Moderating Factors in Tissue Tonometry and Bioimpedance Spectroscopy Measures in the Lower Extremity of Healthy Young People in Australia and Myanmar.

BACKGROUND: Expected values for tissue tonometry and bioimpedance spectroscopy (BIS) in the lower extremity of young people have not been established. These measures are commonly used to assess tissue changes in adult, breast cancer-related lymphedema of the arm. In tropical regions, identification of tissue changes in the lower limbs related to lymphatic filariasis is required; hence expected values and factors contributing to variation in tissue tonometry and BIS in two tropical populations were investigated.

METHODS AND RESULTS: A convenience sample of healthy volunteers aged 8-21 in Myanmar and Australia was recruited. Tissue compressibility at the calf and anterior and posterior thigh was measured using three tonometry devices and free fluid in each leg was assessed using BIS. Data were collected about possible modifiers: leg dominance, age, gender, body mass index (BMI), hydration, and menstrual cycle. Paired t-test and linear regression compared the objective measures with possible modifiers within each population. Statistical significance was set at p < 0.05 with a 95% confidence interval. In Myanmar, increases in free fluid, tissue compressibility, and limb circumference were associated with being older, female, underweight, or in the second half of the menstrual cycle. In young Australians, increases in tissue compressibility and limb circumference were associated with being older or in the second half of the menstrual cycle.

CONCLUSION: When assessing tissue compressibility and free fluid in young people using tonometry and gender, BIS, limb dominance and BMI should be considered in a local context and attempts should be made to minimize the potential influences of hydration and the female menstrual cycle.