Quantitative systematic review: Sources of inaccuracy in manually measured adult respiratory rate data.
Noa Kallioinen, Andrew Hill, Melany J Christofidis and 2 others
PMID 33038030WHAT IT FOUND
Manually counted respiratory rates are frequently wrong.
Short counts underestimate breathing, patients slow down when watched, and staff often skip recording or just write down normal numbers like 18 or 20. Treat recorded rates as unreliable unless you measured them yourself.
Key findings
01Short observation times systematically underestimate respiratory rate, with 15-second counts averaging about 2 breaths per minute lower than the true rate.
02Patients who know their breathing is being measured slow down, causing an average drop of 2.13 breaths per minute compared to when they are unaware.
03Respiratory rate is often omitted from records, with a predicted omission rate of 58.1% in general hospital audits and 47.8% before patient deterioration events.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
Many of the included studies had small sample sizes or used mock patients and healthy volunteers rather than real clinical populations, which may limit how well the findings apply to sick patients. The quality of evidence varied, and for some sources of inaccuracy like observer variability, there were only two studies available. Most studies did not report detailed characteristics of the observers, such as their experience level, making it difficult to determine if certain staff are more prone to these errors. The review focused exclusively on manual measurement, so it does not address errors associated with automated devices.
Declared interests
The fifth author holds a relevant patent for methods and means of physiological monitoring, though the authors state none of the cited papers relate directly to it. All other authors declared no conflicts of interest.
The easy way to misread this
Do not assume that a charted respiratory rate of 18 or 20 means the patient's breathing is normal. These values are frequently estimated rather than measured, and patients often slow their breathing when they know they are being watched. A normal-looking charted rate can mask significant deterioration if the measurement was not taken unobtrusively and for the full 60 seconds.