Respiratory training interventions improve health status of heart failure patients: A systematic review and network meta-analysis of randomized controlled trials

Table 1 Characteristics of included studies

First author (year)	Group (n), age (mean ± SD)	Male/ female	NYHAclass	Attrition rate, %	Experimental group (E)	Control group (C)	Duration (wk)	Outcomes
Adamopoulos 2014	E: 21, 57.8 ± 11.7 C: 22, 58.3 ± 13.2	19/2 17/5	II-III	17.3	IMT computer type, 60% MIP, 30 min/time, 7 d/wk, hospital Aerobic exercise, 20-45 min/d, 3d/wk, home	Sham IMT, 10% MIP Aerobic exercise	12	HR, LVEF, VO2 peak, 6MWT, MLWHFQ score
Bosnak-Guclu 2011	E: 16, 69.5 ± 8 C: 14, 65.7 ± 10.5	12/4 12/2	II-III	16.6	IMT threshold type, 40% MIP, 30 min/time, 7 d/wk	Sham IMT, 15% MIP	6	HR, VO2 peak, 6MWT
Caminitu 2011	E: 30, 74.1 ± 6 C: 30, 73.4 ± 2	25/5 26/4	II	0	Tai chi, 10 movements, 30 mim/time, 2 d/wk, home ET with cycling or walking 30 mim/time, 2 d/wk, home	Endurance training with cycling or walking, 30 min/time, 4 d/wk, home	12	HR, VO2 peak, 6MWT
Chen 2015	E: 42, 62.1 ± 4.1 C: 42, 62.9 ± 5.0	32/10 34/8	I-IV	0	Deep breathing, 20 repeats/3 times/d, inspiratory 2 s, expiratory > 6 s, deep breathing stop 10-28 s	Usual care	8	HR, LVEF, 6MWT
Chen 2017	E: 39, 71.44 ± 13.65 C: 41, 69.08 ± 13.48	18/21 24/17	I-II	21.5	Baduanjin, 35 min/time, 3 d/wk	Usual care	12	MLWHFQ score
Dall'Ago 2006	E: 16, 54 ± 3 C: 16, 58 ± 2	10/6 11/5	NA	27.3	IMT threshold type, 30% MIP, 30 min/time, 7 d/wk	Sham IMT, 0% MIP	12	VO2 peak, 6MWT, MLWHFQ score
Ekman 2011	E: 30, 73 ± 11 C: 35, 73 ± 10	22/8 24/11	II-IV	9.7	Device-guided paced breathing, 20 min/time, 2 times/d	CD player with earphones, 20 min/time, 2 times/d	4	HR
Hägglund 2017	E: 20, 64.1 ± 9.4 C: 20, 65.7 ± 8.5	15/5 11/9	I-III	25	Yoga, 60 min/time, 2 times/wk, hospital	Hydrotherapy, 45 min/time, 2 times/wk, hospital	12	HR, 6MWT
Kawauchi 2017	E1: 13, 56 ± 7 E2: 13, 54 ± 10 C: 9, 56 ± 7	8/5 6/7 5/4	II-III	33.9	E1: IMT computer type, 30% MIP, peripheral muscle training, 7 d/wk. E2: IMT computer type, 15% MIP, 7 d/wk, hospital	Usual care	8	6MWT, MLWHFQ score
Krishna 2014	E: 44, 49.34 ± 5.70 C: 48, 50.14 ± 4.54	32/12 32/16	I-II	29	Yoga, asanas and pranayama style, 60 min/time, 3 d/wk	Drug therapy	12	HR, LVEF, 6MWT, MLWHFQ score
Laoutaris 2004	E: 20, 57.6 ± 2.3 C: 15, 60.0 ± 2.6	18/2 13/2	II-III	5.7	IMT computer type, 60% MIP, 3 d/wk, hospital	Sham IMT, 15% MIP	10	HR, LVEF, VO2 peak, 6MWT, MLWHFQ score
Laoutaris 2007	E: 15, 53.0 ± 2.0 C: 23, 59.0 ± 2.0	12/3 20/3	II-III	0	IMT computer type, 60% MIP, 3 d/wk, hospital	Sham IMT, 15% MIP	10	HR, VO2 peak, 6MWT
Laoutaris 2008	E: 14, 53.4 ± 2.1 C: 9, 57.3 ± 4.0	11/3 9/0	II-III	0	IMT computer type, 60% MIP, 3 d/wk, hospital	Sham IMT, 15% MIP	10	HR, VO2 peak
Laoutaris 2011	E: 10, 37.2 ± 17.7 C: 5, 41.8 ± 14.6	10/0 4/1	Not reported	28.5	IMT computer type, 60% MIP, 2-3 d/wk, hospital Resisted training 45 min/time, 3-5 times/wk, home Aerobic bike or treadmill walk, 30-45 min/d, home	Walk, 30-45 min/d	10	VO2 peak, 6MWT, MLWHFQ score
Laoutaris 2013	E: 13, 57.1 ± 11 C: 14, 58.6 ± 8	10/3 12/2	II-III	3.6	IMT computer type, 60% MIP, 20 min/time, 3 d/wk, hospital Aerobic bike, 20-30 min/d, home Resisted training 1 RM 15min	Aerobic exercise bike 45-55 min/time, 3 d/wk, hospital	12	HR, VO2 peak, 6MWT, MLWHFQ score
