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Biomedical subjects

A Fronek

Publications and source records attributed to A Fronek.

At least 55 records · Page 3Linked to original sources
PubMed1986

Continuous-wave versus range-gated pulsed Doppler power frequency spectrum analysis in the detection of carotid arterial occlusive disease.

Two types of ultrasonic Doppler velocity metering devices currently used in the detection of extracranial carotid artery disease, the continuous-wave (CW) and the range-gated pulsed (RP) Doppler systems, were compared in the present study. Power frequency spectrum analysis (PFSA) was performed on 130 carotid arterial bifurcations with a CW Doppler and 81 carotid arteries with an RP Doppler system. All results were compared with angiographic findings. The frequency bandwidth at 50% peak power (f50%), a quantitative index for defining spectral broadening, detected stenoses equal to or greater than 50% diameter reduction with 93% sensitivity, 92% specificity, and 92% accuracy with the CW system. With the RP Doppler, the same degree of stenosis was identified with 94% sensitivity, 93% specificity, and 93% accuracy. Compared with angiographic classification into 0-24%, 25-49%, and 50-99% diameter reduction categories, CW Doppler PFSA and an 85% overall accuracy, and the RP Doppler overall accuracy was 86%. CW Doppler also correctly identified 15 of 16 internal carotid artery (ICA) occlusions; 8 of 8 ICA occlusions were correctly identified with the RP Doppler. Thus, both techniques detected carotid artery disease with comparable results. For research and ease of operation, an RP Doppler system with a variable sampling volume appears to be most desirable. However, a standard CW system is superior if utility and cost-effectiveness are of prime importance.

Arterial Occlusive Diseases↗
PubMed1985

Cutaneous postocclusive reactive hyperemia monitored by laser doppler flux metering and skin temperature.

The initial Laser Doppler Flux (LDF) values and skin temperature in the first, third, and fifth finger were evaluated as well as the postocclusion reactive hyperemia (PORH) response to a 4-min suprasystolic compression. The mean values varied from 276.5 to 335.3 mV while the skin temperature ranged from 32.5 to 34.2 degrees. The LDF-monitored PORH response was very reproducible with an average increase of 144.7 +/- 63.6 mV (from an initial LDF value of 327.1 +/- 134 mV). Four different time-related indices were analyzed: t/2recovery = 6.0 +/- 5.5 sec; trecovery (time to reach the initial value) = 16.7 +/- 11.5 sec; tmax (peak of overshoot) = 48.2 +/- 20.6 sec and t/2 overshoot (time to reach 50% of the tmax on the downslope) = 97.4 +/- 31.8 sec. The simultaneously monitored skin temperature changes lagged significantly behind the LDF changes probably due to the large heat capacitance of the tissue. It is expected that the described results obtained from 20 normal subjects will serve as a basis for future clinical studies involving skin perfusion disorders.

Adolescent↗
PubMed1985

Oxygen inhalation--induced transcutaneous PO2 changes as a predictor of amputation level.

Noninvasive transcutaneous PO2 (TcpO2) determinations have been developed to study peripheral arterial occlusive disease. To evaluate this technique as a predictor of amputation outcome, a blind, prospective study of 101 patients undergoing 119 amputations (23 above-knee [AK], 57 below-knee [BK], and 39 forefoot) was performed. TcpO2 measurements were obtained from the dorsum of the foot and 10 cm distal to the patella, both prior to and 10 minutes after inhalation of 100% oxygen. On the basis of preliminary results, initial TcpO2 values greater than 10 mm Hg or an increase greater than 10 mm Hg after oxygen inhalation were considered to predict a successful outcome, whereas failure was predicted when the initial TcpO2 value was less than 10 mm Hg and the increase after oxygen inhalation did not exceed the 10 mm Hg level. In the BK amputation group the test was 95% sensitive, 100% specific, and 95% accurate. Retrospective utilization of the above criteria in patients who had undergone both oxygen inhalation testing and AK amputation suggested that 9 of 17 limbs (53%) might have undergone a more distal BK amputation successfully. These results document the effectiveness of an initial TcpO2 determination coupled with the response to 100% oxygen inhalation as an excellent predictor of the outcome of lower extremity amputations.

Adult↗
PubMed1985

The prevalence of peripheral arterial disease in a defined population.

