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PubMed2004

The use of air displacement plethysmography in children and adolescents with cystic fibrosis.

OBJECTIVES: The purpose of this paper was to evaluate the use of air displacement plethysmography (ADP) in children and adolescents with cystic fibrosis (CF). Specifically, the primary aim of this study was to compare estimates of fat-free mass (FFM) measured from ADP and dual energy X-ray absorptiometry (DEXA) in children and adolescents with CF. The secondary aim was to compare the effect of using predicted thoracic gas volume (VTG) and measured VTG for the calculation of FFM by ADP in this population. METHODS: Cross-sectional FFM measurements were taken using ADP and DEXA in 52 children and adolescents with CF, ranging in age from 6.3 to 16.6 y. RESULTS: Bland-Altman analysis showed that ADP values of FFM were on average 0.59 kg higher than DEXA values (95% limits of agreement = 3.61 to -2.43 kg); however this difference was not significant. There was no significant correlation (r = -0.26, P = 0.07) between the mean FFM and difference in FFM between ADP and DEXA. Using either predicted or measured VTG did not significantly affect FFM estimates in individuals with CF who had normal lung function (bias = -0.39 +/- 0.86 kg; r = -0.02, P = 0.93). CONCLUSIONS: ADP is an appropriate technique for use in children and adolescents with CF.

Absorptiometry, Photon↗
PubMed2006

Air displacement plethysmography can detect moderate changes in body composition.

OBJECTIVES: To determine the sensitivity of air displacement plethysmography (APD) for evaluation of changes in body composition in normal subjects. DESIGN: Comparison of measurements with and without oil or water loads. SUBJECTS AND METHODS: Ten healthy volunteers were analyzed, without and with 1 l and 2 l of oil or water. The measured and true changes in fat mass and fat-free mass were compared by paired t-tests. A correlation study and a Bland & Altman procedure was performed on the 60 measurements of adiposity changes in 30 subjects carrying 0.5 l (n=8 x 2), 1 l (n=10 x 2) and 2 l (n=12 x 2) oil and water loads. RESULTS: Fat-free mass increased when the 10 subjects were carrying water. When they carried oil, fat mass increased, however, a approximately 0.5 kg increase of fat-free mass was also detected. Two liters loads led to distinct changes: +1.49+/-0.59 kg fat and +0.50+/-0.60 kg fat-free with oil and +0.37+/-0.57 kg fat and +1.70+/-0.56 kg fat-free with water (both P<0.001). Mixed loads (+1 l oil and 1 l water) led to detect +0.85+/-0.48 kg fat and +1.09+/-0.45 kg fat-free (both P<0.005 vs without load). For the 30 subjects analyzed thrice, measured changes in fat and fat-free mass were slightly underestimated (-15%, NS) but correlated with the true changes. Measured changes in adiposity were correlated with the true changes, with no bias as indicated by the Bland & Altman procedure. CONCLUSION: APD detects approximately 2 kg changes in fat or fat-free mass in small populations.

Adipose Tissue↗
PubMed2001

Precision of measurement and body size in whole-body air-displacement plethysmography.

OBJECTIVE: To investigate methodological and biological precision for air-displacement plethysmography (ADP) across a wide range of body size. DESIGN: Repeated measurements of body volume (BV) and body weight (WT), and derived estimates of density (BD) and indices of fat mass (FM) and fat-free mass (FFM). SUBJECTS: Sixteen men, aged 22--48 y; 12 women, aged 24--42 y; 13 boys, aged 5--14 y; 17 girls, aged 5--16 y. MEASUREMENTS: BV and WT were measured using the Bodpod ADP system from which estimates of BD, FM and FFM were derived. FM and FFM were further adjusted for height to give fat mass index (FMI) and fat-free mass index (FFMI). RESULTS: ADP is very precise for measuring both BV and BD (between 0.16 and 0.44% of the mean). After removing two outliers from the database, and converting BD to body composition, precision of FMI was <6% in adults and within 8% in children, while precision of FFMI was within 1.5% for both age groups. CONCLUSION: ADP shows good precision for BV and BD across a wide range of body size, subject to biological artefacts. If aberrant values can be identified and rejected, precision of body composition is also good. Aberrant values can be identified by using pairs of ADP procedures, allowing the rejection of data where successive BD values differed by >0.007 kg/l. Precision of FMI obtained using pairs of procedures improves to <4.5% in adults and <5.5% in children.

