Forearm and biceps circumferential variations in skin tissue dielectric constant and firmness.

Tissue dielectric constant (TDC) and skin firmness assessed via indentation force (FORCE) help quantify lymphedema and track changes. We sought to determine potential differences in these parameters dependent on arm circumferential locations. Thus, TDC and FORCE were measured in 40 healthy women at medial, anterior and lateral locations on forearm and biceps. In five other women with unilateral lymphedema (68.6±7.6 years), TDC was measured at corresponding circumferential forearm positions. Measurements were done in triplicate using compact noninvasive devices. Results for healthy women (23.8±2.7 years) showed forearm medial TDC values (26.7±2.2) were less than anterior (28.0±2.4) or lateral (28.0±2.5) positions (p<0.001). Lymphedema patients had elevated values but similar medialanterior- lateral patterns (33.7±8.0, 39.8±10.2 and 42.9±10.0). Biceps medial TDC values (24.1±2.2) were also less than either anterior (27.0±2.1) or lateral (28.2±3.3). Contrastingly, medial FORCE values at forearm and biceps were less than at anterior and lateral locations (p<0.001) and increased in the order of medialanterior- lateral on forearm (p<0.001). The present findings provide reference values for both TDC and FORCE of commonly measured arm sites with specificity as to circumferential variations. This observed variation indicates the need for care in locating measurement positions for tracking patients with lymphedema.

Factors affecting interpretation of tissue dielectric constant (TDC) in assessing breast cancer treatment related lymphedema (BCRL).

Tissue dielectric constant (TDC) measurements are increasingly used as quantitative adjunctive tools to detect and assess lymphedema. Various factors affect measured TDC values that may impact clinical interpretations. Our goal was to investigate possible impacts of: 1) anterior vs. medial arm measures, 2) total body water (TBW%) and arm fat percentages (AF%), 3) measurement depth, and 4) skin firmness. In 40 healthy women (24.5±2.5 years), TDC was measured bilaterally on anterior forearm to 0.5, 1.5, 2.5, and 5.0 mm depths using a multiprobe device and on anterior and medial aspects using a compact device. TBW% and AF% were measured at 50KHz and skin firmness measured by skin indentation force (SIF). Results showed: 1) No statistically significant difference in TDC values between anterior and medial arm, 2) a moderate direct correlation between TDC and TBW% (r=0.512, p=0.001), 3) an inverse correlation between TDC and AF% (r= -0.494, p<0.001) with correlations greatest at the deepest depth, and 4) a slight but statistically significant inverse correlation between TDC and SIF (r= -0.354, p=0.001). TDC values with compact vs. multiprobe were within 6% of each other with interarm (dominant/nondominant) ratios not significantly different. The findings provide a framework to help interpret TDC values among divergent conditions.

Tissue dielectric constant ratios as a method to characterize truncal lymphedema.

Truncal lymphedema is one possible complication of breast cancer treatment. It affects many women and is diagnosed based on symptoms and clinical assessment. Because changes occur late in the process, it is useful to have a quantitative assessment that is applied earlier to detect more subtle changes and quantitively assess treatment progress. Our goal was to describe a possible method to accomplish this via measurements of tissue dielectric constant (TDC). TDC was measured at lateral thorax, anterior forearm, and biceps in 120 women awaiting surgery for breast cancer. Inter-side TDC ratios were defined as values measured on the at-risk (cancer-side) lateral thorax divided by TDC values measured on contralateral thorax, forearm, and biceps. These ratios, designated as thorax-thorax, thorax-forearm, and thorax- biceps were (mean ± SD) 1.017 ± 0.121, 1.138 ± 0.223, and 1.263 ± 0.255 respectively. Corresponding truncal lymphedema thresholds were determined by adding 2.5SD to each mean yielding thresholds of 1.32, 1.70 and 1.90. For these thresholds, 99.4% of patients would have inter-side ratios less than the threshold value. Thus, from assessments in a non-lymphedematous patient-group a set of reference threshold-ratios are now available against which patients surgically treated for breast cancer may be prospectively compared.

