title: Factors associating with oxygenation of lower-limb muscle tissue in hemodialysis patients.
abstract: OBJECTIVE
  To evaluate the lower-limb muscle oxygenation in hemodialysis (HD) patients and identify the factors associating with muscle oxygenation.
  
  
  METHODS
  Sixty-seven HD patients (53 men and 14 women; mean age, 67.1 ± 1.2 years; mean HD duration, 5.6 ± 0.9 years) were recruited. In addition, 15 healthy individuals (nine men and six women; mean age, 38.2 ± 4.6 years) were recruited as the control group. Lower-limb muscle regional saturation of oxygen (rSO2) was monitored on the lateral side of the gastrocnemius muscle before HD using an INVOS 5100C (Covidien Japan, Tokyo, Japan), which utilizes near-infrared spectroscopy. Here, we evaluated the association between lower-limb muscle rSO2and clinical parameters.
  
  
  RESULTS
  The rSO2values were significantly lower in patients undergoing HD than in healthy individuals (50.0% ± 1.7%vs76.8% ± 2.5%,P< 0.001). Lower-limb muscle rSO2showed significant positive correlations with diastolic blood pressure, blood urea nitrogen concentration, serum creatinine concentration, serum potassium concentration, serum inorganic phosphate concentration, and serum albumin concentration as well as negative correlation with HD duration. We conducted a multiple linear regression analysis using parameters that were significantly correlated with the lower-limb muscle rSO2in a simple linear regression analysis. Multiple regression analysis demonstrated that lower-limb muscle rSO2was independently associated with serum inorganic phosphate (standardized coefficient: 0.27) and serum albumin concentrations (standardized coefficient: 0.24). In addition, there were no differences in lower-limb muscle rSO2between diabetic and non-diabetic HD patients. This study has several limitations. Firstly, its sample size was relatively small. Secondly, we could not evaluate the association between lower-limb muscle rSO2and calculated nutritional markers, including normalized protein catabolic rate and body mass index, anthropometric measurements representing nutritional status, and the severity of protein-energy wasting. Finally, we did not routinely examine the arterial vascular status of HD patients without symptoms of peripheral artery disease. As such, it is possible that some HD patients with subclinical peripheral artery disease may have been included in this study.
  
  
  CONCLUSIONS
  In HD patients, the oxygenation of lower-limb muscle tissue was associated with serum inorganic phosphate and albumin concentrations, both of which represent nutritional status.
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Haruhisa
authors.initials: H
authors.lastname: Miyazawa
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Ookawara
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Kiyonori
authors.initials: K
authors.lastname: Ito
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yanai
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ishii
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Taisuke
authors.initials: T
authors.lastname: Kitano
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Shindo
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Ueda
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kaku
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Hirai
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Hoshino
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tabei
authors.affiliation: Haruhisa Miyazawa, Susumu Ookawara, Kiyonori Ito, Katsunori Yanai, Hiroki Ishii, Taisuke Kitano, Mitsutoshi Shindo, Yuichiro Ueda, Yoshio Kaku, Keiji Hirai, Taro Hoshino, Yoshiyuki Morishita, Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, Saitama 330-8503, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Morishita
keywords: Albumin; Hemodialysis; Inorganic phosphate; Lower-limb muscle; Nutritional status; Protein-energy wasting; Regional saturation of oxygen; Sarcopenia