Administration of Medical Gases

Describe the differences between Hypoxia, Hypoxaemia and Hypercapnia

Hypoxia - inadequate O2 at cellular level Hypoxaemia - abnormal deficiency in concentration of O2 in arterial blood Hypercapnia - greater than normal CO2 in blood

Describe the implications and benefits of oxygen therapy

• O2 is a medication and should be treated as such
• Should only be given to those with a clinical need
• Oxygen treats hypoxaemia and NOT breathlessness
• Oxygen treatment should be titrated to achieve normal saturations in healthy adults (94-98%)

By increasing oxygen content in the lungs you can force the haemoglobin to carry more O2 thereby reducing affects of Hypoxia

What are some basic health and safety principles for using medical gases such as oxygen or entonox?

• Cylinders should be stored in well ventilated special cupboards, not used for any other purpose, empty and full cylinders stored separately, properly supported off the floor
• No smoking, naked flames, sources of heat, oil or grease near cylinders and particularly no oil or grease near valves or outlets
• No dropping or rolling cylinders on ground
• Always check label

Describe the process of setting up oxygen for use

• Check label
• Check contraindications
• Ensure cannula securely attached
• Open valve fully (black knob)
• Use flow regulator for appropriate litres
• Watch contents gauge

What are the types of masks and cannulas that can be used with oxygen?

• Bag Valve Mask (BVM) 15L
• Non-rebreather mask 10-15L
• Simple face mask 5-10L
• Venturi mask 4L
• Nasal cannula 2-6L
• Nebuliser 6-8L

Describe some challenges of recording an accurate oxygen saturation

Heavily applied nail varnish, poor circulation due to cold or illness

Describe the properties of entonox

• 50% nitrous oxide, 50% oxygen
• self administered and inhaled gas that is quick to act but quick to dissipate in effect

Explain the effect of temperature on entonox

Gases can separate at -6*. Before use invert canister a few times.

Describe the process of setting up Entonox for use

• Ensure demand valve clean and ready for use
• Fit new filter and mouthpiece
• Push hose firmly into Schrader valve and hear click
• Slowly turn cylinder on (black knob)
• Purge test demand valve
• Check for leaks, instruct pat on use

What are the contraindications for Entonox?

• Chest injury and/or suspected pneumothorax
• Air embolism
• Severe head injury with impaired consciousness (possible air embolism)
• Decompression sickness (consider risk if anyone has been diving last 24hrs)
• Violently disturbed psychiatric patients
• Severe bollous emphysema
• Abdominal pain with gross distension
• Intraocular injection of gas in last 8 weeks

What are some indications for entonox use?

• Cardiac chest pain
• Moderate to severe pain
• Labour pains