Oxygen delivery devices and suctioning — study notes

FiO2 vs Flow Rate: Key Concepts

  • FiO2 refers to the oxygen concentration that a device can provide, while the flow rate is the volume or speed of delivery, delivered as liters per minute (L/min).

  • Important definitions:

    • FiO2: FiO2∈[24%,60%] depending on device, with specific ranges per device listed below\text{FiO}_2 \in [24\%, 60\%]\text{ depending on device, with specific ranges per device listed below}

    • Flow rate: Q∈[range in L/min per device].Q \in \text{[range in L/min per device]}.

  • General context: Different devices are chosen based on patient needs for oxygen supplementation, balancing required oxygen concentration (FiO2) with tolerable delivery rate and patient comfort.

  • Nescent device overview (what each is best for):

    • Nasal cannula: long flexible tube with two prongs in the nose; suitable for lower oxygen needs.

    • Simple face mask: covers nose and mouth; suitable for short-term, moderate oxygen needs.

    • Venturi mask (Venti mask): mask with color-coded valves to deliver more precise FiO2.

    • Non-rebreather mask: emergent high-oxygen delivery; has a reservoir bag and a one-way valve to limit air entry; used in high-need situations.

  • Nasal cannulas- 1-6L/min, 24-44%

    • Use water-based lubricant in the nares to prevent dryness and friction caused by continuous oxygen flow; avoid oil-based (petroleum) lubricants.

    • Rationale: Oxygen flow can dry mucous membranes; lubrication increases comfort and reduces mucosal injury.

    • Description: long flexible tube with two prongs that go into the patient’s nose; used for patients with lower oxygen requirements.

    • Oxygen delivery specifics:

      • FiO2 range: FiO2∈[24%,44%]\text{FiO}_2 \in [24\%, 44\%]

      • Flow rate: Q∈[1,6] L/minQ \in [1, 6] \ \text{L/min}

    • Practical implications:

      • Suitable for patients who do not require high concentrations of oxygen.

      • Provides relatively gentle delivery with good tolerability.

Simple Face Mask

  • Description: mask that goes over the nose and mouth to deliver oxygen; used for short-term moderate oxygen requirements.

  • Oxygen delivery specifics:

    • FiO2 range: [35%,60%][35\%, 60\%]

    • Flow rate: Q∈[6,10] L/minQ \in [6, 10] \ \text{L/min}

  • Practical implications:

    • Provides higher FiO2 than nasal cannula but can be less precise due to mask fit and breathing pattern.

    • Suitable for short-term moderate needs.

  • Non-rebreather mask with reservoir bag- 10-15L/min, 60-100%

    • Reservoir bag must be fully inflated prior to applying the mask.

    • Full inflation ensures adequate reservoir for high concentrations of oxygen during inspiration.

    • Non-Rebreather Mask

      • Description: high-oxygen delivery mask used in emergent situations; attached to a reservoir bag with a one-way valve that prevents room air from entering and allows exhaled air to escape.

      • Oxygen delivery specifics:

        • FiO2 range: FiO2∈[60%,90%]\text{FiO}_2 \in [60\%, 90\%]

        • Flow rate: Q∈[10,15] L/minQ \in [10, 15] \ \text{L/min}

      • Important operational detail:

        • Reservoir bag must be inflated for proper function.

        • One-way valve prevents room air from diluting the mixture; exhaled air exits through vents.

  • Partial rebreather bag-6-10L/min, 40-70%

    • Bag should be kept to roughly two-thirds full during use.

    • This setup provides a mix of inspired oxygen with the reservoir, but not as high as a fully inflated non-rebreather.

  • Aerosol mask / face tent/ tracheostomy mask-28-100

    • Helpful for patients with facial trauma or claustrophobia; can also be used when a close-sealed mask is not tolerated.

    • Provides a more open fit while delivering oxygen.

    • Used with nebuliser

  • Venturi device

    • Not a stand-alone mask; attaches to a delivery system.

    • Key concept: Venturi delivers precise inspired oxygen (FiO₂) to the patient.

    • FiO₂ specificity: up to 40%40\% (i.e., FiO2≤0.40FiO_2 \le 0.40).

    • Significance: Allows controlled oxygen concentration without the need for intubation.

    • Description: mask that goes over the nose and mouth; delivers more precise oxygen concentration via color-coded valves that control the concentration.

    • Oxygen delivery specifics:

      • FiO2 range: FiO2∈[24%,60%]\text{FiO}_2 \in [24\%, 60\%]

      • Flow rate: Q∈[4,12] L/minQ \in [4, 12] \ \text{L/min}

    • Practical implications:

      • Allows precise control of FiO2, which is valuable for patients needing specific oxygen concentrations.

      • The color-coded valves correspond to different FiO2 settings.

