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PubMed1976

The relationship between the course of psoriasis and transepidermal water loss, photoelectric plethysmography and reflex photometry.

The transepidermal water loss (TWL), photoelectric plethysmography and reflex photometry were parallelly registered on the involved hands and forearms of psoriatics. The TWL values showed a fairly good correlation with the clinical course of the disease: they increased during the active phase and decreased after return to normal. The vascular tests did not show a strict parallelism with the clinical state. On the basis of the findings, the temporal relations between epidermal and vascular factors during the different phases of the psoriatic process are discussed. The TWL can be used to predict a relapse occurring on the area investigated but not on a distant area.

Erythema↗
PubMed2005

A comparison of computerised strain gauge plethysmography with D-dimer testing in screening for deep-vein thrombosis.

There has been a significant increase in the amount of diagnostic testing performed to confirm or refute a diagnosis of deep-vein thrombosis (DVT), often in low-risk patients. D-dimer testing and computer-assisted strain gauge plethysmography (SGP) are rapid, inexpensive methods of excluding DVT and, in combination with a clinical probability score for DVT, both have been used to accurately exclude DVT. D-dimer testing, SGP and a combination of both in excluding DVT were compared in 243 ambulant outpatients who followed a prespecified investigation protocol. The negative-predictive value of D-dimer testing alone was 100%, 93.9% (95% CI 93.6-94.1) and 80% (95% CI 73.7-86.3) in patients with a low, moderate and high pretest probability (PTP) score for DVT respectively. The corresponding results for SGP were 95.6% (95% CI 95.5-95.7), 86.1% (95% CI 85.9-86.4) and 77.8% (95% CI 75.9-79.7) in patients with a low, moderate and high PTP score for DVT respectively. D-dimer testing provided a rapid, cost-effective method for excluding DVT in low-risk ambulant patients, which was superior to SGP. Combined use of the modalities did not improve any aspect of clinical decision making.

Biomarkers↗
PubMed1994

Strain gauge plethysmography and Doppler ultrasound in the measurement of limb blood flow.

The maintenance of adequate oxygen delivery (DO2) and tissue uptake (VO2) has become central dogma in the management of the critically ill. However, these parameters are derived using gas tensions measured in mixed venous blood and may not reflect changes in regional blood flow. Therefore, it has become necessary to provide estimates of blood flow to specific organs and to evaluate the most adequate techniques available. In order to define the best means of assessing blood flow to the lower limb noninvasively in normal subjects, measurements of superficial femoral arterial blood flow using Doppler ultrasound (DU) and strain gauge plethysmography (SGP) were compared in 10 normal volunteers at rest and during exercise. To evaluate the effect of strain gauge positioning, results of measurements made under four different combinations of cuff/strain gauge placement were compared in 15 other volunteers. The correlation of the limb blood flow obtained using the two methods at rest and exercise was 0.57 and 0.62 and the limits of agreement (d +/- 2SD) were 0.40 +/- 2.49 and -0.86 +/- 5.22 ml 100 ml-1 tissue min-1 at rest and on exercise, respectively. Results obtained using SGP were more reproducible (Coef. repeat. 0.45 vs. 0.94 ml 100 ml-1 tissue min-1, for SGP and DU, respectively). The various combinations of cuff/strain gauge positioning showed a tendency to over-read when the latter was placed on the thigh, but were not significantly different (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Thermography and plethysmography, a non-invasive alternative to venography in the diagnosis of deep vein thrombosis.

One plethysmographic and two thermographic methods were evaluated against venography in 102 patients with suspected deep vein thrombosis (DVT). Seventy-one patients had venographically verified DVT, which in 21 cases was restricted to the calf. Plethysmography (PG) gave a sensitivity and specificity of 63% and 94%, respectively. The former was influenced by a limited sensitivity of 14% in the sub-group with distal DVT. The sensitivity and specificity of temperature profiles (TP) were 87% and 39%, respectively, while the corresponding values for thermo-camera (TC) were 83% and 55%, respectively. Using a combined diagnostic approach of PG and TP, additional evaluation of posterior and lateral profiles and pattern recognition, 96% sensitivity and 81% specificity were reached. The combination of PG and TP will be an essential diagnostic complement when venography is not possible or inconclusive, as well as having a role in diagnostic screening in a large number of patients.

