JKDA 2023; 6(2): 47-51
Published online November 25, 2023
https://doi.org/10.56774/jkda23013
© Korean Society of Dialysis Access
Correspondence to : Soo Jeong Choi
Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, 170 Jomaru-ro, Jung-dong, Wonmi-Gu, Bucheon 14584, Korea
Tel: 82-32-621-5169, Fax: 82-32-621-5016, E-mail: crystal@schmc.ac.kr
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Although the arteriovenous fistula is considered the best access due to low complications, it faces challenges such as poor maturation rates and patency issues. The present paper describes the current status of far-infrared therapy as a treatment modality to enhance AVF maturation and access survival. The mechanism underlying FIR therapy involves vasodilatory, angiogenesis, and the induction of vasodilation and anti-inflammatory factors. Thermal effect of FIR therapy involve upregulation of endothelial nitric oxide synthase, while non-thermal effects include reduced oxidative stress and improved endothelial function. In conclusion, FIR therapy presents potential benefits for improving vascular access flow and survival.
Keywords Arteriovenous fistula, Far-infrared therapy, Dialysis
A hemodialysis (HD) access, also known as a vascular access, is a conduit for accessing the bloodstream during hemodialysis treatment. This vascular access enables blood to flow through flexible tubes to the dialysis machine, where it undergoes dialysis process by passing through a specialized filter known as a dialyzer. A well-functioning vascular access is an important and essential factor for achieving adequate dialysis in hemodialysis patients. Arteriovenous Fistula (AVF) has been considered as the best access due to low complication (infection and thrombosis). But, AVF should overcome limitations of poor maturation rate (20-50%) and patency. Half of AVF needs an intervention within 1 year for stenosis [1]. High age, female sex, comorbidity, arterial stiffness, anatomical location (primarily radio-cephalic), small vein diameter and surgeon experience are all risk factors of access short survival [1-4]. Therefore, recent KDOQI guidelines recommend individual approach for access formation [5]. Many researchers have tried to improve vascular access survival with medications and other techniques. The surveillance and preemptive PTA were disappointed in this point. Although systemic management for such as dipyridamole+aspirin and fish oil have been successful, systemic levels of such agents may expose the patients to significant adverse effects [6,7]. Therefore, local treatment modalities began to be developed, and Far-infrared (FIR) therapy is one of them. FIR therapy is a new treatment modality for AVF maturation and access survival [8-11].
The present paper describes the current status of FIR therapy in HD patients.
Infrared radiation is an invisible electromagnetic energy, and the range with wavelengths between 5.6-1,000 µm is referred to as FIR. Infrared radiation likely transfers various energy forms into subcutaneous tissue level without causing stimulation or excessive heating. FIR radiation produces both thermal and non-thermal effects [12]. FIR therapy transfers energy in the surrounding skin [13]. FIR therapy improves skin blood flow and angiogenesis [14]. FIR therapy also improves endothelial function and reduces the frequency of some cardiovascular diseases [15-17]. The first FIR therapy was ‘Waon’ sauna therapy in Japanese patients with chronic heart failure [18,19]. This FIR sauna irradiates the entire body at 60°C for 15 minutes, followed by a further 30 minutes covered in blankets to cause an increase in core body temperature of around 1°C [20,21]. Localized FIR therapy is the other form, which typically consists of a device with ceramic plates [22]. This local FIR therapy improved hemodynamic function in chronic heart failure [22]. This thermal effect leads to vasodilation and angiogenesis for wound healing and peripheral ischemia [12]. And, FIR radiation inducts vasodilation and anti-inflammatory factor such as nitric oxide and heme oxygenase, which inhibits vascular endothelial inflammation [16,23]. Heme oxygenase-1 (HO-1) is one of the genetic factor in cardiovascular diseases and AVF patency, and FIR therapy can aid in the patency and maturation of AVF through non-thermal reactions mediated by HO-1 [24].
The previous FIR protocol in HD patients was similar to the protocol used by Lin et al. [10] in their research on the effects of FIR on AVF maturation [25,26]. FIR therapy was administered for 40 min during each HD session. Specialized FIR emitters (WS TY-101N; WS Far Infrared Medical Technology Co., Ltd., Taipei, Taiwan) were used for FIR therapy. Electrified ceramic plates were positioned approximately 25 cm above the skin surface at the needling site. The irradiating power density was about 10 and 20 μW/cm2 when the radiator was set at a distance of 30 and 20 cm above the skin surface, respectively. Radiation therapy was continued every HD session. Chang et al. [27] introduced PD protocol with FIR therapy taken at least 4 times a week. FIR therapy was centered on the navel region, i.e., the entire abdominal cavity, from the lower edge of the sternum to the groin. The recommended safe distance that still allows reaching the skin was 25 cm. Before going to bed, the PD patients were irradiated for 40 min after the dialysate input.
