Respiratory rate is a strong indicator of clinical trajectory and forms the basis of patient care and assessment. However, clinicians often face barriers to easily obtaining a respiratory rate without inefficient methods or costly technology. To remedy this, several phone applications have emerged where clinicians can tap out each breath to calculate a respiratory rate. We aimed to map the available evidence for tap-per-breath applications used in healthcare settings. We searched for articles using multiple databases; including primary research articles which evaluated tap-per-breath apps in healthcare settings. 14 articles were selected for this review, mostly cross-sectional and hospital based. Most applications reported high usability and efficiency, although results of accuracy were mixed across the included literature. Median-based apps were more often an accurate measure of respiratory rate, however more research is required. Articles were commonly limited in generalisability due to poorly defined reference standards, small sample sizes, or using retrospective video recordings for patient assessment. Studies showed favourable usability and efficiency across the literature, with median-based apps demonstrating greater consistency and accuracy of respiratory rate measurements. Though the scope of this review and limited evidence restrict any far-reaching clinical implications until further evidence emerges.

Among the vital signs of patient assessment, respiratory rate (RR) has long been a reliable and effective means to detect early clinical deterioration. Notwithstanding its clinical relevance, nurses, doctors and paramedics often struggle to adopt respiratory rate in their standard practice – likely due to the onerous ergonomics of traditional methods such as manual counting with a watch or clock. These prominent barriers to respiratory assessment have driven the development of tap-per-breath mobile applications – where clinicians can “tap-out” each breath on a phone screen, employing an algorithm to calculate the rate per minute. This review aims to be an educational resource for tap-per-breath apps, how they can be used, and what future research awaits. There are several tap-per-breath apps available for healthcare workers to use, some with an established evidence-base, and some without. A prominent and well researched candidate for these apps is the RRate mobile application, developed by Karlen et al. in 2014. This has since been followed by various similar devices and apps, including Medtimer and ALRITE – all with a less substantial base of evidence. Clinicians can use tap-per-breath apps to enable easier respiratory rate measurement, with potentially more accuracy than the popular 15-second count. This not only gives an accurate snapshot to the physiology of a patient, but could allow clinicians to more frequently measure respirations, and detect patient deterioration earlier in their care trajectory. The uses for these applications extend beyond the familiar bedside respiratory assessment, with potential for this technology in newborn resuscitation, low-resource settings, and mass casualty triage. Whilst evidence is promising, this review is limited to educational use and only provides a conceptual map of what these apps do, and how they could be used. Further research should aim to systematically map the existing evidence for these apps and quantify effect sizes to determine if tap-per-breaths apps are accurate, efficient, and here to stay.