-invasive O2 supplementation
  • Expanding neck mass
  • GCS 8 or less in acute trauma
  • Inability to protect airway
  • Anticipated worsening of clinical condition