Xenon, a by-product of oxygen production during fractional distillation of air. It is said to be a noble gas and is present in air 0.0000087%.
First recognized 50 years ago as an xenon gas anesthesia in 1957, used for orchidectomy in a 81- year-old. The patient woke up after 2 minutes.
Rediscovered in 1990, it is very expensive, 100 times more than N20. It is also used in X-ray tubes, lights; radioactive Xe is used in CBF and lung volume studies. At present it is used as an xenon gas anesthesia in Germany, Netherlands, Sweden, Russia and Japan.
Physical properties: Xenon has an atomic number of 54 and molecular weight 131.3. It is colourless, odourless, non-irritating, four times heavier than air, freezes at-Ill .9°C and boils at -107.1 o Xenon is non-flammable and does not support combustion; does not react with sodalime but diffuses through rubber.
Xenon gas anesthesia is more potent than N20 and has a MAC > NO. Xenon gas anesthesia can be used as a sole anaesthetic agent in 71% in Oxygen. The blood/gas coefficient is 0.115, lowest among all available agents.
Uptake and distribution: Xenon gas anesthesia is chemically inert. Used in a closed circuit, a prolonged de-nitrogenation is necessary; because of its fast uptake, nitrogen may accumulate in the circuit and hypoxic mixtures may be delivered.
It has a MAC of 70%, hence more potent than N20, so needs less supplementation. During induction, “concentration and second gas effect” are seen. Diffusion into cavities like pneumothorax, lung cyst, cavities in the brain, bowel and emboli is similar to nitrous oxide. There is no biochemical reaction, elimination is through the lungs.
Effect on organs: There is good haemodynamic stability with little effect on blood pressure. On trans-oesophageal echocardiography no change in left ventricular function was seen with 65% xenon. Xenon gas anesthesia is not metabolized in the liver or kidney, it is not teratogenic and does not trigger malignant hyperthermia in animals.
Xenon gas anesthesia does not deplete the ozone layer. Its analgesic, hypnotic and lack of cardiovascular effects is unique and is a choice in patients with low cardiac reserve. There may be a slight increase in pulmonary resistance.
With xenon gas anesthesia an ideal agent has arriyed except for its prohibitive cost. It has to be used in closed circuit or in low- flow systems.