Therapeutic interventions for oxygenation

  • Chest physiotherapy (CPT)

    • Indications: Commonly used for patients with cystic fibrosis or similar conditions with thick, difficult-to-clear secretions.

    • Components: Postural drainage, percussion, and vibration to loosen and mobilize secretions.

    • Practical considerations: Treatments may be nauseating; schedule 1–2 hours after meals or before meals to minimize vomiting (bold red emphasis in the card).

    • Rationale: Facilitates mobilization and clearance of thick secretions to improve airway clearance and gas exchange.

  • Positive airway pressure

    • CPAP: Continuous Positive Airway Pressure — maintains a constant positive pressure to keep airways open.

    • BiPAP: Bilevel Positive Airway Pressure — provides two levels of pressure (higher during inspiration, lower during expiration) to support breathing.

    • Overall purpose: Both modalities apply positive pressure to keep airway structures open and improve oxygenation/ventilation.

  • Suctioning

    • Purpose: Removal of secretions, fluids, or other obstructions to improve airway patency and gas exchange.

Best practices for suctioning (card 135)

  • Preoxygenation/hyperoxygenation

    • Before suctioning, provide the patient with 100% oxygen to prevent desaturation during the procedure.

    • Rationale: Suction removal can also remove oxygen; starting from a fully oxygenated baseline minimizes hypoxemia.

  • Insertion vs withdrawal of the catheter

    • Do not apply suction while inserting the catheter.

    • Apply suction intermittently while withdrawing the catheter (i.e., suction during withdrawal, not during entry).

  • Duration and number of passes

    • Limit suctioning to 10-15 seconds10\text{-}15\ \text{seconds} per pass.

    • Maximum of 3 passes3\ \text{passes} per suction Sequence to reduce process-related hypoxemia and patient discomfort.

  • Rationale and patient comfort

    • Suctioning is disruptive and can significantly reduce oxygen saturation; allow recovery and spontaneous breathing between passes.

    • Encourage the patient to breathe between suction attempts to minimize the time the airway is actively suctioned.

  • Practical emphasis from the card

    • There are bold red items highlighted as critical points (as noted in the card visualization); refer to these during clinical practice.

Summary notes and real-world relevance

  • Key distinctions between delivery devices affect FiO₂ delivery, patient tolerance, and risk for mucosal injury or claustrophobia.

  • Venturi masks offer precise FiO₂ delivery without intubation, which is particularly important when exact oxygen percentages are needed.

  • Chest physiotherapy can dramatically improve clearance of thick secretions but requires scheduling considerations to minimize adverse effects like nausea.

  • Positive airway pressure therapies (CPAP/BiPAP) support airway patency and ventilation in various respiratory conditions.

  • Suctioning must balance effective clearance with minimizing desaturation; preoxygenation and limiting duration/passes are essential safety practices.

Real-world connections and implications

  • In cystic fibrosis or chronic sputum production, CPT can reduce infection risk and improve ventilation by facilitating mucus clearance.

  • Venturi-based oxygen delivery is often preferred when precise FiO₂ control is needed, such as during titration to maintain target oxygen saturation.

  • For patients with facial trauma or claustrophobic tendencies, alternatives to full-face masks (e.g., aerosol masks) can improve tolerance and adherence.

  • Suctioning protocols emphasize patient safety and comfort, recognizing that repeated suctioning without adequate recovery periods can lead to hypoxemia, arrhythmias, or patient distress.

Quick reference values (for study recall)

  • Preoxygenation target: 100%100\% O₂ prior to suctioning.

  • Suction duration per pass: 10-15 seconds10\text{-}15\ \text{seconds}.

  • Max suction passes: 33 passes per session.

  • Venturi FiO₂ capability: up to 40%40\%, i.e., FiO2≤0.40FiO_2 \le 0.40.

  • Nasal cannula lubrication: water-based only (not oil-based).

  • Non-rebreather bag: fully inflated before use.

  • Partial rebreather bag: maintains approximately 23\frac{2}{3} full.

  • Clinical tips:

    • Always confirm that FiO2 and flow settings align with patient needs and clinical goals.

    • For NRB masks, ensure the reservoir bag inflates fully; otherwise, FiO2 will be reduced.

    • Venturi masks are preferred when precise FiO2 control is necessary due to patient condition.

Quick Reference (Numerical Highlights)

  • Nasal Cannula: extFiO2∈[24%,44%], Q∈[1,6] L/minext{FiO}_2 \in [24\%, 44\%], \ Q \in [1, 6] \ \text{L/min}

  • Simple Face Mask: extFiO2∈[35%,60%], Q∈[6,10] L/minext{FiO}_2 \in [35\%, 60\%], \ Q \in [6, 10] \ \text{L/min}

  • Venturi Mask: extFiO2∈[24%,60%], Q∈[4,12] L/minext{FiO}_2 \in [24\%, 60\%], \ Q \in [4, 12] \ \text{L/min}