The Interactive Effect between Genetic Background of Heme Oxygenase-1 and Far Infrared Therapy on Arteriovenous (AV) Fistula Function in Hemodialysis Patients

INTERVENTION: 1. HD patients who are randomized into the treatment group will receive 40 minutes of far infrared therapy (FIR therapy) during hemodialysis three times per week for a year. 2. A Wide Spectrum (WS) TY101 FIR emitter (WS Far Infrared Medical Technology Co., Ltd., Taipei, Taiwan) will be used for FIR therapy. Its generated wavelengths range between 3 and 25 microm (a peak between 5 and 6 microm). The top radiator will be set at a height of 25 cm above the surface of the AV fistula with the treatment time set at 40 minutes during HD thrice a week for a year. CONDITION: Malfunction of AV fistula of hemodialysis (HD) patients PRIMARY OUTCOME: The primary end point was the survival time of the AV fistula with unassisted patency, which was defined as the time from the commencement of the study to the first episode of fistula malfunction. We defined AV fistula malfunction as the need for any interventional procedure (surgery or angioplasty) to correct an occlusive or malfunctioning fistula which can not sustain an extracorporeal blood flow greater than 200 ml/min during HD after excluding the following stenosis‐unrelated events, such as infectious complication, progressive aneurysmal formation, or steal syndrome. SECONDARY OUTCOME: Access blood flow: The access flow (Qa) was measured during HD by ultrasound dilution method using the Transonic hemodialysis monitor (HD02, Transonic Systems, Inc., Ithaca, New York). The technique uses two ultrasound sensors attached to the two HD tubing lines, one to the arterial and the other to the venous catheters, approximately 3 to 5 inches from the connection of the tubing to the dialysis needles. Initially, tubing lines are reversed, and ultrafiltration is turned off. A measured bolus of saline (10 ml) is injected into the venous catheter, resulting in changes in sound velocity that are measured by the transducers on the catheters. This change is then calculated by the Transonic software, giving the result of Qa (ml/min). If Qa could not be obtained by this method, it would be measured by the variable pump flow‐based doppler ultrasound method. INCLUSION CRITERIA: (1) receiving 4 hours of maintenance HD therapy three times weekly for at least 6 months at Taipei veterans general hospital, (2) using a native AV fistula as the present vascular access for more than 6 months, without interventions within the last 3 months, and (3) creation of AV fistula by similar surgical skills with end‐to‐side anastomosis at upper extremity.