FIR therapy in HD patients was studied for vascular access flow, vessel diameter, primary patency, cumulative patency (or occlusion) [28].
Lin et al. [10] showed FIR therapy improves access flow and maturation of newly created AVFs. FIR therapy for 1 year improved vascular access flow and a better unassisted patency of AVF [8]. But, Choi et al. [26] didn’t find an improved patency in AVF after 1 year. Lai et al. [11] reported that FIR therapy after PTA enhanced unassisted patency at 1 year in AVG, while it had no effect in AVF. Io et al. [29] revealed that FIR therapy increased intervention interval, expended fistula diameter, and improved intimal thickening in 13 patients underwent previous percutaneous transluminal angioplasty.
Bashar et al. [30] showed a meta-analysis on 4 RCTs, examining the primary (unassisted) and secondary patency rates of AVFs with FIR therapy in 2014. Patients received FIR therapy showed a significant increase in unassisted patency compared to the control group. Additionally, for secondary patency, patients received FIR therapy also demonstrated a significant difference in patency rates [30]. Wan et al. [28] conducted a meta-analysis of 21 RCTs investigating the protective effect of FIR therapy on AVFs in 2017. They found a significant increase in blood flow, diameter, and primary AVF patency in the group of patients receiving FIR therapy.
Although definite mechanism of FIR therapy is unknown, these results show thermal and non-thermal effects on hemodialysis access. Upregulation of endothelial nitric oxide synthase is considered to be a thermal effect which improves access blood flow [16,31,32]. In addition, this perivascular approach is appealing given without (a) stress of the adventitial and medial layers and (b) denudation of the endothelial layer [33]. Decreases in oxidative stress, suppression of inflammation, and improved endothelial function [6,16,23,32,34] have been suggested to be non-thermal effects.
FAITH on fistula (a randomized, controlled) trial has been explored to reveal the effect of FIR on AVF maturation and on number of AVFs without intervention still functioning after 1 year [35]. Vascular cell adhesion molecule (VCAM) is a well-known biomarker of endothelial dysfunction, and intracellular adhesion molecules (ICAM) is a marker for inflammation in atherosclerosis. Recent partial report of that study shows a single FIR therapy attenuated the decrease in soluble VCAM and ICAM in AVF while there was no significant change of inflammation and vaso-regulatory factors [25]. Therefore, the hypothesis that single FIR leads to an acute release of vascular protective dilatory factors and reduce inflammatory contractile factors is unproven. Other objectives of FAITH on fistula trial will reveal the long-term effect of AVF maturation on newly placed AVFs and overall patency in prevalent and incident AVFs [35].
There was a prospective randomized controlled trial on the effects of FIR therapy on AVF maturation and patency in patients with diabetic end-stage renal disease conducted by Chen et al. [36]. In addition, they also studied the effect on serum Asymmetric dimethylarginine (ADMA) level, an endogenous inhibitor of nitric oxide synthase, which plays a crucial role in the pathophysiology of AVF dysfunction. The study showed a decrease in ADMA levels and increase in AVF blood flow, maturation rate, and 1-year patency rate [36].
FIR has been used in HD patients for pain reduction and ischemia improvement. Choi et al. [26] reported FIR therapy decreased the needling pain which is similar with that of buttonhole technique. Chen et al. [36] revealed the 6-month FIR therapy improves ankle brachial index in hemodialysis patients with peripheral artery disease. They suggested FIR therapy is a promising and non-invasive therapeutic modality to treat vascular access related hand ischemia [36]. Taiwan researchers adopted FIR therapy in peritoneal dialysis. A 3- month FIR therapy treated encapsulating peritoneal sclerosis in a 45-year old men [37].
Chang et al. [27] intended 6-month FIR therapy in patients on peritoneal dialysis to improve peritoneal permeability and inflammatory response. But, their results didn’t show significant change of abdominal vessel, peritoneal Kt/V and inflammatory cytokines.
Choi et al. [26] evaluated the safety of FIR therapy. Thirty-two percent of participants discontinued FIR therapy than in other reports (3.4-12.5%) [8,9]. While others [8,11] reported no complications associated with FIR therapy, side effects such as an itching sensation and delayed hemostasis were reported. The FAITH trial monitors adverse events every three months, with the final data collection scheduled for April 2024 [35].
While FIR therapy improves vascular access flow with thermal effect, FIR therapy shows improvement of maturation and decrease of intervention risk in AVF. The non-thermal mechanism remains to be explored in clinical settings. More large and multicenter studies are needed to evaluate the effect of FIR therapy on access survival in hemodialysis patients.
This study was supported by the Soonchunhyang University Research Fund.
JKDA 2023; 6(2): 47-51
Published online November 25, 2023 https://doi.org/10.56774/jkda23013
Copyright © Korean Society of Dialysis Access.
