Ordinal scales are not accurate to assess and measure respiratory rates in children

Background: Respiratory rate is an important vital sign used in the initial and ongoing assessment of acutely ill children. It is also used as a predictor of serious deterioration in a patient’s clinical condition. Predefined ordinal scales to assess respiratory rate may be used to increase the reporting of respiratory rate where a count is potentially deemed too time consuming and laborious. Aims: The aim of this study was to assess the agreement in respiratory rate assessment when a ordinal scale was used. Method: 100 healthcare professionals who regularly measured children’s respiratory rates as part of their normal working role were shown videos of five different children of varying ages breathing at different rates. They were then asked to use a pre-defined scale of very slow, slow, normal, fast and very fast to grade the child’s respiratory rate. Results: There was a moderate to fair agreement between observers when a pre-defined ordinal scale was used to assess respiratory rate, with a Fleiss Kappa statistic of 0.333. Within different groups of healthcare professionals there was a similar level of agreement seen, with a Fleiss Kappa statistic for paediatric nurses of 0.334, paediatric doctors 0.365 and other healthcare professionals 0.318. At higher respiratory rates there was better agreement observed. Conclusion: An ordinal scale may be of use where a standard visual count is not practicable, however the level of agreement found between healthcare professionals is unlikely to be high enough for this method of respiratory rate assessment to be taken and used regularly in clinical practice.