Characterizing the tissue dielectric constant of skin basal cell cancer lesions.

BACKGROUND: Measuring tissue dielectric constant (TDC) of cancer tissues to distinguish them from normal or non-cancerous tissues has been an active area of research that has targeted several different cancer types usually using in vitro specimens. The goal of this study was to determine if and to what extent TDC values measured in vivo at 300 MHz using a simple hand-held measuring device might differentiate between skin cancer lesions and non-cancerous skin. MATERIALS AND METHODS: Triplicate TDC measurements were made in 32 patients who were subsequently diagnosed with skin basal cell carcinoma (BCC) and in 14 patients subsequently diagnosed as having non-cancerous lesions. Lesion TDC values were compared to contralateral unaffected skin and between lesion types. RESULTS: A significantly lower TDC value (mean ± SD) of BCC lesions (TDCL ) vs TDC values of contralateral non-affected skin (TDCC ) was found (22.4 ± 16.2 vs 38.1 ± 15.2, P < .00001). A similar pattern was found for non-cancerous lesions with lesion TDC values less than non-affected skin (14.5 ± 9.0 vs 29.1 ± 9.0, P < .0001). However, TDC values were not statistically different between BCC lesions and non-cancerous lesions (22.4 ± 16.2 vs 14.5 ± 9.0, P = .096) and calculated TDCL /TDCC ratios between BCC lesions and non-cancerous lesions also were not significantly different (0.596 ± 0.345 vs 0.501 ± 0.261, P = .364). CONCLUSIONS: (1) Main results do not support using TDC measurements to differentiate in vivo skin cancer lesions from non-cancerous lesions. (2) TDC values strongly suggest reduced water content of both cancerous and non-cancerous lesions. (3) Lesion TDC measurements provide reference values for future studies.

Accuracy and reliability of a hand-held in vivo skin indentation device to assess skin elasticity.

OBJECTIVE: The aim of this study was to evaluate the performance of a hand-held indentation device for fast and reliable determination of skin stiffness. METHODS: Device accuracy to indentation depths of 0.6 and 1.3 mm was first evaluated on plastic foam materials with mechanical properties verified by a laboratory material testing device. Subsequently, the device's sensitivity to detect age-related changes in skin stiffness was evaluated among 46 healthy women (18-79 years). Finally, the reproducibility of the method was tested with six healthy subjects. RESULTS: High correlation was detected between indentation stiffness of reference material and Young's modulus determined with mechanical testing device (0.6 mm indenter: r = 0.97, P = 0.05; 1.3 mm indenter: r = 0.98, P = 0.04). Age-related decrease of 38% in skin stiffness was observed in healthy volunteers (P < 0.05). The coefficient of variation for 0.6 and 1.3 mm indenters was 7.4% and 8.5%, respectively. No trend related to hysteresis effect was observed from repeated measurements. CONCLUSIONS: The presented indentation technique was accurate against the laboratory material testing device. Furthermore, skin changes related to ageing could be detected with the indentation technique. The new device was found to be feasible for monitoring skin stiffness in cosmetics and clinical conditions.

Race-related differences in tissue dielectric constant measured noninvasively at 300 MHz in male and female skin at multiple sites and depths.

BACKGROUND/PURPOSE: We hypothesized that reported race-related differences in skin properties cause skin and skin-to-fat water differences among races that are measureable by skin tissue dielectric constant (TDC) values that depend strongly on water content. Our first aim was to test this hypothesis. Also, since inter-side TDC ratios are used to assess edema and lymphedema, the second aim was to test if TDC ratios are race-dependent. The third aim was to determine the extent to which TDC depends on total body water (TBW) and fat (TBF). METHODS: Tissue dielectric constant was measured to 1.5 or 5.0 mm depths bilaterally on chest, forearm and ankle in 100 young (19-39 years) adults with 10 male and 10 female per self-expressed race. Races were African-American, Asian, Asian-Indian, Caucasian and Hispanic groups. TBW and TBF were measured using bioimpedance. RESULTS: Tissue dielectric constant values decreased from chest to forearm to ankle (P<.001) independent of race with most values greater for males but with inter-arm TDC ratios independent of gender, site, depth, or race. For females, forearm TDC values differed among races (P<.01) with Asian and Asian-Indian values tending to be least. For males, chest TDC values differed among races (P<.01) mainly due to large African-American TDC values. For the composite group, TDC was strongly (P<.001) positively correlated with TBW and negatively correlated with TBF. CONCLUSIONS: Tissue dielectric constant dependence on race of the type herein uncovered should be considered in assessing skin hydration comparisons that include different race or ethnic subjects. Further, the demonstrated relationship between TDC and body composition should be considered as an important covariate. However, despite these variations, the inter-arm TDC ratio remains robust as a potential indicator of unilateral tissue water changes.

