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PubMed1993

Doppler velocimetry study of maternal hemodynamics and fetal vascular pattern in a case of chronic hypertension with superimposed severe preeclampsia and impending fetal death.

A case is presented of chronic hypertension with superimposed severe preeclampsia; absence of end-diastolic velocity in the umbilical artery had been noted at gestational age of 20 weeks. Because the fetus was previable, the mother was treated with pharmacotherapy according to the maternal hemodynamics; uteroplacental circulation and fetal vascular blood flow were monitored by Doppler velocimetry. Deterioration of the fetal condition occurred during crossover of maternal hemodynamics from a low-resistance to a high-resistance state. Serial Doppler velocimetry studies done within 40 minutes of fetal death are described. There were two types of absent end-diastolic velocity in the umbilical artery, and the pathophysiology and clinical management may be quite a different in these two situations.

Adult↗
PubMed1993

Effects of skin blood flow and temperature on bioelectric impedance after exercise.

To examine the effects of increased skin blood flow (BFsk) and skin temperature (Tsk) on bioelectric impedance (BIA), 30 young males participated as subjects. All subjects underwent the following measurements: 1) BFsk and Tsk for the chest, biceps, thigh, and calf; 2) body composition using the BIA prediction equations and underwater weighting (UW); and 3) triceps skinfold (SFtri) thickness. After the baseline studies (M1) the subjects exercised for 30 min at approximately 83% of maximal heart rate. The above measurements were repeated immediately after exercise (M2), and at 1-h recovery from exercise (M3). Repeated measures ANOVA showed that mean Tsk and BFsk, and for the four measured sites were significantly increased from M1 to M2 (P < 0.05) and decreased from M2 to M3 (P < 0.05). These changes did not affect BIA measurement for resistance (R) and reactance between M1 and M2 (P > 0.05), and between M2 and M3 (P > 0.05). With regression analysis the following independent variables were identified as strong contributing factors for predicting fat-free mass (FFM): 1) SFtri and total body water for M1 and M3; and 2) WT, SFtri, and Tsk of the chest for M2. Two FFM equations have little multicolinearity (M1 and M2), e.g., they have low root mean square errors (< or = 2.6 kg), very high values for R2 (> or = 0.94), and relatively low values for coefficient of variations (< or = 5.65%). Differences (P < 0.05) were observed between the UW method and the Lukasi equation for estimating FFM for M1 and M3, but not for M2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Biological zero of laser Doppler fluxmetry: microcirculatory correlates in the hamster cheek pouch during flow and no flow conditions.

The microcirculation of the hamster cheek pouch was visualized by the intravenous injection of FITC-dextran 150,000 during normal flow conditions and when flow was interrupted by clamping proximal to the pouch. Laser Doppler fluxmetry (LDF) was used to evaluate flow during control, 30 min of occlusion and after reperfusion. Intravital video recordings of the microcirculation during occlusion show that blood moves between the different arteriolar segments after occlusion and during the whole period of no flow. This motion was oscillatory in nature, had maximum velocity of order of 30 microns sec-1, and was related to progressive decrease of arteriolar diameter. The LDF output was in the range of 60-100 AU during control. This value fell in the range of 5-25 +/- 15% AU during occlusion and was assumed to constitute the biological zero for this system. The variability of the LDF signals was characterized by the autoregressive modeling power spectrum technique. The power spectra during control, occlusion, and reperfusion were similar, suggesting that motion of blood not related to perfusion or blood flow is present in all conditions. These findings suggest that the biological zero arises from signals that are not flow related and that it should be subtracted from the flow signal.

Animals↗
PubMed1993

[Doppler microprobe allows evaluation of local coronary circulation].

The local coronary flow in 42 patients (mean age: 59 +/- 9 years) with ischemic heart disease was assessed by means of an 0.018" intracoronary Doppler guidewire. Study population was divided into two groups: group I--"normal vessels" (diameter stenosis < 30%) and group II--"stenosis vessels" (diameter stenosis > 60%). Measurements of: averaged peak velocity (APV), diastolic-systolic velocity ratio (DSVR) were performed in proximal segments of normal vessels and proximally to stenosis in group II. APV and DSVR were recorded at rest (bas) and during papaverine induced hyperemia. Coronary flow reserve (CFR) was calculated as ratio hyperemic and resting values of APV. Mean value of APV at rest was highest for left main stem, lowest for venous by-passes (SVBG) but did not differ among three coronary arteries (LAD, LCX, RCA). CFR value was significantly higher for group I then for group II (2.75-3.3 vs 1.8-2.0) but did not differ significantly among particular arteries in both groups. Mean value of DSVRbas in both examined groups was lowest for right coronary artery and for SVBG (ca. 1.0) and did not change significantly during hyperemia. This value was significantly higher (ca. 2.0) for left coronary arteries (LAD, LCX) then for RCA and SVBG and significantly decreased after administration of papaverine.

Aged↗
PubMed1993

[Doppler microprobe for evaluation of coronary circulation after successful coronary angioplasty].

The influence of angiographically successful coronary angioplasty (PTCA) in 27 patients (mean age 64 +/- 8 years) was assessed by means of 0.018" intracoronary Doppler guidewire. Averaged peak flow velocity (APV) and diastolic-systolic velocity ratio (DSVR) were recorded in resting conditions (bas) and during papaverine induced hyperemia before and after PTCA. Coronary flow reserve (CFR) was calculated as ratio of hyperemic and resting APV. The parameters mentioned above were estimated proximally and distally to coronary stenosis to be dilated. Mean value of APVbas for distal part of the vessels was significantly lower (about 46-57%) then for the two proximal segments. PTCA caused significant increase of APVbas as for proximal (about 21-69%) as for distal segments (about 62-77%). That procedure caused significant increase of CFR only for right coronary artery (RCA). Mean values of DSVRbas in proximal position for left descendens (LAD) and left circumflex (LCx) arteries before PTCA were significantly higher than DSVbas for distal position but did not differ for RCA. PTCA caused significant increase of DSVRbas in distal position only for LAD and LCx. Our results showed that angiographically successful PTCA causes significant increase of APVbas for right and left coronary arteries and normalization of DSVRbas in distal segments of LAD and LCx.

