Oxygen Desaturation

ABCs
  • Check ABCs and vitals
  • Place on cardiac monitor
  • Start oxygen ->
    • NRB mask at 15 L/min to maintain SpO₂ > 94%
    • If COPD (CO₂ retainer) target 88 to 92%
    • If unsure → aim for 92% and send urgent VBG/ABG to check PaCO₂
  • If unstable or unresponsive ->
    • Call for assistance and ICU assessment
    • If intubated and on MV -> involve RT
    • Suction mucus plug
    • If issues with a tracheostomy -> ENT
HPI + examinations
  • Cardiac → chest pain, palpitations, dyspnea, diaphoresis, peripheral edema
  • Infectious → fever, chills, purulent sputum
  • Obstructive -> choking, aspiration, swallowing issues
  • Thrombotic -> hemoptysis, pleuritic CP, calf swelling, syncope (→ PE)
  • PMH of asthma, COPD, ILD, IHD, CHF, VTE or PE
  • Examination ->
    • Lungs: wheeze, crackles, absent or unequal breath sounds
    • Heart: new murmurs + JVP
    • Volume status: peripheral edema, mottling
    • Extremities: signs of DVT or calf swelling
workup
  • ABG or VBG (urgent) + CXR
  • D-dimer BNP hs-Troponin
  • ECG -> ischemia, RV strain (S1Q3T3, RAD, RBBB)
  • Consider CTPA if PE is suspected and the patient is stable
management
  • Oxygen escalation ladder
    • Nasal cannula: 1–5 L/min
    • Simple face mask: 5–10 L/min
    • NRB mask: >10–15 L/min
      (Titrate up based on severity)
  • Condition-specific treatment
  • Asthma exacerbation
    • Keep on NRB 15 L/min
    • SABA (Ventolin 2.5 mg) + SAMA (Atrovent 0.5 mg) every 20 mins
    • IV Methylprednisolone 40–60 mg
    • Reassess after 3 doses (1 hour)
    • If silent chest/confusion → ICU
  • Pneumothorax
    • Urgent CXR surgical referral if confirmed
    • If tension is suspected -> don’t delay intervention
  • Lung collapse
    • Suspect with unequal/absent breath sounds
    • Order CXR -> involve the respiratory team
  • Pulmonary embolism
    • If stable -> arrange CTPA (get consent, check renal function)
    • If delay or unstable -> consider empiric anticoagulation + bedside echo
  • Fluid overload
    • CHF history, orthopnea + CXR congestion
    • Start IV Furosemide
      • 20–40 mg IV if diuretic-naïve
      • If on oral diuretics → 1–2.5x total daily PO dose IV
      • Increase dose if no response (don’t repeat same dose)
      • Max single dose: 80–200 mg
      • Max daily dose: 600 mg/day

Last reviewed · May 2026

MOC