What is Entonox?

Entonox is the trade name for a mixture of fifty percent nitrous oxide (N2O or paradise gas) and fifty percent oxygen (O2).

What is Entonox used for?

It is used for short-term inhalation anesthesia during minor surgical procedures, during painful treatment in children (who are able to cooperate and hold the mask themselves). Its analgesic effect is strong (equivalent to 5 to 10 mg of morphine) and is characterized by a rapid onset and offset (i.e., it works very quickly and wears off very quickly).

How is Entonox administered?

Entonox is administered by inhalation from a cylinder. Self-administration of Entonox is safe because if enough is inhaled to initiate anesthesia, the patient will no longer be able to hold the valve, drop it, and soon exhale the residual gas. Unlike other anesthetic gases, the presence of an anesthetist is not required for administration. The 50% oxygen in Entonox ensures that the person will have enough oxygen in their airways to make the application safe.

When should Entonox not be administered (contraindications)?

In patients with signs or symptoms of pneumothorax, pneumopericardium, severe emphysema, gas embolism, or head injury.

After diving at depths with the risk of decompression sickness (nitrogen bubbles).

After cardiopulmonary bypass with extracorporeal circulation or after coronary bypass without extracorporeal circulation.

In patients early after intraocular gas injection (eg SF6, C3F8) until the gas is completely absorbed, as the volume or pressure of the gas may increase and subsequently cause blindness.

In patients with severe dilatation of the gastrointestinal tract.

 In patients with heart failure or cardiac dysfunction (e.g. after cardiac surgery) to avoid the risk of further deterioration of cardiac function.

In patients who show signs of confusion or show other symptoms of increased intracranial pressure.

In patients with reduced consciousness or reduced ability to cooperate and follow instructions due to the risk that further nitrous oxide sedation may affect natural protective reflexes.

In patients with a diagnosed but untreated deficiency of vitamin B12 or folic acid or with a diagnosed genetic disorder of the enzyme system associated with the metabolism of these vitamins.

For patients with facial injuries where mask use may present problems or risks.