The BTS/SIGN guideline specifies that the accurate measurement of oxygen saturation is essential in the assessment of all children with acute wheezing. It recommends that oxygen saturation probes and monitors should be available for use by all healthcare professionals assessing acute asthma in primary care. It is important to use the appropriate size paediatric probe to ensure accuracy. Any patient who presents to the GP practice with any features of a moderate exacerbation should be referred to an emergency department for further assessment and monitoring.