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Biomedical subjects

A Fronek

Publications and source records attributed to A Fronek.

16 recordsLinked to original sources
PubMed1979

Quantitative transcutaneous arterial velocity measurements with Doppler flowmeters.

A controlled in vitro and in vivo comparative evaluation of four Doppler ultrasonic blood velocimeters was performed to evaluate their ability to measure fluid velocity throughout a wide range of flow rates and velocity profiles, during both steady and pulsatile flow. The instruments tested were the Versatone Bidirectional Doppler M-9, the Sonicaid BV380, the Parks 806 B, and the Delalande DUD 400. All instruments responded linearly to velocities of from 5 to 70 cm/s, and were accurate to within 5% through a wide range of in vitro changes in velocity, pulse frequency, and cross-sectional velocity profile. Quantitative velocity measurements and their derivatives are an inexpensive, simple, and useful tool in the evaluation conditions of patients with peripheral vascular disease, and widespread clinical trials of their value are appropriate at this time.

Animals↗
PubMed1979

Forearm arterial injuries.

The effects of single forearm arterial injuries with and without associated neurological injuries were studied. Fifty subjects were evaluated: seven patients with isolated arterial lacerations, 15 patients with isolated nerve lacerations, 13 patients with combined nerve and arterial injuries, and 15 control subjects. A series of noninvasive peripheral vascular studies were correlated with the symptoms produced by a controlled cold-environment exposure. The hemodynamic alterations associated with symptoms of hand ischemia, and particularly with cold intolerance, were studied. Unrepaired single arterial injuries caused modest, consistent alterations in hand vascularity, but few signs of ischemia or symptoms of cold intolerance. The remaining intact artery demonstrated a consistent increase in flow velocity. Combined nerve and artery injuries caused the most significant alterations in hand vascularity, and median nerve and associated artery injuries caused the most disabling symptoms. Single arterial lacerations had no effect on the rate or completeness of recovery from associated nerve injuries.

Arteries↗
PubMed1978

The importance of combined multisegmental pressure and Doppler flow velocity studies in the diagnosis of peripheral arterial occlusive disease.

The value of combined multisegmental pressures and quantitative Doppler flow velocity determinations in the preoperative vascular laboratory evaluation was analyzed in 100 consecutive patients with angiographically documented peripheral arterial occlusive disease. Several new observations were made: (1) erroneously normal or even high segmental pressure readings appear to be caused by increased arterial wall stiffness and may produce falsely elevated or erroneously normal pressure, suggesting less disease than exists, especially when only ankle pressure screening is used. (2) The addition of quantitative flow velocity determinations significantly improved the reliability of diagnostic decision making. The diagnosis of proximal arterial occlusive disease based on combined pressure-velocity measurements was confirmed angiographically in 143 of 148 limb studies (96.6%), including several with normal pressures and reduced velocity values--a pressure-velocity dissociation. (3) A decrease of the leg segment:arm pressure ratio combined with only a slight reduction of velocity indices suggests a stenosis with good local collateral flow and vessel patency at the site of measurement--a reversed pressure-velocity dissociation. (4) A decreased lower limb segment/arm pressure ratio combined with a significant reduction of velocity indices is evidence of arterial stenosis with poor local collateral flow. The combined multisegmental pressure and velocity evaluation of patients suspected of arterial occlusive disease substantially increases the reliability of noninvasive diagnosis and offers a new level of differential diagnostic interpretation.

Ankle↗
PubMed1977

A microscope-television system for studying flow velocity in human skin capillaries.

A noninvasive technique for studying blood flow dynamics in human skin capillaries is described. A light microscope combined with a closed-circuit TV system was used to monitor and record capillary blood flow velocity on video tape. Arterial pulsations were recorded plethysmographically and converted into video signals by modulating the position of a square, white area in the televised scene. Twelve healthy subjects were studied. The mean (+/- SD) resting capillary blood flow velocity was 0.65 +/- 0.3 mm/s at an average skin temperature of 30.4 +/- 2.3 degrees C. Spontaneous fluctuations at a frequency of 6-10 cycles/min were observed in most subjects. A well-pronounced flow pulsatile component could be demonstrated in all capillaries studied. The technique can be used in clinical practice for studying the physiology and pathophysiology of cutaneous microcirculation in man. It can be expected that the method may become an important diagnostic tool in diseases that involve disturbances of the microcirculation, such as diabetes, hypertension, and atherosclerosis.