Local Skin Cooling as an Aid to the Management of Patients with Breast Cancer Related Lymphedema and Fibrosis of the Arm or Breast.

Based on preliminary observations that topical cooling appeared to soften lymphedematous and fibrotic tissue, our goal was to systematically and quantitatively evaluate this effect. For this purpose, topical cooling was used as part of treatment of lymphedematous and fibrotic skin of women with breast cancer related lymphedema (BCRL) and localized fibrosis. Skin tissue hardness was assessed via the force required to indent skin to 4 mm (F4.0) and 1.3 mm (F1.3) and skin water was assessed by measurements of tissue dielectric constant (TDC). Measurements were done before cooling, after cooling, and after a single treatment session in 20 women with arm involvement and in 12 women with breast involvement. Pre-cooled arm and breast skin temperatures (mean ± SD) of 32.4 ± 1.4°C and 33.8 ± 1.0°C were reduced to 23.7 ± 2.0°C and 24.7 ± 1.6°C respectively via application of cold washcloths. Cooling was associated with a significant (p<0.001) decrease in F4.0 and F1.3 at arm and breast sites. At arm sites, force reductions ranged from 24% to 28% depending on indentation depth. Although the precise mechanism linking cooling to softening is as yet not fully understood, the fact that tissue is softened carries with it many potential benefits to patient and therapist. The near immediate tissue softening is associated with less pressure on underlying nerve endings and less input to sensory nerves thereby interrupting the pain cycle resulting in rapid pain relief. The rapidly softened tissue and decreased perception of pain offers the patient hope and encouragement in their therapeutic journey to reclaiming functional use of their affected body. Further, because softer tissue becomes more pliable, myofascial lengthening, scar tissue releasing, and other aspects of treatment are easier to perform thereby reducing treatment time and effort while achieving improved functional mobility.

Age-related differences in tissue dielectric constant values of female forearm skin measured noninvasively at 300 MHz.

BACKGROUND/PURPOSE: We hypothesized that reported age-related shifts in skin water from less-to-more mobile states would result in increased skin tissue dielectric constant (TDC) values as TDC values depend strongly on water content and state. One aim was to test this hypothesis. Further, as skin-to-fat TDC values are used as a tool for edema and lymphedema assessment, a second aim was to establish reference values suitable for young and older women. METHODS: TDC was measured bilaterally on volar forearm skin in young (20-40 years) and older (≥60 years) women. There were four groups with 50, 50, 100, and 50 subjects per age group measured to depths of 0.5, 1.5, 2.5, and 5.0 mm, respectively. RESULTS: For each age group, TDC values decreased with increasing depth (P < 0.001). TDC values at 0.5 and 1.5 mm were greater for older women (P < 0.001). At 2.5 mm, there was no age-group difference (P = 0.108). At 5.0 mm the direction of the difference reversed with older TDC values less than the younger (P < 0.001). CONCLUSION: Results are consistent with age-related shifts in water state from less-to-more mobile and explain depth-dependence differences between age groups. Data also give age-related TDC reference values for assessing local edematous or lymphedematous states.

Young adult gender differences in forearm skin-to-fat tissue dielectric constant values measured at 300 MHz.

