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PubMed2003

Prospective evaluation of chronic venous insufficiency based on foot venous pressure measurements and air plethysmography findings.

PURPOSE: The purpose of this study was to evaluate lower extremity venous function in patients with chronic venous insufficiency, with foot venous pressure (FVP) measurements and air plethysmography (APG). METHODS: Eighty-five limbs of 63 patients with a history of chronic venous insufficiency (CVI) from 1995 to 1999 were studied. FVP parameters studied included ambulatory venous pressure (AVP), percent decrease in FVP with manual calf compression (%drop), ratio of increase in FVP over 4 seconds after release of compression (4SR%), and time to 90% recovery of FVP were measured. APG parameters studied included functional venous volume, 90% refilling time (VFT90), venous filling index, ejection fraction, and residual volume fraction. RESULTS: Venous filling index and 90% refilling time were significantly decreased in limbs with stasis syndrome compared with the control group. AVP, %drop, and 4SR% also showed significantly decrease in limbs with stasis syndrome compared with those without it. AVP, %drop, and 4SR% were significantly different for the primary group compared with the secondary group, whereas no differences were found with regard to any APG parameter. CONCLUSIONS: APG enables prediction of the presence of CVI, whereas FVP measurements are more useful for evaluation of clinical severity of CVI.

Adult↗
PubMed2003

Recurrence after varicose vein surgery: a prospective long-term clinical study with duplex ultrasound scanning and air plethysmography.

OBJECTIVE: We observed long-term venous ultrasound and plethysmographic changes after varicose vein surgery, to determine factors that influence recurrence. METHODS AND MATERIALS: This observational sequential prospective study was carried out in an institutional referral center with day surgery. Subjects were 92 consecutive patients, ages 20 to 75 years, with symptomatic varicose veins in 127 limbs, who were able to complete regular assessment. Superficial varicose vein surgery included significant perforator vessels only, defined at preoperative duplex ultrasound scanning and air plethysmography. Similar follow-up assessments were performed at 3 weeks, 3 months, and 1, 3, and 5 years. RESULTS: At 3 weeks venous reflux but not muscle pump function was consistently improved in all limbs. However, inadequate surgery at the major junctions was clearly identified as contributing to recurrence of disease in 7.2% of limbs. Recurrence of varicose veins occurred in 1 of 100 limbs (1%) at the saphenofemoral junction and in 8 of 33 (25%) limbs at the saphenopopliteal junction. However, after 3 years disease recurrence at these sites had increased to 23% and 52%, respectively. Incompetent perforator vessels increased progressively in number. Clinical recurrence was 47.1%, and consistent with this was gradual deterioration in air plethysmographic measures of reflux, with physiologic recurrence (venous filling index, >2 mL/s) in 66% at 5 years. Late recurrence was predicted in limbs with multiple sites of reflux preoperatively, venous filling index greater than 2 mL/s, and some other persistent abnormality at duplex scanning at 3 weeks. There was no recurrence in 40 limbs in which these factors were normal at at 3 weeks. However, 29 of 53 limbs with normal venous filling index after operative intervention had deteriorated at 3 years. CONCLUSION: Incomplete superficial surgery, in particular at the saphenofemoral and saphenopopliteal junctions, is a less frequent cause of recurrent disease, and neovascular reconnection and persistent abnormal venous function are the major contributors to disease recurrence.

Adult↗
PubMed1994

Validation of air plethysmography, photoplethysmography, and duplex ultrasonography in the evaluation of severe venous stasis.

