[Vascular reactions of the palatal mucosa in humans to various stimuli observed by impedance plethysmography and reflexion photoelectric plethysmography (author's transl)].
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Humans↗
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[Physiological reactions of the human palatal mucosa to various amounts of pressures--observed by impedance plethysmography and reflexion photoelectric plethysmography (author's transl)].
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Humans↗
The judicial use of venous duplex imaging and strain gauge plethysmography (single or combined) in the diagnosis of acute and chronic deep vein thrombosis.
Sixty-eight patients (79 limbs) with clinically suspected deep vein thrombosis were evaluated by duplex imaging, strain gauge plethysmography and venography. The diagnostic accuracies were projected over a spectrum of disease incidences ranging from 10 to 90 per cent of the population. The sensitivity, specificity, positive and negative predictive values, and over-all accuracy in detecting acute deep vein thrombosis were 90.9, 87.1, 83.3, 93.1, and 88.7 per cent, respectively, for venous duplex imaging, and 81.8, 69.6, 56.3, 88.9 and 73.5 per cent, respectively, for strain gauge plethysmography. The positive predictive value and over-all accuracy of venous duplex imaging were statistically significantly higher than that of strain gauge plethysmography. When both tests were combined and compared with venous duplex imaging alone, none of these parameters were statistically significant. For chronic deep vein thrombosis, the sensitivity, specificity, positive predictive value, negative predictive value and over-all accuracy for venous duplex imaging were 75, 86, 80, 86 and 82 per cent, respectively. Fourteen per cent had inconclusive results obtained at venous duplex imaging. When strain gauge plethysmography was combined with venous duplex imaging, the over-all accuracy was 82 per cent. As the true incidence of the disease increases, the positive accuracy differences between strain gauge plethysmography and venous duplex imaging decrease to a negligible level. We concluded that over-all, venous duplex imaging is superior. However, the strain gauge plethysmography has reasonable accuracy and may be used in places where venous duplex imaging is not available. Combined use of venous duplex imaging and strain gauge plethysmography would be helpful in patients with inconclusive results obtained at venous duplex imaging and, as the true incidence increases, the positive accuracy rate of strain gauge plethysmography becomes close to that of venous duplex imaging.
Acute Disease↗
Detection of deep vein thrombosis with impedance plethysmography and real-time compression ultrasonography in hospitalized patients.
BACKGROUND: Serial testing with impedance plethysmography or compression ultrasonography has been demonstrated to be feasible and accurate for the detection of deep vein thrombosis (DVT) in symptomatic outpatients, and these techniques are replacing contrast venography in this patient category. Limited data, however, are available on the clinical utility of these noninvasive tests in symptomatic hospitalized patients. The objectives of our study were to determine the feasibility of ascending contrast venography and to evaluate the accuracy of these two noninvasive methods for the detection of DVT in symptomatic hospitalized patients. METHODS: A prospective, "blind" comparison of impedance plethysmography and compression ultrasonography with ascending contrast venography was performed in consecutive hospitalized patients with clinically suspected DVT of the leg. RESULTS: Of the 127 potentially eligible patients, 44 had to be excluded; 25 of these could not undergo venography (feasibility of venography, 80.3%). The sensitivity, specificity, and positive and negative predictive values of impedance plethysmography for proximal DVT were 96%, 83%, 82%, and 97%, respectively. For compression ultrasonography, these measures for proximal DVT were 97%, 86%, 87%, and 97%, respectively. The overall prevalence of DVT was 53%, of which 85% was located proximally. CONCLUSIONS: Contrast venography cannot be performed in about 20% of consecutive symptomatic patients. Both impedance plethysmography and compression ultrasonography are feasible and valid alternatives to contrast venography in the diagnostic treatment of these patients.
Feasibility Studies↗
Assessment of acute and old deep venous thrombosis in upper extremity by venous strain gauge plethysmography.
