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At least 271 records · Page 15Linked to original sources
PubMed1979

A continuous wave Doppler velocimeter for monitoring blood flow in the popliteal artery, compared with venous occlusion plethysmography of the calf.

A transcutaneous Doppler velocimeter has been used for monitoring changes in blood flow in the popliteal artery during and after exercise of the calf muscles on a calf-ergometer. The instrument and the positioning of the probe are described. The validity of the Doppler measurements has been assessed by comparing results after exercise and after 5 min arterial occlusion with venous occlusion plethysmography. For 10 healthy volunteers calibration lines were found which are curved. This can be ascribed partly to alinearity of the Doppler instrument and partly to changes of the diameter of the popliteal artery. Displacement of the probe with respect to the artery, which influences the measured velocity signal, can be detected and to a certain extent corrected by taking into account the intensity of the Doppler signal. The largest deviation of a data point from the corresponding calibration line varies for the ten subjects between 90 and 170 Hz in the high flow range (mean Doppler frequency around 1000 Hz) and between 20 and 60 Hz in the low flow range (mean Doppler frequency below 200 Hz).

Adult↗
PubMed1991

Plethysmography in the assessment and treatment of sexual deviance: an overview.

Theoretical and practical implications of previous research on plethysmography in the assessment and modification of sexual preferences has been limited by insufficient attention to definitional and procedural issues and sample heterogeneity. This paper reviews current theory and research on the use of the penile plethysmograph to diagnose or predict sexual deviance and to monitor therapeutic change in the modification of sexual preferences. Phallometric tests are discussed in terms of the basic components of the measurement technique, evidence of technical adequacy, and general principles underlying their use. The review points to a need to guard against false expectations and erroneous conclusions about sexual deviance based on this measurement technique. A case is made for closer attention to previously untested working assumptions and issues of definition, etiology, and measurement. Directions for future research are proposed.

Humans↗
PubMed2001

Error analysis of a natural breathing calibration method for respiratory inductive plethysmography.

Respiratory volumes are measured non-invasively by recording rib cage and abdominal motions using respiratory inductive plethysmography (RIP). Qualitative diagnostic calibration (QDC) of RIP is based on the natural variability in the relative rib-cage-to-abdomen contribution during tidal breathing. ODC does not require subject cooperation but it has previously been shown that accuracy may deteriorate when breathing pattern changes. The aim of this study was to investigate the causes and situations where QDC accuracy deteriorates. The QDC method was compared to PRA (calibration during voluntarily preferential rib cage or abdomen breathing) in ten adults. A reference RIP calibration was obtained from all validation data (REF). The PRA method had better accuracy than the ODC method (p<0.01). The volumetric error ranged between 10% and 136% with QDC and between 5% and 33% with PRA. The PRA calibration factors were within 6% of those from REF, while the QDC rib-cage factor was underestimated by 15% and the abdominal factor was overestimated by 38%. Small natural variability in the relative rib-cage-to-abdomen contribution was related to poor accuracy. Each compartment's variability depended on its magnitude, which is a violation of the QDC assumptions.

Calibration↗
PubMed2000

Numerical model of deep venous thrombosis detection using venous occlusion strain gauge plethysmography.

Strain gauge plethysmography (SGP) is a non-invasive method used in the detection of deep venous thrombosis (DVT). The technique is based on the measurement of calf volume changes in response to venous occlusion by a thigh cuff, the volume changes reflecting the rates of arterial inflow and venous outflow. A numerical model of the blood circulation within the limb and the response of this to a SGP test has been derived, based on treating the different parts of the circulatory system in the leg as resistance and capacitance elements. The simulation results were compared with clinical studies and support the ability of SGP to detect non-occlusive clots of more than 50-60% of the lumen, as well detecting calf vein occlusion. The non-linear behaviour of the venous compliance with intra-luminal pressure appears to be a particularly important factor within the model. In addition, increases in venous tone due to post-operative venospasm were shown to be a potential source of false positive results.

Humans↗
PubMed1991

Impedance plethysmography in human limbs. Part 1. On electrodes and electrode geometry.