Minsung Lee1, Soo Jeong Choi2
1Division of Nephrology, Department of Internal Medicine, Ewha Womans University College of Medicine, Seoul, Korea
2Division of Nephrology, Department of Internal Medicine, Soonchunhyang University College of Medicine, Bucheon, Korea
Correspondence to:Soo Jeong Choi
Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, 170 Jomaru-ro, Jung-dong, Wonmi-Gu, Bucheon 14584, Korea
Tel: 82-32-621-5169, Fax: 82-32-621-5016, E-mail: crystal@schmc.ac.kr
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Although the arteriovenous fistula is considered the best access due to low complications, it faces challenges such as poor maturation rates and patency issues. The present paper describes the current status of far-infrared therapy as a treatment modality to enhance AVF maturation and access survival. The mechanism underlying FIR therapy involves vasodilatory, angiogenesis, and the induction of vasodilation and anti-inflammatory factors. Thermal effect of FIR therapy involve upregulation of endothelial nitric oxide synthase, while non-thermal effects include reduced oxidative stress and improved endothelial function. In conclusion, FIR therapy presents potential benefits for improving vascular access flow and survival.
Keywords: Arteriovenous fistula, Far-infrared therapy, Dialysis
A hemodialysis (HD) access, also known as a vascular access, is a conduit for accessing the bloodstream during hemodialysis treatment. This vascular access enables blood to flow through flexible tubes to the dialysis machine, where it undergoes dialysis process by passing through a specialized filter known as a dialyzer. A well-functioning vascular access is an important and essential factor for achieving adequate dialysis in hemodialysis patients. Arteriovenous Fistula (AVF) has been considered as the best access due to low complication (infection and thrombosis). But, AVF should overcome limitations of poor maturation rate (20-50%) and patency. Half of AVF needs an intervention within 1 year for stenosis [1]. High age, female sex, comorbidity, arterial stiffness, anatomical location (primarily radio-cephalic), small vein diameter and surgeon experience are all risk factors of access short survival [1-4]. Therefore, recent KDOQI guidelines recommend individual approach for access formation [5]. Many researchers have tried to improve vascular access survival with medications and other techniques. The surveillance and preemptive PTA were disappointed in this point. Although systemic management for such as dipyridamole+aspirin and fish oil have been successful, systemic levels of such agents may expose the patients to significant adverse effects [6,7]. Therefore, local treatment modalities began to be developed, and Far-infrared (FIR) therapy is one of them. FIR therapy is a new treatment modality for AVF maturation and access survival [8-11].
The present paper describes the current status of FIR therapy in HD patients.
Infrared radiation is an invisible electromagnetic energy, and the range with wavelengths between 5.6-1,000 µm is referred to as FIR. Infrared radiation likely transfers various energy forms into subcutaneous tissue level without causing stimulation or excessive heating. FIR radiation produces both thermal and non-thermal effects [12]. FIR therapy transfers energy in the surrounding skin [13]. FIR therapy improves skin blood flow and angiogenesis [14]. FIR therapy also improves endothelial function and reduces the frequency of some cardiovascular diseases [15-17]. The first FIR therapy was ‘Waon’ sauna therapy in Japanese patients with chronic heart failure [18,19]. This FIR sauna irradiates the entire body at 60°C for 15 minutes, followed by a further 30 minutes covered in blankets to cause an increase in core body temperature of around 1°C [20,21]. Localized FIR therapy is the other form, which typically consists of a device with ceramic plates [22]. This local FIR therapy improved hemodynamic function in chronic heart failure [22]. This thermal effect leads to vasodilation and angiogenesis for wound healing and peripheral ischemia [12]. And, FIR radiation inducts vasodilation and anti-inflammatory factor such as nitric oxide and heme oxygenase, which inhibits vascular endothelial inflammation [16,23]. Heme oxygenase-1 (HO-1) is one of the genetic factor in cardiovascular diseases and AVF patency, and FIR therapy can aid in the patency and maturation of AVF through non-thermal reactions mediated by HO-1 [24].
The previous FIR protocol in HD patients was similar to the protocol used by Lin et al. [10] in their research on the effects of FIR on AVF maturation [25,26]. FIR therapy was administered for 40 min during each HD session. Specialized FIR emitters (WS TY-101N; WS Far Infrared Medical Technology Co., Ltd., Taipei, Taiwan) were used for FIR therapy. Electrified ceramic plates were positioned approximately 25 cm above the skin surface at the needling site. The irradiating power density was about 10 and 20 μW/cm2 when the radiator was set at a distance of 30 and 20 cm above the skin surface, respectively. Radiation therapy was continued every HD session. Chang et al. [27] introduced PD protocol with FIR therapy taken at least 4 times a week. FIR therapy was centered on the navel region, i.e., the entire abdominal cavity, from the lower edge of the sternum to the groin. The recommended safe distance that still allows reaching the skin was 25 cm. Before going to bed, the PD patients were irradiated for 40 min after the dialysate input.