Adipose Tissue↗
PubMed2002

Comparison of percent body fat estimates using air displacement plethysmography and hydrodensitometry in adults and children.

PURPOSE: The purpose of the study was to compare estimates of body density and percentage body fat from air displacement plethysmography (ADP) to those from hydrodensitometry (HD) in adults and children and to provide a review of similar recent studies. METHODS: Body density and percentage body fat (% BF) were assessed by ADP and HD on the same day in 87 adults aged 18-69 y (41 males and 46 females) and 39 children aged 8-17 y (19 males and 20 females). Differences between measured and predicted thoracic gas volumes determined during the ADP procedure and the resultant effects of those differences on body composition estimates were also compared. In a subset of 50 individuals (31 adults and 19 children), reliability of ADP was measured and the relative ease or difficulty of ADP and HD were probed with a questionnaire. RESULTS: The coefficient of reliability between %BF on day 1 and day 2 was 96.4 in adults and 90.1 in children, and the technical error of measurement of 1.6% in adults and 1.8% in children. Using a predicted rather than a measured thoracic gas volume did not significantly affect percentage body fat estimates in adults, but resulted in overestimates of percentage body fat in children. Mean percentage body fat from ADP was higher than percentage body fat from HD, although this was statistically significant only in adults (29.3 vs 27.7%, P<0.05). The 95% confidence interval of the between-method differences for all subjects was -7 to +9% body fat, and the root mean square error (r.m.s.e.) was approximately 4% body fat. In the subset of individuals who were asked to compare the two methods, 46 out of 50 (92%) indicated that they preferred the ADP to HD. CONCLUSION: ADP is a reliable method of measuring body composition that subjects found preferable to underwater weighing. However, as shown here and in most other studies, there are differences in percentage body fat estimates assessed by the two methods, perhaps related to body size, age or other factors, that are sufficient to preclude ADP from being used interchangeably with underwater weighing on an individual basis.

Adipose Tissue↗
PubMed2004

Within- and between-laboratory precision in the measurement of body volume using air displacement plethysmography and its effect on body composition assessment.

OBJECTIVE: To determine and compare the extent of within- and between-laboratory precision in body volume (BV) measurements using air displacement plethysmography (ADP), the BOD POD body composition system, and to interpret any such variability in terms of body composition estimates. DESIGN: Repeated test procedures of BV assessment using the BOD POD ADP were reproduced at two laboratories for the estimation of precision, both within and between laboratories. SUBJECTS: In total, 30 healthy adult volunteers, 14 men (age, 19-48 y; body mass index (BMI), 19.7-30.3 kg/m2) and 16 women (age, 19-40 y; BMI, 16.3-35.7 kg/m2), were each subjected to two test procedures at both laboratories. Two additional volunteers were independently subjected to 10 repeated test procedures at both laboratories. MEASUREMENTS: Repeated measurements of BV, uncorrected for the effects of isothermal air in the lungs and the surface area artifact, were obtained using the BOD POD ADP, with the identical protocol being faithfully applied at both laboratories. Uncorrected BV measurements were adjusted to give estimates of actual BV that were used to calculate body density (body weight (BWt)/actual BV) from which estimates of body composition were derived. The differences between repeated BV measurements or body composition estimates were used to assess within-laboratory precision (repeatability), as standard deviation (SD) and coefficient of variation; the differences between measurements reproduced at each laboratory were used to determine between-laboratory precision (reproducibility), as bias and 95% limits of agreement (from SD of the differences between laboratories). RESULTS: The extent of within-laboratory methodological precision for BV (uncorrected and actual) was variable according to subject, sample group and laboratory conditions (range of SD, 0.04-0.13 l), and was mostly due to within-individual biological variability (typically 78-99%) rather than to technical imprecision. There was a significant (P<0.05) bias between laboratories for the 10 repeats on the two independent subjects (up to 0.29 l). Although no significant bias (P=0.077) was evident for the sample group of 30 volunteers (-0.05 l), the 95% limits of agreement were considerable (-0.68 to 0.58 l). The effects of this variability in BV on body composition were relatively greater: for example, within-laboratory precision (SD) for body fat as % BWt was between 0.56 and 1.34% depending on the subject and laboratory; the bias (-0.59%) was not significant between laboratories, but there were large 95% limits of agreement (-3.67 to 2.50%). CONCLUSION: Within-laboratory precision for each BOD POD instrument was reasonably good, but was variable according to the prevailing conditions. Although the bias between the two instruments was not significant for the BV measurements, implying that they can be used interchangeably for groups of similar subjects, the relatively large 95% limits of agreement indicate that greater consideration may be needed for assessing individuals with different ADP instruments. Therefore, use of a single ADP instrument is apparently preferable when assessing individuals on a longitudinal basis.

