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A study of 820 patients at risk for deep-vein thrombosis of the legs and pulmonary-arterial thrombo-embolism (PATE) serves to illustrate that screening by means of ultrasonic flowmetry and venous-occlusion plethysmography is capable of detecting asymptomatic phlebothrombosis.
We studied the venous capacity of the lower limbs by strain gauge plethysmography during venous occlusion (delta v60) and by a dependency test (delta v postural) (from the supine to the sitting position). We were also interested by the performance of the calf musculovenous pump, assessed in two positions: sitting and standing (delta v exercise). The volume changes are increasing when we consider limbs with sequelae of deep vein thrombosis, normal lower limbs and extremities with primary varices. delta v60: 2.13%, 2.84%, 4.24%; p less than 0.01. delta v postural: 1.32%, 1.94%, 3.66%; p less than 0.01. delta v exercise: 0.48%, 1.47%, 2.09%; p less than 0.01. The study of the expelled volume during calf muscle exercise is easier in the sitting than in the standing position and it leads to a better discrimination between normal limbs and limbs suffering from sequelae of deep vein thrombosis. The dependency test with measurement of the venous capacity when going from the supine to the sitting position (with the leg dependent) and the assessment of the calf muscles pump, also in the sitting position, are the basis of a simple approach to the quantitation of venous insufficiency.
Foot volumetry, strain-gauge plethysmography and photoplethysmography were performed on 15 patients testing three different elastic stockings. Improvement of venous function and enhancement of the musculovenous pump effect was shown at foot volumetry and photoplethysmography. No effect on refilling times was found.
The method of occlusive plethysmography giving an exact quantitative assessment of resistance of the venous bed was used for the examination of 91 patients with different degrees of alterations of the venous outflow before and after surgery. An analysis of the data obtained has shown the efficiency of the method as allowing to supplement and sometimes to substitute invasive methods of examination especially for the assessment of the venous outflow in profound veins and of effects of the surgical treatment.
129 children and adolescents had 111 bronchial histamine and 85 allergen challenges. Airways resistance measured by the occlusion technique was found to be inferior to the body plethysmography in discriminating children with hyperreactive or allergic airways from healthy children.
Digital plethysmography records digital pulsation and measures blood flow by occlusion and perfusion pressure. The pulsatile curve is modified in vasomotor disorders of the extremities, and is delayed and flattened in obstructive arteriopathy. In Raynaud's phenomenon, the basal flow (at 22 degrees C) decreases with clinical severity, and suppression of post-ischemic blood flow by cold seems to be an attribute of Raynaud's disease. Digital perfusion pressure is usually greater than or equal to 70% of the humeral systolic pressure. When it decreases under hot conditions, organic obstructive arteriopathy is indicated; decreases due to local cooling allow quantification of hyperreactivity to cold of the digital artery.
The diagnostic accuracy of segmental air plethysmography using a pulse volume recorder in the detection of deep vein thrombosis (DVT) was assessed. Measurements in 25 limbs with phlebographic proof of DVT and 25 limbs with normal phlebographic examination results were used to develop criteria. With these criteria, a prospective analysis of 50 limbs of patients suspected of having DVT was done. High sensitivity and specificity rates were found for proximal DVT. An accurate plethysmographic diagnosis could not be obtained for nonocclusive DVT or thrombosis confined to calf veins. The accuracy of the segmental air technique was comparable with that of other plethysmographic techniques.
Thoracic gas volume (TGV) and specific airway resistance (sRaw) are commonly measured using pressure type and flow type body plethysmographs. Within-subject variability of the data, defined as the coefficient of variation of eight to ten measurements during the same session, was assessed with the two kinds of instruments and compared in fifteen normal subjects. The reproducibility of data obtained several days apart was also compared. All measurements were made in a 480-l body chamber, which could be used in both the pressure and the flow mode. The signals were processed digitally using three different algorithms: 1) simple linear regression (LR); 2) linear regression with drift correction achieved by adding to, or subtracting from the plethysmographic signal a term proportional to time (LRC); 3) Fourier analysis (FFT). Within-subject variability of TGV was much larger with flow than with pressure plethysmography when the signals were processed by LR (14.5 +/- 7.5 vs 6.3 +/- 3.0%; p less than 0.001), but almost the same using LRC (6.7 +/- 3.2 vs 5.4 +/- 2.7%) and FFT (6.1 +/- 2.4 vs 5.0 +/- 2.4%). For sRaw, variabilities were larger and less influenced by methodological factors. Adequate digital processing may therefore largely remedy the inherently greater variability of TGV measurements with flow plethysmographs.
