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PubMedDate not supplied

Opto-electronic plethysmography.

Recent developments of Opto-Electronic plethysmography allow a noninvasive and accurate measurement of the volume of the chest wall and its different thoraco-abdominal compartments, without any calibration specific on the subject under analysis. OEP provides the complete ventilatory pattern without using any device attached to the subject in any conditions and posture. Combined with pressure and airflow measurements, it can be used to study statics, dynamics and energetics of the chest wall and to estimate possible blood shifts between the thorax and the extremities.

Asthma↗
PubMed1992

Mercury in silastic strain gauge plethysmography for the clinical assessment of the microcirculation.

We have used the mercury in silastic strain gauge plethysmography (MSG) system, which is wholly non-invasive, to obtain values (mean +/- s.e.m.) for the following parameters in the legs of supine control subjects: venous pressure (Pv) 9.89 +/- 0.88 mmHg, vascular compliance (Comp) 3.50 +/- 0.29 ml 100 g-1 mmHg-1 x 10(-2), microvascular hydraulic conductivity (Kf) 4.10 +/- 0.16 ml min-1 100 g-1 mmHg-1 x 10(-3) and isovolumetric venous pressure (Pvi) 22.12 +/- 0.82 mmHg. On passive foot-down tilting of control subjects through about 45 degrees, both Pv and Pvi rose to 28.00 +/- 2.33 and 36.58 +/- 2.29 mmHg respectively. The increases in both parameters were highly significant, P < 0.0001. We found that the time course of the vascular compliance component was short if small pressure steps were used. The value increased markedly if large steps were used. We also observed that none of the microvascular parameters studied in the arms differed from those in the legs of the same subjects. We observed that the mean value Kf in the arms of 12 young, non-neuropathic diabetics (9.08 +/- 6.12 x 10(-3)) was significantly greater than that of age and sex-matched controls (P < 0.001). Studies on 14 venous ulceration patients indicated that the values for Kf and Pv were unchanged, whilst those of vascular compliance (5.60 +/- 0.58 x 10(-2) ml 100 g-1 mmHg-1) and Pvi (37.30 +/- 2.25 mmHg) were significantly greater than those found in age-matched controls (P < 0.002 and 0.001, respectively). We feel that Pvi is a useful index of microvascular perfusion. We attribute the pressure-dependent difference, in the time course of the vascular compliance response, to the veni-arteriolar reflex. We feel that the pressure dependency of this response might form the basis for the assessment of peripheral autonomic neuropathy. We believe that the MSG system offers a means of monitoring the development of pathologies resulting from microvascular under-perfusion and, of course, the improvement in response to therapeutic interventions.

Adult↗
PubMed1978

[Comparison of oscillation method and body plethysmography for assessment of airway resistance (author's transl)].

Airway resistance was measured by body plethysmography and also by an oscillographic method for assessment of the impedance of the respiratory tract. The results were compared in 42 unselected patients. The correlation between the two values for airway resistance was satisfactory (r = 0,804 p less than 0,001). However, when correlation was sought between each type of resistance-value and other lung function data (FEV1, IGV), the resistance measured by plethymography correlated better than the one measured by the oscillation method. This difference was even more pronounced when 21 patients with manifest bronchospasm were reevaluated after bronchodilatation. Nevertheless, the oscillation method for assessment of the resistance of the respiratory tract serves as a new and practicable tool for bed-side lung function testing, as well as for testing of patients who are unable to cooperate for routine spirography.

Adolescent↗
PubMed2004

Determination of body composition using air displacement plethysmography, anthropometry and bio-electrical impedance in rural elderly Mexican men and women.

BACKGROUND AND AIMS: Air displacement plethysmography with the BOD-POD is a new densitometry technique, and has been found to be an accurate method to measure body composition. The aim of this study was to assess body composition in a group of free living healthy subjects 60 years of age or older from a rural area of Northwest Mexico, and to evaluate body composition by anthropometry and bioelectrical impedance (BIA) using equations reported for other elderly populations. METHODS: Body composition was evaluated in 21 women and 26 men with the BOD-POD, by anthropometry, and BIA and compared to different equations using the Bland- Altman procedure. RESULTS: Body fat in elderly women and men was 42.7 and 30.2 % respectively. In women, Segal's equation using BIA 1, based on standing height, showed no significant differences with the BOD-POD. There was satisfactory agreement between Segal's equation and BOD-POD. In men similar results was found with Deurenberg's equation using B1A 2 based on recumbent length. CONCLUSIONS: Segal's and Deurenberg's equations were accurate and precise for the estimation of body fat in the elderly of this study. The use of these equations could improve the estimation of body composition for similar elderly subjects. Further studies are recommended with a larger size samples to include elderly subjects from other Latin American countries.