Adult↗
PubMed1980

Before cannulation of the radial artery: collateral arterial supply evaluated by strain-gauge plethysmography.

Systolic arterial pressure in the thumb was measured using strain-gauge plethysmography before and after compression of the radial artery in 259 patients (aged 11--75 years), undergoing vascular or open-heart surgery. In 38 hands (in 27 patients aged 37--75 years), manual compression of the radial artery reduced the arterial pressure in thumb to less than 40 mmHg (5.3 kPa), and consequently the collateral ulnar arterial supply was judged to be inadequate. Because 27 out of 259 patients (10.4%) would be without adequate blood supply to one or both thumbs following occlusion of the radial arteries, cannulation of the radial artery should be performed only after ensuring the presence of an adequate collateral ulnar arterial supply.

Adolescent↗
PubMed1982

The detection of deep venous thrombosis by impedance plethysmography in hip surgery patients.

Cuff impedance plethysmography has been performed on 120 patients undergoing total hip replacement surgery, all of whom have had venography. The low incidence of thrombosis (17.5%) precluded any accurate data on sensitivity, but specificity was 85%, positive accuracy 48%, negative accuracy 92% and validity 82%. There was a high false positive rate in the first postoperative week (40% of 25 negative venograms). The technique is of value for the exclusion of thrombi in such patients after the eighth postoperative day. Venography will still be required for the positive identification of thrombi in any research protocol.

Aged↗
PubMed2005

Emotions and airway resistance in asthma: study with whole body plethysmography.

The role of emotions as potential triggers of asthmatic airway obstructions was examined by whole body plethysmography. Three affectively homogeneous picture series (IAPS) were presented with video glasses to induce pleasant, unpleasant, and neutral emotional states in 32 asthmatic and 32 nonasthmatic participants while they were seated in a Jaeger Bodytest plethysmograph. Airway resistance, specific airway resistance, thoracic gas volume, and mood were measured immediately after each presentation, in addition to specific airway resistance before and during each presentation. Airway resistance and specific airway resistance were significantly increased after and during pleasant and unpleasant stimulation compared to neutral stimulation in asthmatic patients and also, but less pronounced, in nonasthmatic controls. The results show that the experience of pleasant and unpleasant emotions can provoke increased airway resistance especially in asthmatic patients.

Adult↗
PubMed1995

Computerized evaluation of the peripheral blood flow during maximal vasodilatation in humans using venous occlusion plethysmography.

Forearm blood flow was studied with venous occlusion plethysmography after ischaemic exercise in 10 healthy volunteers and 10 hypertensive patients. The peak blood flow was calculated by three methods: the manual conventional graphic technique and by fitting of a tangent to the inflow curve with the help of a computer. In addition a computer-aided derivation of an exponential curve adapted to the initial part of the inflow curve was used for the calculation of the maximal blood flow. With the two tangential techniques the peak mean blood flow values did not differ significantly and were 58 ml min-1 100 ml-1 tissue while the exponential derivation procedure gave in both groups about 40% higher maximal flow values. The effect of venous occlusion on the linear velocity of the brachial arterial blood flow blood was studied with Ultrasound Doppler Flowmetry. The maximal flow velocity after ischaemic exercise decreased by about 18% during 50 mmHg venous occlusion; the influence of the venous stasis was least during the first heart beats after the onset of the venous occlusion. The effect of the venous stasis was similar but less pronounced in the hypertensive patients. In conclusion, forearm blood flow during maximal vasodilatation is reduced by venous occlusion and the best estimate of the flow is obtained from the earliest part of the venous occlusion inflow curve, as indicated by the use of the computer-aided exponential derivation technique.

