Introduction: A common misconception is that increased work of breathing (WOB) in hospitalized patients can be ruled-out when arterial O 2 tension (or saturation) is adequate and arterial PCO 2 is not elevated. Unrecognized WOB increase leads to respiratory muscle fatigue, cessation of respiratory function, and cardiac arrest. We previously developed a WOB Scale for bedside use adding points (maximum 7) based on respiratory rate (1 to 20 bpm = 1 point; 21 to 25 bpm = 2 points; 26 to 30 bpm = 3 points; and > 30 bpm = 4 points), nasal flaring (No = 0 points; Yes = 1 point), activation of the sternocleidomastoid muscle (No = 0 points; Yes = 1 point), and activation of abdominal muscles (No = 0 points; Yes = 1 point). A WOB Scale > 3 points typical identifies a patient in need of intervention to reduce or support WOB increase. However, widespread application of our WOB Scale - especially outside intensive care environments - would likely benefit from a simplified approach. Thus, we investigated developing a “reflex” approach whereby measurement of all four components would be contingent on the respiratory rate level. Methods: We analyzed 110 WOB Scale measurements in a mixed population of ICU and General Ward patients and assessed WOB Scale levels hypothesizing that a respiratory rate of 1 point (1 to 20 bpm) would be predictive of a low WOB Scale (i.e., not exceeding 3 points); thus, obviating the need to perform a complete WOB Scale evaluation. Results: The WOB Scale distribution showed that most patients had normal WOB with only 14 patients (12.7%) having a WOB Scale > 3 points (i.e., 1 point = 60; 2 points = 24; 3 points = 12; 4 points = 6; 5 points = 7; 6 points = 1; 7 points = 0). A respiratory rate level of 1 point (i.e., 1 to 20 bpm), occurred in 68 patients and only 3 (1.5%) had a WOB Scale > 3 points. Yet, when the respiratory rate level was 2 points (i.e., 21 to 25 bpm), which occurred in 28 patients, 3 (10.7%) had a WOB Scale > 3 points. Respiratory rate levels of 3 or 4 points (> 26 bpm) were associated with activation of at least one accessory respiratory muscle examined in 64% of the patients. Conclusions: A respiratory rate of 20 bpm or less predicted low WOB in most patients supporting a Reflex WOB Scale whereby respiratory accessory muscle activation is assessed only when the respiratory rate exceeds 20 bpm.