• Normal range: 12–20 breaths/min in adults
• RR > 30 = red flag
• RR < 8 = respiratory arrest zone
• RR trend ↑ = early clue that something’s wrong

ABCs and Vitals

• Recheck RR manually (don’t trust the monitor)
• Observe:
  • Work of breathing: accessory muscle use, nasal flaring, retractions
  • O₂ saturation
  • Mental status (early hypoxia or CO₂ retention)

Red Flags

• RR > 30 → sepsis, PE, severe pneumonia, impending respiratory failure
• RR < 8 → opioid/sedative overdose, raised ICP or end-stage disease
• RR rising over time → don’t wait for BP to crash

Causes of Tachypnea

System	Examples
Pulmonary	Pneumonia, PE, asthma/COPD exacerbation, pneumothorax
Cardiac	Acute heart failure, ACS
Metabolic	DKA, metabolic acidosis, sepsis
Neurological	Anxiety, pain, brain injury
Others	Fever, anemia, hyperthyroidism, pregnancy

Causes of Bradypnea

• Drug overdose (opioids, benzos)
• Raised intracranial pressure
• Severe hypothyroidism
• End-of-life physiology
• Neuromuscular disorders (e.g., myasthenia gravis)

WORKUP

• ABG/VBG
• CXR or bedside lung ultrasound
• ECG (especially if PE suspected)
• Labs: electrolytes, lactate, D-dimer, troponin, CRP

RR as a Clinical Clue

• RR is often the first vital to rise in deterioration
• Don’t ignore a high RR in a “stable” patient — it may precede:
  • Hypoxia
  • Sepsis
  • Acute heart failure
  • PE
  • Silent aspiration