Tenders for fiber-optic laryngoscopes often ask for “ISO 7376, green system”. The two are related but not the same: one is an international standard, the other a name for parts built to one of the fittings it defines.
What ISO 7376 is
ISO 7376 is the international standard for laryngoscopes used for tracheal intubation. It applies to laryngoscopes with rigid blades and battery-powered illumination, and it sets the critical dimensions for handles and blades with interchangeable hook-on fittings. It also contains general requirements, including a minimum light output, and test methods for illumination, rigidity and strength.
At the time of writing, the edition in force is ISO 7376:2020, amended in 2025 to clarify its optical output and illumination requirements, and a further revision is in development. Video laryngoscopes now have their own part, ISO 7376-2. When a supplier quotes the standard, ask which edition.
The hook-on fitting
Most laryngoscopes with detachable blades use a hook-on fitting. A slot in the base of the blade hooks onto a bar on the handle head; the blade then swings up, clicks into the working position and the light comes on. Folding it down switches the light off. ISO 7376 fixes the critical dimensions of this connection, so that conforming blades and handles from different makers can be used together.
What the green marking identifies
There are two ways of lighting the airway. In a conventional laryngoscope, a small lamp sits in the blade near the tip and draws power through contacts at the fitting. In a green-system fiber-optic laryngoscope, the light source sits in the handle head and the blade carries only a light guide, a glass fiber bundle or a solid guide, which takes the light to a window near the tip.
The two layouts use different fitting dimensions and light-source positions, so their parts are not designed to work together. To tell them apart, handles and blades made to the fiber-optic fitting are usually marked in green, with a ring, band or dot; hence the name green system. Our article on fiber-optic green system and conventional laryngoscopes covers the practical differences.
Why interchangeability matters to buyers
Hospitals rarely replace every blade and handle at once. Handles stay in service for years, while blades are added, replaced or switched between reusable and single-use. A shared fitting means that:
- new blades can be used on handles already in service, from the same maker or another;
- reusable and single-use green-system blades can share the same handles;
- a hospital is not tied to one supplier for replacements, which keeps tenders open to competition;
- in an emergency, a blade brought from another area is more likely to fit the handle at hand.
What the marking does not guarantee
The green marking is applied by the maker. It is not a certificate, and no third party issues it. It shows which fitting a part is built to, but on its own it does not prove conformity with the standard, and it says little about performance.
- Light output. The standard sets a minimum, but the light reaching the larynx depends on the lamp or LED in the handle, the batteries, the light guide in the blade and how well the parts line up. A blade from one maker on another maker’s handle can be dimmer than either maker’s own pairing.
- Durability. How a blade stands up to repeated cleaning and sterilisation depends on its materials, how the light guide is fixed and sealed, and the surface finish. The marking says nothing about this.
- Quality of manufacture. Consistent dimensions, smooth edges, a well-finished tip and a firm click come from manufacturing control. The evidence lies in the maker’s quality system, its test reports and your own inspection of samples.
A short buyer checklist
- Ask which edition of ISO 7376 the supplier declares conformity with, and for the supporting test report.
- Check that handles and blades carry the green marking and that the instructions for use (IFU) state compatibility with green-system parts.
- Try samples on your own handles: the blade should hook on easily, click firmly into position, light at once and switch off when folded.
- Ask how light output was measured (handle, blade, distance, battery condition), not just for a figure.
- Ask for the validated reprocessing instructions for reusable blades and handles.
- Confirm that spare lamps or LED heads, batteries and chargers are available.
If you are matching new blades to handles already in service, send the make and model of your handles to our export team.