Respiratory rate is among the first vital signs to change in deteriorating patients. The aim was to investigate the agreement between respiratory rate measurements by three different methods.Methods:
This prospective observational study included acutely admitted adult patients in a medical ward. Respiratory rate was measured by three methods: a standardised approach over 60 s while patients lay still and refrained from talking, by ward staff and by a wireless electronic patch (SensiumVitals). The Bland-Altman method was used to compare measurements and three breaths per minute (BPM) was considered a clinically relevant difference.Results:
We included 50 patients. The mean difference between the standardised approach and the electronic measurement was 0.3 (95% CI: −1.4 to 2.0) BPM; 95% limits of agreement were −11.5 (95% CI: −14.5 to −8.6) and 12.1 (95% CI: 9.2 to 15.1) BPM. Removal of three outliers with huge differences lead to a mean difference of −0.1 (95% CI: −0.7 to 0.5) BPM and 95% limits of agreement of −4.2 (95% CI: −5.3 to −3.2) BPM and 4.0 (95% CI: 2.9 to 5.0) BPM. The mean difference between staff and electronic measurements was 1.7 (95% CI: −0.5 to 3.9) BPM; 95% limits of agreement were −13.3 (95% CI: −17.2 to −9.5) BPM and 16.8 (95% CI: 13.0 to 20.6) BPM.Conclusion:
A concerning lack of agreement was found between a wireless monitoring system and a standardised clinical approach. Ward staff's measurements also seemed to be inaccurate.