MC

Lab 9/24/25

Oxygen Delivery Equipment and Practice Notes

  • Practice setup overview

    • Start by setting the flow to five liters per minute (5 L/min). The manometer/mouth of the regulator is read as a level in the bulb; halfway through the bulb indicates the setting near 2.5 L/min on a typical gauge with markings 1, 2, etc.
    • When you enter the room, connect the device to the patient’s nasal cannula first to feel the setup, then proceed to full leads and oxygen delivery.
    • Hospital setups use quick-connect systems. The wall outlet and station valve/quick connect provide a regulated supply. The wall system includes a station outlet that requires you to connect patient delivery devices.
    • Each nurses’ station/floor has a station valve outlet with a shut-off valve. The valve exists for safety: if there is a problem in the room, you can shut off the oxygen source quickly. Oxygen supports combustion, so turning it off is crucial in a fire.
    • There are two gas sources in the room: air and oxygen. For the station/outlet, you turn on oxygen and set the patient delivery device to the desired flow (e.g., 5 L/min).
    • You will see a bubble humidifier attached to certain setups. In practice, you may see humidification devices and connections that look different but serve the same purpose.
    • The “Christmas tree” connector is a common term for certain modular connection points in the tubing; ribbed tubing can indicate a particular connection layout.
    • When connecting to the wall, do not pull by the mask; ensure all connections are snug and fully threaded; wall connections are designed to be secure and ribbed to prevent accidental disconnection.

  • Humidity and gas therapy basics

    • Bubble humidifier: adds moisture by bubbling gas through a water reservoir; typically used with simple masks or nasal cannula flow; humidity level is important for mucosal integrity and patient comfort.
    • Humidification goal: maintain airway moisture to prevent mucosal drying and improve comfort; dry gas can dry nasal passages and irritate airways.
    • Molecular gas path (nasal/face masks with humidified gas): gas can pass through a humidifier or be delivered as a molecular gas (not directly through a liquid humidifier) depending on the device; this affects moisture content and potential deposition.
    • Humidity percentage and surface area: the amount of humidity depends on surface area and contact time, analogous to evaporation on larger surfaces (like an ocean vs a small pool).
    • Gas heating and humidity interplay: heated humidification and the speed of gas flow influence moisture delivery to the patient’s airways.

  • Equipment types and interfaces

    • Nasal cannula
    • Common flow: 1–6 L/min (example shown at 5 L/min)
    • FiO2 typically ranges in practice around ~24–44%, depending on flow and patient breathing.
    • Gentle, comfortable, allows talking and eating/drinking but provides lower FiO2 than masks.
    • Simple mask (open face mask)
    • Flow range: about 6–15 L/min (to avoid CO2 rebreathing)
    • FiO2 roughly 35–60%, varies with fit and flow.
    • Open oxygen mask (non-closed/open-level mask)
    • Used for general oxygen delivery when a tighter seal is not required; contributes to moderate FiO2 depending on flow and fit.
    • Non-rebreather mask (NRB)
    • Typical flow: 10–15 L/min; bag should remain inflated during exhalation (keep a little fill to prevent collapse)
    • High FiO2, often close to 90% if flow and bag integrity are maintained; used for patients needing high oxygen concentrations.
    • Partial rebreather mask
    • Similar to NRB but with no/less valve to prevent complete exhaled air from leaving; allows some rebreathing of exhaled CO2
    • Provides moderate-to-high FiO2 depending on flow and bag inflation; not as precise as NRB.
    • Venturi (Venturi mask) / Air-entrainment masks
    • Known FiO2 tied to adapter color and flow (adapter plus flow give a known FiO2)
    • Example given: to obtain about 40% FiO2, use a Venturi adapter at about 10 L/min; the adapter sets the FiO2 more predictably than simple masks
    • Useful when precise FiO2 is required; can deliver up to about 50% (depending on the adapter and device) but with a fixed flow and entrained air
    • Large volume nebulizer / aerosol mask (cool aerosol)
    • Delivers medicated aerosols and humidified gas
    • Requires corrugated tubing and a water trap to collect condensate and prevent water from reaching the patient
    • Water for nebulization should be sterile or distilled; not tap water or saline (saline can crystallize and cause problems)
    • Typically used with a mask or face tent; can deliver humidity and medications
    • Face tent
    • Used when facial injuries, burns, or trauma prevent a mask from fitting well
    • Delivers humidified gas around the lower face/neck without direct contact on the face
    • Trach collar
    • Delivers humidified oxygen directly to a tracheostomy tube (neck area)
    • Important to avoid humidifier spills into the trach tract
    • Water trap and tubing considerations
    • Water trap (in-line) is placed between tubing sections to collect condensate and keep it out of the patient circuit
    • Corrugated tubing is common; length can be adjusted (cut to fit) and sometimes different brands require different connectors
    • Connector terminology
    • “Christmas tree” adapters: common term for a multi-branch connector used in gas delivery systems
    • 15 mm adapters: used to connect various components in respiratory circuits across devices

