Oxygen Delivery Devices and Flow Rates: A Nurse's Guide

William Kelly, MSN, FNP-C

Updated June 2026 · Medically reviewed for nurses

11 min read

Oxygen delivery devices and flow rates are essential concepts for every nurse. Oxygen is a life-saving therapy that nurses and respiratory therapists administer every day in the hospital.

Whether your patient is on chronic oxygen or in acute respiratory failure, oxygen will commonly be ordered — and it's up to you as the nurse to administer it. Knowing each device and its flow rate will help you care for any patient who needs oxygen.

The Role of Oxygen

Oxygen is used every day in and out of the hospital. To understand oxygen delivery devices and flow rates, we first need a few basic principles.

Oxygen is the most important gas in our atmosphere for human and animal life. Our cells use oxygen to create energy (Krebs cycle, anyone?). Our ability to make energy without oxygen is very limited — without it, cells die within minutes.

Oxygen occurs naturally in the atmosphere at a concentration of 21%. Another term for oxygen concentration is FiO2, the fraction of inspired oxygen.

When we breathe in, air enters the lungs and reaches the alveoli — small sac-like structures. The oxygen diffuses across the alveoli into the bloodstream, where it attaches to hemoglobin on red blood cells. Blood then carries oxygen throughout the body, where tissues absorb it to fuel the cells.

Key Respiratory Concepts

Three definitions make the rest of this guide click into place.

Blow-by Oxygen

Blow-by Oxygen< 30% FiO2 · ≥ 10 L/min

Blow-by oxygen is exactly that — oxygen that "blows by." It doesn't apply oxygen directly, but indirectly by blowing on the patient's face. It's usually only used in infants and young toddlers who get agitated by masks or tubing. It delivers less than 30% FiO2, not much above room air. If used, the rate should be at least 10 L/min through a simple mask, or even tubing through a styrofoam cup that a toddler may find less scary.

Nasal Cannula

Nasal Cannula25–40% FiO2 · 2–6 L/min (2–4 ideal)

Nasal cannula is tubing that runs from the oxygen source to the patient's bilateral nares. It's the most common oxygen delivery in the hospital, especially for non-critical and chronic-oxygen patients like those with COPD. It's typically started at 2 L/min and titrated up to 6 L/min, though 2–4 L/min is ideal, delivering 25–40% FiO2 depending on respiratory rate, tidal volume, and mouth breathing. At rates > 2 L/min it can be irritating and dry the nares, so oxygen should be heated and humidified at higher flow rates when possible.

Simple Face Mask

Simple Face Mask35–50% FiO2 · 6–10 L/min

A simple face mask hooks directly to an oxygen source and covers both the mouth and nose, similar to nasal cannula but in mask form. It allows flow rates of 6–10 L/min with an FiO2 of 35–50%. It tends to be a temporary solution used while titrating oxygen delivery.

Ventimask

Ventimask (Venturi Mask)24–60% FiO2 · ~3–10 L/min

A Ventimask or Venturi mask is a face mask connected to corrugated tubing with a venturi valve on the end. It mixes oxygen with room air to provide a consistent high flow of oxygen even with irregular respiratory rates or tidal volumes. Different colored venturi pieces deliver an FiO2 of 24–60% (levels > 40% are generally not used and likely offer no added benefit). The flow rate is indicated on the valve, generally 3–10 L/min. Ventimasks are usually used with COPD patients needing higher oxygen when there's concern for CO2 retention, and can help with asthma exacerbations and general distress. It's not used long-term.

Non-Rebreather

Non-Rebreather (NRB)up to ~95% FiO2 · 10–15 L/min

A non-rebreather is typically what's used first when a patient needs high-flow oxygen and the nasal cannula isn't cutting it. It provides the highest concentration of oxygen for a spontaneously breathing patient — up to 95% FiO2 — without additional machines. A reservoir bag attaches to the mask with a one-way valve between them, which prevents exhaled CO2 from entering the reservoir and only allows oxygen. Exhalation ports on the sides let expired air out and keep room air from coming back in (one is usually left unblocked to prevent suffocation if the oxygen stops). At 10–15 L/min it delivers up to ~95% FiO2, though a small amount of room air leaks in, making the real FiO2 more like 80–90%. This is not a long-term solution; unless titrated down, patients need BiPAP, HFNC, or intubation.

High-Flow Nasal Cannula

High-Flow Nasal Cannula (HFNC) is a newer way to deliver a high flow and FiO2 of oxygen for patients with higher requirements. COVID patients tended to do well on it, but it works for many types of respiratory distress. It uses a specific machine and tubing to deliver very high flow that is heated and humidified.

CPAP & BiPAP

CPAPContinuous Positive Airway Pressure · 5–20 cm H2O

CPAP is a form of non-invasive ventilation that helps open the alveoli for better gas exchange. It's useful in acute pulmonary edema (as in CHF) because it reduces intrathoracic pressure, can reduce preload and increase cardiac output, and decreases alveolar congestion. It's also used for obstructive sleep apnea (OSA) to keep the airway open. Oxygen isn't always added (especially for OSA alone). Pressure is set at 5–20 cm H2O, usually starting at 5–8; higher pressures increase intrathoracic pressure. Oxygen is added to keep SpO2 > 90%.

BiPAPBilevel Positive Airway Pressure

BiPAP is the "upgraded" version of CPAP and can often be used as an alternative to intubation. It's great for hypercapnic respiratory failure (think COPD), using a higher pressure during inspiration and a lower pressure during expiration. It has three settings:

• Rate: a backup/spontaneous respiratory rate, usually 8–12 rpm (most patients breathe faster).
• IPAP: inspiratory positive airway pressure, 5–30 cm H2O (usually started at 8–12). Higher IPAP increases tidal volume.
• EPAP: expiratory positive airway pressure, typically 3–5 cm H2O.

Oxygen is added to keep SpO2 > 90%; FiO2 is started at 100% and titrated down. BiPAP is used for acute COPD exacerbations and acute respiratory failure like CHF or ARDS. It's not good for patients who are nauseous, have thick secretions, or are altered, given the aspiration risk.

Mechanical Ventilation

Ventilatorcontrols both oxygenation and ventilation

Mechanical ventilation is the best way to control a patient's oxygenation and ventilation (gas exchange). It's used as a last resort when a patient is in severe respiratory distress and can't tolerate non-invasive ventilation — they may be altered, unable to protect their airway, vomiting, or persistently hypoxic despite other oxygenation. The patient must be intubated, likely sedated, and connected to the ventilator, which controls the respiratory rate, IPAP, EPAP, inspiratory flow rate, and FiO2. If ventilation can be avoided, it should be — some patients (severe COPD or ARDS) are difficult to wean off the vent.

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