The purposes of this study were to evaluate the efficiency of occlusion strain gauge plethysmography in the diagnosis of symptomatic deep venous thrombosis in upper extremities, to compare early (one month) and late clinical evolution (many years) to plethysmography data and, finally, to set up normal and pathological values. Four groups of patients were tested. Sixteen patients with confirmed acute thrombosis, 6 patients with unconfirmed thrombosis, 15 with an old thrombosis (mean follow-up: 7 years) as well as 15 healthy volunteers. The outflows measurements were significantly lowered (p less than 0.05) in the arms with acute thrombosis compared to the contralateral arms, to the affected arms of patients with thrombosis excluded and to both volunteers' arms. Pathological values for the different outflow parameters could be defined as follows: Maximum venous output less than 110 ml/100 ml/minute, Outflow after 3 seconds less than 1.2 ml/100 ml, Strandness index less than 0.16. On month after the acute episode we found a good correlation between the usually favourable clinical evolution and venous haemodynamics assessed by plethysmography. The mild late post-thrombotic syndrome of most patients with an old thrombosis was not well demonstrated by plethysmography.
Adult↗
[Study of vasomotility in man using plethysmography and flowmetry].
The interpretation of cardiac hemodynamics is indissociable from the study of the peripheral vascular circulation. The latter may now be assessed by non-invasive techniques. Measuring the systemic blood pressure is useful but, in itself, insufficient. The venous sector is usually studied by plethysmographic methods. The commonest of those is occlusion plethysmography either with a mercury gauge or by impedence plethysmography. It is possible to measure venous distensibility, the venous tone. Postural plethysmography improves the study protocol by eliminating the artefact of venous occlusion while respecting the spatial cardiovascular adaptation. The study of the permeability of the capillary walls is a useful complement to venous investigations. Arterial function is approached routinely by qualitative plethysmography which provides little useful information; on the other hand, the measurement of mean arterial blood flow gives a quantitative and physiologically useful parameter. Even better than the mean arterial flow is the pulsatile arterial blood flow which may be measured by pulsed wave Doppler echo, non-invasive electromagnetic flowmetry and NMR flowmetry. Cutaneous blood flow is measured by laser Doppler. It is now possible to measure global pulsatile arterial flow of a segment of limb including its principal and collateral arteries, or the blood flow of a selected artery or even cutaneous blood flow alone. Future trends lie in improving the accuracy of all these measurements of flow and in increasing the possibilities of controlling tissue metabolism. In addition, studies in the microcirculation will become increasingly important: capillary flow, intracapillary distribution, transcapillary exchanges.
Capillary Permeability↗
Plethysmography. A treatise on its evolution, differential methodology and clinical utilization. 1973.
Plethysmography is the observation and use of volume changes in physiologic entities. The most influential short-term effect is caused by the pulsatile flow of blood. Attempts to convert these pulsatile volume changes into minimum required blood flow per unit of time have been successful clinically. Plethysmography can be accomplished by encapsulating digits, limbs and entire bodies. Volume changes in the member cause volume changes in the fixed chamber which then influences an observational medium. Plethysmography can also be accomplished with a strain gauge, direct application of electricity to flesh, changing opacity effects on tissue, ultrasound (the Doppler effect) or the piezoelectric method. The piezoelectric plethysmograph was successfully tested on 55 patients.
Blood Circulation↗
Noninvasive diagnosis of acute deep vein thrombosis. A comparison between thermography, plethysmography and phlebography.
Fifty-five patients with clinical signs of acute DVT were investigated with thermography, plethysmography and phlebography. A comparison between phlebography and thermography showed a diagnostic agreement of 84%. Thermography was found, however, to have a low reliability for the localization of acute thrombi and was therefore combined with plethysmography in an attempt to obtain better results in this respect. Compared to the invasive phlebography, the noninvasive combination of thermography and plethysmography adequately located acute DVT in 95% of the cases.
Acute Disease↗
Impedance plethysmography: correlation with contrast venography.
Impedance plethysmography is a noninvasive, indirect test for deep venous occlusion in the lower limbs. The results of ascending contrast venography impedance plethysmography have been compared in 315 limbs. Impedance plethysmography was positive in 77 of 79 limbs with acute deep vein thrombosis proximal to the calf. It was positive in 6 of 27 limbs with clot isolated in the calf. Only 7 false-positive plethysmograms were found in 161 normal contrast venograms. The clinical implications of these data are discussed.
False Positive Reactions↗
Venous thrombosis in patients who have undergone major hip or knee surgery: detection with compression US and impedance plethysmography.