Capillaries↗
PubMed1977

The pulse-reappearance time: an index of over-all blood flow impairment in the ischemic extremity.

A simple test is described to evaluate limb blood supply. The technique utilizes the delayed reappearance of the volume pulse after transient arterial occlusion. As monitored from the toe by a mercury-in rubber gauge, pulse reappearance (PRT) was instantaneous (less than one second) and the 50 percent of control amplitude reappearance time (PRT/2) was 3.4 +/- 0.8 seconds in 22 control subjects. A significant delay of the PRT and especially of PRT/2 was found in 60 patients with angiographically documented ischemic disease of the lower extremities. The delay was correlated closely with the severity of the disease: the mean PRT/2 for single level arterial disease (aortoiliac, femoropopliteal, posterior tibial, or anterior tibial artery obstruction) was approximately 25 seconds, and the mean PRT/2 associated with multilevel occlusion was 71 seconds. Since the technique is very simple, it may be used as a quick screening and follow-up procedure to detect the presence and over-all severity of peripheral arterial occlusive disease.

Arterial Occlusive Diseases↗
PubMed1976

Quantitative ultrasonographic studies of lower extremity flow velocities in health and disease.

Quantitative Doppler ultrasonographic flow velocity determinations are reported from 39 normal control subjects and 80 patients with angiographically documented peripheral arterial disease, in whom femoral, posterior tibial and dorsalis pedis arteries were studied. The mean control values of the most useful parameters were: femoral artery: peak forward velocity (PFV) cm/sec: 40.7 +/- 10.9, deceleration (Dec.) cm/sec2:250.9 +/- 60.0, peak/mean velocity (P/MV): 4.8 +/- 1.6; posterior tibial artery: PFV: 16.0 +/- 10.0, Dec.: 129.8 +/- 75.7, P/MV: 4.8 +/- 2.5; dorsalis pedis artery: PFV: 168 +/- 5.7, Dec.: 137.9 +/- 54.5, P/MV: 6.0 +/- 4.1. The values of these measurements in the patients with arterial occlusive disease were all significantly lower, and also permitted distinguishing those with multilevel disease from those with a single site of occlusion. Quantitative evaluation of the Doppler ultrasonogram permits obtaining detailed functional information on the degree of arterial flow impairment in patients with peripheral arterial occlusive disease.

Adult↗
PubMed1975

[Proceedings: The ankle arterial pressure during reactive hyperemia in healthy patients and patients with arterial occlusive disease].

In 8 healthy subjects and in 16 patients with arterial occlusions in the iliac or ilio-femoral region ankle blood pressure and blood flow velocity were measured by Doppler ultrasound during postocclusive reactive hyperemia. In the normal subjects the ankle blood pressure decreased significantly within the initial 30 sec after release of the occlusion. The pressure values showed a negative relation to the simultaneous increases in flow velocity (r = 0.67). In the patients the pressure decreased further and the reduction was prolonged with the protracted course of the reactive hyperemia.

Ankle↗
PubMed1975

Effects of carotid hypotension on aortic hemodynamics in the unanesthetized dog.

The effects of occlusion of the brachiocephalic artery on aortic hemodynamics were assessed in 12 chronically instrumented dogs in the unanesthetized state. Continuous measurements of ascending aorta pressure and flow were made. In the steady state following occlusion, heart rate increased by 36% and mean arterial pressure by 45%, while cardiac output was unchanged from preocclusion levels. Hydraulic power delivery to the systemic circulation by the left ventricle was increased during occlusion, while the fraction of total power associated with pulsations decreased. Values of peripheral resistance and ascending aorta input impedance were both increased during occlusion. Graded occlusions of the brachiocephalic artery produced graded, monotonic increases in the entire aortic impedance spectrum between 2 and 20 Hz with more sensitive responses occurring with the smaller, submaximal responses. Considered with results of previous studies, these results suggest that activation of smooth muscle in large conduit arteries is also associated with the pressor response which accompanies carotid hypotension and that such activation has a hemodynamically significant effect.

Animals↗