Common physiological pathways leading to respiratory compromise1

Hypoxic Respiratory Failure
Hypercapnic Respiratory Failure
Sleep Disordered Breathing Related Arousal Failure
Primary Issue

Decreasing ability to oxygenate blood due to congestion (e.g., fluid, pus, etc.) in lung tissue (alveoli).

Inadequate ventilation to clear carbon dioxide secondary to hypoventilation.

Failure of patient to initiate hyperventilatory ‘arousal response’ following sleep apnea related hypoventilation. Failure of arousal response is often related to opioid/sedative administration.

Common Causes

  • Pneumonia
  • Pulmonary edema
  • Pulmonary embolism
  • Atelectasis
  • Pulmonary fibrosis

  • Central hypoventilation
  • Asthma
  • COPD
  • Neuromuscular disorders
  • Chest wall disorders

  • Obstructive sleep apnea
  • Central sleep apnea
  • Cheyne-Stokes respiration

Precipitating Vital Signs

  • ↑ Respiratory rate
  • ↑ Minute ventilation
  • ↓ Blood CO2
  • SpO2 is maintained until precipitous drop at respiratory failure

  • Normal or ↓ respiratory rate
  • ↑ Blood CO2
  • Lagging drop in SpO2
  • Due to plateau of oxyhemoglobin dissociation curve, SpO2 is maintained above 90% through a significant rise in CO. Further masked by use of supplemental oxygen

  • Sawtooth pattern of of drops and increases in RR and MV
  • Results in reciprocal sawtooth rises and falls in blood oxygen and CO2

  1. Lynn, L. A., & Curry, J. P. Patterns of unexpected in-hospital deaths: a root cause analysis. Patient Saf Surg. 2011;5(1):3.