Lin 2011	E: 40, 56.8 ± 16.2 C: 40, 57.5 ± 16.2	26/14 24/16	II-IV	16.3	Deep breathing, 20 repeats/3 times/d, inspiratory 2 s, expiratory 10 s, deep breathing stop 2-10 s, hospital	Drug therapy, diet counseling	Discharge	HR, 6MWT
Martinez 2001	E: 11, 60 ± 14 C: 9, 57 ± 13	16/4	II-III	Not reported	IMT threshold type, 30% MIP, 15 mins/time, 6 d/wk	Sham IMT, 10% MIP	6	VO2 peak, 6MWT
Mello 2012	E: 15, 54.3 ± 2 C: 12, 53.3 ± 2	9/6 5/7	II	5.4	IMT threshold type, 30% MIP, 10 min/time, 3 times/d, 7 d/wk	No intervention	12	VO2 peak, MLWHFQ score
Palau 2014	E: 14, 68 ± 4.62 C: 12, 74 ± 1.19	7/7 6/6	III-IV	3.7	IMT threshold type, 30% MIP, 20 min /time, 2 times/d	Usual care	12	VO2 peak, 6MWT, MLWHFQ score
Pan 2017	E: 42, 65.2 ± 5.9 C: 42, 67.2 ± 6.4	28/14 29/13	II-III	0	Fast inhalation (0.8-1 s) and slow exhalation (4 s), 10 min/time, 6 times/d (hospital), 3 times/d (home)	Usual care	12	HR, 6MWT
Parati 2008	E: 12, 64 ± 9 C: 12, 62.8 ± 10	9/3 9/3	II-III	0	Device-guided paced breathing, 18 min/time, 2 times/d	Conventional treatment	10	LVEF, VO2 peak, MLWHFQ score
Pullen 2008	E: 9, 52.1 ± 3.3 C: 10, 50.5 ± 12.8	2/7 7/3	I-III	0	Yoga, hatha style, 70 min/time, 3d/wk	Drug therapy Education	8	VO2 peak, MLWHFQ score
Pullen 2010	E: 21, 55.8 ± 7.6 C: 19, 52.5 ± 12.7	10/11 13/6	I-III	15	Yoga, hatha style, 60 min/time, 3 d/wk	Drug therapy Education	8	VO2 peak, MLWHFQ score
Seo 2016	E: 18, 55.8 ± 7.6 C: 18, 55.8 ± 7.6	25/11	II-IV	19.4	CD-guided diaphragmatic breathing retraining, 15 min/time, 2 times/d, 5 d/wk, home	Education	8	6MWT
Winkelmann 2009	E: 12, 54 ± 12 C: 12, 59 ± 9	7/5 4/8	Not reported	36.8	IMT threshold type, 30% MIP, 30 min/time, 7d/wk Aerobic braked cycle ergometer, 20-45 min/time, 3 d/wk	Aerobic braked cycle ergometer, 45 min/time, 3 d/wk	12	VO2 peak, 6MWT, MLWHFQ score
Yao 2010	E: 80, 52.4 ± 6.32 C: 70, 51.7 ± 7.26	47/33 42/28	II	0	Tai chi, 42 movements, ≥30 min/time, 5 d/wk	Drug therapy, diet and lifestyle counseling	24	LVEF, 6MWT, MLWHFQ score
Yeh 2004	E: 15, 66 ± 12 C: 15, 61 ± 14	10/5 9/6	I-IV	10	Tai chi, 5 movements, 60 min/time, 3 d/wk	Drug therapy, diet counseling, exercise advice	12	VO2 peak, 6MWT, MLWHFQ score
Yeh 2011	E: 50, 68.1 ± 11.9 C: 50, 66.6 ± 12.1	28/22 36/14	I-III	9	Tai chi, 5 movements, 60 min /time, 3 d/wk	Drug therapy, exercise advice Education 1 time/2 wk	12	VO2 peak, 6MWT, MLWHFQ score
Yeh 2013	E: 8, 68 ± 11 C: 8, 63 ± 11	4/4 4/4	I-III	0	Tai chi, 5 movements, 60 min/time, 3 d/wk	Aerobic exercise 60 min/time, 3 d/wk	12	HR, VO2 peak, 6MWT, MLWHFQ score
Zheng 2017	E1: 9, 59.45 ± 7.20 E2: 8, 58.90 ± 8.60 C: 7, 59.10 ± 9.10	6/3 6/2 5/2	II-III	13.9	E1. Qigong, 30-40 min/time/d E2. Walking, 30-40 min/time/d	Usual care	12	LVEF, 6MWT, MLWHFQ score
Zhong 2016	E: 50, 63.5 C: 50, 66.2	31/19 28/22	II-IV	14	Abdominal breathing (inspiratory: expiratory =1:1-2, 4 repeats/time), and leg exercise (5-8 min/time), 2 times/d	Usual care	Discharge	HR, 6MWT

IMT: Inspiratory muscle training; MIP: Maximal inspiratory pressure; HR: Heart rate; VO₂ peak: Peak oxygen uptake; 6MWT: 6-min walking distance test; MLWHFQ: Minnesota Living with Heart Failure questionnaire.