Electrode design and electrode positioning are important factors in blood flow measurements using impedance plethysmography. Optimal electrode type and accurate positioning will decrease measurement errors and improve the signal-to-noise-ratio. Disk electrodes were found to be superior to tape electrodes because of their better skin-electrode stability and because they prevent limb compression. The distance between current electrodes and potential electrodes should be greater than 2.3 R (disk electrodes) and 1.5 R (tape electrodes) to avoid the influence of the so-called diffusion resistance (R is the radius of the limb at the electrode site).

Adult↗
PubMed1993

Electrical impedance plethysmography: its use in studying the cerebral circulation of the rabbit.

Electrical impedance plethysmography (EIP) is a noninvasive method that may be useful for both the continuous and serial measurement of changes in pulsatile cerebral blood volume and perhaps cerebral blood flow (CBF). It has not been well validated by comparison with other methods. To attempt to validate the EIP technique, the relationship between the peak amplitude of the transcranial, cardiac-synchronous impedance waveform (dZp) and cerebral blood flow measured by the radiolabelled microsphere technique (CBFrlm) and laser Doppler spectroscopy (CBFlds) was studied in rabbits. CBF was altered by inducing hypertension using metaraminol, hypotension by controlled haemorrhage or hypocarbia by hyperventilation. Twenty-three comparisons between dZp and CBFlds and 19 comparisons with CBFrlm were made in eight rabbits. The percentage change between each measurement using the three techniques in each animal was calculated. Using pooled data from all the animals, the linear regression equations were dZp = 0.5 CBFrlm + 33 (r = 0.38, p = 0.22, SE = 79) and dZp = 0.84 CBFlds + 19.6 (r = 0.46, p = 0.09, SE = 72). It is concluded that, in the anaesthetised rabbit, when large changes in CBF are induced by the manoeuvres described above, changes in dZp correlate very weakly with changes in either cortical or global CBF, and are influenced by other factors such as pulsatile intracranial blood volume.

Animals↗
PubMed1992

Impedance plethysmography for blood flow measurements in human limbs. Part 2. Influence of limb cross-sectional area.

The cross-sectional area of a limb varies along the extremity. This is of great importance when impedance plethysmography is used for limb blood flow studies. The actual measurement site, as well as the interelectrode distance, must be carefully selected to avoid underestimation of the blood flow value. The distance between the potential electrodes should be less than 10 cm for an adult subject.

Adult↗
PubMed1997

Vibration plethysmography: a method for studying the visco-elastic properties of finger arteries.

Vibration plethysmography records changes in vascular volume produced by fast vibrations of cuff pressure. From these, waveforms of dynamic vascular compliance (DVC) are obtained. A total of 46 recordings of DVC, photo-electric plethysmogram (PG), cuff pressure (CP), and indirect blood pressure (BP) are performed on two adjacent fingers (third and fourth) in 23 healthy subjects. The shape and polarity of the DVC waveform markedly depends upon CP or transmural pressure (TP) (TP = BP - CP). The correlation coefficient between DVC and PG waveforms is nearly -1 at negative mean TP, near zero at zero TP, and approaches +1 at positive TP. For CP moving between systolic and diastolic BP, the DVC waveform shows a diastolic peak, with its maximum close to the zero value of instantaneous TP. xy-diagrams of PG against TP and of DVC against TP plotted for the diastolic phase of single pulses reveal a close coincidence of the DVC peak with the maximum slope of the PG/TP curve. A similar relationship appears when slow changes in PG and the amplitude of PG pulse waves are plotted against mean TP.

Adult↗
PubMed1994

Five-electrode field plethysmography technique for separation of respiration and cardiac signals.

Respiration monitoring by means of electric field plethysmography is influenced by cardiac activity, which represents an artefact although of physiological relevance itself. For a separation of respiration and cardiac signals, a portable plethysmograph was developed, which uses a fifth electrode in addition to the conventional tetrapolar electrode arrangement. The separation is attained by weighted software subtraction of two detected signals. In a comparative way, three mathematical methods are discussed for the effective determination of individual weighting factors. Results of the practical applications indicate the best results for a method based on Fast Fourier Transformation.