Adult↗
PubMed1986

Digital pulse plethysmography (DPG) in studies of the hemodynamic response to nitrates--a survey of recording methods and principles of analysis.

Digital pulse plethysmography (DPG) has proved a technically simple, noninvasive, sensitive and informative technique for studying the effects of nitroglycerin and other nitrates on peripheral arteries. The importance of performing nitrate evaluation by DPG mainly in elderly subjects is emphasized. On the basis of observations with DPG some indirect conclusions on the effect of nitrates on the coronary arteries are justified. A review, with recommendations based on own experience, is given of various recording techniques and principles of evaluating quantitatively the digital volume pulse contour, with special reference to the influence of nitrates on the position and appearance of dicrotism. DPG seems to be a convenient, noninvasive and helpful procedure in studies on the development of nitrate tolerance.

Fingers↗
PubMed1980

Umbilical artery catheterization in newborns. IV. Strain-gauge plethysmography for the diagnosis of catheter-related thrombo-embolism in the legs.

Strain-gauge plethysmography was performed shortly after withdrawal of the catheter in 48 of 49 newborn ifnats who had undergone umbilical artery catheterization. Plethysmorgraphy was used to find a noninvasive method for diagnosing catheter-related thrombo-embolism in neonates. The results were compared with the findings at aniography. The method permits simultaneous measurements of the systolic blood pressure and of the resting and submaximal blood flow in both legs. Nine infants howed angiographic signs of total or partial occlusion in one leg, and 8 of them were investigated with plethysmorgraphy. The systolic blood pressure was signifcantly reduced in ifants with total and/or partial occlusion, but the blood flow was reduced only in infants with total occlusion. The peak flow after sugrasystolic occlusion was significantly otener delayed in infants with thrombo-embolism in the leg.

Catheterization↗
PubMed2006

Forearm plethysmography in the assessment of vascular tone and resistance vasculature design: new methodological insights.

AIM: High peripheral resistance and structural alteration in resistance arteries are central phenomena in essential hypertension and have been widely examined by forearm venous occlusion plethysmography; at rest for studying vascular tone, and during reactive hyperaemia for studying vascular structure. This work concerns the influence of venous pressure on hyperaemic vascular resistance (Rmin), the reproducibility of hyperaemic and resting vascular resistances (Rrest) and the relation between forearm and total peripheral vascular resistance (TPR). METHODS: In four healthy subjects, intravenous and intra-arterial blood pressures were measured simultaneously with plethysmographic recordings of hyperaemic and resting forearm blood flows. Reproducibility was examined in 15 young and 14 middle-aged healthy subjects and in 21 untreated hypertensive patients. RESULTS: Rmin remained low in the first recorded cardiac cycle, but rose in the second, even though corrected for the venous pressure rise, suggesting vascular tone recovery along with venous congestion. Between-day reproducibility of Rmin was high in middle-aged normotensive (8.7%) and hypertensive subjects (10.6%), but Rmin fell significantly between successive days in the young subjects. Rrest correlated with TPR, but required up to 40 min to reach steady state and showed high day-to-day variation in young (21.8%) and hypertensive subjects (16.2%). CONCLUSIONS: During hyperaemia, vascular resistance should be measured in the first cardiac cycle following venous occlusion to minimize influences of venous pressure rise and possible tone recovery. Rrest seems to reflect TPR. About 20 subjects may be needed to detect 15% changes between days in Rrest, fewer when concerning Rmin and TPR.

Adult↗
PubMed1999

Measurement of leg arterial compliance of normal subjects and diabetics using impedance plethysmography.

In this study, compliance, a mechanical characteristic of the lower leg arteries, was measured noninvasively. Changes in blood volume and pressure were measured using impedance plethysmography and a mercury sphygmomanometer, respectively. Compliance was calculated by dividing the change in blood volume by the change in pulse pressure (systolic-diastolic pressure). Subjects were 24 asymptomatic persons ranging from 30 to 58 years and 14 diabetics ranging from 41 to 59 years. Peak compliance, mean pressure, and systolic pressure were statistically analyzed using a t test between the asymptomatic and diabetic groups. The average peak compliance of the asymptomatic and diabetic groups was measured as 2.79 and 1.82 microL/mmHg/cm, respectively, and these were significantly different (p < 0.01). It was also found that compliance is a better parameter in differentiating vascular disease than the mean or systolic blood pressure.

