Oxygen Therapy in Acute Illness (BTS 2017)

Algorithm Steps

1. ▶

   Start

   Patient Requires Oxygen Assessment

   Hypoxia suspected or confirmed

   1. ●

      Action

      Initial Assessment

      Check SpO2 on room air

      • Pulse oximetry (SpO2)
      • Respiratory rate and pattern
      • Work of breathing
      • Mental status
      • ABG if hypercapnia risk
      1. ◆

         Decision

         At Risk of Hypercapnia?

         Identify CO2 retainers

         • Known COPD
         • Severe obesity (BMI >40)
         • Neuromuscular disease
         • Chest wall deformity
         • Bronchiectasis
         • Previous hypercapnic respiratory failure
         1. ●

            Action

            Standard Target: 94-98%

            For most acutely ill patients

            • Target SpO2 94-98%
            • Start with appropriate device
            • Titrate to maintain target
            • Do not exceed target unnecessarily
            1. ◆

               Decision

               Select Oxygen Device

               Based on oxygen requirement

               • Nasal cannula: 1-6 L/min (24-44%)
               • Simple face mask: 5-10 L/min (40-60%)
               • Non-rebreather mask: 10-15 L/min (60-90%)
               • High-flow nasal cannula if available
               1. ●

                  Action

                  Nasal Cannula

                  For mild hypoxia

                  • 1-6 L/min flow rate
                  • Approximate FiO2: 24-44%
                  • Comfortable for prolonged use
                  • Can eat/drink/talk
                  1. ●

                     Action

                     Monitor Response

                     Titrate to target

                     • Continuous SpO2 monitoring
                     • Adjust flow to maintain target
                     • Reduce O2 if above target
                     • ABG if not improving or hypercapnia risk
                     • Document target range on prescription
                     1. ⚠

                        Warning

                        ⚠️ Escalate Care

                        If not responding to high-flow O2

                        • Consider high-flow nasal cannula (HFNC)
                        • Consider NIV/CPAP
                        • ICU referral if deteriorating
                        • Review diagnosis
                     2. ●

                        Action

                        Stable on Target

                        Continue current therapy

                        • Document oxygen prescription
                        • Regular SpO2 monitoring
                        • Wean O2 as condition improves
                        • Consider cause of hypoxia
                        1. ✓

                           Outcome

                           Wean Oxygen

                           When clinically improving

                           • Reduce flow rate gradually
                           • Maintain SpO2 within target
                           • Trial on room air if SpO2 stable on low-flow
                           • Document SpO2 on room air before discharge
               2. ●

                  Action

                  Simple Face Mask

                  Moderate oxygen needs

                  • 5-10 L/min (minimum 5L)
                  • FiO2 approximately 40-60%
                  • Higher flow = higher FiO2
               3. ●

                  Action

                  Non-Rebreather Mask

                  Severe hypoxia

                  • 10-15 L/min
                  • FiO2 60-90%
                  • Reservoir must stay inflated
                  • For critical hypoxia
         2. ●

            Action

            Controlled O2: 88-92%

            For hypercapnia risk patients

            • Target SpO2 88-92% initially
            • Use Venturi mask 24-28% to start
            • Check ABG within 30-60 min
            • Adjust target based on ABG
            • May increase to 94-98% if pH normal
            1. ●

               Action

               Venturi Mask

               Controlled FiO2 delivery

               • 24%, 28%, 31%, 35%, 40%, 60% options
               • Color-coded valves
               • Use specified flow rate on valve
               • Preferred for hypercapnia risk
               1. ◆

                  Decision

                  Check ABG

                  For hypercapnia risk patients

                  • pH <7.35 with high CO2 = respiratory acidosis
                  • May need NIV if acidotic
                  • Adjust target if CO2 normal