BACKGROUND/PURPOSE: Skin-to-fat tissue dielectric constant (TDC) values depend on measurement depth and gender. Our goal was to assess male-female differences in TDC values associated with differing skin depths. METHODS: Bilateral forearm TDC measurements were made on young adult male and females with mean ages from 24.7 to 27.3 years. There were four measurement groups distinguished by the TDC measurement depth and include the following numbers of subjects for each gender; 30, 150, 60, and 50 for probe-measurement depths of 0.5, 1.5, 2.5, and 5.0 mm. Data were subsequently compared with values calculated with a simple two-layer model. RESULTS: For females and males, there was a significant difference in TDC values among depths (P < 0.001) with TDC values decreasing with increasing depth. Gender comparisons showed that TDC values of males were significantly (P < 0.001) greater than values for females at each depth. Male-female percentage differences ranged from 14.8% to 22.0%. Model calculations suggest that gender differences might be explained by skin thickness differences. CONCLUSION: Findings indicate that decisions with regard to skin water content among or between groups based on TDC measurements need to account for gender and are best made when corresponding skin thickness measurements are available. However, changes in TDC values assessed in individual patients and comparisons between corresponding skin areas in affected and non-affected sites are not limited. Thus, assessments of acute treatment effects and assessments of inter-arm or inter-leg TDC differences or ratios within genders are a useful and suitable method to characterize edema and lymphedema features.

Tissue Dielectric Constant (TDC) as an Index of Skin Water in Women With and Without Breast Cancer: Upper Limb Assessment Via a Self-Contained Compact Measurement Device.

Previous work showed tissue dielectric constant (TDC) measurements at 300 MHz useful to evaluate local skin water and then a hand-held compact version provided values similar to the original multi-probe system when assessed in healthy subjects. Our current goals were to use the compact portable device to determine: 1) its utility in assessing agerelated differences between younger healthy women vs. women with breast cancer (BC); 2) upper-arm site differences in women with BC and 3) its utility and limitations of a single measurement vs. averaging triplicate measurements. A total of 84 women were included; 42 were young (24.0 ± 2.4 years) self-described healthy women (group A) and 42 were older (65.5 ± 1.6 years) women with recently diagnosed BC who were awaiting surgery (group B). In both groups TDC values were assessed on the anterior forearm and in group B at the hand, forearm and biceps with all measurements bilateral and in triplicate Results showed the following. 1) Forearm TDC values are similar for younger and older groups with no significant differences (NSD) between groups or between dominant and nondominant sides or inter-arm ratios. 2) Hand TDC values are about 21% greater than forearm and biceps values but inter-arm ratios (at-risk/contralateral) are NSD among sites with values for hand, forearm and biceps of 1.027 ± 0.180, 0.997 ± 0.066 and 1.010 ± 0.075 respectively. 3) Based on limits of agreement analyses, single TDC measurements are adequate for most forearm and biceps evaluations but multiple measurements are likely needed for hand measurements. 4) Theoretical detection thresholds for nilateral lymphedema using a 3SD limit of inter-arm ratios are 1.57, 1.20 and 1.24 for and, forearm and biceps. These ratios indicate likely useful forearm and biceps thresholds but a less useful ratio at the hand due primarily to the large variance in hand TDC values among patients.

Tissue dielectric constant (TDC) as an index of localized arm skin water: differences between measuring probes and genders.

An easily measured, non-invasive, quantitative estimate of local skin tissue water is useful to assess local lymphedema and its change. One method uses skin tissue dielectric constant (TDC) values that at 300 MHz TDC depend on free and bound water within the measurement volume. In practice such measurements have been done with a research-type multi-probe, but recently a hand-held compact-probe has become available that may be more clinically convenient. Because most available published data is based on multiprobe measurements it is important to characterize possible differences between devices that unless known might lead to ambiguous quantitative comparisons between TDC values. Thus, our purpose was to evaluate potential differences in measured TDC values between multi-probe and compact-probe devices with respect to probe effective sampling depth, anatomical site, and gender and also to compare compact-probe TDC values measured on women with and without breast cancer (BC). TDC was measured bilaterally on forearms and biceps of 32 male and 32 female volunteers and on 12 female patients awaiting surgery for breast cancer. Results show that 1) TDC values at 2.5 mm depth were significantly less than at 1.5 mm; 2) Female TDC values were significantly less than male values; 3) TDC values were not different between females with and without BC; and 4) dominant/non-dominant arm TDC ratios were not significantly different for any probe among genders or arm anatomical site. These findings indicate that probe type differences in absolute TDC values are present and should be taken into account when TDC values are compared. However, comparisons based on inter-arm TDC ratios are not statistically different among probes with respect to gender or anatomical location.