PURPOSE: The purpose of this study was to validate the diagnostic capabilities of the most commonly used noninvasive modalities for evaluation of chronic venous insufficiency. METHODS: Twenty limbs in 20 patients were studied with air plethysmography (APG), photoplethysmography (PPG), and duplex ultrasonography. Ten limbs (group 1) were clinically without any venous disease. Group 2 consisted of 10 limbs with severe, class 3 venous stasis. Duplex ultrasonography, complemented with Doppler color-flow imaging was used to examine the superficial and deep venous systems to identify reflux. RESULTS: Ultrasonography identified deep venous reflux in eight of 10 limbs in group 2. Severe superficial reflux was identified in the two remaining limbs. Seven limbs with deep reflux also demonstrated severe superficial reflux. Superficial venous reflux was identified in one leg in group 1. APG accurately separated normal limbs from those with reflux. Parameters that were significantly different (p < 0.05) between the two groups were the venous filling index, (group 1 = 1.37 +/- 1.16 ml/sec, group 2 = 29.5 +/- 6.2 ml/sec.), venous volume (group 1 = 107 +/- 10.1 ml, group 2 = 220 +/- 22.5 ml), ejection fraction (group 1 = 52.5% +/- 2.3%, group 2 = 32.5% +2- 4.6%), and residual volume fraction (group 1 = 21.4 +/- 2.0%, group 2 = 52.1% +/- 2.5%). PPG refill times were significantly shortened in group 2 versus those of group 1 (6.4 +/- 0.89 sec vs 20.2 +/- 1.1 sec). The sensitivity of PPG refill times to identify reflux was 100%, but the specificity was only 60%, whereas the sensitivity and specificity for the residual volume fraction was 100%. The venous filling index was able to identify reflux and determine whether only superficial reflux was present with a sensitivity of 100% and a specificity of 90%. The kappa coefficient of agreement between duplex scanning and APG was 0.83, whereas between duplex and PPG it was only 0.47. CONCLUSION: APG accurately identifies limbs with and without venous reflux when compared with duplex ultrasonography. APG is a better method of evaluating clinically significant venous reflux than PPG. PPG is a sensitive method of detecting reflux, but the specificity is poor, and PPG refill times cannot accurately predict the location of reflux. The combination of APG and duplex ultrasonography provides the best means of assessing venous reflux.

Adolescent↗
PubMed1996

A correlation of air plethysmography and color-flow-assisted duplex scanning in the quantification of chronic venous insufficiency.

PURPOSE: Air plethysmography has been useful in assessing patients who have chronic venous insufficiency. Limb reflux times determined by color-flow-assisted duplex scanning have been shown to correlate with the severity of chronic venous insufficiency. The purpose of this study was to compare air plethysmographic measurements with reflux times obtained by color-flow-assisted duplex scanning in patients with chronic venous insufficiency. METHODS: One hundred twenty-two limbs in 61 consecutive patients with various stages of chronic venous insufficiency were evaluated; air plethysmographic and color-flow-assisted duplex scans were performed at the same sitting. Fifty-nine of the patients had venous ulceration. Values obtained by air plethysmographic scans included venous filling index, ejection volume, residual volume, ejection fraction, and residual volume fraction. Color-flow-assisted duplex scan values included reflux times in the deep and superficial venous segments and total and mean limb reflux times. RESULTS: Using the Pearson correlation, the venous filling index was found to correlate significantly with total limb venous reflux times, mean total limb reflux times, and venous reflux times in the deep venous system, as determined by color-flow-assisted duplex scans (p < 0.001). CONCLUSIONS: Limb reflux time as determined by color-flow-assisted duplex scans correlated significantly with the air plethysmographic variable accepted as a measure of the severity of venous reflux, the venous filling index. This study confirms the validity of total limb reflux times in the quantification of chronic venous insufficiency.

Adult↗
PubMed1998

The role of air plethysmography in the diagnosis of chronic venous insufficiency.

