Prediction of limb lean tissue mass from bioimpedance spectroscopy in persons with chronic spinal cord injury.
BACKGROUND
Bioimpedance spectroscopy (BIS) is a non-invasive, simple, and inexpensive modality that uses 256 frequencies to determine the extracellular volume impedance (ECVRe) and intracellular volume impedance (ICVRi) in the total body and regional compartments. As such, it may have utility as a surrogate measure to assess lean tissue mass (LTM).


OBJECTIVE
To compare the relationship between LTM from dual-energy X-ray absorptiometry (DXA) and BIS impedance values in spinal cord injury (SCI) and able-bodied (AB) control subjects using a cross-sectional research design.


METHODS
In 60 subjects (30 AB and 30 SCI), a total body DXA scan was used to obtain total body and leg LTM. BIS was performed to measure the impedance quotient of the ECVRe and ICVRi in the total body and limbs.


RESULTS
BIS-derived ECVRe yielded a model for LTM in paraplegia, tetraplegia, and control for the right leg (RL) (R(2) = 0.75, standard errors of estimation (SEE) = 1.02 kg, P < 0.0001; R(2) = 0.65, SEE = 0.91 kg, P = 0.0006; and R(2) = 0.54, SEE = 1.31 kg, P < 0.0001, respectively) and left leg (LL) (R(2) = 0.76, SEE = 1.06 kg, P < 0.0001; R(2) = 0.64, SEE = 0.83 kg, P = 0.0006; and R(2) = 0.54, SEE = 1.34 kg, P < 0.0001, respectively). The ICVRi was similarly predictive of LTM in paraplegia, tetraplegia, and AB controls for the RL (R(2) = 0.85, SEE = 1.31 kg, P < 0.0001; R(2) = 0.52, SEE = 0.95 kg, P = 0.003; and R(2) = 0.398, SEE = 1.46 kg, P = 0.0003, respectively) and LL (R(2) = 0.62, SEE = 1.32 kg, P = 0.0003; R(2) = 0.57, SEE = 0.91 kg, P = 0.002; and R(2) = 0.42, SEE = 1.31 kg, P = 0.0001, respectively).


CONCLUSIONS
Findings demonstrate that the BIS-derived impedance quotients for ECVRe and ICVRi may be used as surrogate markers to track changes in leg LTM in persons with SCI.
James J. Peters VA Medical Center, Bronx, NY, USA. christopher.cirnigliaro@va.gov
Christopher M
CM
Cirnigliaro
Michael F
MF
La Fountaine
Racine
R
Emmons
Steven C
SC
Kirshblum
Pierre
P
Asselin
Ann M
AM
Spungen
William A
WA
Bauman
D015502:Absorptiometry, Photon; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D058266:Dielectric Spectroscopy / Q000295:instrumentation / Q000379:methods*; D017097:Electric Impedance; D004566:Electrodes; D006801:Humans; D008297:Male; D008875:Middle Aged; D010264:Paraplegia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D011237:Predictive Value of Tests; D011782:Quadriplegia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D013118:Spinal Cord Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D055815:Young Adult