Table 2.

Multifocal body composition and body compartment assessment techniques available for hospitalized children

Method	Body Compartment	Advantage	Limitation
BIA [23, 24]	Fat mass, fat free mass estimated from total body water	Quick, portable, inexpensive, safe, reproducible, non-invasive, does not require highly trained personnel, Increasing evidence in utilization of fluid status assessment [25, 26]	Sensitive to hydration, individual level prediction errors, limitations to prediction equations (e.g., sex, age, ethnicity), limited standardization of reportable measures
CT [23, 27]	Adipose tissue, skeletal muscle, bone, organs	Accurate, L3 cross sectional area good correlation with total body muscle volume	Radiation exposure, costly, requires expertise, body size limitation, availability of site and disease state
MRI [23, 27]	Adipose tissue, skeletal muscle, visceral organs	Accurate	Costly, requires expertise, not portable
B-Mode ultrasound [23, 27–29]	Localized muscle thickness and fatty infiltration Localized skin thickness – multisite equations for FM estimations Fluid overload – lung scoring [30], inferior vena cava diameter [31]	Portable, safe, minimal training, reproducible, beneficial for abdominal adiposity discrimination between subcutaneous and visceral May differentiate volume-dependent hypertension from volume-independent hypertension in dialysis	Muscle measurement more prone to error due to compressibility, site selection, transducer position and hydration, secondary processing required for fatty infiltration of muscle, 2 dimensional Fluid assessment not reliable, not correlated with extracellular fluid volume
Anthropometry	Weight/Length – fat estimation BMI – fat estimation SFT – fat estimation Circumferences: MUAC – total body muscle estimation [32, 33] Leg – site specific muscle estimation Arm – site specific muscle estimation	Quick, portable, easy, inexpensive, non-invasive, safe SFT performs well in CKD MUAC with good correlation to BMI z scores ≤ –2 [32]	Insensitive, altered by hydration, best used serially, dependent on accurate weight and height measurements Difficulty attaining accurate weight and height measures in ICU SFT with operator variability, performs poorly in dialysis [34]
Physical assessment [14, 35, 36]	Subjective surrogate measures for change in fat, muscle, and edema	Reliable, clinically validated	Requires additional measures to confirm assessment
% Fluid overload [37]	Relative TBW %FO = ((Fluid in – Fluid out)/ ICU admission wt) × 100 Weight modified (CKRT) %FO = ((CKRT initiation wt – ICU Admission wt)/ ICU admission wt) × 100 %FO = ((CKRT initiation wt –hospital wt)/ hospital admission wt) × 100	Quick, easy to perform, validated	Reliant on precise and accurate I/O measurement and calculations, does not account for insensible losses, requires accurate weight measurements, fluid accumulation not site specific
Non-Invasive Blood Volume Monitoring [38]	relative blood volume; hematocrit dilution changes during hemodialysis	Validated method to achieving euvolemic weights while limiting dialysis-associated morbidities	Specific to hemodialysis, requires specialized equipment

BIA, bioelectrical impedance analysis; CT, computed tomography; MRI, magnetic resonance imaging; L3, lumbar vertebra 3; BMI, body mass index; SFT, skin fold thickness; CKD, chronic kidney disease; ICU, intensive care unit; MUAC, mid-upper arm circumference; FO, fluid overload; CKRT, continuous kidney replacement therapy; wt, weight; I/O, ins and outs; TBW, total body water

Adapted from multiple sources within table