Adult↗
PubMed1986

The reproducibility of limb blood flow measurements in human volunteers at rest and after exercise by using mercury-in-Silastic strain gauge plethysmography under standardized conditions.

A study to assess the reproducibility of limb blood flow measurements by venous occlusion plethysmography using mercury-in-Silastic strain gauges was performed in six normal volunteers under standardized conditions. Using this technique forearm and calf blood flow were measured at rest and between 2 and 3 min after submaximal exercise on six separate occasions over a 1 month period. The mean coefficient of variation for resting forearm blood flow was 10.5% (range 7.8-15.6%). The mean coefficient of variation for resting calf blood flow was 11.5% (range 7.4-14.2%). The mean coefficient of variation for post-exercise calf blood flow was 13% (range 11.5-16.4%). The results suggest that limb blood flow measurement by this technique may be useful in studies where serial measurements are required.

Extremities↗
PubMed2000

The influence of the hand circulation on the assessment of venous distensibility of the human forearm with venous occlusion plethysmography.

AIMS: To determine the influence of the hand circulation on the determination of venous distensibility with venous occlusion plethysmography. METHODS: In a randomised study, duplicate measurements of forearm venous distensibility, with and without a wrist cuff, were made over occlusion periods of 3 and 12 min in eight volunteers. Treatments were compared with paired Student's t-tests and differences are presented as 95% confidence intervals (CI). Intra-subject variability was assessed with analysis of variance. RESULTS: Non-significant differences in increases in forearm volume between the occlusions with and without wrist cuff were found for the 3 min occlusion (CI: -0.4, + 0.2%) and the 12 min occlusion period (CI: -0.7, + 0.2%). However, the coefficient of variation was lower with the use of a wrist cuff; after 3 min occlusion (12% vs 19%) and after 12 min of occlusion (14% vs 24%). Forearm volume after 12 min of venous occlusion was 0.5% (CI: + 0.4, + 0.7) higher than after 3 min. CONCLUSIONS: Although venous distensibility was equal when assessed with and without wrist cuff, exclusion of the hand circulation reduces intraindividual variability. Equilibrium in forearm volume is not reached after 3 min period of venous occlusion, as often assumed. The magnitude of the additional increase after prolonged occlusion stresses the need for well-controlled studies.

Adult↗
PubMed2002

Repeatability of local forearm vasoconstriction to endothelin-1 measured by venous occlusion plethysmography.

AIMS: We investigated the repeatability of the forearm blood flow response to intra-arterial infusion of endothelin-1 (ET-1), assessed by venous occlusion -plethysmography. METHODS: In eight healthy men (aged 18-50 years), on four separate occasions, ET-1 (2.5 or 10 pmol min-1) was infused for 120 min via a 27 SWG cannula sited in the brachial artery of the nondominant arm. Each dose level was administered twice on consecutive visits. The dose order was randomized. Results are expressed as percentage change from baseline at 120 min (mean +/- s.e. mean). RESULTS: ET-1 caused significant vasoconstriction (P < 0.0001 anova) at both doses (38 +/- 3%, 2.5 pmol min-1 and 62 +/- 3%, 10 pmol min-1; mean visit 1 and 2). There was no difference in the response to either dose on repeated challenge. Responses appeared to be less variable when expressed as percentage change in the ratio of blood flow (infused:noninfused) in both arms than as percentage change in blood flow in the infused arm alone, as indicated by repeatability coefficients (15% vs 21%, 2.5 pmol min-1 and 11% vs 13%, 10 pmol min-1; ratio vs infused arm alone). CONCLUSIONS: We have shown dose-dependent vasoconstriction in the forearm vascular bed to intra-arterial infusion of ET-1 and that this response is less variable when expressed as percentage change in the ratio of forearm blood flow than percentage change in the infused arm. These data should also provide useful information to determine the power of early clinical pharmacology studies investigating the activity of endothelin receptor antagonists.

