Why do we need Oxygen (O2)?
Its essential for life. It combines chemically with glucose (Krebs Cycle) to provide energy for the metabolic processes of the body.
Hypoxia
Inadequate Oxygen tension at cellular level
Characteristics of Hypoxia
Tachycardia Hypertension Peripheral vaso-constriction Dizziness Mental confusion
Hypoxaemia
An abnormal deficiency in the concentration of O2 in arterial blood
Characteristics of Hypoxaemia
Cyanosis Restlessness <GCS Cheyne-Stokes respiration Apnoea Hypertension Tachycardia
Cheyne-Stokes respiration
Cheyne–Stokes respiration is an abnormal pattern of breathing characterized by progressively deeper and sometimes faster breathing, followed by a gradual decrease that results in a temporary stop in breathing called an apnoea.
Hypercarbia
Greater then normal CO2 in the blood
O2 Implication in Practice
O2 is a medication and should be treated as such..
Only prescribed & administered to those with clinical need.
Oxygen therapy should be Titrated to achieve normal saturation values in healthy adults(94/98%)
O2 is treatment for…
…Hypoxaemia and not breathlessness
By increasing the O2 content within the lungs
Haemoglobin is forced to carry more O2. Reversing the effects of Hypoxia on the brain, heart and other vital organs.
Hypoxia
deficiency in the amount of oxygen reaching the tissues
Oxygen cylinders
O2 is stored in cylinders on ambulances.
In UK O2 cylinders are clearly marked with ‘Oxygen’ or ‘O2’ and charged at 2000psi.
Must be maintained in good working order.
Two sizes of O2 cylinder
CD = 460L HX = 2300L
How long does a cylinder last?
Should be changed when a 1/4 full.
Divide capacity of cylinder by flow rate.
(amount in cylinder - 1/4) / (flow rate)
O2 use CAUTIONS
Combustible materials ignite easier and burn fiercer in the presence of pure O2.
Oil, Grease, Sparks, Flames or any other type of ignition source may also cause and explosion if it comes into contact with O2 equipment.
Health & Safety (1 of 4)
Cylinders must be stored in well ventilated positions in special areas or cupboards provided.
Full and empty cylinders should be kept separate.
The storage area must not be used for any other purpose.
Cylinders should be properly supported off the floor.
Health & Safety (2 of 4)
Cylinders should not be allowed to get rusty, dirty, be repainted or have their markings obscured.
Cylinders must not be stored near stocks of combustible and or flammable materials.
warning sings prohibiting smoking or naked lights must be visible.
Adequate access must be provided and maintained to and from storage area.
Health & Safety (3 of 4)
No smoking when using O2
Do not use in the presence of naked flames
Exercise care when using O2 in presence of machinery or equipment which can create sparks.
Oil or grease must not come into contact with the outlet, valves or associated equipment due to risk of explosion.
Health & Safety (4 of 4)
Newly charged cylinders must have a securely fixed seal on outlet.
The outlet face must not be damaged.
Avoid dropping or rolling cylinders along ground when moving them.
Avoid excessive force when turning the valve key or when connecting and apparatus.
Regulators
These are attached to the cylinders to reduce the pressure form 2000psi to around 60psi.
They incorporate a contents gauge and flow meter, attached directly or at the end of piping system, to assist in varying the flow rate of oxygen being delivered to the patient.
Free flow O2 therapy
Spinning ball flow-meter - on all vehicles
O-15 Litres per minute
Variable % depending on mask used
Non Re-Breather Masks
These masks can be used on all patients who require high concentrations of O2 due to trauma.
There are 2 sizes: Adult & Paediatric
These masks are to be used with a high flow rate of 15 Litres per minute to deliver 100% O2 to the patient.
Ensure that the reservoir bag is inflated prior to use.
These masks are for single patient use and are disposable.
Critical Illnesses requiring high levels of supplemental Oxygen (non re-breather 100%)
Shock Sepsis Major Trauma Near-drowning Anaphylaxis Major Pulmonary Haemorrhage Carbon Monoxide Poisoning
Critical Illnesses requiring high levels of supplemental Oxygen - General Principles
Initial is reservoir bag at 15 L/min
Once stable reduce O2 to target saturation of 94-98%
Patients with COPD who develop critical illness should receive the same initial saturation targets but will need assessment and further controlled O2 therapy.
Nasal Cannulae, Venturi 28% & Tracheostomy
Designed to deliver low to medium flow O2 concentrations.
