What is Oxygen?

Oxygen (O2)is a colourless gas. It is present in the atmosphere at a concentration of approximately 21%. It is a vital part of the body's production of energy; the process of aerobic metabolism produces energy and carbon dioxide from glucose and oxygen.

Oxygen in pure form is a medical gas and as such is a prescription only medicine (POM).


Oxygen cylinder sizes:

  1. D (340l). 340 litres and charged to 2000 psi 
  2. CD - this cylinder has the regulator and therapy head incorporated into the design and is also lightweight.
  3. HX - this cylinder also has the regulator and therapy head incorporated into the design but is larger and for ambulance use.
  4. F size - larger than the D size and usually in a vehicle. 1360 litres and charged to 2000 psi

The CD size is slowly replacing the D size bottle

The main parts of the D and F size equipment to identify are:

  1. Regulator - Reduces cylinder pressure to 60 psi.
  2. Therapy head - Enables you to control the amount of oxygen administered to the patient.
  3. Key - Used to open or close the cylinder.


Oxygen Masks
  1. Medium concentration mask - Used for mild hypoxia or someone with COAD. Delivers approx 50% oxygen at 15 litres per minute
  2. Non-Rebreather mask - Used for trauma and when high flow O2 is required. Has an reservoir bag on the front.  Delivers practically 100% oxygen at 15 litres per minute.
  3. During CPR using a bag and mask with oxygen delivers approximately 60% oxygen at full flow.
  4. During CPR using a bag and mask with oxygen reservoir delivers practically 100% oxygen at full flow.

Administration - Click here to view Oxygen guidelines for Adults


Entonox (trademark of BOC Gases) or Nitronox is a 50/50 mixture of nitrous oxide (N2O) and Oxygen (O2). It has pain-relieving properties and is self administered. The classic indication for administration of Entonox is a conscious casualty (Who's not in the contra-indications for use) that is in moderate to severe pain. Entonox is a good choice for pain relief as it is fairly quick to take act but the effects wear off quickly so it does not mask any symptoms.

Administration - Click here to view Entonox dosage and procedures


Suction equipment is used to clear the airway of a patient whether they are conscious or unconscious.

The equipment comes in a number of forms, a fitted unit on the ambulance, a portable battery powered unit or a hand activated aspirator. The last one is only good enough for a small amount of blood/vomit as it only has a little reservoir.

Suctioning (General Guidelines)
• Maintenance of an open airway has priority over all other treatments (Other than catastrophic Haemorrhage in Trauma), including control of the cervical spine
• If unable to keep the airway clear of secretions that are blocking the airway, roll the patient onto his or her side to allow for postural drainage. If time permits, first stabilize the cervical spine in a trauma patient with a suspected spinal injury
• Rigid plastic suction devices such as a yankauer suction catheter should be used for suctioning of the upper airway
• Catheter suctioning is useful for suctioning of small children, infants, and when suctioning through an OPA or NPA 
• Patients should be pre-oxygenated with 100% oxygen prior to being suctioned if this will not cause further airway obstruction or force material into the airway
• Suctioning is done to the upper airway only, no non-visualized or deep suctioning. BLIND SUCTIONING IS NOT PERMITTED
• The suction should be adjusted to provide suction based on the patient’s condition, age, and equipment being utilized.
• Suctioning pressures higher than those recommended may result in damage to the mucosa of the trachea and bronchi
• Determine the depth the suction device will be inserted, by measuring the device against the distance from the corner of the patient’s mouth to the tip of the earlobe on the same side
• Suction device tip should be inserted without suction being activated. This prevents valuable O2 being removed.
• The catheter should only be advanced as far as the tip can be visualized
• Once the tip of the suction device is in place, suction should be activated and secretions removed.
• Suctioning attempts should last no more than five seconds under most circumstances

For a non-breathing patient
• Ventilate the patient using 100% oxygen for two minutes between suctioning attempts
• The suction device should be cleaned using sterile water or saline
Suctioning a severely compromised airway
• If the airway is compromised to such a degree (by blood, vomit, etc.) that normal suctioning will not clear the airway and facilitate establishing a patent airway, extended suctioning may be required
• Visualize the airway and use manual methods to assist suctioning to clear the airway. (Finger Sweep)
• Position the patient to facilitate suctioning and clearing the airway
• Consider load and go if the airway cannot be cleared with extended suctioning and manual methods
Suctioning through a Oro/Nasopharyngeal airway
• Pre-oxygenate the patient, if possible
• Select a catheter which will pass easily into the NPA
• Compare the outside diameter of the suction catheter to the inside diameter of the NPA
• Suction catheter should be slightly smaller in diameter than the diameter of the lumen of the NPA
• Measure the suction catheter for length in an identical manner utilized to measure for the NPA
• Advance the suction catheter into the NPA the depth measured without suction being applied
• Activate the suction once the catheter has been properly inserted
• Continue suctioning as catheter is withdrawn
• Reassess the positioning of the NPA and patency of the airway
• Ventilate the patient with 100% oxygen, if indicated

After Care

Once the suction equipment has been used:

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  • People who suffer from such diseases as chronic bronchitis or emphysema (known as Chronic Obstructive Airway Diseases or COAD's) should be monitored if administering high flow O2.