Adult↗
PubMed2002

Reproducibility of air plethysmography for the evaluation of arterial and venous function of the lower leg.

This study assessed the test-retest reliability of air plethysmographic parameters for the evaluation of arterial and venous function of the lower extremity in normal, healthy adults. Fourteen voluntary subjects underwent air plethysmographic tests on two occasions, 1-2 weeks apart, with three tests being performed at each visit. Test-retest reliability was assessed via correlation coefficients and the intraclass correlations. Differences in the parameters of arterial inflow (AI), venous volume (VV), venous refilling time (VFT), venous refilling index (VFI), ejection volume (EV) and residual fraction (EF) obtained on the two separate occasions were small (r = 0.81 approximately 0.95; ICC = 0.94 approximately 0.99), whereas differences in ejection fraction (EF), residual volume (RV) and venous outflow (OF) measurements were much larger (r = 0.50 approximately 0.61; ICC = 0.58 approximately 0.95). The findings demonstrate that evaluation of blood flow in the lower limbs of healthy individuals using air plethysmography is reliable in test-retest measures, suggesting that this technique represents a sensitive method for quantifying changes in parameters of arterial and venous functions of the lower extremity.

Adult↗
PubMed2000

Quantitative assessment of superficial venous insufficiency using duplex ultrasound and air plethysmography.

OBJECTIVE: The purpose of this study was to quantitatively evaluate venous reflux in limbs with isolated superficial venous insufficiency using color duplex ultrasound. In addition, air plethysmography (APG) was used to investigate possible correlations of duplex-derived peak velocity, duration of reflux, and CEAP classification. METHODS: One hundred and forty-six legs in 109 patients with isolated superficial venous insufficiency refluxing throughout the length of the limb were selected for prospective study by duplex scan. Reflux was defined as duration of reflux >/=0. 5 seconds. This study was conducted in a university hospital. Venous reflux was evaluated with the patients standing, by the duration of reflux, retrograde peak velocity, reflux volume at the saphenofemoral and saphenopopliteal junction as well as the greater saphenous vein in the thigh. Values obtained by APG were the venous volume (VV), venous filling index (VFI), ejection fraction (EF), and residual venous fraction (RVF). A significant difference was defined as P <.05. Three groups of limbs were analyzed: group A limbs with a retrograde peak velocity greater than 30 cm/second and a duration of reflux of less than 3 seconds; group B with a retrograde peak velocity >/=30 cm/second and a duration of more than 3 seconds; and group C with a retrograde peak velocity of less than 30 cm/second and a duration of reflux of more than 3 seconds. RESULTS: Groups A and B contained 103 limbs, and 24 of these were in CEAP class 5 and 6. Group C contained 43 limbs, none of which were in class 5 or 6. APG demonstrated significant reflux in group A, and VFI was significantly higher compared to group B and group C (P =.0007 and P =.0064, respectively). A significant correlation was demonstrated between peak retrograde reflux velocity and VFI. CONCLUSIONS: Severe chronic venous insufficiency is found in limbs with high reflux velocity (greater than 30 cm/second) and the duration of reflux does not correlate with severe chronic insufficiency.

Adult↗
PubMed1997

Filling and emptying characteristics of lower limb venous network in athletes. Study by postural plethysmography.

