Objective To evaluate a novel device (Respimometer) for objective measurement of respiratory rate (RR) in low-resource settings.

Design Description of prototype development, with proof-of-concept pilot field study at four paediatric healthcare facilities in Butembo, Democratic Republic of the Congo (DRC). The instrument was tested in healthy adult volunteers (n=10) and Congolese children (n=42) and compared with timed breaths (adults) or by reference comparator capnography (children). Correlation and Bland-Altman plots were generated for paired measurements.

Results The Respimometer is shaped like an oral thermometer and is placed in the mouth of the participants. RR is measured by thermistors positioned at the nasal outlet, which detect the temperature change between inhaled and exhaled breaths. In adult volunteers, the correlation coefficient between the delivered RR and the Respimometer measurement was median 0.992 (IQR 0.980–0.999). Measurement bias was −0.50 min⁻¹ (95% CI −1.1 to +0.07, p=0.093), with upper and lower limits of agreement of −5.2 min⁻¹ and 4.2 min⁻¹, respectively. Among Congolese children, there was no evidence of bias: mean difference in RR +1.0 min⁻¹ (95% CI −2.1 to +4.1, p=0.52). The upper and lower limits of agreement were −18 and +20 min⁻¹, respectively.

Conclusion The Respimometer can accurately measure the RR in healthy adults and children in DRC. A simple and accurate instrument could facilitate the diagnosis of pneumonia by community health workers in low-income and middle-income countries, leading to reduced pneumonia-related deaths.