PURPOSE: The role of air plethysmography (APG) in the diagnosis of venous disease is not well defined. We conducted this study to investigate the value of APG in the diagnosis of chronic venous insufficiency and to determine its correlation with the clinical severity of disease and the anatomic distribution of reflux. METHODS: We studied 186 lower extremities with duplex scanning and venography and measured the venous volume, venous filling index (VFI), ejection fraction, and residual volume fraction with APG. Limbs were categorized according to the Society for Vascular Surgery and International Society for Cardiovascular Surgery classification of clinical severity of disease and according to the anatomic distribution of valvular incompetence. RESULTS: Sixty-one limbs had no evidence of disease (class 0), 60 limbs had mild disease (classes 1, 2, and 3), and 65 limbs had severe disease (classes 4, 5, and 6). According to the results of duplex scanning and venography, there was no evidence of reflux in 56 limbs. Isolated superficial venous reflux occurred in 52 limbs, and perforator reflux, alone or in conjunction with superficial reflux, occurred in 30. Deep reflux, with or without superficial reflux, was found in 25 limbs. Deep and perforator reflux, with or without superficial reflux, was found in 19 limbs. The VFI had a sensitivity of 80% and 99% positive predictive value for any type of reflux. The VFI was significantly different between groups of limbs with different clinical severities of disease or different types of reflux. The incidence of deep or perforator reflux in limbs with a normal VFI value was 7%, and it was 82% in limbs with a VFI of more than 5. Among 86 limbs with VFI values not corrected with use of a thigh tourniquet, 28% did not have evidence of deep or perforator reflux, and among 15 limbs with VFI values corrected with the use of a tourniquet, 33% had perforator reflux, deep reflux, or both. All APG parameters had low positive predictive values for severe disease or ulceration. The ejection fraction and residual volume fraction did not influence the clinical severity of disease, did not discriminate between types of reflux, and in combination with the VFI did not improve the predictive value of APG. CONCLUSIONS: The VFI measured by APG is an excellent predictor of venous reflux, provides an estimate of the clinical severity of disease, and at high levels predicts deep reflux, perforator reflux, or both. Correction of an abnormal VFI with a thigh tourniquet is an unreliable predictor of the absence of deep or perforator incompetence. The predictive value of APG for severe disease or ulceration is poor. The ejection fraction and residual volume fraction, individually or in combination with the VFI, add little to the diagnostic value of APG, and their routine performance may not be clinically justified.

Blood Volume↗
PubMed1999

The postthrombotic syndrome in relation to venous hemodynamics, as measured by means of duplex scanning and strain-gauge plethysmography.

PURPOSE: Venous hemodynamics were evaluated in relation to the postthrombotic syndrome (PTS) 7 to 13 years after deep venous thrombosis (DVT). METHODS: The presence of flow, reflux, and compressibility of 1394 vein segments in 82 patients was assessed by means of duplex scanning. The venous outflow resistance was measured by means of strain-gauge plethysmography. The venous hemodynamics were related to the clinical severity of the PTS, characterized by the CEAP (clinical, etiologic, anatomic, pathophysiologic) classification. RESULTS: In patients with severe clinical symptoms of PTS, the prevalence of reflux was significantly higher. There was no relationship between the severity of the PTS and the noncompressibility or the combination of reflux and noncompressibility or an increased venous resistance. By means of multiple regression analysis with the variables of age, gender, reflux, and venous resistance, age and reflux were shown to be the main contributors to the severity of PTS. Significantly more patients (64%) with severe signs of PTS had a combination of deep and superficial reflux. In each of the traceable vein segments, the mean of the CEAP classification was calculated for the vein segments with and without reflux. In the proximal superficial femoral vein (P <.001), distal superficial femoral vein (P <.05), and popliteal vein (P <.05), a significantly higher mean CEAP classification was found in the veins with reflux, whereas in the distal, long, and short saphenous veins, no such relationship was found. CONCLUSION: Most patients with severe PTS had a combination of deep and superficial reflux. Reflux in the deep proximal veins contributes significantly to the PTS.

Adult↗
PubMed1997

Respiratory function parameters in infants using inductive plethysmography.

A signal processing technique has been developed to determine respiratory function parameters by processing displacement data obtained from the abdomen and the rib cage of infants using respiratory inductive plethysmography. The technique transforms time-variant signals into the frequency domain, where they are filtered to reduce unwanted signal components. The phase relationship between the abdominal displacement and the rib cage displacement is determined from the phases of the filtered signals. Flow-volume loops, which are currently of great interest in respiratory medicine, are obtained from waveforms representing respiratory tidal flow and respiratory tidal volume. The index of respiratory timing is determined from a waveform representing respiratory tidal flow. The technique has been verified by statistical comparison with data simultaneously obtained using pneumotachography in a clinical study involving 49 infants.

Artifacts↗
PubMed2002

Diagnosis of anesthetic-induced upper airway obstruction in children using respiratory inductance plethysmography.