Leg volume changes were assessed in healthy volunteers by mercury strain gauge postural plethysmography in order to study the effects of different types of physical training on lower limb venous distensibility and emptying. Seven endurance trained subjects (E), seven muscle strength trained subjects (M) and seven sedentary subjects (S) were submitted to a tilt table test. The test measured leg filling volumes FV (ml.100 ml-1) during 30 head-up tilt, half-emptying time T1/2 (seconds) and venous output at the 6th second of emptying (VO6) (ml.100 ml-1.min-1) during return to horizontal position. Comparative tests were made using an ANOVA test. Results showed significantly higher values for FV and VO6 in E (FV: 3.9 +/- 0.2 ml.100 ml-1 in E vs 2.5 +/- 0.2 and 2.2 +/- 0.2 ml.100 ml-1 in M and S, respectively; VO6: 9.2 +/- 1.1 ml.100 ml-1.min-1 in E vs 6.9 +/- 0.7 and 5.5 +/- 0.5 ml.100 ml-1.min-1 in M and S, respectively) whereas no significant differences were observed between groups for T1/2. M and S had the same physiological responses to orthostatic stress. Endurance training seems to increase lower limb venous distensibility without affecting venous emptying and venous return from the lower limbs. These results suggest that the greater venous distensibility in endurance-trained subjects does not result from alterations of the visco-elastic properties of deep vein walls and that it is probably a physical response to hypervolemia consecutive to chronic aerobic training.

Adult↗
PubMed1977

Combined use of leg scanning and impedance plethysmography in suspected venous thrombosis. An alternative to venography.

Venography is the standard method for the diagnosis of venous thrombosis but is invasive and may cause discomfort. We evaluated the combination of impedance plethysmography and 125I-fibrinogen leg scanning as an alternative to venography in 200 symptomatic patients. One or both of these less invasive tests was positive in 81 of 86 patients with positive venograms (sensitivity of 94 per cent) and both were negative in 104 of 114 patients with negative venograms (specificity of 91 per cent). These two tests detected all 60 patients with popliteal or more proximal venous thrombosis and 21 of 26 patients with calf-vein thrombosis. In addition, this approach detected 21 of 22 patients with calf-vein thrombosis with symptoms for eight days or less. These results suggest that the combination of these two less invasive tests can be used as an alternative to venography in selected patients with clinically suspected venous thrombosis.

Adolescent↗
PubMed1989

The limitations of impedance plethysmography in the diagnosis of acute deep venous thrombosis.

We reviewed our experience with impedance plethysmography (IPG) and duplex scanning in the diagnosis of acute deep venous thrombosis (DVT) to determine their respective accuracy and current role in our noninvasive vascular laboratory. During a recent 22-month period 1776 patients were evaluated in our laboratory for DVT. Sixty patients (64 limbs) underwent ascending venography within 48 hours of testing (49 limbs were evaluated by all three modalities). With the venograms used as the reference standard, B-mode scanning correctly identified the presence of acute thrombus in 24 of 27 limbs (88.8%) and the absence of thrombus in 31 of 34 limbs (91.2%), for an overall accuracy of 90.6%. IPG alone was less sensitive (75%) and less specific (44.8%), with an overall accuracy of only 57.1%. Twenty-eight IPGs were performed on patients with negative venous scans. Two positive IPGs were the result of chronic venous occlusion and two others detected clinically significant isolated iliac vein thrombi, but 13 patients had false positive IPGs. One false negative IPG occurred. The difference in the sensitivity of scan alone vs scan plus IPG was not significant (chi 2 = 0.045; difference not significant), but the decrease in specificity was chi 2 = 17.3; p less than 0.001). The rarity of isolated iliac vein thrombosis and the high false positive rate for IPG do not justify its continued use if B-mode venous scanning is available. Although positive scan results may be used confidently to institute therapy without the need for venography, in high-risk patients with a strong clinical suspicion of proximal DVT despite a negative scan venography should be obtained before withholding anticoagulation.

Acute Disease↗
PubMed2000

The value of air plethysmography in predicting clinical outcome after surgical treatment of chronic venous insufficiency.

