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PubMed1979

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↗
PubMed1985

Lung volumes measured by helium dilution and by body plethysmography with mouth and oesophageal pressures: a comparative study in patients with lung disease.

A comparison was made between the helium dilution technique and body plethysmography--using both mouth pressure and oesophageal pressure against box pressure--for measuring functional residual capacity (FRC). In patients with restrictive lung disease (n = 9) no major differences in FRC were noted between the techniques. In patients with obstructive lung disease (n = 17), helium dilution underestimated FRC by a mean of 0.9 l and conventional body plethysmography (mouth-box pressure) overestimated it by 0.4 l in comparison with FRC obtained by oesophageal pressure against box pressure. The difference between the techniques increased with increasing lung volumes. It is concluded that conventional body plethysmography measures FRC more accurately than the helium dilution technique in patients with obstructive lung disease.

Female↗
PubMed2004

Spontaneous changes in guinea-pig respiratory pattern during barometric plethysmography: role of catecholamines and nitric oxide.

Barometric plethysmography for unrestrained animals is a non-invasive method that allows repetitive measurements of pulmonary function, but habituation of the conscious animal to this technique has not been explored. Respiratory frequency (f(R)) and 'enhanced pause' (P(enh)) were measured by barometric plethysmography for a period of 8 h in guinea-pigs. Compared with basal values, during the first hour of recording a progressive increase in P(enh) (up to 25-50%) and a corresponding decrease in f(R) were recorded, followed by a relative plateau in each for up to 8 h. These changes were avoided by a 30-min pretreatment with propranolol and l-NAME (nitric oxide synthase inhibitor), with P(enh) values as high as this plateau phase since the beginning of recording. Atropine, salbutamol or budesonide did not modify the progressive increment in P(enh). We concluded that catecholamines and nitric oxide are released when guinea-pigs are introduced into the plethysmographic chamber, leading to initial low P(enh) values. These mediators probably diminish owing to habituation of the animal to the new environment, with an apparent progressive increment in P(enh). These spontaneous changes in P(enh) and f(R) must be taken into account during barometric plethysmography in order to avoid misinterpretation of the results.

Animals↗
PubMed1995

Investigating the origin of cyclic changes in limb volume using mercury-in-silastic strain gauge plethysmography in man.

1. Vasomotion, a phenomen frequently observed in skeletal muscle microcirculation, has been observed under physiological conditions and found enhanced during critical reduction of tissue perfusion due to hypoxic hypoxia, haemorrhage and local hypotension. We used a computer assisted non-invasive plethysmographic method to investigate periodic changes of limb volume (volumotion), which we previously found in critically ill patients. The current study was designed to investigate the origin of volumotion. 2. Simultaneous recordings of limb circumference of both calves were obtained. In patients with peripheral vascular disease and patients with minor surgery the cross-correlation with spontaneous breathing was investigated. In patients who had undergone major abdominal or vascular surgery we analysed for cross-correlations between MSG plethysmography signals of both legs and changes in central venous, arterial and ventilation pressures. In this group the effects of positive-pressure ventilation and positive end-expiratory pressure (PEEP) were also studied. 3. No ventilation-related volumotion was observed during spontaneous breathing. During positive-pressure ventilation a ventilation-related peak was found in the Fourier transform in agreement with the ventilation frequency applied. The amplitude of ventilation-related volumotion decreased significantly after a pressure cuff applied to the thigh was inflated above central venous pressure. We observed a significant increase in the amplitude of ventilation-related volumotion when PEEP was applied. 4. Ventilation-related volumotion showed significant cross-correlation between both legs. Slow wave volumotion (0.5-7 cycles min-1) was frequently observed, but always appeared unilaterally. Whilst we looked for correlations between slow wave volumotion and changes in central venous pressure and arterial blood pressure, respectively, significant cross-correlation with the MSG plethysmography recordings was only observed at the frequency of the positive-pressure ventilation. 5. The fact that periodic changes of limb circumference matching the frequency of the positive-pressure ventilation were detectable with the MSG plethysmography system demonstrates that small volume changes (less than 0.02 ml (100 ml tissue)-1) can be assessed using this system. As slow wave volumotion was observed unilaterally and revealed no correlation either with breathing, ventilation or arterial and central venous pressure, we suggest that slow wave volumotion is a local event most likely reflecting arteriolar vasomotion.