OBJECTIVE: Upper airway obstruction is the most rapid and clinically relevant cause of hypoxia during sedation and anesthesia. This study was designed to determine if respiratory inductance plethysmography (RIP) could quantify the degree of upper airway obstruction caused by induction of general anesthesia. METHODS: RIP tracings were obtained during induction of general anesthesia in healthy children. Three sets of measurements were obtained during: (1) a 3 minute control period without anesthetics, (2) 3 minutes of 50% nitrous oxide, and (3) halothane administration to complete the induction of general anesthesia. Clinical impression of upper airway obstruction (none, partial, or complete) was correlated with two separate RIP analysis techniques. RESULTS: Three hundred ninety-five breathing epochs from 20 children (ages 3-10 years) were analyzed by both phase shift and phase inversion techniques. Although both techniques had good general correlation with severity of airway obstruction, neither was sufficiently reliable for accurate prediction of severity of airway obstruction. CONCLUSIONS: We investigated two methods for analyzing RIP tracings during varying degrees of upper airway obstruction in anesthetized children. We found that neither technique was sufficiently accurate for predicting the severity of upper airway obstruction and would not be useful as a predictor of upper airway obstruction in the clinical or research settings.

Airway Obstruction↗
PubMed2000

Respiratory inductance plethysmography in healthy infants: a comparison of three calibration methods.

Respiratory inductance plethysmography (RIP) measures respiration from body surface movements. Various techniques have been proposed for calibration in order that RIP may be used quantitatively. These include calculation of the proportionality constant of ribcage to abdominal volume change (K). The aims of this study were to 1) establish whether a fixed value of K could be used for calibration, and 2) compare this technique with multiple linear regression (MLR) and qualitative diagnostic calibration (QDC) in normal healthy infants. Recordings of pneumotachograph (PNT) flow and RIP were made during quiet (QS) and active sleep (AS) in 12 infants. The first 5 min in a sleep state were used to calculate calibration factors, which were applied to subsequent validation data. The absolute percentage error between RIP and PNT tidal volumes was calculated. The percentage error was similar over a wide range of K during QS. However, K became more critical when breathing was out of phase. A standard for K of 0.5 was chosen. There was good agreement between calibration methods during QS and AS. In the first minute following calibration during QS, the mean absolute errors were 3.5, 4.1 and 5.3% for MLR, QDC and fixed K respectively. The equivalent errors in AS were 11.5, 13.1 and 13.7% respectively. The simple fixed ratio method can be used to measure tidal volume with similar accuracy to multiple linear regression and qualitative diagnostic calibration in healthy unsedated sleeping infants, although it remains to be validated in other groups of infants, such as those with respiratory disease.

Calibration↗
PubMed2002

Effect of elastic compression stockings in patients with varicose veins and healthy controls measured by strain gauge plethysmography.

BACKGROUND/AIMS: Oedema is one of the most frequent signs of chronic venous insufficiency and may be present at all stages of this disorder. The aim of this study was to compare the effects of four different types of elastic compression stockings on oedema prevention in patients with varicose veins. METHODS: An increase in foot volume after elevation of the leg was evaluated by strain gauge plethysmography in 20 limbs with varicose veins and 14 normal limbs, and the effects of four different compression stockings--8, 14, 22 and 30-40 mmHg--were compared. RESULTS: All stockings significantly reduced the foot volume increase compared with the no stockings patient group and the normal group. There was no significant difference in the volume increase in the normal group for all four stockings, while there was a significantly smaller volume increase in the 22 mmHg stocking compared to the 14 mmHg stocking in the patient group. Between the 22 mmHg and 30-40 mmHg stockings or between the 14 mmHg and 8 mmHg stockings, there was no significant difference in the volume increase. CONCLUSION: Elastic stockings, even with a pressure as low as 8 mmHg, can prevent oedema in patients with varicose veins, as well as in normal controls. However, the 22 mmHg and 30-40 mmHg stockings were better at preventing foot oedema in patients with varicose veins than those exerting less compression.

Bandages↗
PubMed2001

Effect of scalp and facial hair on air displacement plethysmography estimates of percentage of body fat.