Nasal Cannula
1 L/min = 24%
2 L/min = 28%
4 L/min = 36%
8 L/min = 52%
Venturi face mask
4 L/min = 28%
Tracheostomy
flow rate = 10 L/min
Serious illnesses requiring moderate levels of supplemental O2 if the patient is hypoxic
Acute Hypoxaemia - as yet undiagnosed Acute Asthma, pneumonia, Ca lung Post operative breathlessness Acute heart failure PE Pleural effusions (fluid in pleural space) Pneumothorax (air in pleural space) Deterioration of lung fibrosis or other interstitial disease. Severe anaemia Sickle cell crisis
Administration and Dosage
The O2 concentration delivered to the patient is determined by the choice of mask and flow rate.
It is important to administer the correct oxygen concentration & flow rate for the patients condition.
COPD and other conditions requiring O2 therapy
COPD Exacerbation of cystic fibrosis Chronic neuromuscular disorders. Chest wall disorders Morbid obesity
COPD and other conditions requiring O2 therapy - General Principles
Prior to availability of blood gases, use 28% venturi mask with saturation target of 88-92%
If saturation remains below 88% use nasal cannulae at 5L/min with target of 88-92%
Patients with alert cards, previous Noninvasive Ventilation or Intermittent positive pressure ventilations or with SpO2 ,88% should be treated as high priority with a hospital pre-alert.
If diagnosis is unknown treat as COPD if;
- over 50
- Long term smoker with chronic breathlessness on minor exertion.
Hypoxic Drive - what is it?
The hypoxic drive is a form of respiratory drive in which the body uses O2 chemoreceptors instead of CO2 receptors to regulate the respiratory cycle.
in hypoxic drive an increase in O” will cause chemoreceptor reflexes to trigger a decrease in respirations.
Normal Respiration is driven mostly by?
The levels of carbon dioxide in the arteries, which is detected by central chemoreceptors and very little by the oxygen levels.
Hypoxic drive - how to administer O2 to COPD patient on domiciliary O2
For known COPD patients on long term (more then 15 hours a day) domiciliary O2. Deliver O2 via nasal cannulae at the flow rate normally used by the patient at home whether the have acute respiratory distress or not.
Hypoxic drive - how to administer O2 to COPD patient NOT on domiciliary O2
COPD pat not on domiciliary O2 presenting with acute respiratory distress deliver O2 via nasal cannulae at a concentration of 28% (2Lpm) and monitor O2 saturation - Sats of 92% maybe satisfactory for these patients.
Administration and Dosage
For COPD patients who are acutely Hypoxic (body is deprived of adequate oxygen supply) due to causes other then COPD O2 therapy appropriate for that condition should be given until the effects of the hypoxia have been addressed then adjusted to maintain appropriate O2 Saturation levels.
Conditions for which patients should be monitored closely, BUT O2 therapy is not required unless hypoxic:
- myocardial infarction
- stroke
- pregnancy and obstetric emergencies
- hyperventilation or dysfunctional breathing
- most poisoning and drug overdose
- paraquat or bleomycin
- metabolic or renal disorders
- acuter and sub-acute neurological and muscular conditions producing muscle weakness.
Conditions for which patients should be monitored closely, BUT O2 therapy is not required unless hypoxic - GENERAL PRINCIPLES
If the patient is hypoxaemic, the initial therapy is nasal cannulae at 2-6Lpm or simple face mask at 5-10Lpm unless SpO2 is <88% then use reservoir mask/non-rebreather
Monitoring O2 therapy
If a patients respiratory rate falls below 10 breaths per minute O2 therapy should be discontinued and the patient monitored for improvement.
If the patients respiratory rate improves O2 therapy should be re-instated at a lower concentration.
If the respiratory rate remains below 10bpm ventilations should be assisted with a bag and mask with supplemental O2
Administer with caution
caution should be exercised with neonates.
after prolonged administration of high % O2 a condition termed ‘Detrimental Fibroplasia’ can result
Over-Oxygenation
Any patient who is receiving O2 must be monitored and SpO2 reading taken as soon as practicable.
if their respiratory rate drops below 10 breaths per minute then oxygen therapy must be discontinued.
If after 30 seconds, their respiratory rate has not improved, then assisted ventilations via bag & mask with reservoir bag attached and supplemental O2 at a rate of 12 to 15 breaths per minute must be commenced.
Reporting
O2 is a prescription only medicine and your are required by law to report its use.
You must record on the patient report form:
The concentration given
How long for
Effect of O2 on patient
SpO2 reading (before & after administration)