Respiratory Rate
ABCs
definitions
- normal → 12–20 breaths/min
- tachypnea → > 20
- bradypnea → < 12
- RR > 30 → red flag
- RR < 8 → respiratory arrest zone
- check oxygen saturation and vitals
- recheck respiratory rate manually
- observe work of breathing, O₂ saturation, mental status
call senior / ICU early if
- RR ≥ 30 or < 8
- silent chest
- exhaustion, altered mental status, unable to speak full sentences
- accessory muscle use
- rising oxygen requirements
- hemodynamic instability
causes
- pulmonary → pneumonia, PE, asthma/COPD exacerbation, pneumothorax
- cardiac → acute heart failure, ACS
- metabolic → DKA, metabolic acidosis, sepsis (tachypnea); severe hypothyroidism (bradypnea)
- neurological/drug → anxiety, pain, brain injury (tachypnea); opioid/sedative overdose, raised ICP (bradypnea)
- other → fever, anemia, hyperthyroidism, pregnancy (tachypnea); end-of-life physiology, neuromuscular disorders (bradypnea)
workup
- focused HPI and exam
- ECG, CXR
- CBC, U&E, CRP
- VBG/ABG
- troponin, BNP
- D-dimer
- consider CT-PA if PE suspected
calculator NEWS2 · MDCalc ↗︎
management
- ensure airway patency
- position upright
- provide oxygen
- target SpO₂ 94–98% in most patients
- target 88–92% if risk of hypercapnic respiratory failure
- escalate for RR > 30 or RR < 8
- treat underlying cause (sepsis, PE, DKA, COPD/asthma, pulmonary edema, pneumothorax)
- opioid-induced (RR < 8) → naloxone 0.04–0.4 mg IV, titrate q2–3 min
studying for the IM exam? the IM Rapid Review covers respiratory rate and ventilation in the same format. see the sample chapter.
Last reviewed · June 2026