[Determination of the microcirculatory blood flow by pulp plethysmography]

A method for clinical determination of blood inflow at the tip of digit, using mercury strain gauge plethysmography with venous occlusion, is presented, including a satisfactory way of calibration of the "closed type" gauges. Theoretical considerations and experimental data allow to consider the accuracy of the method (of +/- 7 p.cent) to be of clinical value.

[Plethysmographic and in vitro studies of the vasodilator effect of furosemide (Lasix)]

The beneficial effect of furosemide in treatment of chronic and particularly of acute congestive heart failure has been attributed to its potent diuretic action. In recent studies [16], it has been postulated that the effect of this diuretic agent is primarily vascular in origin. The results of venous occlusion plethysmographic experiments (modificated Whitney-gauge technique) carried out in this study on the forearm of 6 healthy men, show that furosemide (40 mg. i.v.) does not influence arterial blood flow (4-5 ml/100 ml tissue - min). In contrast furosemide induces a prompt significant (p less than 0.001) and sustained (about 45 min) increase in venous capacitance (deltaV/100 ml tissue = 15%) and a corresponding decrease in E'. The direct effect of furosemide on vascular muscle tone was studied in vitro on portal vein and aortic strip preparations from 76 male rats. In 18 experiments mechanical and electrical activity (using three pressure electrodes) were simultaneously recorded. The results of the in vitro experiments show: 1. Only extremely high furosemide concentrations (greater than 500 mg/l) induce slight relaxation of aortic strips. 2. Furosemide causes in contrast a marked dose-dependent per cent decrease of the integrated isometric tension in portal vein preparations: 14 mg/l reduce the initial tension (= 100%) to 80%; 35 mg/l to 65%; 70 mg/l to 50% and 100 mg/l to 35%. 3. The venodilating furosemide effect is significantly (p less than 0.001) increased by reduction in external Na+-concentration [Na+]0 to 120 mM though further reduction in the [Na+]0 to 90 mM does not cause additional changes in the relaxation slope. 4. The simultaneous records of electrical activity demonstrate that the relaxing effect of furosemide is based on decreased spike frequency in shortened bursts as well as on pronounced impairment of conduction velocity without relevant changes in pacemaker frequency. These in vitro results are discussed from the point of view that a furosemide induced decrease in Na+-permeability may determine the changes obtained in electrical and mechanical behaviour of portal veins of the rat.

Venous occlusion plethysmography. Part 1: basic principles and applications

A complete review of plethysmographic methods using the venous occlusion technique is given. All methods known to the author are covered, with comments on their applications. A comprehensive list of relevant literature concludes the review.

Differntiation of primary from secondary varicose veins by Doppler ultrasound and strain gauge plethysmography

The Doppler ultrasonic velocity detector and the strain gauge plethysmograph were used to differentiate qualitatively and quantitatively primary from secondary varicose veins. Studies were performed in 21 limbs of 14 normal persons, nine limbs of eight patients with varices secondary to deep venous disease. The latter group of patients was identified by ultrasonic evidence of venous reflux through imcompetent deep venous valves. There was no significant difference in the maximum venous outflow of the limbs of the three groups of persons as determined by plethysmography. The primary hemodynamic abnormality in patients with varicose veins was significant venous reflux through imcompetent venous valves. This reflux was obliterated by tourniquet compression of the varices in patients with primary varicose veins. However, secondary varicose veins are distinguished by persistent abnormal deep venous reflux after compression of the varices. These diagnostic techniques not only provide accurate noninvasive diagnostic information but also may facilitate determination of prognosis and therapy of patients with varicose veins.

Measurement of collateral cerebral hemispheric blood pressure by ocular pneumoplethysmography

A new technic of ocular pneumoplethysmorgraphy for the simultaneous determination of blood pressures in the ophthalmic artery branches of the internal carotid arteries is described. It provides a noninvasive, atraumatic method for assessing hemispheric blood flow. When performed with simultaneous carotid compression, it provides a means for assessing the availability of collateral blood flow to the ipsilateral cerebral hemisphere. Clinical applications related to carotid artery disease and carotid artery surgery are discussed.

[Methodical aspects of pneumatic segment plethysmography. II. The problem of cuff width and cuff-pressure]

Pneumatic segment-plethysmography was used to investiage the influence of different cuff-widths and cuff-pressures on arterial inflow to the calf. It was demonstrated that 1. using consistently 80 Torr for the small respectively 50 Torr for the wide cuff no significant difference for small suprapatellar thigh-circumferences was found. On the contrary for large suprapatellar thigh-circumferences there was a statistically significant difference of the arterial inflow; 2. using both cuffs for all thigh-circumferences, a confirmity of arterial inflow was found if a coupling-factor was individually calculated in each case from upper arm- and thigh-pressure; 3. the arterial inflow to the calf did not differ at pressures of 42 Torr and 50 Torr, whereas at 70 Torr arterial inflow was significantly diminished.