OBJECTIVE: The objective of this study was to determine the effect of body hair (scalp and facial) on air displacement plethysmography (BOD POD) estimates of percentage of body fat. RESEARCH METHODS AND PROCEDURES: A total of 25 men (31.4 +/- 8.0 years, 83.4 +/- 12.2 kg, 181.8 +/- 6.9 cm) agreed to grow a beard for 3 weeks to participate in the study. Total body density (g/cm(3)) and percentage of body fat were evaluated by BOD POD. To observe the effect of trapped isothermal air in body hair, BOD POD measures were performed in four conditions: criterion method (the beard was shaven and a swimcap was worn), facial hair and swimcap, facial hair and no swimcap, and no facial hair and no swimcap(.) RESULTS: The presence of only a beard (facial hair and swimcap) resulted in a significant underestimation of percentage of body fat (16.2%, 1.0618 g/cm(3)) vs. the criterion method (17.1%, 1.0597 g/cm(3), p < 0.001). The effect of scalp hair (no swim cap worn) resulted in a significant underestimation in percentage of body fat relative to the criterion method, either with facial hair (facial hair and no swimcap; 14.8%, 1.0649 g/cm(3)) or without facial hair (no facial hair and no swimcap; 14.8%, 1.0650 g/cm(3), p < 0.001 for both). DISCUSSION: A significant underestimation of percentage of body fat was observed with the presence of facial hair ( approximately 1%) and scalp hair ( approximately 2.3%). This underestimation in percentage of body fat may be caused by the effect of trapped isothermal air in body hair on body-volume estimates. Thus, excess facial hair should be kept to a minimum and a swimcap should be worn at all times to ensure accurate estimates of body fat when using the BOD POD.

Adipose Tissue↗
PubMed2005

Percentage fat in overweight and obese children: comparison of DXA and air displacement plethysmography.

OBJECTIVE: To compare percentage body fat (percentage fat) estimates from DXA and air displacement plethysmography (ADP) in overweight and obese children. RESEARCH METHODS AND PROCEDURES: Sixty-nine children (49 boys and 20 girls) 14.0+/-1.65 years of age, with a BMI of 31.3+/-5.6 kg/m2 and a percentage fat (DXA) of 42.5+/-8.4%, participated in the study. ADP body fat content was estimated from body density (Db) using equations devised by Siri (ADP(Siri)) and Lohman (ADP(Loh)). RESULTS: ADP estimates of percentage fat were highly correlated with those of DXA in both male and female subjects (r=0.90 to 0.93, all p<0.001; standard error of estimate=2.50% to 3.39%). Compared with DXA estimates, ADP(Siri) and ADP(Loh) produced significantly (p<0.01) lower estimates of mean body fat content in boys (-2.85% and -4.64%, respectively) and girls (-2.95% and -5.15%, respectively). Agreement between ADP and DXA methods was further examined using the total error and methods of Bland and Altman. Total error ranged from 4.46% to 6.38% in both male and female subjects. The 95% limits of agreement were relatively similar for all percentage fat estimates, ranging from +/-6.73% to +/-7.94%. DISCUSSION: In this study, conversion of Db using the Siri equation led to mean percentage fat estimates that agreed better with those determined by DXA compared with the Lohman equations. However, relatively high limits of agreement using either equation resulted in percentage fat estimates that were not interchangeable with percentage fat determined by DXA.

Absorptiometry, Photon↗
PubMed2005

Air displacement plethysmography: validation in overweight and obese subjects.

OBJECTIVE: Patients with moderate and severe obesity, because of their physical size, often cannot be evaluated with conventional body composition measurement systems. The BOD POD air displacement plethysmography (ADP) system can accommodate a large body volume and may provide an opportunity for measuring body density (D(b)) in obese subjects. D(b) can be used in two- or three-compartment body composition models for estimating total body fat in patients with severe obesity. The purpose of this study was to compare D(b) measured by ADP to D(b) measured by underwater weighing (UWW) in subjects ranging from normal weight to severely obese. RESEARCH METHODS AND PROCEDURES: D(b) was measured with UWW and BOD POD in 123 subjects (89 men and 34 women; age, 46.5 +/- 16.9 years; BMI, 31.5 +/- 7.3 kg/m2); 15, 70, and 10 subjects were overweight (25 < or = BMI < 30 kg/m2), obese (30 < or = BMI < 40 kg/m2), and severely obese (BMI > or = 40 kg/m2), respectively. RESULTS: There was a strong correlation between D(b) (kilograms per liter) measured by UWW and ADP (r = 0.94, standard error of the estimate = 0.0073 kg/L, p < 0.001). Similarly, percent fat estimates from UWW and ADP using the two-compartment Siri equation were highly correlated (r = 0.94, standard error of the estimate = 3.58%, p < 0.001). Bland-Altman analysis showed no significant bias between D(b) measured by UWW and ADP. After controlling for D(b) measured by ADP, no additional between-subject variation in D(b) by UWW was accounted for by subject age, sex, or BMI. DISCUSSION: Body density, an important physical property used in human body composition models, can be accurately measured by ADP in overweight and obese subjects.