Because patients with peripheral arterial disease (PAD) may be asymptomatic or may present with atypical symptoms or findings, the true population prevalence of PAD is essentially unknown. We used four highly reliable, sophisticated noninvasive tests (segmental blood pressure, flow velocity by Doppler ultrasound, postocclusive reactive hyperemia, and pulse reappearance half-time) to assess the prevalence of large-vessel PAD and small-vessel PAD in an older (average age 66 years) defined population of 613 men and women. A total of 11.7% of the population had large-vessel PAD on noninvasive testing, and nearly half of those with large-vessel PAD also had small-vessel PAD (5.2%). An additional 16.0% of the population had isolated small-vessel PAD. Large-vessel PAD increased dramatically with age and was slightly more common in men and in subjects with hyperlipidemia. Isolated small-vessel PAD, by contrast, was essentially unrelated to sex, hyperlipidemia, or age, although it was somewhat less common before age 60. Intermittent claudication rates in this population were 2.2% in men and 1.7% in women, and abnormalities in femoral or posterior tibial pulse were present in 20.3% of men and 22.1% of women compared with the noninvasively assessed large-vessel PAD rate of 11.7%. Thus assessment of large-vessel PAD prevalence by intermittent claudication dramatically underestimated the true large-vessel PAD prevalence and assessment by peripheral pulse examination dramatically overestimated the true prevalence.

Adult↗
PubMed1985

The sensitivity, specificity, and predictive value of traditional clinical evaluation of peripheral arterial disease: results from noninvasive testing in a defined population.

In a companion article we have reported the prevalence, in an older, defined population, of traditional assessments (intermittent claudication and abnormal pulse examination) of peripheral arterial disease (PAD) as compared with the results of highly accurate noninvasive testing. In this article we report the sensitivity, specificity, and positive and negative predictive values for claudication and abnormal pulses for the diagnosis of large-vessel and small-vessel PAD as determined by noninvasive testing. Claudication and abnormal pulses were completely unrelated to isolated small-vessel PAD. In contrast, both claudication and abnormal pulses were significantly correlated with large-vessel PAD. Claudication and an abnormal femoral pulse showed a high specificity and positive predictive value but a low sensitivity for large-vessel PAD. Conversely, an abnormal dorsalis pedis pulse showed a good sensitivity but low specificity and positive predictive value. The best single discriminator was an abnormal posterior tibial pulse, which had high sensitivity, specificity, and positive predictive value. Various combinations of claudication and pulse abnormalities revealed a good sensitivity for broader criteria but at the expense of specificity, whereas stricter criteria had a good specificity and positive predictive value but a poor sensitivity. No combination was superior to an abnormal posterior tibial pulse alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Noninvasively diagnosed peripheral arterial disease as a predictor of mortality: results from a prospective study.

Intermittent claudication has been reported in previous studies to approximately double the risk of subsequent mortality. However, a history of claudication is often present in the absence of significant peripheral arterial disease (PAD) and absent in the presence of PAD. For this reason we evaluated the association between large-vessel and small-vessel PAD, measured by highly reliable and valid noninvasive tests, and mortality in 567 older subjects from a defined population followed-up for an average of 4 years. Large-vessel PAD was strongly and significantly predictive of all-cause mortality in both men and women with a relative risk of 4 to 5, and this finding was independent of other cardiovascular disease risk factors in multivariable analysis. In addition, this finding persisted after exclusion of subjects with extant cardiovascular disease at baseline. The associations of both claudication and abnormal peripheral pulses with mortality were weaker than the large-vessel PAD association. Isolated small-vessel PAD was unrelated to subsequent mortality. These findings suggest older subjects of both sexes at a high risk of impending mortality can be identified through noninvasive testing for large-vessel PAD.

Adult↗
PubMed1985

An objective sequential compression test to evaluate the patency of the radial and ulnar arteries.

The effect of sequential compression of the radial and ulnar artery on finger pulse volume oscillations was recorded by photoplethysmography. The effect of the compression was studied in 25 control subjects and 15 patients with angiographically documented obstructions of the radial or ulnar artery. Under normal conditions a reduction of oscillations by 35% was observed in the first, third, and fifth finger. On the other hand, an obstruction of the radial or ulnar artery results in a significant reduction or even disappearance of oscillations if the unobstructed artery is compressed. It is concluded that this test offers objective evaluation and documentation of the patency condition of the major arteries supplying the hand circulation.

