Xenon is Greek for stranger. It was discovered in 1898 and
found to be the only noble gas to be anaesthetic under normobaric conditions. Xenon is
extremely scarce with an average room containing only 4ml.
Manufacture is by fractional distillation of air and costs
2000 times more than N 2 O.
Commercial uses include lasers, high intensity lamps,
flash bulbs, aerospace, X-ray tubes and medicine.
- Colourless, odourless, tasteless.
- Monatomic gas, atomic number = 54, molecular weight = 131,3
- Gas undr normal temperature and pressure
- 9 stable isotopes.
- Freezing point -111,9 o C, Boiling point -108,1 o C.
- 4 times more dense than air.
- Nonflammable and will not support combustion.
- Diffuses freely through rubber and silicone components.
- First used in 1951 by Cullen on an 81yr old man having an
- Very close to the ideal agent
- The very large electron shell of xenon ca be distorted and polarised by nearby
molecules, creating a dipole.
- Xenon inhibits the plasma membrane Ca 2+ pump, altering excitability. It
inhibits the nociceptive responsiveness of spinal dorsal horn neurons.
- MAC = 71%. (With more widespread usage the Russians have
noticed the MAC to be closer to 60%)
- Minimal haemodynamic effects.
- Lowest blood/gas partition coefficient = 0,115 of currently
available inhalational agents.
- Low oil/water partition co-efficient of 20.
- Rapid induction and eduction regardless of duration of
- 4 stages of anaesthesia noted with 70% Xenon/ 30% oxygen.
- Whole body paraesthesia & hypo-algesia.
- Euphoria & increased psychomotor activity.
- Analgesia with partial amnesia (after 3-4min).
- Surgical anaesthesia with a degree of muscle relaxation.
- Equivalent analgesia when compared with equipotent doses of
N 2 O The analgesia produced by both gases is not reversible by naloxone.
- No occupational/ environmental disadvantages.
Specific effects on the body
- Central depression causes a decrease in respiratory rate
with a compensatory increase in tidal volume and can progress to apnoea
- Higher density and viscosity (compared with oxygen, air
and N 2 O) theoretically makes xenon more likely to increase airway
resistance. Clinically the airway resistance is slightly less than that seen with N 2 O
and it can be used safely in lung disease
- Diffusion hypoxia is very mild as the blood/gas partition
of Nitrogen (0.014) is only 10 times less than that of Xenon (0.14) as opposed to the
almost 40 times less than Nitrous Oxide (0.47)
- No inhibitory effects on cardiac ion channels i.e. calcium,
sodium and inward potassium channels.
- No significant change in contractility, blood pressure and
- Some reports of decrease in heart rate with variability in
- No sensitisation of the myocardium to adrenaline
- May attenuate the myocardial depressant effects of
- In an animal study, xenon anaesthesia produced the highest
regional blood flow to brain, liver, kidneys and GIT. The control groups were 1%
halothane in Nitrous oxide and thiopentone with fentanyl.
- Central nervous system
- Xenon increases cerebral blood flow,
increases intracranial pressure and decreases cerebral perfusion pressure in acute head
injury patients. This is not associated with cerebral oligaemia or ischaemia.
- This increase in cerebral blood flow is reveresed by mild
- At present it is not recommended for neurosurgery.
- Attenuates surgical stress due to
analgesia. Does not have any short or long term cortisol suppresion effects.
- Platelet aggregation potentiated at 2atm (relevant to
- No reported haematological toxicity.
- Malignant hyperthermia
- Seems not to trigger malignant hyperthermia.
- Metabolism and elimination
- Unlikely to be involved in any biochemical events in the
- Eliminated via the lungs.
- Under special conditions xenon is capable of forming
compounds with very reactive elements e.g. clathrates, fluorides & chlorides
Potential ways to make xenon anaesthesia economically
- Decreasing manufacturing costs.
- This is only practical in large air
- Current price is 10 US$/ litre
- Manufacture will increase as aerospace
applications grow, but as this xenon is then lost to the atmosphere this will not
contribute to decreasing the cost.
- Use in a fully closed breathing system
- Use of semiclosed systems (facemasks/LMA/spontaneous
breathing) cost £1200/hr.
- Very low flow e.g. 0,3 l/min will cost £160-180/hr.
- Fully closed automated systems are available that are
suitable for xenon anaesthesia
- Gas piston circle
- physioflex device
- Balanced circle systems.
- Circle priming
- Recycling devices are the only way of guaranteeing the
availability of a sufficient amount of xenon for routine clinical use.
- Gas analysis
- Xenon can be measured with mass spectrometry, piezoelectric
absorption, thermal conductivity and ultra-sound.
- Nitrogen must be washed out by giving a high flow of pure
oxygen for at least 5 minutes
- Normal induction and muscle relaxation
- After intubation connect the patient to an appropriate
anaesthesia delivery system
- The hypnotic concentration of 40-45% is achieved
- The anaesthetic concentration of 60-70% takes approximately
- Colourless and odourless gas with no irritation to the
respiratory tract. Well tolerated with gas induction
- Low blood/gas and oil/water partition co-efficients
allowing rapid induction and eduction
- Produces unconsciousness with analgesia and a degree of
- MAC of 60-70% allows a reasonable inspired oxygen
- It does cause respiratory depression, to the point of
- It is cardiac stable.
- Not metabolised in the body and is eliminated rapidly and
completely via the lungs.
- It is non toxic and is not associated with allergic
- Stable in storage, no interaction with anaesthesia circuits
or soda lime. Should not be used with rubber anaesthesia circuits as there is a high
loss through the rubber
- Non flammable
- Expensive - Routine usage will only be possible with a
closed circuit delivery system that recycles xenon.
Owing to environmental concerns there may be no
alternative but to use xenon even if it incurs an increase in cost.