Tissue dielectric constant (TDC) measurements as a means of characterizing localized tissue water in arms of women with and without breast cancer treatment related lymphedema.

Quantitative measurements to detect lymphedema early in persons at-risk for breast cancer (BC) treatment-related lymphedema (BCRL) can aid clinical evaluations. Since BCRL may be initially manifest in skin and subcutis, the earliest changes might best be detected via local tissue water (LTW) measurements that are specifically sensitive to such changes. Tissue dielectric constant (TDC) measurements, which are sensitive to skin-to-fat tissue water, may be useful for this purpose. TDC differences between lymphedematous and non-lymphedematous tissue has not been fully characterized. Thus we measured TDC values (2.5 mm depth) in forearms of three groups of women (N = 80/group): 1) healthy with no BC (NOBC), 2) with BC but prior to surgery, and 3) with unilateral lymphedema (LE). TDC values for all arms except LE affected arms were not significantly different ranging between 24.8 ± 3.3 to 26.8 ± 4.9 and were significantly less (p < 0.001) as compared to 42.9 ± 8.2 for LE affected arms. Arm TDC ratios, dominant/non-dominant for NOBC, were 1.001 ± 0.050 and at-risk/ contralateral for BC were 0.998 ± 0.082 with both significantly less (p < 0.001) than LE group affected/control arm ratios (1.663 ± 0.321). These results show that BC per se does not significantly change arm LTW and that the presence of BCRL does not significantly change LTW of non-affected arms. Further, based on 3 standard deviations of measured arm ratios, our data demonstrates that an at-risk arm/contralateral arm TDC ratio of 1.2 and above could be a possible threshold to detect pre-clinical lymphedema. Further prospective measurement trial are needed to confirm this value.

Changes in tissue water and indentation resistance of lymphedematous limbs accompanying low level laser therapy (LLLT) of fibrotic skin.

Our goal was to determine effects of low-level-laser-therapy (LLLT) on skin water and tissue indentation resistance (TIR) in patients with arm (N = 38) or leg (N = 38) lymphedema. Skin water was determined from tissue dielectric constant (TDC) measurements and TIR determined from measurements of force resulting from tissue indentations of 3-4 mm. A limb-location with fibrosis was identified by palpation and treated with an LLLT device for one minute at each of five points within a 3 cm2 area. TDC and TIR at these sites and corresponding sites on the contralateral limb were measured prior to LLLT (pre-LLLT), immediately after LLLT (post-LLLT) and after a manual lymphatic drainage (MLD) session (post-MLD). Results, from arms and legs, showed that post-LLLT values of TIR and TDC were significantly less than pre-LLLT. TIR values remained significantly reduced at post-MLD whereas TDC values were not significantly different from pre-LLLT values. On follow-up visit, 17 previously LLLT treated legs were sham treated with an inactive LLLT unit and measurements replicated. A TIR and TDC change-pattern similar to that obtained with the active LLLT was obtained, but sham-related reductions in TIR and TDC immediately post sham-treatment were significantly less than achieved with the prior active LLLT treatment.

Medical compression: effects on pulsatile leg blood flow.

