Breath carbon monoxide
Breath Carbon Monoxide (CO) Monitor or Smokerlyzer
A CO monitor measures the level of CO on your breath. This is used as a validational, motivational and educational tool in smoking cessation as it is the easiest, quickest and lowest cost method of ascertaining smoking satus[1]. The CO monitor replaces self-reported smoking as this has previously been shown to be unreliable[2].
Some writers have described CO monitors as "The Stethoscope of Smoking Cessation"[3]. Another widely used term is the 'Smokerlyzer', coined by UK company Bedfont Scientific Ltd, as identified by Dr Chris Steele in 1994[4]
The CO monitor measures CO in Parts Per Million (PPM), this level has been shown to have a close relationship with the level of CO in the blood known as carboxyhaemoglobin (%COHb) or 'blood CO'[5]. This allows for the level of CO in the blood to be indirectly measured on the breath by the CO monitor by using an algorithm[6]. Recent clinical studies have also found that there is a direct link between the level of CO on an expectant mother's breath and the level of CO in her unborn child's blood, this is known as "Feotal carboxyhaemoglobin" (%FCOHb)[7]. this level has also been found to be on average 1.8 times higher in the baby than in the mother[8]. This relationship is also used in some more advanced CO monitors in order to educate on the dangers of smoking whilst pregnant.
The National Institute for Clinical Excellence (NICE) stipulates that a non-smoker is identified by a reading of less than 10ppm CO[9]. Recent NICE guidlines for pregnant smokerls have been published stipulating a level of 7ppm as the indentification of a non-smoker[10]. This guidance can be viewed at: http://www.nice.org.uk/
Taking a Breath CO Reading
Taking a CO reading is very simple:
1. The patient inhales and holds their breath for approximately 15 seconds, this is illustrated by a count-down timer on the CO monitor
2. When the timer reaches 0 the patient places their mouth around the mouthpiece, making a complete seal, and exhales slowly but fully until the lungs are empty.
3. The CO monitor will then give a reading in PPM and %COHb, some more advanced CO monitors will also show the level of %FCOHb.
4. This level can then be interpreted using a CO conversion chart to show how high that particular patients' reading is. Such a conversion chart can be found here - CO Interpretation Chart
CO Poisoning
Another use for the breath CO monitor is screening for and diagnosing CO poisoning within the emergency services. Carbon monoxide is a colourless, odourless and tasteless gas which is therefore very difficult to detect[11]. CO poisoning can occur in many ways where incomplete combustion is present, the most common being house fires or faulty gas appliances. Sometimes when patients are succesfull in stopping smoking they may still have a high CO reading due to the aforementioned reasons. Although this is rare the Health Protection Agency has produced an algorithm to help with the diagnosis of CO poisoning and what to do in the event of diagnosis. This is available here - HPA CO Poisoning Algorithm
For more information on CO poisoning visit Wikipedia's CO Poisoning page.
References
- ^ M. Jarvis (1986) Low cost carbon monoxide monitors in smoking assessment. Thorax pp.886-887
- ^ J Irving (1988) Evaluation of a Portable Measure of Expired-Air Carbon Monoxide. Preventive Medicine 17 pp.109-115
- ^ R Bittoun (2008) Carbon Monoxide Meter: The Stethoscope of Smoking Cessation
- ^ C Steele (1994) Is Smoking a Disease?
- ^ M. Jarvis (1986) Low cost carbon monoxide monitors in smoking assessment. Thorax pp.886-887
- ^ M. Jarvis (1986) Low cost carbon monoxide monitors in smoking assessment. Thorax pp.886-887
- ^ C Gomez (2005) Expired air carbon monoxide concentration in mothers and their spouses above 5ppm is associated with decreased fetal growth. Preventive Medicine 40 pp. 10-15
- ^ P Cole et al (1972) Smoking During Pregnancy and its Effect on the Fetus
- ^ NHS Stop Smoking Services; Service and Monitoring Guidance 2010/11
- ^ National Institute of Clinical Excellence: How to stop smoking in pregnancy and following childbirth guidance
- ^ M Ainsworth-Smith (2009) Find the Cause Before the Cause Finds You! Ambulance Today pp.21