Far-Infrared Therapy: A Novel Treatment to Improve Access Blood Flow and Unassisted Patency of Arteriovenous Fistula in Hemodialysis Patients

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Figure 1.
Flow chart of the study participants for the randomized, controlled trial to evaluate the effect of far-infrared (FIR) therapy on survival of arteriovenous fistula (AVF) in the hemodialysis (HD) patients.
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Figure 2.
Comparison of 1-yr survival curves for unassisted patency of AVF between the HD patients with or without FIR therapy. P < 0.01 for the comparison between the two survival curves by log rank test.

Table 1.

Clinical characteristics of the two groups of HD patients with and without FIR treatment during the study period^a

Characteristic	Control Group	FIR Group	P
n	73	72
Age (yr)	59.2 ± 15.0	61.9 ± 14.4	0.87
Gender (male)	38 (52.1)	37 (51.4)	0.94
HD duration (mo)	79.2 ± 42.2	85.2 ± 41.1	0.76
Prevalence of hypertension	39 (53.4)	40 (55.6)	0.80
Prevalence of diabetes	24 (32.9)	25 (34.7)	0.81
History of AVF malfunction^b	34 (46.6)	33 (45.8)	0.81
No. of angioplasty (patients/procedures)	20/46	20/49	0.87
No. of surgical revision (patients/procedures)	14/19	13/20	0.56
Duration of AVF (mo)	58.7 ± 33.8	56.8 ± 36.4	0.91
Creation of another AVF (n)^c	4 (5.5)	1 (1.4)	0.18
Renal transplantation (n)	1 (1.4)	2 (2.8)	0.55
Peritoneal dialysis (n)	2 (2.7)	2 (2.8)	0.99
Death with functioning AVF (n)	2 (2.7)	3 (4.2)	0.64
Loss to follow-up (n)	0	1 (1.4)	0.31

↵^a Data are n (%) unless otherwise indicated. AVF, arteriovenous fistula; FIR, far-infrared; HD, hemodialysis.
↵^b Defined as the need for any interventional procedure (surgery or angioplasty) to correct a malfunctioning or occlusive fistula not resulting from the following stenosis-unrelated events, such as infectious complication, progressive aneurysmal formation, or steal syndrome.
↵^b Creation of another AVF during this 1-yr study.

Table 2.

Access flow and the hemodynamic parameters of the 72 HD patients in the single HD session with or without FIR therapy^a

Parameter	HD Session without FIR	HD Session with FIR	P
SBP₁ (mmHg)	134.2 ± 23.9	130.7 ± 19.0	0.86
SBP₂ (mmHg)	132.1 ± 19.1	129.4 ± 17.3	0.74
Δ(SBP₂ − SBP₁) (mmHg)	−2.1 ± 14.5	−1.3 ± 14.8	0.68
Qa₁ (ml/min)	976.6 ± 491.2	967.8 ± 421.0	0.94
Qa₂ (ml/min)	943.2 ± 472.2	981.0 ± 430.8	0.36
Δ(Qa₂ − Qa₁) (ml/min)	−33.4 ± 132.3	13.2 ± 114.7	0.021
CO₁ (L/min)	4.75 ± 1.38	4.72 ± 1.10	0.91
CO₂ (L/min)	4.45 ± 1.25	4.34 ± 1.16	0.88
Δ(CO₂ − CO₁) (L/min)	−0.30 ± 0.75	−0.38 ± 0.74	0.77
Qa₁/CO₁	0.223 ± 0.090	0.217 ± 0.076	0.78
Qa₂/CO₂	0.216 ± 0.082	0.235 ± 0.099	0.42
Δ[(Qa₂/CO₂) − (Qa₁/CO₁)]	−0.007 ± 0.057	0.018 ± 0.056	0.027
TPR₁ (mmHg × min/L)	21.29 ± 5.56	20.86 ± 4.81	0.89
TPR₂ (mmHg × min/L)	22.86 ± 6.09	22.67 ± 5.57	0.92
Δ(TPR₂ − TPR₁) (mmHg × min/L)	1.56 ± 4.35	1.82 ± 3.98	0.81

↵^a CO, cardiac output; Qa, access flow; SBP, systolic BP; TPR, total peripheral resistance; 1, timing of measuring the parameter is within the first hour after initiation of HD session or immediately before FIR treatment; 2, timing of measuring the parameter is 40 min after timing 1 or immediately after FIR treatment. Boldface P values indicate P < 0.05.

