Don't Hyperventilate Over Triage Respiratory Rates

Abstract

Are triage respiratory rates inaccurate? Absolutely. In this month’s Annals, Bianchi et al compared standard nurserecorded triage respiratory rates with those measured by a research assistant during 60 seconds and those obtained by a commercial respiratory rate sensor (BioHarness; Zephyr Technology, Corp, Annapolis, MD). Tachypnea ( 20 breaths/ min) was missed 77% of the time. This statistic is alarming because emergency physicians fundamentally rely on triage vital signs to help assess their patients. With tachypnea being missed three fourths of the time, we must be receiving false reassurance for substantial numbers of patients. Tachypnea is an integral diagnostic element of systemic inflammatory response syndrome and a key component of pneumonia scores (eg, Pneumonia Severity Index, CURB 65); accordingly, erroneous triage respiratory rates should result in misclassifications of patients. Is there any evidence this is really a problem? During your last shift, how many patients were harmed because their triage respiratory rate was inaccurate? Bianchi et al concluded that the solution is to change how respiratory rate is measured, perhaps by using the BioHarness device routinely at triage. This would be a time-consuming and expensive change for every emergency department (ED). But perhaps it must be done for the sake of accuracy. Let’s critically examine what we already know about respiratory rates, examine the implications of these new data, and then try to make sense of this conundrum. Taking vital signs is a standard prelude to every ED visit and essentially all health care encounters. There is little dispute that respiratory rate is the least objective vital sign. Bianchi et al demonstrated that routine triage assessments do not agree with measurements taken during a full minute (as recommended by the World Health Organization). Previous ED studies reported similar results. Indeed, the interrater reliability of measuring respiratory rates during a full minute is also poor, although this criterion standard has not been questioned. It is widely assumed that triage nurses often estimate respiratory rates rather than formally counting respirations for 15 seconds and multiplying by 4. Recorded values such as 14 or 18 breaths/min, which are indivisible by 4, support this contention. Bianchi et al reported that triage nurses most commonly record rates of 16 to 18 breaths/min, which seems consistent with anecdotal observations elsewhere. d