PURPOSE: The role of air plethysmography (APG) as a predictor of clinical outcome after surgery in venous disease is yet to be defined. The purpose of this study was to investigate the value of APG in predicting clinical outcome after venous surgery for chronic venous insufficiency (CVI). METHODS: Seventy-three extremities in 71 patients with Class 3 through 6 CVI were assessed preoperatively with CEAP (c linical, e tiologic, a natomic, p athophysiologic) criteria, standing reflux duplex ultrasound scan, and APG with measurements of preoperative venous filling index (VFI), venous volumes, ejection fraction, and residual volume fraction. After surgical treatment of the affected limbs, repeat APG studies were obtained within 6 weeks. Established venous reporting standards were used for follow-up to calculate clinical symptom scores (CSSs) in each patient. RESULTS: Superficial venous reflux occurred alone in 24 limbs or in conjunction with perforator incompetence in 26 limbs. Deep and superficial reflux, with or without perforator incompetence, was found in 16 limbs, and seven limbs had isolated deep insufficiency. Follow-up was available in 60 of 71 patients (mean period, 44.3 months). Postoperative APG demonstrated significant hemodynamic changes after surgery as measured with VFI, venous volumes, ejection fraction, and residual volume fraction. Mean CSSs decreased from 7.35 +/- 0.56 preoperatively to 1.79 +/- 0.32 at late follow-up after surgery (P <.001). With the use of logistic regression, the parameter correlating most closely with clinical outcome was the VFI. A normal postoperative VFI (</= 2 mL/s) predicted a good clinical outcome (CSS </= 2) in follow-up patients, with a positive predictive value of 94%, a specificity of 89%, and a sensitivity of 70%. CONCLUSIONS: Normalization of the VFI after venous surgery for CVI is predictive of a good clinical outcome. This APG measurement may be a useful parameter to predict adequacy of surgery in patients with venous insufficiency.

Adult↗
PubMed2001

Air plethysmography: the answer in detecting past deep venous thrombosis.

PURPOSE: In this study we assessed the accuracy of air plethysmography (APG) as a means of detecting earlier deep venous thrombosis (DVT), in comparison with venography, to develop a preoperative test for patients with varicose veins. METHODS: In this retrospective analysis of prospectively acquired data, 202 patients referred with the clinical suspicion of chronic venous obstruction (224 lower limbs) and 41 patients (41 lower limbs) who had symptoms and signs suggestive of DVT, but had deep veins that appeared normal on venography, were studied with both venography and APG. RESULTS: The results of venography were negative for past DVT in 169 legs and confirmed past DVT in 96 limbs. The DVTs were confined to the calf in 19 limbs and were found at popliteal level, more proximal, or both in 77 limbs. A total of 95% of the limbs that had earlier proximal DVT (73 of 77) were identified by means of an APG outflow fraction with occlusion of the superficial veins in the first second (OFs) of less than 28%. This is analogous to the Q wave of the electrocardiogram, which is a means of denoting the presence of myocardial infarction. The specificity rate of the method in the detection of past proximal DVT was 96%, the positive predictive value was 92%, and the negative predictive value was 98%. CONCLUSION: APG is a practical, inexpensive, easy-to-perform, accurate, noninvasive method for the diagnosis of hemodynamically significant (ie, proximal or extensive calf DVT) chronic venous obstruction that could replace venography.

Adult↗
PubMed2001

Evolution of deep venous thrombosis: a 2-year follow-up using duplex ultrasound scan and strain-gauge plethysmography.

OBJECTIVE: The development of the post-thrombotic syndrome (PTS) and recurrence of deep venous thrombosis (DVT) are not yet fully understood. The aim of the study was to identify factors that lead to the long-term complications of DVT. METHODS: In a 2-year prospective follow-up study, duplex scanning and strain-gauge plethysmography were used to evaluate DVT in relation to the development of long-term complications. Each of the 12 segments examined was assigned as a thrombosis score (TS). A total TS was calculated for each leg. Patent segments were assigned a TS = 0, noncompressible vein segments with flow TS = 1 and noncompressible vein segments without flow TS = 2. The degree of resolution of DVT and the incidence, timing, and outcome of further thrombotic events were measured during 24 months of follow-up. RESULTS: The study involved 86 legs with DVT. The 2-year follow-up was completed for 70 legs. Within 3 months, only 1% of the originally occluded proximal deep vein segments were still occluded. Between all time intervals, from month 12 to month 24, for example, thrombus regression continued in 36% of the legs and thrombus propagation continued in 27%. Multiple regression analysis revealed that an increase in age (P = .008) and proximal location of the original DVT (P = .05) was significantly related to thrombus propagation. Multiple regression analysis showed that the risk factors for clinical signs of PTS were a high venous outflow resistance after 1-month and 12-month follow-ups (P <or= .002) and a high thrombosis score in the proximal veins after 3 months (P = .008). CONCLUSIONS: In the follow-up of older patients and patients with proximal DVT, evolution was shown to be an unstable process with continuing propagation for 2 years. The risk factors for the development of PTS were a slow decrease in venous outflow resistance or a high thrombosis score of the proximal veins after 3 months.