Fifty-two patients with carotid transient ischemic attacks (TIAs) were subjected to subsequent compression of the common carotid and superficial temporal artery. An EEG recording was monitored simultaneously with plethysmograms from both supraorbital regions during the arterial compression period. All patients were angiographically classified as normal (Group A, n = 25) with less than 50% stenosis (Group B, n = 14) and with more than 50% stenosis (Group C, n = 13), according to the degree of internal carotid stenosis. The carotid compression test was positive in 6 (11%) of our 52 patients, corresponding to 1 (4%) patient from Group A, 1 (7%) from Group B and 4 (30%) from Group C. In contrast, supraorbital photoelectric plethysmography (SOPPL) yielded abnormal results in 17 (33%) of our 52 patients, corresponding to 3 (12%) patients from Group A, 4 (28%) from Group B and 10 (77%) from Group C. We conclude that in view of the false positive results (12%) obtained with the SOPPL technique, the clinician who interprets these findings should be careful and combine these tests with other tests, preferably hemodynamic, for a final decision about the patient's status.
Through a catheter placed in a superficial vein on the finger, we observed a pulsatile venous pressure. To delineate the relationship between the pulsatile venous pressure and the pulse volume amplitude (PVA) recorded by photoelectric plethysmography (PEPG), both tracings were simultaneously recorded. When the PVA changed acutely or gradually, the venous pulse pressure and mean venous pressure simultaneously followed the same trend. We also found that mean PVO2 (135 mm Hg) was greater when the PVA and venous pulse pressure increased above the level (50 mm Hg) observed when they decreased. These findings suggested that the finger pulse detected by PEPG, as well as by pulse oximetry, is caused by pulsations in veins rather than by pulsations in arterial beds. In experiments to evaluate the validity of this hypothesis, we found that the average value of hemoglobin saturation (%SaO2) measured by the pulse oximeter of the dependent fingertip and finger base when dependent was 1.5% and 7.8% lower than when the fingertip and finger base were elevated. Also, the PVA detected by the pulse oximeter followed the same trend as %SaO2. This finding was explained by venous congestion in the dependent finger. On the basis of the high venous pressure, the behavioral trends between the PVA and venous pressure, the high PVO2, and the low %SaO2 and PVA in the dependent finger, we conclude that the PVA of the PEPG is determined mainly by venous pulse volume generated by shunting of arterial pulse via open arteriovenous (AV) anastomoses in the cutaneous circulation.
Clinically significant thromboembolic disease originating from the paralyzed leg of hemiplegic patients can occur unexpectedly and may affect morbidity and mortality in the rehabilitation setting. Impedance plethysmography (IPG), a simple, noninvasive technique, can accurately reveal deep vein thrombosis (DVT) in the large veins of the thigh. IPG studies were performed on the lower extremities of 20 hemiplegic patients considered at high risk for DVT. Each patient had one or several of the following potential risk factors: mild swelling, vague leg discomfort, loss of sensation, poor or absent muscle power at the ankle, at least one week of complete bedrest, repeated minor trauma. None of the patients had major signs or symptoms of DVT at the time of testing (ie, severe pain and tenderness, increased temperature or redness, a palpable venous cord, or positive Homans' sign). Seven patients had an abnormal IPG in the paralyzed lower limb and DVT was confirmed in each case by venography. After appropriate anticoagulation therapy, the seven patients resumed their rehabilitation programs. It was concluded that IPG can be successfully used in the early detection of DVT in high-risk hemiplegic patients, thus leading to prompt medical management, reduced morbidity and mortality, and improved rehabilitation outcome.
Although impedance plethysmography (IPG) is a test of recognized value in the diagnosis of acute proximal deep venous thrombosis (DVT), its meaning in patients with bilaterally abnormal IPGs is unclear. Consequently, we sought to determine the clinical significance of the bilaterally abnormal IPG in hospitalized patients. In a five-month prospective study, 19% (81/425) of all IPGs done at our institution were bilaterally abnormal (55% of all abnormal IPGs). Acute proximal DVT was found in 26% (14/53) of patients with bilaterally abnormal IPGs who underwent further diagnostic testing. Thirty-five percent of the patients with DVT were found to have either bilateral lower extremity DVT or clots in the inferior vena cava. A numerical score, the venous function index (VFI), was computed for the 101 legs for which further definitive diagnostic evaluations for DVT had been completed. The mean VFI of seven for legs with acute proximal DVT was significantly less than the mean VFI of 13 for legs with no DVT. Fifty percent of legs with a VFI less than or equal to five had DVT, whereas only 7% of legs with a VFI greater than 15 had DVT. The bilaterally abnormal IPG is a common clinical occurrence, is frequently associated with acute DVT, and the VFI is helpful in discriminating legs with acute proximal DVT from normal legs in patients with a bilaterally abnormal IPG.
Digital plethysmography allows investigation of maximum digital pulse (M.D.P.) after immersion of hands at 45 degrees C over three minutes. It is correlated with digital arterial blood flow. Reactivity to cold is determined from the ratio M.D.P./digital pulse after local and body cooling over 3 minutes. Tests were performed on 65 controls, 69 patients with idiopathic Raynaud's syndrome, 12 with scleroderma, 10 with digital arteritis and 15 with Raynaud's phenomenon secondary to hemorheologic affections. Maximum digital pulse was significantly decreased in patients with digital arteritis and scleroderma. The M.D.P. was normal in controls and patients with idiopathic Raynaud's syndrome, and was significantly increased in patients with a rheologic Raynaud's phenomenon. Digital artery reactivity differentiates the populations studied: it was maximum in patients with scleroderma, moderate in controls and patients with isolated digital arteritis and marked in patients with idiopathic Raynaud's disease and those with rheologic Raynaud's phenomena.
