Table 3.

Intervention details.

		Population Characteristics			Breathwork Intervention Characteristics
Study reference/ year/ country	Study design a. Study type b. Design c. Setting	Diagnosis	Experimental group a. No. of participants (N) and sex b. Mean age	Control group a. No. of participants (N) and sex b. Mean age	Type of breathwork intervention	Breathwork protocol (treatment)	Details of breathwork intervention a. Duration of session b. No. of sessions c. Treatment duration d. Follow-up	Breathwork protocol (control)
Bonn et al. [61] 1984 England	a. Open pilot b. Between subject c. Clinical	Agoraphobia	a. N = 7 (4 females, 3 males) b. 35.5	a. N = 5 (3 females, 2 males) b. 39	Slow diaphragmatic breathing	Breathing retraining via guided diaphragmatic respiration, 8–10 BPM	a. 120 min b. 9 sessions c. 10 weeks d. 1, 6 months	Real-life exposure (9 × 120 min/9 weeks)
Conrad et al. [53] 2007 United States	a. Open pilot b. Between subject c. Research	Panic disorder	a. N = 13 (11 females, 2 males) b. 39.2	a. N = 15 (10 females, 5 males) b. 40.7	Direct attention to breathing, instructions to breathe more slowly and/or shallowly	Paying attention to breathing or breathing at a slower pace than usual or breathing shallower than usual or breathing shallower and slower than usual	a. 180 min b. 1 session c. NA d. NA	Same as treatment
de Ruiter et al. [64] 1989 The Netherlands	a. Randomized trial b. Between subject c. Clinical	Panic disorder with agoraphobia	a. N = 13 (7 females, 6 males) b. 34.0	a. N = 27 (17 females, 10 males) b. 34.0	Breathing retraining cognitive restructuring (BRCR)	Voluntary hyperventilation, hyperventilation and catastrophic thinking explanation, muscle relaxation training, slow diaphragmatic breathing training	a. 60 min b. 8 sessions c. NA d. NA	Graded self-exposure in vivo (8 × 60 min); breathing retraining or cognitive restructuring (4 × 60 min) plus graded self-exposure in vivo (4 × 60 min)
Gorman et al. [54] 1994 United States	a. Open pilot b. Between subject c. Research	Panic disorder/ agoraphobia	a. N = 24 (15 females, 9 males) b. 36.3	a. N = 18 (12 females, 6 males) b. 32.5	CO2 inhalation and room-air hyperventilation	(a) Air breathing (20 min). (b) 5% CO2 (20 min) or hyperventilation (15 min), metronome-guided breathing (30 BPM). (c) Air breathing (15 min). (d) 5% CO2 (20 min) or hyperventilation (15 min). (e) Air breathing (15 min). (f) 7% CO2 (20 min).	a. 35 min b. 1 session c. NA d. NA	Same as treatment
Herhaus et al. [67] 2022 Germany	a. Randomized trial b. Between subject c. Clinical	Panic disorder/ agoraphobia	a. N = 26 (19 females, 7 males) b. 35.7	a. N = 26 (17 females, 9 males) b. 35.7	Heart rate variability-biofeedback (HRV-BF) training	Heart rate variability-biofeedback at 0.1 Hz breathing (10 × 20 min), and at-home breathing training with 0.1 Hz breathing via audio track (2 × 20 min/day)	a. 20 min b. 10 sessions c. 4 weeks d. NA	Sham HRV-B biofeedback without paced breathing (10 × 20 min/4 weeks)
Hibbert and Chan [62] 1989 England	a. Randomized trial b. Between subject c. Research	Panic disorder with agoraphobia	a. N = 21 (13 females, 8 males) b. 35.0	a. N = 19 (13 females, 6 males) b. 35	Controlled breathing training	First treatment session: provocation test (rebreathing using a paper bag, 2 min of forced ventilation, rebreathing with the bag); second treatment session: paced breathing, overbreathing	a. Not reported b. 2 sessions c. 3 weeks d. NA	Psychoeducation (1 ×/1 week) plus diary homework (1 × 30 min/day) followed by anxiety management strategies
Ito et al. [63] 1996 England	a. Randomized trial b. Between subject c. Clinical	Panic disorder with agoraphobia	a. N = 10 b. 37.0	a. N = 9 b. 38	Slow deep breathing	Slowed breathing (2 × 5 min/day) plus self-exposure (30–45 min) × 7 sessions/10 weeks, plus therapist-accompanied internal exposure (2 × 30 min/2 weeks). Daily exposure homework: 60 min external plus 30 min internal exposure. Exposure protocol: hyperventilation (1 min), shaking head side to side (30 s), running on spot (1 min), head between legs (30 s) and then quickly lifting head up. Slow breathing after each exercise to return to baseline anxiety level.	a. Not reported b. 7 sessions c. 10 weeks d. 4, 10, 14, 24 weeks	Slowed breathing (2× 5 min/day) plus self-exposure (30–45 min) × 7 sessions/10 weeks, plus therapist-accompanied external exposure (1 × 60 min/1 week). Daily between-session exposure homework: 90 min of external exposure. Exposure protocol same as treatment.