Aged↗
PubMed2005

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

Deglutition disorders can occur at any age but are especially prevalent in the elderly. The resulting morbidity and mortality are being recognized as major geriatric health issues, Because of difficulties in studying swallowing in the frail elderly, a new, non-invasive, user-friendly, bedside technique has been developed. Ideally suited to such patients, this tool, an intermediary between purely instrumental and clinical methods, combines respiratory inductance plethysmography (RIP) and the computer to detect swallowing automatically, Based on an automated analysis of the airflow estimated by the RIP-derived signal, this new tool was evaluated according to its capacity to detect clinical swallowing from among the 1643 automatically detected respiratory events, This evaluation used contingency tables and Receiver Operator Characteristic (ROC) curves, Results were all significant (chi2(1,n=1643)>100, p<0.01). Considering its high accuracy in detecting swallowing (area under the ROC curve greater than 0.9), this system would be proposed to study deglutition and then deglutition disorders in the frail elderly, to set up medical supervision and to evaluate the efficiency of a swallowing disorder remedial therapeutic.

Aged↗
PubMedDate not supplied

Effects of dilevalol in hypertension assessed by digital pulse plethysmography.

For two weeks, with the exception of one case involving long-term therapy, 15 hypertensive patients received 100 mg of dilevalol once daily and seven patients received 50 mg. Blood pressure and heart rate were measured and digital pulse plethysmography (DPG) was performed before and after the two-week trial. Systolic and diastolic blood pressure decreased significantly during treatment; heart rate did not change. There were also significant changes on the three DPG measures of vasodilatation: peak amplitude increased, the dicrotic index decreased, and peak amplitude on the differentiated DPG increased. A weak correlation was found between the changes in systolic blood pressure and changes in the two measures of DPG peak amplitude. It is concluded that dilevalol is effective in the treatment of hypertension and that DPG is a sensitive noninvasive method to measure vasodilatation.

Adult↗
PubMed2006

Noninvasive assessment of cutaneous vascular function in vivo using capillaroscopy, plethysmography and laser-Doppler instruments: its strengths and weaknesses.

Given that functional abnormalities of the microcirculation are one of the primary abnormalities in cardiovascular disease pathogenesis, various noninvasive clinical tools have been developed recently to assess the microvascular function, particularly at the skin. The common techniques used to assess cutaneous microvascular function in vivo include capillaroscopy, venous occlusion plethysmography, and laser-Doppler instruments (laser-Doppler fluximetry and laser-Doppler imaging). These noninvasive techniques can be used as an early measure of functional abnormalities within the microvascular tree, predominantly in population at high risk for cardiovascular events. This review discusses some underlying application principle of these techniques, including its clinical significance, method reproducibility and limitations.

Cardiovascular Diseases↗
PubMed1991

[Computer-assisted calibration of inductive plethysmography].

A software program was written assisting calibration and measurement of the inductive plethysmography RESPITRACE. In 6 subjects calibration was carried out using both methods and a confirmation was found in the 20% area of dispersion. The use of only one measuring tape enables a very precise measurement of ventilation.

Adult↗
PubMed1991

Impedance plethysmography: a new method for continuous muscle perfusion monitoring.

Vigilant postoperative monitoring of the buried muscle flap is critical after free transfer because early diagnosis of vascular insufficiency is essential to allow prompt correction. We have identified a monitoring method utilizing needle electrodes and impedance plethysmography that gives a beat-to-beat representation of muscular perfusion. In 25 New Zealand White rabbits the gastrocnemius muscle was isolated on its vascular pedicle, and two intramuscular needle electrodes were placed. The instantaneous impedance changes of the muscle (corresponding to the pulsatile volume changes of perfusion) were measured and recorded. Using this representation of perfusion, an independent judge was able to correctly diagnose muscular ischemia 100 percent of the time (n = 25). Further, the judge was able to correctly distinguish the ischemia as arterial (n = 10) or venous (n = 10) in origin 100 percent of the time. Additionally, we monitored muscle perfusion transcutaneously in five free muscle flaps and demonstrated a reliable impedance signal that correlated with perfusion.

Animals↗
PubMed1991

The assessment of the microcirculatory effects of dobutamine using mercury in silastic strain gauge plethysmography in man.