Table 2 Effects of respiratory training interventions on outcomes in the network meta-analysis

		None	Aerobics	IMT_Pn	IMT_Pl	IMT_Pm	IMT_Ph	Qi_Ex
	Outcome of heart rate
The outcomes of VO2 peak	None	-	-1.31	0.11	-1.17	-1.04	-1.58	-1.74
			(-2.23, -0.39)	(-1.06, 1.28)	(-2.36, 0.02)	(-2.16, 0.09)	(-2.71, -0.46)	(-2.26, -1.23)
	Aerobics	-5.9	-	1.42	0.14	0.27	-0.27	-0.43
		(-8.36, -3.43)		(-0.07, 2.91)	(-0.89, 1.16)	(-0.94, 1.49)	(-1.10, 0.56)	(-1.25, 0.38)
	IMT_Pn	0.41	6.31	-	-1.28	-1.15	-1.69	-1.85
		(-0.96, 1.77)	(3.69, 8.93)		(-2.95, 0.39)	(-2.77, 0.47)	(-3.31, -0.07)	(-3.13, -0.58)
	IMT_Pl	-3.37	2.53	-3.78	-	0.13	-0.41	-0.57
		(-5.41, -1.32)	(1.15, 3.91)	(-6.00, -1.55)		(-0.95, 1.22)	(-1.13, 0.31)	(-1.74, 0.59)
	IMT_Pm	-3.87	2.03	-4.28	-0.5	-	-0.54	-0.71
		(-5.07, -2.68)	(-0.13, 4.19)	(-5.77, -2.79)	(-2.17, 1.16)		(-1.72, 0.63)	(-1.87, 0.46)
	IMT_Ph	-6.07	-0.18	-6.48	-2.71	-2.2	-	-0.16
		(-8.35, -3.80)	(-1.12, 0.77)	(-8.93, -4.03)	(-3.72, -1.69)	(-4.15, -0.26)		(-1.23, 0.91)
	Qi_Ex	-0.42	5.48	-0.83	2.95	3.46	5.66	-
		(-1.20, 0.36)	(2.90, 8.07)	(-2.40, 0.75)	(0.76, 5.14)	(2.03, 4.88)	(3.25, 8.07)
	Outcome of 6-min walking distance test
The outcome of Minnesota Living with Heart Failure Questionnaire (MLWHF)	None	-	0.97	-1.97	0.5	1.09	3.19	1.17
			(0.03, 1.92)	(-4.19, 0.26)	(-0.72, 1.72)	(0.01, 2.17)	(1.69, 4.68)	(0.64, 1.71)
	Aerobics	1.06	-	-2.94	-0.48	0.12	2.22	0.2
		(-0.42, 2.53)		(-5.20, -0.68)	(-1.74, 0.79)	(-1.02, 1.26)	(0.79, 3.64)	(-0.70, 1.10)
	IMT_Pn	0.1	-0.95	-	2.46	3.06	5.15	3.14
		(-1.60, 1.81)	(-3.06, 1.16)		(0.29, 4.64)	(1.11, 5.00)	(2.75, 7.56)	(0.89, 5.39)
	IMT_Pl	1.32	0.26	1.21	-	0.59	2.69	0.68
		(-0.41, 3.04)	(-1.51, 2.04)	(-1.07, 3.50)		(-0.38, 1.56)	(1.49, 3.89)	(-0.59, 1.95)
	IMT_Pm	2.1	1.04	2	0.78	-	2.1	0.08
		(0.92, 3.29)	(-0.46, 2.55)	(0.28, 3.72)	(-0.95, 2.52)		(0.69, 3.51)	(-1.05, 1.22)
	IMT_Ph	1.79	0.73	1.68	0.47	-0.31	-	-2.01
		(0.05, 3.53)	(-0.49, 1.95)	(-0.62, 3.99)	(-1.26, 2.20)	(-2.08, 1.45)		(-3.53, -0.50)
	Qi_Ex	1.42	0.37	1.32	0.1	-0.68	-0.37	-
		(0.59, 2.25)	(-1.21, 1.94)	(-0.57, 3.20)	(-1.77, 1.97)	(-2.09, 0.73)	(-2.21, 1.48)

IMT_Pn: Inspiratory muscle training without pressure or < 10% maximal inspiratory pressure, MIP; IMT_Pl: Inspiratory muscle training with low pressure, 10%-15% MIP; IMT_Pm: Inspiratory muscle training with medium pressure, 30%-40% MIP; IMT_Ph: Inspiratory muscle training with high pressure, 60% MIP or MIP plus aerobics; Aerobics: Aerobic exercise or weight training; Qi_Ex: Tai chi, yoga, and breathing exercise.