Aged↗
PubMed1977

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↗
PubMed1991

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↗
PubMed2005

Comparison of critical closing pressures extracted from carotid tonometry and finger plethysmography.

BACKGROUND: The reliability of critical closing pressure (CrCP) estimates derived from peripheral blood pressure (BP) measurements is unclear. We attempted to evaluate the influences of peripheral circulation on determining CrCP. METHODS: Twenty-five young healthy volunteers were studied. BP waves were obtained with plethysmography (Portapres) and carotid applanatory tonometry, respectively, for analysis. Transcranial Doppler was used to monitor cerebral flow velocity. Using linear regression analysis, beat-to-beat CrCP was calculated at rest, during voluntary hyperventilation and during 5% CO2 inhalation. RESULTS: Twenty of 25 participants demonstrating satisfactory tonometric tracings for both tests were included in the analysis. The systolic BP measured using plethysmography was higher than that derived from tonometry (139.4 +/- 24.7 vs. 105.5 +/- 29.6, p < 0.001). CrCP values derived from tonometry were all positive and higher than CrCP values derived from plethysmography (62.9 +/- 19.9 vs. 11.1 +/- 17.8, p < 0.001). The changes in CrCP induced by 5% CO2 inhalation and hyperventilation had a correlation between two BP monitoring methods (r = 0.52, p = 0.001). CONCLUSIONS: Pressure waveform is an important determinant in calculating CrCP by linear regression analysis. The relative changes in CrCP induced by hemodynamic challenges remained a relevant indicator of cerebrovascular regulation regardless of the methods used for non-invasive BP recording.

Adolescent↗
PubMed1996

Comparison of respiratory inductance plethysmography with thoracoabdominal compression in bronchial challenges in infants and young children.

Respiratory inductance plethysmography measuring thoracoabdominal asynchrony (TAA) has been claimed to be a useful tool for measuring changes in airway resistance in infants. In this study we evaluated the response to methacholine by thoracoabdominal compression and respiratory inductance plethysmography. Seventeen infants (mean age, 13.1 +/- 4.7 mo) with recurrent episodes of cough or wheeze underwent bronchial challenge with inhaled methacholine. Lung function was evaluated by measuring maximal expiratory flow at resting lung volume (VmaxFRC), and the degree of TAA was measured by phase angle (theta). Methacholine was inhaled for 1 min during tidal breathing using increasing doubling concentrations until a fall of at least 40% in VmaxFRC was achieved (final concentration). All infants responded to the final concentration of methacholine by a significant fall in VmaxFRC (from 31 +/- 10 to 12 +/- 5 ml/s/kg, p < 0.001). All but one infant responded to methacholine at the final concentration with a significant increase in phase angle (median theta increased from 11.7 to 31.7 degrees, p < 0.001). In two other infants there was an early response in theta compared with the response in VmaxFRC. Phase angle increase after methacholine was expressed as Z-scores (the difference between postmethacholine theta and postbuffer theta divided by the standard deviation of postbuffer theta). An increase of at least 2.0 Z-scores in theta was observed at the same concentration of methacholine when VmaxFRC fell by at least 40% in 15 of the 17 infants (88%). We conclude that respiratory inductance plethysmography is a sensitive method to measure bronchial reactivity to methacholine in most of the infants studied (14 of 17, 82%). A concentration of methacholine causing an increase in theta of at least 2.0 standard deviations above baseline is equivalent to the concentration causing a 40% fall in VmaxFRC.

Airway Resistance↗
PubMed1980

The influence of limb elevation, examination technique, and outflow system design on venous plethysmography.