Adverse changes in the microcirculation are currently considered as the most likely common pathway of organ failure, dramatically manifest in the multiple organ failure syndrome. We have investigated 28 patients presenting with gross cardiovascular instability due to septic shock or haemorrhage, using standard invasive methods of monitoring (Physiological Profile). We combined this study with a computer assisted mercury-in-rubber strain gauge plethysmography (MSG) measurement, for a parallel (non-invasive) assessment of peripheral microcirculatory function. We started the investigation on patient arrival in ICU and continued it during their resuscitation regime, which essentially consisted of fluid loading together with inotropic support, where necessary. We found highly significant changes in isovolumetric venous pressure (Pvi), determined by the MSG technique, when we compared survivors (27.29 +/- 1.65 mmHg, mean +/- s.e.m.) with non-survivors (39.5 +/- 2.97 mmHg, P less than 0.001). To investigate the role of dobutamine in patient improvement we compared the Pvi values obtained from the MSG studies and demonstrated a significant decrease from the initial value (38.2 +/- 2.4 mmHg) to the final one (25.4 +/- 2.4 mmHg), obtained after weaning the patients off dobutamine. Marked cyclic changes in limb circumference (vasomotion) were also observed and their appearance correlated well with accepted parameters of cardiovascular instability. We propose that changes in both Pvi and Vm are useful indices of microvascular hypoperfusion which is probably the underlying cause of pathology in both patient groups.

Dobutamine↗
PubMed1991

Impedance plethysmography in the diagnosis of asymptomatic deep vein thrombosis in hip surgery. A venography-controlled study.

We prospectively evaluated the accuracy of computerized impedance plethysmography (CIP) in the diagnosis of asymptomatic deep vein thrombosis (DVT) in 246 consecutive high-risk patients scheduled for hip surgery, with bilateral venography used for comparison. The CIP was performed as a surveillance program every third day. If the CIP remained negative, bilateral venography was performed on postoperative day 10 +/- 1 or on day of treatment 14 +/- 1 in nonoperated-on patients. If the CIP became positive, venography was performed within 24 hours. The sensitivity and specificity of CIP for proximal and distal DVT were 19% (confidence interval [CI], 13% to 24%) and 91% (CI, 87% to 94%), respectively. The positive and negative predictive values were 52% (CI, 38% to 65%) and 70% (CI, 65% to 74%), respectively. The sensitivity and specificity of CIP for proximal DVT were 24% (CI, 13% to 34%) and 90% (CI, 87% to 94%), respectively; the positive and negative predictive values were 31% (CI, 20% to 51%) and 87% (CI, 83% to 90%), respectively. We conclude that, because of its low sensitivity, CIP cannot be used in the surveillance of DVT in high-risk patients or for outcome measurements in clinical trials on DVT prophylaxis.

Aged↗
PubMed1991

The failure of serial pneumatic cuff venous occlusion plethysmography to predict patients at risk for pulmonary emboli after trauma.

Over a three month period, attempts to perform serial Pneumatic Cuff Venous Occlusion Plethysmography (VP) were carried out in 51 severely injured patients felt to be at risk for Pulmonary Embolus (PE). Studies could not be performed in 25 of these patients due to the nature of their injuries. Of the remaining 26 patients, two showed evidence of deep vein thrombosis (DVT). Venography confirmed the diagnosis in only one of these patients. Serial VP failed to predict PE in all five patients in whom it was diagnosed. This article concludes that serial VP is not an effective predictor of PE in these patients.

Humans↗
PubMed1991

Failure of computerized impedance plethysmography in the diagnostic management of patients with clinically suspected deep-vein thrombosis.

Before a new diagnostic modality can be introduced in clinical medicine, the validity of both a normal and abnormal test result have to be assessed prospectively in an appropriate patient group. We have evaluated the clinical validity of a new computerized impedance plethysmography (CIP) in the diagnostic management of 381 consecutive patients with clinically suspected venous thrombosis. In patients with serially normal CIP results, the diagnosis of venous thrombosis was refuted and, consequently, they were not treated with anticoagulant therapy and all were followed up for a period of 6 months to estimate the occurrence of symptomatic venous thromboembolism. The study was prematurely terminated by the safety monitoring committee because of an unacceptably high incidence of confirmed venous thromboembolism (10 patients, 3.2%; 95% confidence interval: 1.6% to 6%), including 4 episodes of fatal pulmonary embolism. In a subsequent explanatory study using ultrasonography in 29 other symptomatic patients who had at least 2 repeated normal CIP test results, the failure of CIP to detect proximal vein thrombosis was confirmed in 4 patients (14%). The reasons for this failure are probably related to the use of a modified device to measure impedance in the CIP apparatus, resulting in a lower ability to separate patients without venous thrombosis from those with the disease. We concluded that CIP is insensitive for the detection of proximal vein thrombosis and, therefore, not clinically useful in the diagnostic management of patients with suspected venous thrombosis.