FIR therapy in HD patients was studied for vascular access flow, vessel diameter, primary patency, cumulative patency (or occlusion) [28].
Lin et al. [10] showed FIR therapy improves access flow and maturation of newly created AVFs. FIR therapy for 1 year improved vascular access flow and a better unassisted patency of AVF [8]. But, Choi et al. [26] didn’t find an improved patency in AVF after 1 year. Lai et al. [11] reported that FIR therapy after PTA enhanced unassisted patency at 1 year in AVG, while it had no effect in AVF. Io et al. [29] revealed that FIR therapy increased intervention interval, expended fistula diameter, and improved intimal thickening in 13 patients underwent previous percutaneous transluminal angioplasty.
Bashar et al. [30] showed a meta-analysis on 4 RCTs, examining the primary (unassisted) and secondary patency rates of AVFs with FIR therapy in 2014. Patients received FIR therapy showed a significant increase in unassisted patency compared to the control group. Additionally, for secondary patency, patients received FIR therapy also demonstrated a significant difference in patency rates [30]. Wan et al. [28] conducted a meta-analysis of 21 RCTs investigating the protective effect of FIR therapy on AVFs in 2017. They found a significant increase in blood flow, diameter, and primary AVF patency in the group of patients receiving FIR therapy.
Although definite mechanism of FIR therapy is unknown, these results show thermal and non-thermal effects on hemodialysis access. Upregulation of endothelial nitric oxide synthase is considered to be a thermal effect which improves access blood flow [16,31,32]. In addition, this perivascular approach is appealing given without (a) stress of the adventitial and medial layers and (b) denudation of the endothelial layer [33]. Decreases in oxidative stress, suppression of inflammation, and improved endothelial function [6,16,23,32,34] have been suggested to be non-thermal effects.
FAITH on fistula (a randomized, controlled) trial has been explored to reveal the effect of FIR on AVF maturation and on number of AVFs without intervention still functioning after 1 year [35]. Vascular cell adhesion molecule (VCAM) is a well-known biomarker of endothelial dysfunction, and intracellular adhesion molecules (ICAM) is a marker for inflammation in atherosclerosis. Recent partial report of that study shows a single FIR therapy attenuated the decrease in soluble VCAM and ICAM in AVF while there was no significant change of inflammation and vaso-regulatory factors [25]. Therefore, the hypothesis that single FIR leads to an acute release of vascular protective dilatory factors and reduce inflammatory contractile factors is unproven. Other objectives of FAITH on fistula trial will reveal the long-term effect of AVF maturation on newly placed AVFs and overall patency in prevalent and incident AVFs [35].
There was a prospective randomized controlled trial on the effects of FIR therapy on AVF maturation and patency in patients with diabetic end-stage renal disease conducted by Chen et al. [36]. In addition, they also studied the effect on serum Asymmetric dimethylarginine (ADMA) level, an endogenous inhibitor of nitric oxide synthase, which plays a crucial role in the pathophysiology of AVF dysfunction. The study showed a decrease in ADMA levels and increase in AVF blood flow, maturation rate, and 1-year patency rate [36].
FIR has been used in HD patients for pain reduction and ischemia improvement. Choi et al. [26] reported FIR therapy decreased the needling pain which is similar with that of buttonhole technique. Chen et al. [36] revealed the 6-month FIR therapy improves ankle brachial index in hemodialysis patients with peripheral artery disease. They suggested FIR therapy is a promising and non-invasive therapeutic modality to treat vascular access related hand ischemia [36]. Taiwan researchers adopted FIR therapy in peritoneal dialysis. A 3- month FIR therapy treated encapsulating peritoneal sclerosis in a 45-year old men [37].
Chang et al. [27] intended 6-month FIR therapy in patients on peritoneal dialysis to improve peritoneal permeability and inflammatory response. But, their results didn’t show significant change of abdominal vessel, peritoneal Kt/V and inflammatory cytokines.
Choi et al. [26] evaluated the safety of FIR therapy. Thirty-two percent of participants discontinued FIR therapy than in other reports (3.4-12.5%) [8,9]. While others [8,11] reported no complications associated with FIR therapy, side effects such as an itching sensation and delayed hemostasis were reported. The FAITH trial monitors adverse events every three months, with the final data collection scheduled for April 2024 [35].
While FIR therapy improves vascular access flow with thermal effect, FIR therapy shows improvement of maturation and decrease of intervention risk in AVF. The non-thermal mechanism remains to be explored in clinical settings. More large and multicenter studies are needed to evaluate the effect of FIR therapy on access survival in hemodialysis patients.
This study was supported by the Soonchunhyang University Research Fund.
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