Table 3.

Comparison of the access flow and survival of AVF between HD patients with and without FIR therapy for 1 yr^a

Parameter	Control Group	FIR Group	P
No. completing study	64	63	—
Qa₁ (ml/min)	992.8 ± 473.8	975.2 ± 421.9	0.58
Qa₂ (ml/min)	975.9 ± 444.3	948.6 ± 432.7	0.26
Δ(Qa₂ − Qa₁) (ml/min)	−16.9 ± 130.3	−26.6 ± 105.5	0.72
Qa₁/CO₁	0.206 ± 0.088	0.204 ± 0.078	0.90
Qa₂/CO₂	0.223 ± 0.095	0.225 ± 0.107	0.93
Δ[(Qa₂/CO₂) − (Qa₁/CO₁)]	0.017 ± 0.060	0.021 ± 0.059	0.75
Qa₃ (ml/min)	941.1 ± 367.9	1011.6 ± 447.0	0.14
Qa₄ (ml/min)	928.4 ± 387.5	1047.8 ± 463.2	0.07
Qa₃/CO₃	0.194 ± 0.071	0.213 ± 0.077	0.16
Qa₄/CO₄	0.197 ± 0.074	0.237 ± 0.079	0.004
Δ(Qa₄ − Qa₃) (ml/min)	−12.7 ± 153.6	36.2 ± 82.4	0.027
Δ[(Qa₄/CO₄) − (Qa₃/CO₃)]	0.003 ± 0.047	0.024 ± 0.033	0.004
Δ(Qa₃ − Qa₁) (ml/min)	−51.7 ± 283.1	36.3 ± 166.2	0.035
Δ[(Qa₃/CO₃) − (Qa₁/CO₁)]	−0.012 ± 0.064	0.009 ± 0.040	0.031
Δ(Qa₄ − Qa₂) (ml/min)	−47.5 ± 244.5	99.2 ± 144.4	<0.001
Δ[(Qa₄/CO₄) − (Qa₂/CO₂)]	−0.026 ± 0.056	0.013 ± 0.060	<0.001
Δ(Qa₄ − Qa₂) − Δ(Qa₃ − Qa₁) (ml/min)	4.1 ± 184.5	62.9 ± 111.6	0.032
Δ[(Qa₄/CO₄) − (Qa₂/CO₂)] − Δ[(Qa₃/CO₃) − (Qa₁/CO₁)]	−0.014 ± 0.068	0.004 ± 0.068	0.049
No. starting study	73	72	—
patients with new AVF malfunction (%)	22 (30.1%)	9 (12.5%)	<0.01
patients with thrombosis of AVF	6 (8.2%)	2 (2.8%)	0.15
Patients with intervention of AVF	16 (21.9%)	7 (9.7%)	0.044
Total observations (patient-months)	802.4	812.6	—
New episodes of AVF malfunction during study	30	12	—
Episode of AVF malfunction/patient-months	1/26.7	1/67.7	0.03

↵^a Qa₁, access flow measured within first hour after the initiation of the HD session immediately before the commencement of this study; Qa₂, access flow measured 40 min after Qa₁ measurement during the HD session immediately before the commencement of this study; Qa₃, access flow measured before FIR treatment or within first hour after the initiation of the HD session when the study was completed; Qa₄, access flow measured 40 min after Qa₃ or immediately after FIR treatment during the HD session when the study was completed; Δ(Qa₄ − Qa₃), sum of the thermal effect by FIR and the hemodynamic effect by HD on the change of Qa; Δ(Qa₃ − Qa₁), nonthermal effect of 1 yr of FIR on the change of Qa; Δ(Qa₄ − Qa₂), sum of the thermal effect (for 40 min) and the nonthermal effect (for 1 yr) by FIR on Qa; [Δ(Qa₄ − Qa₂) − Δ(Qa₃ − Qa₁)], thermal effect of 40 min of FIR on the change of Qa.