  • Gas supply and safety in hospital settings

    • Station outlet and quick-connect systems provide regulated oxygen; wall outlets are not a 50 psi blast to the patient (you must regulate flow through the device)
    • 50 psi wall outlet pressure exists; the regulator and device controls determine the actual delivered flow and FiO2
    • Oxygen supports combustion; always be mindful of fire hazards and turn off oxygen if a fire risk exists
    • When transporting patients with oxygen, consider transport-compatible setups (e.g., Venturi masks or trach collars) that minimize spillage of water and keep the airway humidified without creating a hazard in the moving environment
    • Water and humidity considerations for transport: avoid full humidifier setups that can spill water; prefer adapters or devices designed for transport
    • For trachs, be aware that humidification needs are different; direct tracheal delivery (via trach collar) bypasses the upper airway humidification route
    • Air vs oxygen: there are times when air (room air) is used for certain respiratory therapies (e.g., some aerosol treatments) to avoid increasing oxygen in COPD patients who are oxygen-sensitive

  • Practical decision-making and clinician roles

    • The observer/clinician guides the session: choosing device, setting flow, and adjusting FiO2; task includes monitoring oxygen saturation (SpO2) and making adjustments
    • Practice scenarios emphasize: if SpO2 remains low (e.g., 80–89%), escalate oxygen support by increasing flow, switching devices, or adding a high-flow option if available
    • If a patient on a nasal cannula on 6 L/min has insufficient saturation, consider upgrading to a mask or a higher-flow system; do not assume FiO2 will reach target because patient breathing pattern changes FiO2 delivery
    • When a patient on high-flow devices has rising needs (e.g., saturations not improving), consider high-flow systems that meet inspiratory demand to prevent entrainment of room air and ensure a consistent FiO2 delivery
    • For transport or short procedures, plan the oxygen strategy ahead (e.g., if trach patient needs humidity during transport, consider a Venturi-based approach or quick disconnects to maintain FiO2 without water spills)

  • Masks and FiO2 practical notes

    • Nasal cannula often chosen for comfort and mobility; rate determines FiO2 but exact FiO2 varies with breathing pattern
    • Simple mask requires a minimum flow (around 6 L/min) to prevent rebreathing CO2; higher flows increase FiO2
    • NRB provides the highest FiO2 among basic masks, nearing 100% if the bag remains inflated and there are no leaks
    • Partial rebreather offers a middle ground with a known FiO2 but less precise than NRB
    • Venturi provides a known FiO2 with specific adapters; it excels when precise oxygen concentration is needed
    • Large volume nebulizers and face tents are useful for humidified oxygen delivery or for administering medicated aerosols; ensure correct water type (sterile or distilled) and appropriate tubing length

  • Practical lab and calculation references

    • Cylinder duration estimation (E cylinder, full around 2250 psi)
    • Formula shown: ext{Minutes} = rac{P_{ ext{psi}} imes 0.28}{ ext{Flow (L/min)}}
    • Example: If P_{ ext{psi}} = 2250 and Flow = 15 L/min, then
      $$ ext{Minutes} = rac{2250 imes 0.28}{15} \