An inhaled gas that relaxes lung blood vessels
Nitric oxide (inhaled)
An inhaled gas used in intensive care to relax the blood vessels in the lungs when their pressure is too high, especially in newborns.
What is Nitric oxide (inhaled)?
Inhaled nitric oxide is a gas given through a breathing machine in intensive care to relax the blood vessels in the lungs. It is used mainly in newborn babies and in some lung conditions where the pressure in the lung blood vessels is too high, which makes it hard for blood to pick up oxygen. It must be weaned off gradually rather than stopped suddenly, because stopping abruptly can cause a rebound rise in lung pressure. It can also form harmful substances in the blood and breathing circuit, so these are closely monitored. It is used only in specialist intensive-care settings.
Education and reference only. This is a plain-language guide to Nitric oxide (inhaled) — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Inhaled nitric oxide is a medical gas delivered into the lungs, usually through a ventilator (breathing machine), in intensive care. When the blood vessels in the lungs are too tight and their pressure is too high, blood struggles to flow through and pick up oxygen. Nitric oxide, breathed in, relaxes those vessels where it is needed most, in the parts of the lung that are being ventilated. It is used particularly in newborn babies with high lung pressures and in some other serious lung conditions. It is a specialist, closely supervised treatment given only in critical-care settings.
How it works
When nitric oxide is breathed in, it acts on the muscle in the walls of the lung's blood vessels and makes them relax and widen. This lowers the high pressure in the lung circulation and lets more blood flow through the well-ventilated parts of the lung, so the blood picks up oxygen more easily. Because it is breathed in, it works mainly in the lungs and has less effect on the rest of the body's blood pressure. Its effect lasts only while it is being given, which is why it is delivered continuously and must be reduced gradually rather than stopped all at once.
Company & origin
Originated / developed by: Specialist manufacturer.
A specialist inhaled gas used in UK intensive care, particularly for newborns and some lung conditions where the pressure in the lung blood vessels is too high.
Practical use
How to take Nitric oxide (inhaled)
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given continuously through a breathing machine by specialist intensive-care teams.
- It must be reduced gradually when stopping, never switched off suddenly, to avoid a rebound rise in lung pressure.
- Blood is checked for methaemoglobin, a form of the blood pigment that cannot carry oxygen well.
- The breathing circuit is monitored for nitrogen dioxide, an irritant gas that can form with oxygen.
- It is used only with the specialist equipment that controls and measures the gas accurately.
Weighing it up
Advantages & disadvantages of Nitric oxide (inhaled)
Advantages
- Relaxes the lung's blood vessels and lowers high lung pressure, helping blood pick up oxygen.
- Acts mainly in the lungs, with less effect on the rest of the body's blood pressure.
- An important option for newborns and some serious lung conditions in intensive care.
Disadvantages
- Must be weaned off gradually, as stopping suddenly can cause a rebound rise in lung pressure.
- Can form methaemoglobin in the blood and nitrogen dioxide in the breathing circuit, both needing monitoring.
- Can only be given with specialist equipment in an intensive-care setting.
Practical use
Good to know
There are several important safety points, all of which are why this gas is used only in intensive care. First, it must be weaned off slowly: stopping it suddenly can cause a sharp rebound rise in lung pressure and a drop in oxygen, so the amount is reduced step by step. Second, nitric oxide can react in the body to form methaemoglobin, a changed form of the blood's oxygen-carrying pigment that cannot carry oxygen well, so blood levels are checked. Third, in the breathing circuit it can combine with oxygen to form nitrogen dioxide, an irritant gas, so this is measured too. The treatment is delivered by specialist equipment that controls and monitors the amount given, and the team watches the response closely throughout.
Who should not take it / use with caution
- Babies whose circulation depends on blood bypassing the lungs in a particular way may not be suitable, under specialist judgement.
- People with certain blood disorders affecting the oxygen-carrying pigment need special care.
- It is used only under specialist intensive-care supervision with the right monitoring.
Monitoring
- Regularly checking blood methaemoglobin levels.
- Measuring nitrogen dioxide in the breathing circuit.
- Watching oxygen levels and lung pressure closely, especially when reducing the gas.
Side effects
- A rebound rise in lung pressure and a fall in oxygen if it is stopped too suddenly.
- A build-up of methaemoglobin, a form of the blood pigment that cannot carry oxygen well.
- Irritation from nitrogen dioxide, an irritant gas that can form in the breathing circuit.
Key interactions
- Other medicines that affect the blood pigment, such as some that cause methaemoglobin, are reviewed alongside it.
- Other treatments for lung pressure may be used together, under specialist guidance.
- Its effects are managed within the wider intensive-care plan rather than as a stand-alone medicine.
Available as: A gas delivered into the lungs through a ventilator using specialist equipment.
Answers
Nitric oxide (inhaled): frequently asked questions
What is inhaled nitric oxide used for?
It is used in intensive care, especially in newborns, to relax the lung's blood vessels when their pressure is too high, helping the blood pick up oxygen.
Why can't it be stopped suddenly?
Stopping it abruptly can cause a rebound rise in lung pressure and a drop in oxygen, so it is weaned off gradually.
What is methaemoglobin and why is it checked?
Nitric oxide can turn some of the blood's oxygen-carrying pigment into methaemoglobin, which cannot carry oxygen well, so blood levels are monitored.
Why is nitrogen dioxide measured?
Nitric oxide can combine with oxygen in the breathing circuit to form nitrogen dioxide, an irritant gas, so this is measured to keep it low.
Where is it given?
It is given only in intensive care, using specialist equipment that controls and monitors the gas, under close supervision.
Authoritative sources
- BNF
- NICE CKS
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