Electrodes↗
PubMed1978

Impedance plethysmography: its limitations as a substitute for phlebography.

Impedance plethysmography (IPG) was used to study 132 legs: 100 in normal volunteers not subjected to radiocontrast phlebography, seven in patients whose limbs were phlebographically normal, and 25 proven by phlebography to have deep venous thrombosis (DVT). There were no false positive IPG results when a maximum venous outflow of 0.2% was the discriminant. However, in the 25 legs with thrombosis in calf, popliteal, femoral, and iliac veins, clots were not detected by IPG in 44--51% of legs, depending upon the discriminant. These results, which are in agreement with data reported elsewhere, indicate that it is reasonable to use the IPG method as the sole diagnostic maneuver when the test result is clearly abnormal, but that if the result is not abnormal, a radiocontrast phlebogram is necessary.

Adult↗
PubMed2001

Accuracy and consistency of respiratory inductive plethysmography for overnight tidal volume measurement.

To validate the accuracy and consistency of respiratory inductive plethysmography (RIP) in measuring tidal volume after an overnight sleep, tidal volumes of 18 patients with suspected sleep-disordered breathing and 8 normal volunteers were measured simultaneously with RIP (VTRIP) and with an ultrasonic airflow meter (VTUFM) before and after an unstrained overnight sleep on supine and lateral decubitus. The bias of the VTRIP was expressed as (VTRIP-VTUFM)/ VTUFM.100%, limits of agreement between VTRIP and VTUFM was measured by averaged bias +/- 2 s. Results showed that in normal subjects, the bias of RIP before and after overnight sleep was precise and consistent in both supine (0.7% and -1.6%) and lateral decubitus (3.7% and -0.56%). In these patients, the bias of RIP before and after sleep in supine also remained small (1.9% and 1.7%), but it became larger in lateral decubitus (24.5% and 20.4%) and 11.5% exceeded the limits of agreement observed in the evening. The patients' body mass indices (BMI) were higher than those of normal subjects (median 34.2 vs. 27.8 kg/m2). Pooled data showed that the bias of VTRIP in the morning on lateral decubitus but not on supine was correlated to BMI (Spearman R = 0.32, n = 52, P = 0.02). Thus, we were led to conclude that the accuracy of VTRIP overnight was precise and consistent in normal subjects, but the deviation of VTRIP measured on lateral decubitus in patients especially in those with excessive obesity was greater, thus, the method should not be used for quantitative determination.

Adult↗
PubMed1990

Respiratory inductance plethysmography and pulse oximetry in the assessment of upper airway patency in a child with Goldenhar's syndrome.

The anaesthetic management of a child with Goldenhar's syndrome and upper airway dysmorphology is presented. She had a history of severe dyspnoea due to deterioration of cor pulmonale caused by upper airway obstruction. The patency of the upper airway and oxygenation were evaluated during the perioperative period with respiratory inductive plethysmography (RIP) and pulse oximetry, which did not show severe upper airway obstruction or oxygen saturation below 80 per cent. Tracheal intubation was performed under inhalational anaesthesia with spontaneous breathing. This case suggests that RIP and pulse oximetry may be useful monitoring devices in the anaesthetic management of patients with upper airway problems as in Goldenhar's syndrome.

Anesthesia, Inhalation↗
PubMed1998

Increased microvascular water permeability in patients with septic shock, assessed with venous congestion plethysmography (VCP).