AIM: Leg compression bandaging is the mainstay of venous ulcer treatment, yet little is known about the impact of therapeutic compression levels on arterial haemodynamics. In this study, the effect of foot-to-knee, four-layer compression bandaging on below-knee arterial pulsatile blood flow was assessed by nuclear magnetic resonance flowmetry. METHODS: In 14 healthy supine subjects, bilateral pulsatile blood flow measured at five below-knee sites without compression; and during compression of one leg to an average malleolar sub-bandage pressure of 40.7±4.0 mmHg. RESULTS: The forefoot-to-knee compression bandaging caused a highly significant (P<0.001) increase in the bandaged leg pulsatile blood flow due to increases in both peak flow and pulse width. CONCLUSION: It is hypothesized that arteriolar vasodilatation, induced either myogenically by reduced transmural pressure or by vasodilatory substance release triggered by increased venous shear stress and veno-arterial interactions, possibly combined with altered vascular compliance, produce the observed compression-related phenomenon. Whatever the mechanism(s), the finding of a compression-associated pulsatile flow increase suggests an arterial linkage, which may play a role in the well-documented beneficial effects of compression bandaging in venous ulcer and lymphedema treatment. Possible beneficial effects of the arterial flow-pulse increase on venous ulcer outcome may be related to a decrease in leukocyte effects in the distal microvasculature.

Assessing lymphedema by tissue indentation force and local tissue water.

Tissue water and mechanical property changes accompany lymphedema, however the relationship between these changes, if any, is unclear. Local tissue water is quantifiable using the tissue's dielectric constant (TDC), but a non-gravity dependent handheld clinical assessment tool to easily quantify corresponding local tissue properties is not widely available. Herein such a tool is described along with results obtained with it and with TDC measurements made in healthy legs and in lymphedematous legs before and after one manual lymphatic drainage (MLD) treatment. Using the handheld device, tissue indentations to various depths could be completed and corresponding indentation forces (IF) recorded. Following tests in gels, foams, and 24 healthy human legs to confirm linearity and repeatability, IF and TDC were measured in 22 legs of 18 lymphedema patients prior to and after one MLD treatment. Results showed that pre-MLD both IF and TDC were significantly (p < 0.001) greater in lymphedematous legs compared to healthy legs and that both IF and TDC significantly (p < 0.001) decreased after MLD. However, no correlation was found between pretreatment IF and TDC nor between post-MLD changes. Thus, measurements of local IF and tissue water provide useful but apparently independent information as to lymphedematous status and its potential change with therapy.

Localized tissue water changes accompanying one manual lymphatic drainage (MLD) therapy session assessed by changes in tissue dielectric constant inpatients with lower extremity lymphedema.

Previous reports described the utility of assessing local tissue water via tissue dielectric constant (TDC) measurements. Our goal was to determine the suitability of this method to evaluate lymphedema changes. For this purpose, we measured changes in TDC produced by one MLD treatment in 27 legs of 18 patients with lower extremity lymphedema. TDC values were measured to a depth of 2.5 mm at the greatest leg swelling site before and after one MLD treatment. Girth at the target site was measured with a calibrated tape measure. TDC values, which range from 1 for zero water to 78.5 for all water within the sampled volume, were measured four times and the average used to estimate local changes. Results showed that in every case the posttreatment TDC was reduced from its pretreatment value with percentage reductions (mean SD) of -9.8 +/- 5.64% (p < 0.0001). Girth changes were smaller being -1.5 +/- 1.93% (p < 0.01). We conclude that since TDC measurements reflect changes to a depth of about 2.5 mm whereas girth measurements reflect conditions of the entire cross-section, TDC assessment may be more sensitive to localized lymphedema changes. This finding suggests that TDC measurements are useful as complementary and perhaps as independent assessment methods of edema/lymphedema and treatment-related changes.

Local tissue water changes assessed by tissue dielectric constant: single measurements versus averaging of multiple measurements.

Previous reports describe the use of average tissue dielectric constant (TDC) measurements to assess local tissue water and its change. Our goal was to determine if a single TDC measurement could be used in place of the average of multiple measurements. The comparison criteria used to test this was the extent to which single and averaged measurements yielded similar TDC values in both normal and lymphedematous tissue. Measurements were made on both ventral forearms to a depth of 2.5 mm in 10 women with unilateral arm lymphedema. The main results showed that the 95% confidence interval for differences between single and averaged TDC values was less than +/- 1 TDC unit for both normal and lymphedematous arms. This finding strongly suggests that for most, if not all, clinical evaluations, suitable assessments can be made using a single TDC measurement.