Adult↗
PubMed1990

Impedance plethysmography.

The technique of impedance plethysmography is described and its application to observation of lung volume changes in the horse at exercise is discussed. The results from horse at rest show that there is a close relationship between rate of lung volume change (flow rate) and the associated impedance changes during both inspiration and expiration. Impedance changes during exercise were related to inspiration and expiration by observation of associated respiratory sounds. Artefacts related to technical difficulties are also indicated.

Animals↗
PubMed2002

Influence of different cuff inflation protocols on capillary filtration capacity in human calves -- a congestion plethysmography study.

It has been suggested that venous congestion plethysmography (VCP) substantially underestimates microvascular permeability by activation of a veni-arteriolar constrictor mechanism, even when using small (< 25 mmHg) congestion pressure steps. We studied human lower limbs of 18 young healthy volunteers to test whether the congestion pressure step size of the VCP protocol has an influence on the values of the capillary filtration capacity (CFC) and isovolumetric venous pressure (P(vi)). Two different dual stage VCP pressure step protocols, with 3 and 10 mmHg steps, were used in randomised order and separated by a transient reduction in congestion pressure. Since lymph flow is known to increase after venous congestion, we also looked to see if changes in the estimated lymph flow (J(v)L) occur as a result of these VCP protocols. The measured CFC (median [25th; 75th percentile]) was 2.6 [2.5; 3.2] x 10(-3) ml (100 ml)(-1) min(-1) mmHg(-1) with the 3 mmHg pressure step protocol, which was not different from the value of 2.9 [2.7; 3.4] x 10(-3) ml (100 ml)(-1) min(-1) mmHg(-1) obtained with 10 mmHg pressure steps. However, when either of these step sizes was applied after a transient venous decongestion, significantly higher values of CFC, 4.0 [3.4; 4.1] x 10(-3) and 3.5 [3.1; 4.5] x 10(-3) ml (100 ml)(-1) min(-1) mmHg(-1), respectively, were obtained (P < 0.05). The assessment of P(vi) was also independent of the pressure protocol (10 mmHg: 8.0 [5.7; 13.2] mmHg and 3 mmHg: 15.7 [12.5; 18.5] mmHg), but when P(vi) was measured after the transient deflation, significantly higher values were found with both 10 and 3 mmHg steps (24.1 [20.9; 27.3] and 30.4 [28.9; 30.9] mmHg, respectively; P < 0.01). The transient pressure reduction was associated with a rise in estimated J(v)L from 0.04 [0.03; 0.05] to 0.12 [0.08; 0.18] and 0.04 [0.04; 0.05] to 0.09 [0.07; 0.10] ml (100 ml)(-1) min(-1), respectively (P < 0.01). The first stage data from these protocols shows that the value of CFC is not influenced by the size of the cumulative venous pressure steps, providing they are of 10 mmHg or less. The data also show that J(v)L can be estimated with small step VCP protocols. We hypothesise that the sudden reduction in cuff pressure after venous congestion is associated with a temporary upregulation of lymph flow. As the congestion pressure is raised again, there is a modulation of the enhanced lymph flow, such that the resulting CFC slope appears greater than that obtained in the first stage of the protocol.

Adult↗
PubMed2001

Compartmental analysis of breathing in the supine and prone positions by optoelectronic plethysmography.