OBJECTIVES: To investigate microvascular water permeability (filtration capacity, Kf) in patients with septic and non-septic shock using a new non-invasive method for studying microvascular parameters in man. SETTING: Intensive Care Unit of a university hospital. PATIENTS AND METHODS: We investigated 28 patients, presenting with cardio-vascular instability due to either septic shock, or non-septic shock (haemorrhage, multiple trauma, respiratory and/or cardiac failure). INTERVENTIONS: We used standard invasive methods of monitoring (in-dwelling arterial lines and pulmonary artery flotation catheters) in combination with computer assisted venous congestion plethysmography (VCP) measurements, for a parallel assessment of peripheral microcirculatory parameters. RESULTS: On admission to the ICU, patients with septic shock revealed a significantly higher mean value of filtration capacity Kf = 6.1 +/- 0.4 x 10(-3) (mean value +/- standard error of the mean, ml.min-1.100 ml tissue-1.mmHg-1 = KfU) than non-septic patients Kf = 3.5 +/- 0.3 KfU (p < 0.02). The Kf values of the septic patients were significantly higher than those from age-matched patients with peripheral vascular disease (4.1 +/- 0.2 KfU, p < 0.001) and those of healthy controls (4.3 +/- 0.2 KfU, p < 0.001); the Kf values of the non-septic patients, however, were not significantly different. The highest mean Kf value observed during the stay on ICU was Kfmax 11.6 +/- 0.2 KfU in the septic group and 5.7 +/- 0.1 KfU in the non-septic group (p < 0.001). Pvi, a value reflecting the balance of hydrostatic and oncotic forces in the microcirculation, was elevated in both patient groups. On admission, in septic patients Pvi was 39.2 +/- 3.3 mmHg and in non-septic patients 35.1 +/- 2.7 mmHg, these values were not significantly different, but significantly higher than the Pvi value of healthy controls (Pvi 21.5 +/- 0.8) (p < 0.001). A weak, however significant, positive correlation was found between Kf and Pvi in both patient groups. No correlations were found between Kf, as well as Pvi, and cardiac index (CI), oxygen delivery index (DO2I), oxygen consumption index (VO2I) and systemic vascular resistance index (SVRI). CONCLUSIONS: An increase in permeability of microvessels will cause a loss of intravascular fluid and may therefore partially explain the large fluid requirements of patients in shock. It will also favour the development of oedema, which is often found in septic patients. We propose that changes in Kf are useful indices of microvascular malfunction and that VCP allows the non-invasive assessment of these parameters.

Adult↗
PubMed2003

Validation of air-displacement plethysmography for estimation of body fat mass in healthy elderly subjects.

BACKGROUND: Air-displacement plethysmography (ADP) is a non-invasive method for body composition analysis that divides the body into fat-free mass (FFM) and fat mass (FM) (= 2 compartment model, 2C). It places low demands on subject performance and is therefore most convenient in the elderly. OBJECTIVE: To validate ADP against dual energy X-ray absorptiometry (DEXA) and to compare it to a four-compartment model of body composition (4C; fat mass, total body water, bone mineral content and residual mass) in the elderly. METHODS: Body composition was assessed by ADP, DEXA and bioelectrical impedance analysis (BIA) in 26 healthy elderly subjects (15 women, 11 men) aged 60-82 years. RESULTS: Despite a high correlation of %FM assessed by ADP and DEXA we observed significant differences between the results of these methods for both sexes (2.5 +/-3.4%; bias +/- SD). Deviations of %FM(ADP) from %FM(DEXA) were dependent on bone mineral content (BMC(DEXA)) fraction of FFM. A low BMC(DEXA) was related to an overestimation of DEXA-derived %FM by ADP. There was a systematic bias between results from ADP and the 4C model. 76% of its variance was explained by the assumption of a fixed density of FFM. 96% of the variance in the density of FFM was explained by water content and only 4% by BMC(DEXA) of FFM. When compared to a 4C model, overestimation of %FM(ADP) increases with increasing water fraction of FFM. CONCLUSION: Although there is a tendency for overestimation of %FM(ADP),ADP is a valid method for body composition measurement in the elderly. The bias in %FM(ADP) is mainly related to water content of FFM and indicates that a correction factor for TBW may improve the accuracy of the ADP measurements in the elderly.

Absorptiometry, Photon↗
PubMed2004

Respiratory kinematics by optoelectronic plethysmography during exercise in men and women.

