Effectiveness of deep breathing exercises on anxiety, depression and sleep quality in patients undergoing coronary artery bypass surgery

This study investigated the effect of deep breathing exercises on sleep quality, anxiety, and depression in coronary artery bypass graft patients. This is a clinical trial with 2 parallel groups (intervention, control) that was conducted on 80 patients underwent coronary artery bypass surgery. Participants were randomly assigned to the groups using a computer-generated random sequence. Allocation was concealed using sealed opaque envelopes prepared by an independent researcher. The intervention group performed deep breathing exercises every three hours, 10 breaths each time, for four days post-surgery. Both groups completed the Hospital Anxiety and Depression Scale at four time points: before intervention (T0), discharge (T1), 15 days later (T2), and one month post-discharge (T3). The Pittsburgh Sleep Quality Index was completed at T0 and T3. Due to the nature of the intervention, blinding of participants and intervention providers was not feasible. However, outcome assessor at T2 and T3 and data analyst were blinded to group assignments to minimize bias. In the intervention group, mean anxiety scores decreased from 10.35 at T0 to 6.97 at T1, 8.92 at T2, and 8.20 at T3 (η² = 0.08, p < 0.05). Depression scores decreased from 10.45 at T0 to 7.92 at T1, 8.77 at T2, and 7.65 at T3 (η² = 0.05, p < 0.05). Sleep quality improved significantly from 9.72 at T0 to 2.82 at T3 (p = 0.0001). Data were analyzed using repeated measures ANOVA with Bonferroni post-hoc tests and independent and paired t-tests. Deep breathing exercises, as a simple and non-pharmacological nursing intervention, can reduce anxiety and depression and improve sleep quality in CABG patients. Nurse-led training of deep breathing is strongly recommended to support psychological well-being and sleep management in these patients.This research has been registered in Iran's Clinical Trials Registry on 18/12/2023 (IRCT20231208060294N1).