Optoelectronic plethysmography (OEP) has been shown to be a reliable method for the analysis of chest wall kinematics partitioned into pulmonary rib cage, abdominal rib cage, abdomen, and right and left side in the seated and erect positions. In this paper, we extended the applicability of this method to the supine and prone positions, typically adopted in critically ill patients. For this purpose we have first developed proper geometrical and mathematical models of the chest wall which are able to provide consistent and reliable estimations of total and compartmental volume variations in these positions suitable for clinical settings. Then we compared chest wall (CW) volume changes computed from OEP(deltaVCW) with lung volume changes measured with a water seal spirometer (SP) (deltaVSP) in 10 normal subjects during quiet (QB) and deep (DB) breathing on rigid and soft supports. We found that on a rigid support the average differences between deltaVSP and deltaVCW were -4.2% +/- 6.2%, -3.0% +/- 6.1%, -1.7% +/- 7.0%, and -4.5% +/- 9.8%, respectively, during supine/QB, supine/DB, prone/QB, and prone/DB. On the soft surface we obtained -0.1% +/- 6.0%, -1.8% +/- 7.8%, 18.0% +/- 11.7%, and 10.2% +/- 9.6%, respectively. On rigid support and QB, the abdominal compartment contributed most of the deltaVCW in the supine (63.1% +/- 11.4%) and prone (53.5% +/- 13.1%) positions. deltaVCW was equally distributed between right and left sides. In the prone position we found a different chest wall volume distribution between pulmonary and abdominal rib cage (22.1% +/- 8.6% and 24.4% +/- 6.8%, respectively) compared with the supine position (23.3% +/- 9.3% and 13.6% +/- 13.0%).

Abdomen↗
PubMed2001

Transfer impedance of the respiratory system by forced oscillation technique and optoelectronic plethysmography.

To estimate the transfer impedance of the respiratory system (Ztr), we applied pressure forcing at the mouth from 1 to 24 Hz in eight healthy subjects and used optoelectronic plethysmography (OEP) to measure volume changes of the chest wall and its different compartments: pulmonary rib cage (RCp), abdominal rib cage (RCa) and abdomen (AB). Spectral analysis allowed assessment of input impedance (Zin) and total (Ztr) and compartmental (ZRCP, ZRCa, and ZAB) transfer impedances. As expected, averaged values of Zin and Ztr were similar at low frequencies (< 8 Hz) while they progressively differed at high frequencies. The percentage contributions of ZRCp, ZRCa , and ZAB to Ztr were, respectively, 35.3 +/- 1.4SD, 13.8 +/- 1.4, and 50.8 +/- 2.8 at low frequencies (< 8 Hz) and 63.1 +/- 5.5, 20.7 +/- 5.2, and 16.2 +/- 2.3 at higher frequencies (> 10 Hz). The validation of our approach was based on the comparison with a physical model comprised of a rubber membrane stretched over and attached to the lip of a bowl. We conclude that the combination of forced oscillations with OEP provides the simultaneous assessment of Zin and Ztr, it does not require the use of a plethysmographic chamber and it allows the separation between the different rib cage-abdominal pathways.

Abdomen↗
PubMed1984

Radionuclide plethysmography and Tc-99m red blood cell venography in venous thrombosis: comparison with contrast venography.

Radionuclide plethysmography (RPG) is a new technique that uses Tc-99m labelled red blood cells to ascertain changes in venous volumes by detecting the change in counts in response to the inflation and deflation of proximal thigh cuffs. Diagnosis of ileofemoral venous occlusion is possible using this technique, which also provides kinetic data of venous outflow. A range of normal values was defined in 19 subjects for per cent change in venous capacitance and venous outflow. Twenty-one patients with suspected deep venous thrombosis were studied prospectively using RPG, radionuclide venography (RV), and contrast venography (CV) to establish the usefulness of RPG alone and in combination with RV in the diagnosis of deep venous thrombosis. RPG proved to be a reliable technique for the diagnosis of ileofemoral venous thrombosis (sensitivity, 91%; specificity, 100%). RV was less sensitive (73%) and less specific (93%) in diagnosing that condition. When RPG is used as the criterion for the detection of ileofemoral vein thrombosis and RV is used as the criterion for the detection of calf vein thrombosis, the combined techniques show improved sensitivity (92%) and specificity (93%) for the detection of all deep venous thromboses.

Adult↗