Adolescent↗
PubMed2002

Recurrence of chronic venous ulcers on the basis of clinical, etiologic, anatomic, and pathophysiologic criteria and air plethysmography.

INTRODUCTION: Leg ulcers associated with chronic venous insufficiency (CVI) frequently recur after healing. The risk of recurrence has not been well defined for patients in different anatomic and hemodynamic groups. We reviewed the risk of ulcer recurrence on the basis of clinical, etiologic, anatomic, and pathophysiologic criteria and hemodynamic characteristics of the affected limb as assessed with air plethysmography (APG). METHODS: Ninety-nine limbs with class 6 CVI were assessed clinically and with standing duplex ultrasound scanning and APG for the definition of clinical, etiologic, anatomic, and pathophysiologic criteria. Leg ulcers were treated with high-pressure compression protocols. Surgical correction of venous abnormalities was offered to patients with appropriate conditions. After ulcer healing, the limbs were placed in compressive garments and followed at 6-month intervals for ulcer recurrence. RESULTS: The mean patient age was 54.3 years, and 46% of the patients were female. Corrective venous surgery was performed in 37 limbs. The mean follow-up time for all 99 limbs was 28 months. The ulcer recurrence rate with life table was 37% +/- 6% at 3 years and 48% +/- 10% at 5 years. The patients who underwent venous surgery had a significantly lower recurrence rate (27% +/- 9% at 48 months) than did those patients who had not undergone surgery (67% +/- 8% at 48 months; P =.005). The patients with deep venous insufficiency (DVI; n = 51) had significantly higher recurrence rates (66% +/- 8% at 48 months) than did the patients without DVI (n = 48; 29% +/- 9% at 48 months; P =.006). This difference was significant even after accounting for the effects of surgery (P =.03). The hazard ratio of ulcer recurrence increases by 14% for every unit increase in the venous filling index (VFI; P =.001). This remains significant even after accounting for the effects of surgery (P =.001). The combination of DVI and a VFI of more than 4 mL/s yields a risk of ulcer recurrence of 43% +/- 9% at 1 year and 60% +/- 10% at 2 years. CONCLUSION: Leg ulcers associated with CVI have a high rate of recurrence. Ulcer recurrence is significantly increased in patients with DVI and in patients who do not have venous abnormalities corrected surgically. The VFI obtained from APG is useful in the prediction of increased risk for recurrence, particularly in association with anatomic data.

Bandages↗
PubMed2003

Evaluation of air-displacement plethysmography in children aged 5-7 years using a three-component model of body composition.

The aim of the present study was to evaluate air-displacement plethysmography (ADP) in children aged 5-7 years. Body-composition measurements were obtained by ADP, (2)H dilution and anthropometry in twenty-eight children. Calculation of body volume by ADP was undertaken using adult and children's equations for predicting lung volume and surface area. Fat-free mass (FFM) was calculated using a three-component model. Measured FFM hydration was then compared with values from the reference child. Differences between measured and reference hydration were back-extrapolated, to calculate the error in ADP that would account for any disagreement. Propagation of error was used to distinguish the contributions of methodological precision and biological variability to total hydration variability. The use of children's equations influenced the results for lung volume but not surface area. The mean difference between measured and reference hydration was 0.6 (sd 1.7) % (P<0.10), equivalent to an error in body volume of 0.04 (sd 0.20) litres (P<0.30), and in percentage fat of 0.4 (sd 1.9) (P<0.28). The limits of agreement in individuals could be attributed to methodological precision and biological variability in hydration. It is concluded that accuracy of ADP was high for the whole group, with a mean bias of <0.5 % fat using the three-component model, and after taking into account biological variability in hydration, the limits of agreement were around +/-2 % fat in individuals. Paediatric rather than adult equations for lung volume estimation should be used.

Body Composition↗