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9.3 Oxygen Sources
How oxygen is supplied will depend on the client’s setting. In an acute care setting, oxygen is delivered directly to the client via a wall oxygen outlet. Oxygen tubing is attached to a flow meter, which is attached to green oxygen outlets. In home settings and complex care facilities, clients may use oxygen concentrators or portable oxygen tanks. See Table 9.3.1 for further description of these sources.
Oxygen Supply Outlets
Figure 9.3.1 Oxygen flow meter
In acute care settings, rooms are equipped with wall-mounted oxygen supply outlets that are nationally standardized in a green colour, whereas air outlets are standardized with a yellow colour. Oxygen flow meters are attached to the green oxygen outlets, and then the oxygenation device is attached to the flow meter.
An oxygen flow meter consists of a glass cylinder containing a steel ball with an opening through which oxygen from the supply source is injected through an adapter. This adapter is commonly referred to as a “tree” because of its appearance. Oxygen is turned on, and the flow rate of oxygen is controlled by turning the green valve on the side of the glass cylinder. The flow rate is set according to the location of a steel ball inside the cylinder and the numbered lines on the glass cylinder. For example, in Figure 9.3.1 the flow rate is currently set at 2 litres per minute (L/min). It is essential to implement safety precautions whenever oxygen is used.
Portable Oxygen Tanks
Figure 9.3.2 Portable oxygen tank
Portable oxygen tanks are commonly used when transporting a client to procedures within the hospital or to other agencies. See Figure 9.3.2 for an image of a portable oxygen tank.
Oxygenation devices are connected to the tank in a similar manner as the wall-mounted oxygen flow meter. It is crucial for nurses and transporters to ensure the tank has an adequate amount of oxygen for use during transport, is turned on, and the appropriate flow rate is set.
Instead of oxygen tanks, oxygen concentrators are commonly used by clients in their home environment. See Figure 9.3.3 for an image of a home oxygen concentrator.
Oxygen concentrators are also produced in portable sizes that are lightweight and easy for the client to use while travelling and mobile in the community.
Oxygen concentrators work by taking the 21% concentration of oxygen in the air, running it through a molecular sleeve to remove the nitrogen and concentrating the oxygen to a 96% level, thus producing between 1 and 6 litres per minute of oxygen.
Oxygen concentrators may provide pulse flow or continuous flow. Pulse flow only occurs on inhalation, whereas continuous flow delivers oxygen throughout the entire breath cycle. Pulse versions are the most lightweight because oxygen is provided only as needed by the client.
Table 9.3.2 Types of Oxygen Tubing and Equipment[2]
Types of Oxygen Tubing and Equipment
Additional Information
Nasal cannula (low-flow system)
Nasal cannula consists of a small bore tube connected to two short prongs that are inserted into the nares to supply oxygen directly from a flow meter or through humidified air to the client. It is used for short- or long-term therapy (such as for COPD clients), and is best used with stable clients who require low amounts of oxygen.
Advantages: Can provide 24% to 40% O2 (oxygen) concentration. Most common type of oxygen equipment. Can deliver O2 at 1 to 6 litres per minute (L/min). It is convenient as the client can talk and eat while receiving oxygen. May be drying to nares if level is above 4 L/min. Easy to use, low cost, and disposable.
Limitations: Easily dislodged, not as effective if a client is a mouth breather or has blocked nostrils or a deviated septum or polyps. Nasal dryness can occur.
Figure 9.3.4 Applying a nasal cannulaFigure 9.3.5 Client with a nasal cannula
Simple face mask (low-flow system)
A mask fits over the mouth and nose of the client and consists of exhalation ports (holes on the side of the mask) through which the client exhales CO2 (carbon dioxide). These holes should always remain open. The mask is held in place by an elastic around the back of the head, and it has a metal piece to shape over the nose to allow for a better mask fit for the client. Humidified air may be attached if concentrations are drying for the client.
Advantages: Can provide 40% to 60% O2 concentration. Flow meter should be set to deliver O2 at 6 to 10 L/min. Used to provide moderate oxygen concentrations. Efficiency depends on how well mask fits and the client’s respiratory demands. Readily available on most hospital units. It provides higher oxygen for clients.
Disadvantages: Difficult to eat with mask on. Mask may be confining for some clients, who may feel claustrophobic with the mask on.
Figure 9.3.6 Simple face mask
Note: exhalation ports/holes/vents on the sides of the mask must be open to allow for gas exchange
Non-rebreather mask (high-flow system)
Consists of a simple mask and a small reservoir bag attached to the oxygen tubing connecting to the flow meter. With a non-rebreather mask, there is no re-breathing of exhaled air. It has a series of one-way valves between the mask and the bag and the covers on the exhalation ports. On inspiration, the client only breathes in from the reservoir bag; on exhalation, gases are prevented from flowing into the reservoir bag and are directed out through the exhalation ports.
Advantages: With a good fit, the mask can deliver between 60% and 80% FiO2 (fraction of inspired oxygen). The flow meter should be set to deliver O2 at 10 to 15 L/min. Flow rate must be high enough to ensure that the reservoir bag remains partially inflated during inspiration.
Figure 9.3.7 Non-rebreather mask
Disadvantages: These masks have a risk of suffocation if the gas flow is interrupted. The bag should never totally deflate. The client should never be left alone unless the one-way valves on the exhalation ports are removed. This equipment is used by respiratory therapists for specific short-term, high oxygen requirements such as pre-intubation and client transport. They are not available on general wards due to the risk of suffocation, the chance of hyper-oxygenation, the possible lack of humidity. The mask also requires a tight seal and may be hot and confining for the client. The mask will interfere with talking and eating.
Face tent (low-flow system)
The mask covers the nose and mouth and does not create a seal around the nose.
Advantages: Can provide 28% to 100% O2. Flow meter should be set to deliver O2 at a minimum of 15 L/min. Face tents are used to provide a controlled concentration of oxygen and increase moisture for clients who have facial burn or a broken nose, or who are are claustrophobic.
Disadvantages: It is difficult to achieve high levels of oxygenation with this mask, but sometimes this mask is the only option
Figure 9.3.8 Face tent
Venturi mask (high-flow system)
High-flow system consisting of a bottle of sterile water, corrugated tubing, a drainage bag, air/oxygen ratio nebulizer system, and a mask that works with the corrugated tubing. The mask may be an aerosol face mask, tracheostomy mask, a T-piece, or a face tent. The key is that the flow of oxygen exceeds the peak inspiratory flow rate of the client, and there is little possibility for the client to breathe in air from the room.
Advantages: The system can provide 24% to 60% O2 at 4 to 12 L/min. Delivers a more precise level of oxygen by controlling the specific amounts of oxygen delivered. The port on the corrugated tubing (base of the mask) sets the oxygen concentration. Delivers humidified oxygen for client comfort. It does not dry mucous membranes.
Disadvantages: The mask may be hot and confining for some clients, and it interferes with talking and eating. Need a properly fitting mask. Nurses may be asked to set up a high-flow system. In other instances, respiratory therapists may be responsible for regulating and monitoring the high-flow systems.