Arterial Occlusive Diseases↗
PubMed1984

Impact of bioengineering on noninvasive diagnostics.

Out of a number of important methods used in laboratory angiology, only a limited group was selected to be discussed in this symposium. Phonoangiography is reviewed from the qualitative and quantitative viewpoint for its practical value and accessibility. Various aspects of pressure and volume detection of the eye pulse are discussed from the viewpoint of carotid artery disease and its noninvasive diagnosis, with special reference to oculoplethysmography as well as the Gee-pneumooculoplethysmography. Impedance plethysmography (IPG) is one of the controversial techniques used in laboratory angiology, with its main application currently in the area of diagnosis of venous obstructive disease. The dilemma of application of IPG in the diagnosis of arterial disease is discussed mainly from an engineering point of view. Spectral analysis will be covered in view of the fast emergence of Doppler Duplex scanning as the major diagnostic mode in extracranial carotid artery disease.

Auscultation↗
PubMed1982

Current status of noninvasive tests in the diagnosis of peripheral arterial disease.

In this review of the current status of the vascular laboratory, the major emphasis has been upon those tests that have become well-established and documented, including resting pressure, pulse volume measurements, velocity studies, and three stress measurements--exercise ankle pressure, postocclusive reactive hyperemia, and the toe pulse reappearance time. Additional technology that may have application to peripheral arterial disease includes photoplethysmography, transcutaneous oxygen tension, laser-Doppler velocimetry, fluorescein angiography, infrared thermography, and transcutaneous electromagnetic flowmetry. These techniques, which are currently in development and experimental trial, were not discussed but are likely to provide significant additional information. The future role of the vascular diagnostic laboratory in the area of peripheral arterial occlusive disease appears clear. It has already become a standard resource of the community hospital and tertiary referral center. Its functions will become more and more generally accepted with time as newly graduating physicians who have been exposed to this technology enter the practice of medicine. It should permit obtaining an evaluation of all patients at the expert level, aid in the education of all physicians concerned with peripheral arterial disease, and play an important part in guaranteeing a higher level of patient care than has heretofore been available.

Arterial Occlusive Diseases↗
PubMed1982

Transcutaneous PO2 measurements in health and peripheral arterial occlusive disease.

Transcutaneous oxygen tensions (tcPO2) of the lower extremity were investigated in 24 control subjects and in 69 patients with various degrees of peripheral arterial occlusive disease. With a modified Clark-type oxygen electrode, tcPO2 was monitored from the right subclavicular region (position 1), upper calf (position 2), and dorsum of the foot (position 3). The tcPO2 was significantly lower in patients when compared to control subjects. The reproducibility of the method was determined from double determinations of the tcPO2 (position 2) in control subjects. The comparison of tcPO2 value between the right and left lower extremity showed no significant differences. The tcPO2 of the foot or leg showed an increase, when positioning the limb below the phlebostatic level. The response of the tcPO2 after transient arterial occlusion (4 minutes) was significantly delayed in patients compared to control subjects. Finally, preliminary results of 35 patients in whom amputations had been performed suggest that tcPO2 measurement may become a useful prognosticator for the determination of the optimal amputation level.

Adult↗
PubMed1982

The response of blood flow velocity in finger nailfold capillaries to contralateral cooling.

The present study was performed in order to determine the effect of contralateral cooling on capillary blood flow velocity (CBV) in human nailfold capillaries during rest and postocclusive reactive hyperemia. The following reactions were found: Mean resting CBV (2 min) was slightly (19%) but not significantly (p greater than 0.05) decreased by cooling of the contralateral hand. However, immediately after the hand was submerged in the cold water (15 +/- 1 degree C) there was a short (3-10 S) but marked decrease of CBV. In 3 of 7 subjects CBV stopped completely for 5-10 S. No change of the skin temperature was seen during the contralateral cooling procedure. There was an increase in periodic and intermittent flow fluctuations of CBV during contralateral cooling, which was not noticed in the digital pulse amplitude (DAPA), indicating a reflex-mediated vasoconstriction at the microcirculatory level. The peak CBV during postocclusive reactive hyperemia (PRH) response was not influenced by contralateral cooling (1.01 +/- 0.57 mm/s before and 0.98 +/- 0.4 mm/s after cooling). However, because of the decrease in mean resting CBV during contralateral cooling, the percent increase in CBV during PRH increased from 66% to 104% by the cooling procedure (p greater than 0.05).