To compare the sensitivity, specificity, and predictive values of compression ultrasonography (US) in postoperative orthopedic patients with those of (a) impedance plethysmography in postoperative patients and (b) compression US in symptomatic outpatients, the authors performed an investigator-blinded cohort study. One hundred thirty-four consecutive inpatients who had undergone elective knee-replacement surgery or surgery for a fractured hip and 65 consecutive outpatients with clinically suspected venous thrombosis who had undergone venography were evaluated. Compression US allowed detection of 11 of 21 (52.4%) proximal-vein thrombi but was insensitive to calf-vein thrombi in the orthopedic patients. Compression US had a significantly greater specificity and positive predictive value than impedance plethysmography for all thrombi in orthopedic patients; compression US also had greater sensitivity. The sensitivity of compression US for proximal-vein thrombi was significantly higher (92.1%) in symptomatic outpatients than in orthopedic patients. The authors conclude that compression US has significant advantages over impedance plethysmography in the detection of proximal-vein thrombi in patients who have undergone hip- or knee-replacement surgery.
Hip Joint↗
Impedance plethysmography and thrombo-embolic disease.
This study compares the results of impedance plethysmography with lower limb venography in 68 patients referred for investigation of clinical deep vein thrombosis, and with the results of ventilation/perfusion isotope scans in 125 patients with suspected pulmonary embolism. Impedance plethysmography had a sensitivity of 100% and a specificity of 61% for the detection of thromboses involving popliteal or more proximal veins (30 patients), but a sensitivity of 90% and a specificity of 68% in the detection of thrombosis at any level, because of a low sensitivity in the detection of isolated calf vein thrombosis (60% in 10 patients). It is a non-invasive, portable and low-cost technique and, in centres where anticoagulation is only given to patients with popliteal or more proximal thrombosis, venography may only be necessary if impedance plethysmography is positive. It may also be of value in the assessment of patients with suspected pulmonary embolic disease and an indeterminate ventilation/perfusion lung scan.
Humans↗
[Measurement of arterial flow in the limbs: plethysmography, isotopes, electromagnetic methods].
Measurement of arterial flow is a very old practice, and intra-arterial recordings of pressure and flow have long served as a reference for experimental studies (fig. 1). The definition of a hemodynamic state is inconceivable unless these two parameters are associated. The electromagnetic method using an intra-arterial sensor measures pulsatile flow. Now, technological advances have led to the appearance of other methods providing measurement of mean (plethysmography) and nonpulsatile flow. As a result, there has been considerable confusion between mean arterial and pulsatile arterial flow (Fig. 2). Various studies have emphasized the physiological importance of pulsatile arterial flow and thus the interest in measuring it. The recording of mean flow has often proved disappointing because values are comparable in groups of normal subjects and those with arterial disease. Mean arterial flow can be measured by isotopic methods and plethysmography. Xenon-133 clearance is the isotopic method most often used. Since determination of microcirculatory flow at rest proved of no use, it was necessary to add a hyperemia test reactive to ischemia to differentiate patients with artery disease from normal subjects. Methods involving technetium and thallium have been little used since they require the presence of a nuclear medicine center and are not easily reproducible. There are numerous plethysmographic methods, but only those are studied here which allow measurement of arterial flow. Plethysmography by venous occlusion measures arterial flow by recording the increase in limb volume. The sensor is a mercury strain gauge.(ABSTRACT TRUNCATED AT 250 WORDS)
Arteries↗
Strain gauge plethysmography in the assessment of venous reflux after subfascial closure of perforating veins: a prospective study of twenty patients.
Doppler ultrasonography and strain gauge plethysmography were used prospectively to study the hemodynamic changes in 20 patients' (5 men and 15 women) legs operated on by means of subfascial closure for insufficiency of perforating veins. In 10 patients (50%) the valves of the deep veins were incompetent as verified by Doppler ultrasonography, and deep vein thrombosis had previously been diagnosed in seven patients. After subfascial ligature, strain gauge plethysmography showed no changes in arterial flow, venous capacity, or in venous emptying rate. However, both venous reflux flow and reflux volume were significantly lowered (p less than 0.01) after surgery as compared to values before operation. The clinical objective results were good in all cases. In two of four patients with fair subjective results the arterial flow was pathologically high, which probably implies the presence of microscopic arteriovenous fistulas. It is concluded that strain gauge plethysmography can quantitate the change in deep venous reflux after ligation of perforating veins.
Adult↗
[Comparative studies on the value of oscillography and venous occlusion plethysmography in the diagnosis of arterial occlusive diseases].