Kim et al. [55] 2012 United States	a. Randomized trial b. Between subject c. Research	Panic disorder/ agoraphobia	a. N = 74 (51 females, 23 males) b. 41.9	a. N = 30 (21 females, 9 males) b. 43	Hypoventilation, hyperventilation	Biofeedback-assisted hypercapnic or hypocapnic breathing therapy (5 ×/5 weeks) plus at-home breathing exercises (2 × day/5 weeks). Breathing exercises: baseline breathing (2 min), breathing more deeply or shallowly to reach PCO2 = 30 mm Hg (lower-CO2 group) or 40 mm Hg (raise-CO2 group) by breathing via audio tape (10 min) followed by breathing without audio tape (5 min). RR maintained at 9 BPM.	a. 17 min b. 5 sessions c. 5 weeks d. 1, 6 months	Delayed treatment
Meuret et al. [56] 2010 United States	a. Open pilot b. Between subject c. Research	Panic disorder with agoraphobia	a. N = 21 (17 females, 4 males) b. 31.4	a. N = 20 (17 females, 3 males) b. 35	Capnometry-assisted respiratory training (CART)	Education and teaching to control end-tidal PCO2 and RR. Between-session exercises (2 × 17 min/day): (a) 2 min physiological baseline recording. (b) 10 min synchronized breathing with recorded tones (weekly BPM targets: 13, 11, 9, 6) and PCO2 of 40 ± 3 mm Hg. (c) 5 min transfer with visual feedback.	a. 60 min b. 5 sessions c. 4 weeks d. None	Cognitive skill training (5 × 60 min/week) plus cognitive homework (2 × 17 min/day)
Meuret et al. [57] 2008 United States	a. Randomized trial b. Between subject c. Research	Panic disorder/ agoraphobia	a. N = 20 b. 41.0	a. N = 17 b. 41	Capnometry-assisted breathing therapy (BRT)	Education, direct attention to respiratory patterns, breathing maneuvers, teaching control of pCO2 and RR. Daily breathing exercises (2 × 17 min/day): (a) 2 min physiological baseline recording. (b) 10 min synchronized breathing with recorded tones (weekly BPM targets: 13, 11, 9, 6) in a normocapnic range (pCO2 > 35 mmHg. (c) 5 min transfer, breathing without pacing tones.	a. 60 min b. 5 sessions c. 4 weeks d. 2, 12 months	Delayed treatment
Wollburg et al. [58] 2011 United States	a. Randomized trial b. Between subject c. Research	Panic disorder	a. N = 45 (30 females, 15 males) b. 41.8	a. N = 20 (11 females, 9 males) b. 45.7	Hypoventilation, hyperventilation	(a) Education. (b) Biofeedback-assisted hypercapnic or hypocapnic breathing therapy (5 ×/5 weeks). (c) At-home breathing exercises (2 × day/5 weeks): training by breathing more deeply or shallowly to obtain the target pCO2 (lower: 30 mmHg, raise: 40 mmHg) at 9 BPM.	a. Not reported b. 5 sessions c. NA d. 1 month	Delayed treatment
Yamada et al. [68] 2017 Japan	a. Open pilot b. Between subject c. Clinical	Panic disorder	a. N = 28 (20 females, 8 males) b. 31.1	a. N = 28 (20 females, 8 males) b. 31.1	Slow diaphragmatic breathing	CBT (weekly). Diaphragmatic breathing retraining (daily): (a) relaxed breathing–supine breathing training w/500 g weight and hand pressure. (b) Seated breathing training w/lumbar spine flexed w/expiration and dorsiflexed w/inspiration. Stretching exercises for breathing muscles.	a. Not reported b. CBT weekly, BT daily. c. 6–13 weeks d. None	Same as treatment
Doria et al. [65] 2015 Italy	a. Open pilot b. Within subject c. Real world	Generalized anxiety disorder	a. N = 69 (41 females, 28 males) b. Not specified	NA	Surdashan Kriya Yoga (SKY)	Ujjayi, slow breathing 3–4 cycles per minute; Nadi Shodhana, alternate nostril breathing, Kapalabhati, fast diaphragmatic breathing; Bhastrika, rapid exhalation at 20–30 cycles/min; and Sudarshan Kriya, rhythmic, cyclical breathing in slow, medium, and fast cycles	a. 120 min b. 10 sessions c. 2 weeks d. 2 weeks, 3 and 6 months	NA
Han et al. [66] 1996 Belgium	a. Open pilot b. Within subject c. Research	Hyperventilation syndrome	a. N = 92 (60 females, 32 males) b. 37.0	NA	Abdominal slow breathing	Hyperventilation (3 min), reattribution of symptoms to hyperventilation, abdominal breathing with slowed expiration, breathing retraining	a. 45 min b. 17 sessions c. 2.5 months d. NA	NA
Meuret et al. [59] 2001 United States	a. Open pilot b. Within subject c. Research	Panic disorder/ agoraphobia	a. N = 4 (2 females, 2 males) b. 42.0	NA	Respiratory biofeedback-assisted therapy	Education, teaching techniques to control respirations, direct attention to respiratory patterns. Home breathing exercises (2 × 17 min/day): (a) 2 min baseline recording. (b) 10 min paced breathing with recorded tones (weekly BPM targets: 13, 11, 9, 6). (c) 5 min transfer, breathing without pacing tones.	a. 80 min b. 5 sessions c. 4 weeks d. 2 months	NA
Tolin et al. [60] 2017 United States	a. Open pilot b. Within subject c. Real world	Panic disorder	a. N = 69 (41 females, 28 males) b. 36.6	NA	Capnometry guided respiratory intervention (CGRI)	Breathing sessions (2 × 17 min/day): (a) baseline breathing (2 min), (b) 10 min paced breathing via audio tape (weekly BPM targets: 13, 11, 9, 6), target PETCO2 level (37–40 mmHg). (c) 5 min transfer, breathing without pacing tones.	a. 17 min b. 56 sessions c. 4 weeks d. 2, 6, 12 months	NA