BackgroundAnxiety-related dyspnea is a compelling symptom among patients with acute heart failure (AHF). Breathing training is a nonpharmacological intervention to relieve dyspnea and anxiety. This study aimed to investigate the effects of breathing training on dyspnea and anxiety among patients with AHF at the emergency department (ED). MethodsTwo-group pre-post intervention study was conducted at the ED of one university hospital in the northeast of Thailand. Data were collected among 96 patients with AHF, which were equally assigned to breathing training (BT) and control groups. The training group received pursed-lip mindfulness breathing training, whereas the control group received usual care (UC). The pursed-lip mindfulness breathing was delivered from the first 40 min of arrival to the 4th hour in the ED. The breathing training consisted of positioning the patients in Fowler's position with the head of the bed elevated at 60 degrees or higher, supporting both arms with pillows, and breathing in through the nose with breathing out via the mouth with pursed lip while counting. Dyspnea and anxiety scores were measured with Dyspnea Visual Analog Scale and Anxiety Visual Analog Scale, respectively. ResultsThe dyspnea and anxiety scores significantly decreased after four hours in both groups. Dyspnea score decreased from 8.85 (SD 1.220) to 3.63 (SD 1.468) after BT (t = 26.111, p < 0.001) in the experimental group whereas in the control group it decreased from 8.98 (SD 1.194) to 6.94 (SD 1.590) after UC (t = 16.181, p < 0.001). Comparing between the groups, dyspnea score reductions were 5.22 (SD 1.468) in the experimental and 2.04 (SD 1.590) in the control (t = 0.101, p < 0.001). Anxiety score decreased from 9.35 (SD 1.000) to 4.44 (SD 1.219) after BT (t = 25.231, p < 0.001) in the experimental while the scores in the control group decreased from 9.48 (SD 1.072) to 8.15 (SD 1.502) after UC (t = 8.131, p < 0.001). The anxiety score reductions were 4.91 (SD 1.219) and 1.33 (SD 1.502) in the experimental and the control groups, respectively (t = 0. 066, p < 0.001). Both the dyspnea and anxiety scores after the intervention were significantly different between the experimental and control groups. ConclusionBoth UC and BT with UC can reduce dyspnea and anxiety in patients admitted to ED with AHF. However, the effect of BT combined with UC was larger comparing to UC only.