Adipose Tissue↗
PubMed2005

Prediction of visceral adipose tissue using air displacement plethysmography in children.

OBJECTIVE: To determine the ability of air displacement plethysmography (ADP) to predict visceral adipose tissue (VAT) volume in children. RESEARCH METHODS AND PROCEDURES: Fifty-five (33 boys/22 girls) white children 13 to 14 years old were studied. Anthropometric measures were collected for body mass, stature, BMI, and waist-to-hip ratio (WHR), and body fat percentage was estimated from triceps and subscapular skinfolds, bioelectrical impedance analysis, and ADP. VAT volume was determined using magnetic resonance imaging, using a multiple slice protocol at levels L1 to L5. RESULTS: Boys had significantly (p < or = 0.05) less VAT volume than girls [645.1 (360.5) cm(3) vs. 1035.8 (717.3) cm(3)]. ADP explained the greatest proportion of the variance in VAT volume compared with the other anthropometric measures. Multiple regression analysis indicated that VAT volume was best predicted by ADP body fat percentage in boys [r(2) = 0.81, SE of the estimate (SEE) = 160.1, SEE coefficient of variation = 25%] and by WHR and BMI in girls (r(2) = 0.80, SEE = 337.71, SEE coefficient of variation = 33%). DISCUSSION: Compared with the other anthropometric measures, ADP explains the greatest proportion of the variance in VAT volume in children 13 to 14 years old. For boys, ADP is the tool of choice to predict VAT volume, yet using the more simply collected measures of BMI and WHR is recommended for girls. However, large SE of the estimates remained, suggesting that if precision is needed, there is no surrogate for direct imaging of VAT.

Adipose Tissue↗
PubMed2007

Body composition of obese subjects by air displacement plethysmography: The influence of hydration.

OBJECTIVE: We investigated whether air displacement plethysmography (ADP) could detect small changes in body composition of obese subjects with alterations in hydration. RESEARCH METHODS AND PROCEDURES: Ten obese subjects (mean BMI, 39.3 +/- 2.8 kg/m2) entered the ADP chamber without and with oil (1, 2, or 4 liters), water (1, 2, or 4 liters), or mixed (1 liter oil + 1 liter water or 2 liters oil + 2 liters water) loads. Real and measured changes in body composition were compared by regression analysis and Bland-Altman procedures. RESULTS: The ADP-measured changes in volume did not differ from the real values and were strongly correlated with them (r = 0.98). In all cases, loads of differing composition and similar volume led to different values of fat, fat-free mass, and percentage fat. Water was detected as increased fat-free mass only with loads of > or =2 liters, most of the water being falsely detected as increased fat mass. The observed changes were correlated with the real ones for fat mass (r = 0.68; p < 0.0001), fat-free mass (r = 0.66; p < 0.0001), and percentage fat (r = 0.61; p < 0.0001), but fat mass changes were overestimated by approximately 1 kg, and fat-free mass changes were underestimated by approximately 1 kg. This underestimation increased with the highest water loads, as shown by the Bland-Altman plot (r = -0.27; p < 0.05). Percentage fat changes were overestimated by 0.8% (p < 0.001); the magnitude of the error was correlated with the weight of the water load (r = 0.62; p < 0.0001). DISCUSSION: ADP accurately measures changes in body volume, discriminating small changes in body composition. It overestimates changes in adiposity, as most of the increased hydration is detected as an enlarged fat mass.

Adipose Tissue↗
PubMed1976

Deep venous thrombosis in acute spinal cord injury: a comparison of 125I fibrinogen leg scanning, impedance plethysmography and venography.

