| Mild–moderate (all of): | Severe (any of): | Life-threatening (any of): | |
| Consciousness | Alert | N/A | Drowsy or unconscious |
| Speech | Can finish a sentence in one breath | Can only speak a few words in one breath | Cannot speak |
| Posture | Can walk, sit up straight, lie flat | Unable to lie flat due to dyspnoea Sitting hunched forward | Collapsed or exhausted |
| Breathing | Respiratory distress is not severe | Paradoxical chest wall movement or Use of accessory muscles of neck or intercostal muscles during inspiration or Subcostal recession | Severe respiratory distress or Poor respiratory effort |
| Skin colour | Normal | N/A | Cyanosis |
| Respiratory rate | <25 breaths/min | ≥25 breaths/min | Bradypnoea (indicates respiratory exhaustion) |
| Heart rate | <110 beats/min | ≥110 beats/min | Cardiac arrhythmia or Bradycardia (may occur just before respiratory arrest) |
| Chest auscultation | Wheeze or Normal lung sounds | N/A | Silent chest or Reduced air entry |
| Oxygen saturation | >94% | 90–94% | <90% or Clinical cyanosis |
Additional information
N/A: Not applicable – may be the same as moderate and does not determine severity category