The effect of limb elevation and the design of the thigh cuff outflow system on venous capacitance and venous outflow, as determined by strain gauge plethysmography, was reviewed in a group of normal limbs without evidence of deep venous thrombosis. We improved the reliability of plethysmography in evaluating venous outflow, particularly in the early period after cuff deflation, by using uniform leg elevation, large diameter outflow tubing, and single rather than simultaneous limb examinations. Based on this experience, an optimum technique of examination emphasizing precise limb elevation, sequential limb examination and proper design of the cuff outflow system was used to evaluate 21 patients with acute venous thrombosis. The results obtained were compared with previously reported results of strain gauge plethysmography in patients with acute venous thrombosis. This technique significantly reduced the incidence of false-positive results.

Extremities↗
PubMed1996

Early and late allergic reaction in the nose assessed by whole body plethysmography.

Physiological changes during late phase nasal responses after allergen challenge are difficult to establish and different criteria are used for the definition of a positive late phase nasal reaction. The objective of this study was to assess the value of whole body plethysmography in detecting changes in nasal airway resistance after allergen challenge and to suggest criteria for the definition of early and late phase nasal reactions. Nasal challenge with allergen was performed in 15 allergic patients. Nasal resistance was followed until 10 h after allergen challenge and on a control day using whole body plethysmography. The mean percentage changes in the inspiratory nasal resistance during the early phase period (0.25-2 h) and the late phase period (4-10 h) were significantly higher on the allergen challenge day than on the control day (p=0.001 and p=0.01, respectively). The mean percentage change in the inspiratory nasal resistance during the early and late phase period on the control day plus 2 times the standard deviation served as cut-off point for a positive reaction. Using this definition, all patients had early reactions and 7 of the 15 patients (47%) also had late reactions. We conclude that whole body plethysmography is a useful, noninvasive method for the measurement of the physiological changes in the nose following allergen challenge.

Adult↗
PubMed1992

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↗
PubMed2002

The use of automated strain gauge plethysmography in the diagnosis of deep vein thrombosis.

The venometer is a nurse- or technician-operated machine that uses automated strain gauge plethysmography to detect deep vein thrombosis (DVT). We compared the venometer with contrast venography to determine its accuracy, and also used it to triage patients between admission with subsequent anticoagulation and out-patient investigation without anticoagulation. We enrolled 307 consecutive patients presenting to the medical admissions unit with suspected DVT, of whom 270 underwent both plethysmography and venography. Plethysmography produced a negative predictive value (NPV) of 97% and a sensitivity of 90% for proximal DVT. It also produced a false negative rate of 10% for proximal DVT, For distal DVT, sensitivity was 66%, specificity 80%, positive predictive value 36% and NPV 93%. We conclude that the automated venometer report is a quick, non-invasive and easy to use initial screening test. However, it is not sufficiently accurate in a medical admissions unit to be a definitive diagnostic test for DVT and may, therefore, be best used in combination with clinical risk assessment and D-dimer assay with more definitive radiological investigations as necessary.

Adolescent↗
PubMed1995

Estimation of total lung capacity from chest radiography and chest CT in children: comparison with body plethysmography.

OBJECTIVE: The purpose of this study was to evaluate two methods of estimating lung volume using chest radiographs and one using chest CT in children. Estimates made with these techniques were compared with total lung capacity calculated with body plethysmography. MATERIALS AND METHODS: CT scans and posteroanterior and lateral radiographs of the chest were obtained in 21 children (14 girls and seven boys) for follow-up evaluation after lung transplantation. Lung volume was measured by CT using a previously validated technique of tracing the margins of the lungs on each axial CT scan. Two methods were used to estimate lung volume on chest radiographs: a technique previously described in adults and children that requires 21 measurements on posteroanterior and lateral radiographs, and a modification of a simplified technique previously reported in adults that uses only two measurements on a posteroanterior radiograph alone. Estimated lung volumes from CT and from both methods using chest radiographs were compared with total lung capacity determined from body plethysmography using regression analysis, and 95% prediction intervals were generated. RESULTS: All three methods of estimating lung volumes from radiographs correlated well with total lung capacity from plethysmography (r = .89-.92). However, we found no statistically significant or clinically meaningful difference among the methods of estimating lung volume. CONCLUSIONS: Lung volumes in children can be accurately estimated from specific measurements made on chest radiographs and on CT scans. Of the two methods tested with chest radiographs, the technique that required only two measurements from a posteroanterior chest radiograph was as accurate as the more complicated technique that required 21 measurements.