Adult↗
PubMed1981

The effect of sensing site on the limb segmental blood pressure determination.

The effect of the sensing site on upper-thigh blood pressure readings was studied. We used a multisensing mercury strain gauge (MSG) plethysmographic method and Doppler ultrasound to monitor the upper-thigh blood pressure from the posterior tibial artery and compared the results with those from the popliteal artery. Upper-thigh pressures were measured in 30 limbs of 15 normal subjects and in 60 limbs of 35 patients with multilevel peripheral arterial occlusive disease. Upper-thigh pressures sensed from a thigh MSG placed just distally to the pressure cuff and monitored by the popliteal artery Doppler probe were significantly higher than the upper-thigh pressure readings obtained from an MSG placed on the calf or toe and monitored by a posterior tibial artery Doppler probe in patients with multilevel arterial lesions. In the control group, no significant pressure differences were found. The importance of placing the sensor (MSG or Doppler probe) close to the pressure cuff is critical to obtain accurate thigh pressures in patients with multilevel arterial occlusive disease. Otherwise, erroneous diagnoses, such as nonexistent aortiliac or common femoral artery stenosis, may be made.

Adolescent↗
PubMed1981

Toe pulse reappearance time in prediction of aortofemoral bypass success.

The noninvasive vascular laboratory has a great potential to influence patient care if it can offer predictive information, which significantly adds to the clinical and angiographic assessment. To evaluate such preoperative data, 80 patients (143 symptomatic limbs) who underwent aortofemoral bypass were re-evaluated one to seven years following surgery. Preoperative vascular laboratory data (segmental pressure profile, quantitative Doppler velocity indices, postocclusive reactive hyperemia and toe pulse reappearance time [TPRT], following a four-minute cuff occlusion), angiography and clinical status were compared with the postoperative symptomatic result. Overall, 27% of the limbs were asymptomatic, 56% of the limbs markedly improved, 7% of the limbs remained unchanged or worse, and 10% of the patients died. Computer analyses of all preoperative data yielded several significant predictive indices, of which the most sensitive was the TPRT. With a TPRT of 0-10 seconds, all patients became either asymptomatic (63%) or markedly improved (37%). With increases in the TPRT, the results worsened, in stepwise fashion. Combinations of pressure and reactive hyperemic indices also permitted successful predictions in patients with multilevel disease. Such preoperative information can play a significant role in identifying the relative risks and benefits of surgery, and may significantly influence the decision for surgery in borderline situations.

Aorta, Abdominal↗
PubMed1981

Thigh pressure artifacts with noninvasive techniques in an experimental model.

In an experimental canine model of isolated and tandem arterial stenoses, noninvasive thigh and calf pressure measurements were evaluated against direct intra-arterial pressures. Under control circumstances, proximal iliac arterial stenosis, and high superficial femoral artery stenosis, the noninvasive measurements were highly accurate. However, when stenoses were created distal to the high pressure cuff, a significant error in the thigh pressure measurement was observed, with an underestimation of thigh pressure and subsequent false implication of a proximal lesion. Two tandem distal lesions produced a significantly more severe thigh measurement artifact. Further, the noninvasive system was incapable of detecting a moderately severe profunda stenosis, although stenoses of the iliac and femoral system were detected in a routine, accurate, and sensitive fashion.

Animals↗
PubMed1980

The peripheral pulse following arterial injury.

There has been little attention paid to the persistence of the pulse following complete forearm arterial transection, and we found no report that has established the etiology or frequency of this phenomenon. Eighteen patients with documented complete radial or ulnar artery transections were evaluated. Nine of the 18 patients had persistently palpable pulse distal to the transections. Seven of the pulses were due to retrograde flow and two were due to transmission from the proximal arterial stump or large collaterals. The Allen test was accurate in demonstrating arterial occlusion in each case. Digital compression of the intact artery eliminated the pulse in those cases due to retrograde flow. Documentation of flow direction and collateral vessels was performed with the Doppler directional velocity meter. The fallibility of the peripheral pulse following complete arterial injury is stressed. The Allen test, digital compression of the intact artery, and Doppler studies should be performed on patients with suspected arterial injuries. The exploration of all wounds in the region of major arteries from which profuse bleeding has occurred is recommended.

Arteries↗
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↗