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Carbon monoxide monitors in clinical practice

Jennifer Percival
RCN Tobacco Education Project

Carbon monoxide (CO) is a poisonous gas. It has no colour or smell and is found in car exhaust fumes, faulty gas boilers and tobacco smoke. In large amounts it is fatal. All smokers take CO into their lungs when they inhale, and it then gets rapidly absorbed into their bloodstream. Smokers can have up to 20% less oxygen circulating in their blood than nonsmokers. A high blood CO level increases the risk of circulatory problems, heart attack and stroke. This is one of the reasons why stopping smoking is one of the best things people can do to improve their health.
Nurses who run smoking cessation clinics understand that patients need to be highly motivated before they will benefit from receiving pharmacotherapy treatments. Many people who try to stop fail in the first few days. A CO monitor is an excellent tool to both validate a smoker's progress and motivate them to continue a cessation attempt. A low CO reading will encourage them to stay stopped as their personal health benefits are clearly demonstrated. The immediate benefits of stopping are increased energy, better circulation and greater concentration.
A CO monitor is a simple tool to use. Although there are several models available, the operating systems are all similar:

  • Take in a deep breath.
  • Hold it for 15 seconds.
  • Put your lips around the cardboard mouthpiece, making a seal.
  • Gently blow out through your mouth all of the air in your lungs.
  • Within a few seconds the indicator will display a CO reading.

Each monitor is supplied with a chart to help you interpret the reading for a patient. The reading shows how the person has been inhaling smoke and how recently, not the number of cigarettes smoked. The deeper people inhale, the higher the CO reading will be.  For example, cigar and pipe smokers can have very high CO readings. The reading is also dependent on the time that has elapsed since they last smoked, as the CO level in the blood halves in 4-5 hours. The longer people go without smoking, the lower their level becomes. People concerned about their exposure to passive smoke can use a CO monitor to check their CO levels.
Many nurses find CO monitors excellent tools to encourage smokers to consider quitting. For a practice nurse doing a new patient or routine health check, having access to a CO monitor may make it easier to bring up the subject of smoking. CO tests could be offered annually to all smokers. Most smokers are unaware of the effects of CO on their circulation, and a reading gives the nurse an opportunity to demonstrate the immediate effects of smoking and discuss their interest in cessation, even with people who are not yet ready to quit.
When working with smokers who are considering making a quit attempt, it is useful to record a CO reading before they start and at regular times during the attempt. CO validation is required by the Department of Health on their monitoring forms for staff working in smoking cessation services. If you do not have a CO monitor, you may be able to borrow one from your local smoking cessation service. The NHS Smoking Helpline (0800 169 0 169) has a list of the services across England and can provide you with contact details (see Resources). Smokers can also buy their own personal breath tester (Freedom Smokerlyzer®), enabling them to monitor their progress.

NHS Smoking Helpline
0800 169 0 169
Open 7am-11pm every day
NHS Pregnancy Smoking Helpline
0800 169 9 169
Open 12 midday to 9pm every day
Textphone users
0800 169 0 171
NHS Smoking Helpline
0800 169 0 169
NHS Asian Tobacco Helplines
Urdu: 0800 169 0 881
Punjabi: 0800 169 0 882
Hindi: 0800 169 0 883
Gujarati: 0800 169 0 884
Bengali: 0800 169 0 885
Open 1pm-9pm Tuesdays