Adolescent↗
PubMedDate not supplied

[Surgical indications in the phlebopathic patient. The role of air plethysmography].

A previous history of deep venous thrombosis (DVT) must be carefully evaluated in every patient affected by chronic venous insufficiency (CVI); the assessment of deep venous system patency is the goal of preoperative diagnosis. Air plethysmography examination allows an outpatient noninvasive testing of calf pump function and deep venous outflow. The authors report the results of a study on 37 patients (40 limbs) with a previous history of DVT, suffering from CVI; in 18 limbs air plethysmography showed a marked increase of calf volume on test exercise, suggesting residual venous obstruction. The authors believe that air plethysmography examination is mandatory before operation in patients with a previous history of DVT.

Adult↗
PubMed2000

Computerized impedance plethysmography in the diagnosis of delayed deep vein thrombosis after total hip replacement.

Although noninvasive techniques have been extensively evaluated in the diagnosis of deep vein thrombosis (DVT), few data exist about the role of computerized impedance plethysmography (CIP) in the diagnosis of delayed DVT after surgery, when patients are at home and the risk of DVT is still high. The aim of this study was to evaluate the reliability of CIP in the diagnosis of proximal and distal delayed DVT in both symptomatic and asymptomatic patients who had undergone elective total hip replacement (THR). Bilateral CIP of lower limbs was performed in 61 patients on days 5, 9, 15 and 45 after THR; for comparison, ascending phlebography was performed on days 45 after THR in all patients on the operated limb or on the limb with positive results on CIP. The overall rate of DVT diagnosed by phlebography was 16.3% (10/61). The sensitivity and specificity of CIP for all DVT were 20% and 98%, respectively, while the accuracy was 85%. The results were not influenced by the presence of symptoms or signs of the lower limbs. Similar results were obtained when considering proximal DVT only. In conclusion, the low sensitivity of computerized impedance plethysmography means that it cannot be used in screening for delayed deep vein thrombosis after total hip replacement, in both symptomatic and asymptomatic patients. However, because of its high specificity, when the results of computerized impedance plethysmography are positive phlebography should be performed to confirm the diagnosis of deep vein thrombosis.

Aged↗
PubMed2006

Reliability of respiratory tidal volume estimation by means of ambulatory inductive plethysmography.

Ambulatory monitoring of ventilatory parameters in everyday life, field research and clinical situations may offer new insights into respiratory functioning in health and disease. Recent technological advances that employ ambulatory inductive plethysmography could make monitoring of respiration outside the clinic and laboratory feasible. Inductive plethysmography provides a method for nonintrusive assessment of both timing (e.g. respiration rate) and volumetric parameters (e.g. tidal volume and minute ventilation), by which tidal volume is initially calibrated to direct measures of volume. Estimates of tidal volume assessed by this technique have been validated in laboratory investigations, usually examining within-individual relations to direct measures over a large range of tidal volume variation. However, the reliability of individual differences in tidal volume or other breathing parameters has not been tested under naturalistic measurement conditions using inductive plethysmography. We examined the test-retest reliability of respiration rate, tidal volume and other volumetric parameters of breathing over a period of six weeks of repeated measurements during baseline conditions and breathing exercises with 16 healthy freely moving volunteers in a Yoga course. Reliability of measurement was evaluated by calculating the average week-to-week between-subject correlation coefficients for each physiological measure. Additionally because body-mass index has been previously positively correlated to tidal volume, we also assessed this relationship as an external criterion of validity of tidal volume estimation. Regarding the latter, similar correlations to those previous studies were found (r = 0.6). Furthermore, reliability estimates were high and consistent across respiratory measures (typically r's = 0.7-0.8). These results suggest the validity of ambulatory inductive plethysmographic measurement of respiration, at least under relatively sedentary conditions. Findings also point to the stability of individual differences in respiratory parameters over consecutive weeks.

Activities of Daily Living↗
PubMed1990

[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↗
PubMed1990

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↗