Adolescent↗
PubMed1990

Impedance plethysmography: basic principles.

Impedance Plethysmography technique has been discussed with explanation of two compartment model and parallel conductor theory for the estimation of peripheral blood flow and stroke volume. Various methods for signal enhancement to facilitate computation of blood flow are briefly described. Source of error in the estimation of peripheral blood flow is identified and the correction has been suggested.

Humans↗
PubMed1990

Diagnosis of aortic occlusive diseases using impedance plethysmography.

Impedance plethysmographic observations have been correlated with aortographic observations in 57 patients suspected of aortic occlusive diseases. Aortic occlusions have been characterised by marked decrease in blood flow index and significant increase in differential pulse arrival time at thigh level bilaterally. Atherosclerotic affection of the aorta has been featured by a bilateral decrease in the value of blood flow index as well as differential pulse arrival time at thigh level. Leriche's syndrome, however, has been found to decrease the blood flow index moderately at thigh in both the legs without any significant change in differential pulse arrival time. Aortography in all the patients has confirmed the diagnosis made by impedance plethysmography.

Aorta, Abdominal↗
PubMed1990

Diagnosis of venous disorders using impedance plethysmography.

Impedance plethysmography (IPG) was carried out in one hundred and forty-one patients suspected of venous disorders using Parulkar's method. In these patients occlusive impedance phlebography (OIP) and venography were also carried out using standard procedures. Comparison of IPG and OIP observations with venographic findings revealed sensitivity of these methods to be 65% and 77.7% in the diagnosis of primary varicosity of veins and chronic deep vein thrombosis respectively with a specificity of 85%. Occlusive impedance phlebograms showing unilateral decrease in OIP parameters were observed to be sufficiently diagnostic. IPG observations in 5 patients with arterio-venous malformation were observed to be different from those in patients with deep vein thrombosis.

Adolescent↗
PubMed1990

[The bronchospasmolytic test with anticholinergic drugs and sympathomimetics: differences between body plethysmography and spirometry measuring procedures].

The different bronchodilator effects after inhalation of anticholinergic and beta-adrenergic drugs due to the different methods of measurement (i.a. body plethysmography vs. spirometry) were studied in 43 patients with COLD and in 20 healthy subjects. The greatest changes occur when the body plethysmographic value Rt was chosen. The spirometric values FEV1 and PEF show the greatest bronchodilator effect. The patients with COLD have the best bronchodilation after inhalation of the beta-adrenergic drug, whereas the healthy subjects show the greatest effect after anticholinergic drugs.

Airway Resistance↗
PubMed1990

[Impedance plethysmography, Doppler echography and phlebography in deep venous thromboses of the lower limbs].

Computerized impedance plethysmography (CIP) and phlebography were performed on 165 consecutive outpatients with clinical suspicion of deep venous thrombosis (DVT) and on 220 consecutive asymptomatic patients hospitalized for hip fracture. Ninety-two asymptomatic patients were examined also with real-time B-mode US. In orthopedic patients CIP sensitivity, specificity, accuracy, positive and negative predictive values were 19.4%, 90.5%, 64.4%, 53.8% and 66.3%, respectively, for proximal and distal DVT, versus 19.7%, 88%, 77.5%, 77% and 86% for proximal DVT. In symptomatic patients CIP sensitivity, specificity, accuracy, positive and negative predictive values were 83%, 87%, 85%, 87% and 82%, respectively, for proximal and distal DVT, versus 91%, 88%, 89%, 82% and 94% for proximal DVT. CIP had great diagnostic utility in symptomatic DVT, whereas its diagnostic efficacy was low in asymptomatic patients. In orthopedic patients US sensitivity, specificity positive and negative predictive values were 44%, 99.2%, 95.7% and 81.6%, respectively. US diagnostic value was relatively high, but further investigation is needed. To date, phlebography seems to be the only effective method in the diagnosis of DVT in asymptomatic high risk patients.

Diagnosis, Computer-Assisted↗