Twenty acute spinal cord injury patients were surveyed for deep venous thrombosis (DVT) by 125I fibrinogen leg scanning, impedance plethysmography (IPG), and venography. Leg scanning was a more sensitive indicator of thrombotic events than IPG or venography. IPG was a reliable indicator of accumulated thrombosis. The incidence of dvt assessed by leg scanning alone was 100 per cent. Its occurrence as determined by either of the screening techniques was found to be considerably greater than those of previous reports.

Adult↗
PubMed2003

Estimates of percentage body fat in young adolescents: a comparison of dual-energy X-ray absorptiometry and air displacement plethysmography.

OBJECTIVE: To evaluate the accuracy of percentage body fat (%fat) estimates from air displacement plethysmography (ADP) against an increasingly recognised criterion method, dual-energy X-ray absorptiometry (DXA), in young adolescents. DESIGN: Cross-sectional evaluation. SETTING: Leeds General Infirmary, Centre for Bone and Body Composition Research, Leeds, UK. SUBJECTS: In all, 28 adolescents (12 males and 16 females), age (mean+/-s.d.) 14.9+/-0.5 y, body mass index 21.2+/-2.9 kg/m(2) and body fat (DXA) 24.2+/-10.2% were assessed. RESULTS: ADP estimates of %fat were highly correlated with those of DXA in both male and female subjects (r=0.84-0.95, all P<0.001; s.e.e.=3.42-3.89%). Mean %fat estimated by ADP using the Siri (1961) equation (ADP(Siri)) produced a nonsignificant overestimation in males (0.67%), and a nonsignificant underestimation in females (1.26%). Mean %fat estimated by ADP using the Lohman (1986) equations (ADP(Loh)) produced a nonsignificant underestimation in males (0.90%) and a significant underestimation in females (3.29%; P<0.01). Agreement between ADP and DXA methods was examined using the total error (TE) and methods of Bland and Altman (1986). Males produced a smaller TE (ADP(Siri) 3.28%; ADP(Loh) 3.49%) than females (ADP(Siri) 3.81%; ADP(Loh) 4.98%). The 95% limits of agreement were relatively similar for all %fat estimates, ranging from +/-6.57 to +/-7.58%. Residual plot analyses, of the individual differences between ADP and DXA, revealed a significant bias associated with increased %fat (DXA), only in girls (P<0.01). CONCLUSIONS: We conclude that ADP, at present, has unacceptably high limits of agreement compared to a criterion DXA measure. The ease of use, suitability for various populations and cost of ADP warrant further investigation of this method to establish biological variables that may influence the validity of body fat estimates.

Absorptiometry, Photon↗
PubMed2004

Use of hand-to-hand impedancemetry to predict body composition of African women as measured by air displacement plethysmography.

OBJECTIVES: To test the validity of a simple, rapid, field-adapted, portable hand-held impedancemeter (HHI) for the estimation of lean body mass (LBM) and percentage body fat (%BF) in African women, and to develop specific predictive equations. DESIGN: Cross-sectional observational study. SETTINGS: Dakar, the capital city of Senegal, West Africa. SUBJECTS: A total sample of 146 women volunteered. Their mean age was of 31.0 y (s.d. 9.1), weight 60.9 kg (s.d. 13.1) and BMI 22.6 kg/m(2) (s.d. 4.5). METHODS: Body composition values estimated by HHI were compared to those measured by whole body densitometry performed by air displacement plethysmography (ADP). The specific density of LBM in black subjects was taken into account for the calculation of %BF from body density. RESULTS: : Estimations from HHI showed a large bias (mean difference) of 5.6 kg LBM (P<10(-4)) and -8.8 %BF (P<10(-4)) and errors (s.d. of the bias) of 2.6 kg LBM and 3.7 %BF. In order to correct for the bias, specific predictive equations were developed. With the HHI result as a single predictor, error values were of 1.9 kg LBM and 3.7 %BF in the prediction group (n=100), and of 2.2 kg LBM and 3.6 %BF in the cross-validation group (n=46). Addition of anthropometrical predictors was not necessary. CONCLUSIONS: The HHI analyser significantly overestimated LBM and underestimated %BF in African women. After correction for the bias, the body compartments could easily be estimated in African women by using the HHI result in an appropriate prediction equation with a good precision. It remains to be seen whether a combination of arm and leg impedancemetry in order to take into account lower limbs would further improve the prediction of body composition in Africans.

Adipose Tissue↗