Estimation of arm muscle mass in hemodialysis patients by segmental bioimpedance (SBIS) MRI and 40K techniques

The aim of this study was to evaluate and compare segmental bioimpedance spectroscopy (SBIS) measurements of arm volume and muscle to 40K and MRI measurements. 31 hemodialysis (HD) patients (17 male and 14 female, weight, 55.7 +/- 4.5 kg, BNH 27.6 +/- 5.5 m3/kg) were studied pre HD. MW and partial body 40K of the arm (PBKArm) were measured. Arm bioimpedance was measured with the Hydra bioimpedance spectroscopic device (Xitron 4200). The length of the arm from wrist to ipsilateral shoulder was measured with soft tape. Arm extracellular (Re) and intracellular resistance (Ri) were obtained from a program based on Cole-Cole model provided by Xitron. Extracellular (ECVa) and Intracellular volumes (ICVa) in the arm were calculated. Arm fluid volume using SBIS was defined as VArm =ECVa+ ICVa. The correlation of the VArin and arm skeletal muscle (MSMRI) was R2=0.65 (MSMRI =0.89*Varm+0.15), that between PBKArm to VArm (R2 =0.53, VArm =2.34*PBKArm + 2.1) and to MSMRI (R2=0.36, MSNM=2.4* PBKArm + 7.6), respectively. This study shows that arm SBIS measurement provides an easy, portable, low-cost technique for estimation of muscle mass in the arm, which can be performed frequently. The technique of arm bioimpedance measurement used to estimate arm muscle also could be useful to estimate whole body muscle after appropriate calibration. This could be of value in nutritional studies in HD patients.