Oscillography and plethysmography in phlebembraxis also occupy an important place in the screening of arterial obstructive diseases. The two methods give reliable results. In patients who have--as was established by oscillography and clinical examination--healthy vessels, as well as in patients with arterial obstructive disease in stage II a good correspondence with the findings of plethysmography in phlebembraxis could be proved, if all the three measuring sizes (first flow, peak flow and peak flow time) were taken into consideration. Hereby the normal values given partly deviate from those ones given in literature. They are guide values which in the individual case may fall below or transgressed also in patients with healthy vessels, whereby the peak flow time is to be regarded as the most reliable measuring size. On account of the slight expenditure of time the plethysmography in phlebembraxis is suitable as screening method, however it is not sufficient as the only method for the angiological prediagnostics. It is a valuable supplementation to the hitherto known unbloody examination methods.
Angiography↗
Exercise strain-gauge venous plethysmography: evaluation of a "new" device for assessing lower limb venous incompetence.
Plethysmography can be used to detect and assess venous incompetence in the lower extremities. The authors recently evaluated a new device designed for this purpose that uses strain gauges to determine changes in lower extremity circumference occurring with (and immediately after) exercise. The device plots a curve of volume against time for each limb and automatically calculates key values such as the volume of blood expelled from the lower limb veins during exercise and the time required for the veins to refill following exercise. The apparatus was incorporated into their noninvasive vascular laboratory and used (along with other standard tests) to study patients referred for suspected venous incompetence. They observed the following: (1) A shortened postexercise refilling time accurately identified limbs with venous incompetence. (2) The clinical severity of venous incompetence was inversely related to the refilling time. (3) Exercise-induced changes in lower extremity volume correlated well with simultaneously determined changes in venous pressure. (4) Valvular incompetence could be localized to the deep or superficial veins based upon the improvement in refilling times seen following placement of elastic tourniquets around the lower limb. (5) The type of exercise performed (knee bends while the patient was standing versus ankle reflexes while sitting) had little effect on results. The authors conclude that exercise venous plethysmography is a useful noninvasive tool for assessing lower limb venous incompetence.
Blood Volume↗
Impedance plethysmography: evaluation of a simplified system of electrodes for the measurement of blood flow in the lower limb.
Venous occlusion plethysmography was used to measure the flow of blood into the lower limbs of 30 normal volunteers. An impedance plethysmograph, using disposable point electrodes, was compared with a mercury in Silastic strain gauge plethysmograph in 20 subjects. The effect of changes in the configuration of the point electrodes was studied in 10 subjects. Impedance plethysmography was shown to be reproducible, and one particular configuration of point electrodes was shown to be superior to the others.
Blood Flow Velocity↗
Strain gauge plethysmography for blood flow measurements in the legs of children.
The arterial resting flow, the arterial peak flow after 3 minutes of circulatory arrest to the leg, and the venous emptying rate were studied by strain gauge plethysmography in the calves of 85 children between 3 and 16 years of age. Most of the children had heart disease; therefore the values obtained can be regarded as reference values only for this type of patient.--The reproducibility of the results of the flow measurements was favourable and equal to that found in the examination of adults and of children using water-filled plethysmographs. --All of the flow functions investigated were significantly higher in the younger children and--but not always significantly--higher in boys than in girls. There was no difference between sides as regards arterial flow, whereas the venous emptying rate was significantly lower in the left calf. --Strain gauge plethysmography is recommended for assessment of circulatory complications after vascular catheterization in children aged 4 years or older.
Adolescent↗
Comparison of digital blood pressure, plethysmography, and the modified Allen's test as means of evaluating the collateral circulation to the hand.
The collateral circulation to the hand was evaluated on 70 hands of healthy volunteers. Comparisons were made between the results of the modified Allen's test alone and the Allen's test combined with either plethysmography or digital blood pressure. The modified Allen's test requires patient cooperation and the results can be subjective. Plethysmography does not require patient cooperation and produces a signal that varies directly with flow; however, this is not a quantifiable signal. Digital blood pressure (measured by the 2300 Finapres noninvasive blood pressure monitor, Ohmeda, Englewood, CO, USA) also requires no patient cooperation. The values produced are of clinical value and reproducible. Both the plethysmograph and digital blood pressure monitors were able to demonstrate the dominant arterial vessel of the hand. The digital blood pressure monitor produces an objective recordable numerical value, an accepted clinical parameter, and it does not require patient cooperation. The use of a digital blood pressure monitor may prove to be an acceptable alternative to the traditional Allen's test.
Blood Pressure↗