Gender differences in resting pulmonary function are attributable to the smaller lung volumes in women relative to men. We sought to investigate whether the pattern of response in operational lung volumes during exercise is different between men and women of similar fitness levels. Breath-by-breath volume changes of the entire chest wall ( V(.)( CW)) and its rib cage ( V(.)( Rc)) and abdominal ( V(.)( Ab)) compartments were studied by optoelectronic plethysmography in 15 healthy subjects (10 men) who underwent a symptom-limited ( W (peak)) incremental bicycle test. The pattern of change in end-inspiratory and end-expiratory V(.)( CW) ( V(.)( CW,EI) and V(.)( CW,EE), respectively) did not differ between the sexes. With increasing workload the decrease in V(.)( CW,EE) was almost entirely attributable to a reduction in end-expiratory V(.)( Ab), whereas the increase in V(.)( CW,EI) was due to the increase in end-inspiratory V(.)( Rc) in both sexes. In men, at W (peak) tidal volume [ V(.)( T), 2.7 (0.2) l] and inspiratory capacity [IC, 3.4 (0.2) l] were significantly greater than in women [1.8 (0.2) and 2.6 (0.2) l, respectively]. However, after controlling for lung size using forced vital capacity (FVC) as a surrogate, the differences between men and women were eliminated [ V(.)( T) /FVC 49 (3) and 45 (3) respectively, and IC/FVC 63 (2) and 65 (3) respectively]. All data are presented as mean (SE). In both men and women the contribution of the rib cage compartment to V(.)( T) expansion was significantly greater than that of the abdominal compartment. We conclude that gender differences in operational lung volumes in response to progressive exercise are principally attributable to differences related to lung size, whereas compartmental chest wall kinematics do not differ among sexes.

Adult↗
PubMed2005

Use of respiratory inductance plethysmography for the detection of swallowing in the elderly.

It is essential to have a user-friendly, noninvasive bedside procedure at our disposal in order to study swallowing and swallowing disorders in the elderly in view of the frailty of this age group. In the present work, respiratory inductance plethysmography (RIP) is proposed as an appropriate clinical tool for such studies. An automated process for the detection of swallowing is used involving the derivative of the respiratory volume signal. The accuracy of the automated detection is given by the area under the Receiver Operating Characteristic (ROC) curve and is found to be greater than 0.9. At the optimal threshold, RIP constitutes a reliable and objective bedside clinical tool for studying swallowing in the elderly, as well as being user-friendly and noninvasive. In addition, RIP can be used to monitor swallowing in order to analyze swallowing disorders and put in place medical supervision of swallowing for individuals who might aspirate.

Age Factors↗
PubMed2003

Usefulness of age-adjusted equations to estimate body fat with air displacement plethysmography in male adolescent athletes.

This study was designed to examine the accuracy of air-displacement plethysmography (ADP) using Lohman's age-adjusted equations (Leq) and Siri's equation (Seq) in estimating body fat (BF) in male adolescent athletes, with the four-compartment (4C) model as reference. Subjects were 51 Caucasian boys (age, 15.5+/-1.2 years; weight, 71.0+/-11.9 kg; stature, 1.79+/-0.12 m). Comparison of means with the Wilcoxon test showed that BF estimates with Seq to be different from those with Leq and 4C model, (8.8+/-4.4 vs. 7.9+/-4.5 and 8.1+/-4.0 kg, respectively) ( p<0.001), suggesting an overestimation of BF. However, BF estimates with the Leq and with the 4C model were identical ( p>0.05). Estimates using Seq and Leq with the 4C model were similar, as shown by the 95% confidence intervals (-4.7-2.4 and -4.0-3.7, respectively). These findings suggest that in male adolescent athletes, the use of Leq improves estimates of BF by densitometry using ADP.

Adipose Tissue↗
PubMed1986

Measurement of nasal and oral respiration using inductive plethysmography.

The role of nasal respiratory function in oral and facial development remains unclear in spite of the long-standing interest of clinicians. Much of the current controversy stems from our inability to define mouth breathing in objective terms and evaluate nasal airway impairment quantitatively. Recent advances in respiratory monitoring technology provide new opportunities to assess upper airway breathing more objectively. The purpose of this study was to describe a new approach for measuring oral and nasal respiration and to test its reliability. The technique involves inductive plethysmography and the data provide an assessment of respiratory mode without the need to enclose the subject's head in an airtight box. The data were compared to pneumotachography and the results demonstrate the reliability of the technique.

Abdomen↗