Assessing local tissue edema in postmastectomy lymphedema.

Overall limb lymphedema can be assessed by several methods but none are suitable to determine local edema. Quantifying local edema could provide important information not previously available. Our goal was to determine the suitability of using the tissue dielectric constant (TDC) as and index of local tissue water to detect and quantify edema in postmastectomy patients with unilateral arm lymphedema. Segmental arm volume and TDC were measured in both arms of 18 women with unilateral lymphedema, and in 15 premenopausal and 15 postmenopausal controls. TDC was measured at a frequency of 300 MHz using open-ended coaxial probes with effective measuring depths of 0.5, 1.5, 2.5 and 5.0 mm. For patients and controls, absolute TDC depended on measurement depth but for any depth the TDC of lymphedematous segments was significantly greater than for non-affected contralateral arms (p<0.001). At a depth of 2.5 mm, the TDC ratio between arms for patients was 1.64+/-0.30 vs.1.04+/-0.04 for both control groups (p<0.001). No patient's TDC ratio was as low as 1.2 and no control subject's TDC ratio was as great as 1.2. Results suggest that this method is a good quantitative discriminator of the presence of lymphedema in patients with unilateral limb lymphedema.

Hand volume estimates based on a geometric algorithm in comparison to water displacement.

Assessing changes in upper extremity limb volume during lymphedema therapy is important for determining treatment efficacy and documenting outcomes. Although arm volumes may be determined by tape measure, the suitability of circumference measurements to estimate hand volumes is questionable because of the deviation in circularity of hand shape. Our aim was to develop an alternative measurement procedure and algorithm for routine use to estimate hand volumes. A caliper was used to measure hand width and depth in 33 subjects (66 hands) and volumes (VE) were calculated using an elliptical frustum model. Using regression analysis and limits of agreement (LOA), VE was compared to volumes determined by water displacement (VW), to volumes calculated from tape-measure determined circumferences (VC), and to a trapezoidal model (VT). VW and VE (mean +/- SD) were similar (363 +/- 98 vs. 362 +/-100 ml) and highly correlated; VE = 1.01VW -3.1 ml, r=0.986, p<0.001, with LOA of +/- 33.5 ml and +/- 9.9 %. In contrast, VC (480 +/- 138 ml) and VT (432 +/- 122 ml) significantly overestimated volume (p<0.0001). These results indicate that the elliptical algorithm can be a useful alternative to water displacement when hand volumes are needed and the water displacement method is contra-indicated, impractical to implement, too time consuming or not available.

Transcutaneous oxygen tension in arms of women with unilateral postmastectomy lymphedema.

Previous reports suggest that skin blood flow is reduced in arms of women with lymphedema due to breast cancer treatment. Since tissue oxygenation depends on blood flow, we sought to determine if transcutaneous oxygen tension (TcPO2) is also reduced and if so, if therapy that reduces edema has a beneficial effect. TcPO2 was measured in fibrotic areas of affected arms and in corresponding sites on non-affected arms of 15 women with unilateral arm lymphedema before and after CDP therapy sequences. Fibrosis was assessed by indentation recovery times (IRT) after applying an indenter-like device to tissue. Volumes and edema percentages were determined from circumferences using automated software calculations. Treatment significantly (p < 0.01) reduced arm edema from 28.6 +/- 22.9% to 18.1 +/- 17.7% (mean +/- SD) and fibrotic segment edema from 42.6 +/- 30.1% to 25.0 +/- 20.4%, and softened fibrotic tissue judged by reductions in IRT (88.7 +/- 60.7 sec vs. 23.1 +/- 38.8 sec, p < 0.001). TcPO2 did not differ between arms initially and did not change with treatment, being 60.1 +/- 8.8 mmHg at the start and 61.8 +/- 9.2 mmHg at the end of treatment. Thus, despite significant amounts of initial edema, TcPO2 was not initially less in affected arms nor was it changed by therapy that improved both edema and fibrosis.