Entonox (Nitrous Oxide 50% / Oxygen 50%)

The pinned product is ENTONOX MEDICINAL GAS (PL007355017, BOC Ltd), the 50:50 premix, and its §4.1 names the page's use: 'short-term relief for procedures inevitably involving pain, such as wound and burn dressing, wound debridement and suturing'. The brand 'Equanox' is not named in this SPC. §2 (verbatim): 'Oxygen 50.0 % +/- 2.0 % Nitrous Oxide 50.0 % +/- 2.0 %'. §4.1 (verbatim): 'Entonox is used exclusively for the relief of pain.' Examples printed: acute trauma; short-term relief in dental work; procedures inevitably involving pain such as wound and burn dressing, wound debridement and suturing; normal labour; acute surgical or medical conditions in which the pain is relieved only to return on cessation of the analgesia. VERBATIM §4.2: 'Entonox is administered through a facemask or mouthpiece. The facemask or mouthpiece is connected to an Entonox supply through a demand valve system which allows the Entonox to be self-regulated by the patient. The demand valve is operated by the act of inhalation of the patient and closes down when the patient ceases to inhale. In nearly all cases, Entonox is self-administered, but it may be administered by attendant medical personnel. Since pain is usually relieved by a concentration of 25% nitrous oxide, continued inhalation does not occur. However, should inhalation continue, light anaesthesia occurs and the mask or mouthpiece drops away as the patient relaxes, or is removed if administration has been by attendant personnel. There are no contra-indications to the use of Entonox in any age group. Entonox should not be used for more than a total of 24 hours, or more frequently than every 4 days, without close clinical supervision and haematological monitoring.' This is a fixed-composition gas titrated by the patient's own inhalation: the SPC prints no flow rate, volume, onset time or per-session duration, and the only printed use limit is the 24 hours total / every 4 days limit, which is a duration rule and not a dose, so maxDose is left unset. No paediatric block is written: the SPC prints no age-specific dose, minimum age or paediatric technique (§4.2 says only 'There are no contra-indications to the use of Entonox in any age group'; the §4.3 gas-entrapment contraindications still apply). KEY SAFETY (verbatim §4.4): 'Caution should be exercised before using Entonox with patients who have known Chronic Obstructive Pulmonary Disease (COPD) or other conditions where compromised chemoreceptor sensitivity/function may be present' (relatively high oxygen concentration may cause respiratory depression and increases in PaCO2); the use of gases containing more than 21% oxygen should be avoided after exposure to agents toxic to the lungs such as paraquat; waste gas should be scavenged to below 100 ppm; Entonox is non-flammable but strongly supports combustion - no smoking, and no oils or grease on the cylinder or equipment.