A new hand-held device that can tell if an asthma sufferer is close to having an attack hours in advance has been developed by researchers.
The hand-held sensor could give patients vital time to take anti-inflammatory medicines and prevent a serious episode that may otherwise land them in hospital.
The Siemens device is the size of a mobile phone and works by analysing a patient's breath and measuring the amount of nitrogen monoxide (NO).
It is so sensitive it can measure amounts as small as one ppb (part per billion), which is the same as the dilution of a cube of sugar in a 50m swimming pool.
The Siemens system first converts nitrogen monoxide from a person's breath into nitrogen dioxide, after which the air flows across the actual sensor.
The manufacturer said only the particles signaling the attack adhere to the sensor's surface. This generates a voltage that is measured by a field-effect transistor.
The intensity of the voltage is directly dependent on the amount of nitrogen monoxide in the patient's breath. On the basis of this value, the patient can decide what dose of anti-inflammatory medication he or she should take.
"We know that exhaled NO levels and inflammation in the lungs often go hand in hand, and that high levels of NO can indicate that a person's asthma is uncontrolled," the Daily Mail quoted Dr Elaine Vickers, Research Relations Manager at Asthma UK, as saying.
"What researchers are not sure of yet is whether this information is sufficient to decide what medicines a person should take.
"The creation of sensitive and accurate hand-held NO monitors such as this is a welcome step forward, however they will require careful evaluation," Vickers added.