Using skull impedance plethysmography, a developmental approach was made to the measurement of mean cerebral blood flow (mCBF) from brain volume exchanging ratio (delta V) involved in bilateral jugular venous occlusion. An experimental study thereof revealed the following results: Comparative examinations were made between total cerebral blood flow obtained by the superior sagittal sinus hydrogen clearance method and delta V X t obtained by the present approach led to the establishment of a linear correlation there between and also of the following calculating formula: mCBF = k X delta V X t (omega X sec) k: proportional coefficient t: blood flow increasing time (10 sec.) The experimental results revealed that the present approach was valid enough as an index of cerebral blood flow. Some future improvements therein seem to make also its clinical application possible. The theory and method of the present approach are described with an examination of several points raised thereby.
In a series of 56 patients with proximal lower-limb deep-vein thrombosis (DVT) diagnosed on ascending venography, impedance plethysmography (IPG) and Doppler ultrasound examinations were performed and the results compared. Both IPG and Doppler ultrasonography were highly sensitive for the diagnosis of proximal occlusive DVT, but considerably less sensitive for the potentially more dangerous proximal non-occlusive thrombosis. If, in the presence of clinically suspected DVT, these non-invasive investigations are both negative, ascending venography remains essential.
Magnetometers measure changes in antero-posterior diameters of the rib cage and abdomen while respiratory inductance plethysmography (RIP) measures changes in chest wall cross-sectional area. We compared Konno-Mead diagrams derived from isovolume calibrated magnetometers and RIP in the DC-mode during room air and CO2 rebreathing in the sitting and supine positions. Chest wall configurations obtained during quiet tidal breathing were similar in both sitting and supine positions. During CO2 stimulated breathing, however, derived chest wall configurations were at times dissimilar. The RIP per cent rib cage contribution to tidal volume was greater than that of magnetometers during room air and CO2 rebreathing in both sitting and supine positions. Changes in end expiratory levels measured by magnetometers and RIP during CO2 rebreathing are in general proportionate to each other; however, the magnetometers usually depicted quantitatively greater decreases in abdominal end expiratory levels during rebreathing. We conclude that the qualitative and quantitative assessment of chest wall configurations and volume displacement vary depending on the method used. RIP by including lateral wall motion may more accurately reflect compartmental displacements, while magnetometers by solely measuring antero-posterior diameter may better reflect changes in abdominal volume and thus diaphragm configuration.
The absolute bioavailability of glyceryl trinitrate from a transdermal therapeutic system (Nitroderm TTS, 20 cm2) was assessed with a new method in 6 healthy volunteers. Instead of measuring plasma concentrations the pharmacological effects of glyceryl trinitrate were followed by digital plethysmography. Each experiment consisted of the establishment of an intravenous dose response curve which was followed by a 1-hour application of the transdermal system and a second intravenous dose response curve. The investigations were repeated after pretreatment of each subject with 0.4 mg pindolol i.v. The results show a satisfactory overall consistency of the data and indicate a release rate of 4.4 +/- SD 1.7 micrograms/min of bioavailable glyceryl trinitrate during the first hour of application of this transdermal system. This corresponds to 75 +/- 29% of the release rate obtained by analysis of residual amounts in the TTS.
The fingertip blood flow measured by mercury strain gauge plethysmography with venous occlusion, at 22 degrees C room temperature, had significantly lower mean values in 190 patients with Raynaud's phenomenon (55 men aged 49 yrs +/- 16, 135 women aged 48 yrs +/- 16) than in 40 age and sex matched controls: 18 ml/100 ml/minute +/- 14.6 versus 35 ml/100 ml/minute +/- 15 at level p less than 0.01. The mean fingertip blood flow was significantly lower (p less than 0.01) in 31 cases of scleroderma and 32 cases of pulpar necrosis (respectively 13 ml +/- 13 and 11 ml +/- 8) than in 55 cases of primary Raynaud's disease (no detectable etiology and normal capillaroscopy 5 years after onset) or in 34 cases of mild Raynaud's phenomenon (respectively 21.6 +/- 16 and 24.4 +/- 18). A warming test (both hands in water at 45 degrees C during 3 minutes) was performed in 50 cases with low basal fingertip blood flow. It induced a "normalized" flow in 22 cases (mostly primary or mild Raynaud), a partly improved flow in 20 cases (mostly secondary Raynaud) and no improvement in 8 cases (scleroderma). The warming test appears to be clinically useful to assess the vasospasm and the vasodilating capabilities.