[A new apparatus for finger occlusion plethysmography. Disucssion of the method and diagnostic possibilities]

Based on the principles of an apparatus for the venous-occlusion plethysmography of the finger, which was developed by Goetz in 1934 and which was adapted for clinical usage by the authors of this article in 1971, a largely improved apparatus, which is also suitable for the usage in hospitals, is now presented. The various clinical methods of examination for the diagnosis of acrale bloodflow disturbances are discussed. Angioneuropathies (as for instance the Raynaud-syndrome) of diseases, which are connected with injuries of vessel-walls and stenosis resp. occlusion (M. Raynaud), can be differentiated with great certainty by means of the temperatures (15 degrees C and 32 degrees C), the quotient and the partial analysis of the volume-pulse form.

[Methodical aspects of pneumatic segment plethysmography. I. The problem of posture and distal venous occlusion]

Pneumatic segment-plethysmography was used to investigate the influence of the position and of distal venous occlusion on the arterial inflow to the calf and on the pressure-dependent venous capacity. It was demonstrated that (1) two of three investiaged positions have no significant influence on the arterial inflow to the calf; (2) the pressure-dependent venous capacities, however, show statistically significant differences related to position of the leg. The following reasons for these results were discussed: the varying tension of the surrounding tissue of the vessels, the basic volumes and the relation of intravenous pressure and the flexibility of the vessels. (3) It could be shown that the arterial inflow at rest measured without distal venous occlusion is significantly higher than the flow measured with distal venous occlusion. (4) On the contrary distal venous occlusion is of no importance in reactive hyperemia after 3 minutes of arterial obstruction. The arterial inflow to the following distal tissue was assumed to be the reason of these findings.

Ophthalmic arterial blood pressures measured by ocular plethysmodynamography

The indirect measurement of ophthalmic arterial blood pressure is an important index in the understanding of cerebral vacsular hemodynamics. Ophthalmodynamometry (ODM), the prototype for such measurement, is, however, replete with difficulties that have limited its widespread use. A preliminary evaluation of a new technique for ODM identified as ocular plethysmodynamography, has yielded accurate opthalmic blood pressure data without the attendant problems. Reproducible values for bilateral ophthalmic arterial pressure levels have been determined in 30 normal volunteers and the levels correlated to brachial arterial pressure levels. In a series of patients with arteriographically demonstrable carotid obstructive lesions, the preoperative and postoperative ophthalmic arterial blood pressure relationships exhibited excellent correlation with the roentgenographic and intraoperative data.

[A method of venous occlusion plethysmography for quantitative study of peripheral hemodynamics in cranio-cerebral trauma]

A method of quantitative investigation of the peripheral blood flow (in ml/100 cm3/min) involving the use of venous occlusion plethysmography is described. Mathematical procedures applied in processing the arterial in flow curves are adduced. Conditions attending an investigation of the blood flow in the forearm vessels are depicted. The expediency of a bilateral examination of the peripheral circulation and vascular resistance in a cerebro-cranial injury is shown, there being, as a rule, a considerable asymmetry between the sides.

Estimation of alveolar pressure during forced oscillation of the respiratory system

A method for obtaining a continuous estimate of alveolar pressure (PAlv) during periodic flow is described; it was developed to improve the precision of measurements of airway and respiratory tissue impedance using the improved resolution of relatively high-frequency (approximately 5 Hz) singlas. The respiratory system was modulated with a piston pump, and lung volume and the volume change due to compression and expansion of alveolar gas were measured plethysmorgraphically; these signals and an analog divider were used to obtain a continuous solution of Boyle's law during flow. The plethysmorgraph was of the "flow" type; with it volume changes at frequencies up to 10 Hz and with rates of change up to 6 l/s were measured without amplitude or phase distortion. The method permits control of frequency and flow amplitude during PAlv measurement and calibration of PAlv in the absence of an active chest wall. However, it is technically complex.

Skin blood pressure in the forehead in patients with internal carotid lesions

The skin blood pressure was measured in the forehead using a photoelectric method in 12 subjects with occlusion and 16 subjects with arteriosclerotic stenosis of the internal carotid artery and compared to 18 normal subjects. The skin blood pressure was in average 37 mm Hg (SD 15) in the patients with occlusion, 44 mm Hg (SD 16) in the patients with stenosis, and 46 mm Hg (SD 10) in the normal subjects. During interruption of the blood supply from the external carotid artery (manual compression of the ipsilateral superficial temporal artery), the skin blood pressure was reduced in average 14 mm Hg in the patients with internal carotid occlusion, 8 mm Hg in the patients with stenosis, and not at all in the normal subjects. Skin blood pressure measured on the arm was in all groups 10 to 20 mm Hg higher than the diastolic arm blood pressure. It is emphasized that this method, as well as other methods using extracerebral registration in an attempt to evaluate the intracerebral arteries, is interesting from a hemodynamic point of view, but is of less diagnostic value in the single patient when compared to the arteriographical investigation.