Adult↗
PubMed1993

[Oxygenation of the dermis and subcutis in dermatoliposclerosis].

Chronic venous insufficiency (CVI) leads to morphological and functional changes in nutritive capillaries resulting in disturbances of the nutrition of the skin. Up to now, data obtained from transcutaneous measured pO2 were taken as an indication for a decreased oxygen supply to the skin. With the aim of obtaining direct information on the tissue oxygenation of dermis and subcutis we have measured the distribution of tissue pO2 values with needle probes (300 microns tip diameter, Eppendorf-Netheler-Hinz-GmbH, Hamburg). 12 patients with CVI III and 8 healthy volunteers were included in this study. The needle probes were inserted into the skin of the proximal third of the lower leg and, in patients, in the areas with mild and with severe sclerosis (ulcer edge). The pO2 data from the needle probes were compared with pO2 data obtained from transcutaneous surface probes (tcpO2) and with data from laser doppler flux measurements LDF). In clinically healthy skin the intracutaneously measured pO2 (icpO2) was 51 +/- 7 mmHg (mean +/- S.D.) and the subcutaneously measured pO2 (scpO2) was 47 +/- 8 mmHg. In lipodermatosclerosis invasively determined pO2-values were lower than in healthy skin, however, no hypoxic or anoxic values were found. Compared with tcpO2-values there was no considerable difference between icpO2-values measured in mild sclerosis and severe sclerosis (icpO2 28 mmHg as compared to 25 mmHg; scpO2 31 mmHg as compared to 27 mmHg). The icpO2 values obtained from the edge of the ulcer showed a large variation from patient to patient (6 mmHg to 42 mmHg). There was no correlation between the pO2 data and the LDF-values.

Aged↗
PubMed1993

Postocclusive reactive hyperemia and postural vasoconstriction in different kinds of leg ulcers--investigations with laser Doppler.

Laser-Doppler fluxmetry was performed in 42 patients with leg ulcers (18 venous, 8 arterial, 12 diabetic-arteriolar and 4 mixed arterio-venous) and in 9 healthy controls. Using a bipolar probe measurement was carried out at the ulcer border and on the dorsum of the foot in the supine and in the sitting position. Reactive hyperemia after three minute arterial occlusion was produced in both body-positions. In every ulcer-group resting and peak fluxes showed a statistically significant increase in the ulcer region as compared to normal skin of the lower leg in the control group, the quotient between peak and resting flux ("reactive hyperemia index" RHI) being significantly lower. The RHI values for four ulcer-patients with a dramatic deterioration worsening eight months later were close to one, while the unchanged and improved cases showed median values above 1,2. Sitting up was followed by a decrease of flux in all ulcer-groups as well as in the control group. On the dorsum of the foot there was an increase of the laser Doppler flux in patients with arterial occlusive disease, i.e. in the group with arterial and mixed ulcers. This study shows that the kind of microcirculatory flow damage is not different in various causes of ulcerations. The reduced reactive hyperemic response compared to the increased resting fluxes (amount of RHI-decrease) might be a useful predictor for healing or non-healing of the ulcer.

Adult↗
PubMed1993

[Experimental research on choroidal circulation. 1. Effect of sectioning or stimulation of the cervical sympathetic nerve upon choroidal blood flow].

Choroidal blood flow (CBF) was continuously measured with a laser doppler flowmeter (LDF) in 32 pentobarbital-anesthetized cats. A rise in intraocular pressure (IOP) caused a decrease in CBF, but when the IOP increase was slight, it induced a CBF increase. A sustained increase of CBF occurred following sectioning of the cervical sympathetic nerve (CSN) in 7 out of 18 eyes, but no noticeable blood flow change was observed in the remaining 11 eyes. Two different vasomotor responses in CBF were observed in response to electrical stimulation of the peripheral cut end of the CSN; one was a decrease and the other an increase. From the present experiments, decrease of CBF elicited by CSN stimulation is considered to be due to an increase in the activity in vasoconstrictor fibers of choroidal capillary blood vessels, but the exact mechanism of the CBF increase is unknown. Slight changes in position of the LDF probe sometimes alter the vasoresponses, suggesting that the site at which CBF was measured is crucial for investigating the effects of dissection or electrical stimulation of the CSN on CBF.

Animals↗
PubMed1993

[An apparatus using laser speckle phenomenon for noninvasive 2-dimensional analysis of microcirculation in the optic nerve head].

A new instrument using the laser speckle phenomenon for noninvasive 2-dimensional analysis of the microcirculation in the optic nerve head (ONH) was developed. The ONH was illuminated with a diode laser spot and its image speckle was detected by an area array sensor. The difference between a pair of output data for successive scannings of the image speckles at the sensor plane was calculated and integrated for each pixel to obtain the average difference (AD), which is a quantitative index of blood speed. The results were displayed in color graphics showing the 2-dimensional variation of the AD level in the area of interest. The AD had good correlation with the speed of ground glass in a range between 0 and 8 mm/sec. Using this instrument, the effect of intraocular pressure (IOP) on the circulation in the area of the rabbit ONH free from surface vessels was studied. The coefficient of reproducibility was 4.7% when measured in this area twice at 5-minute intervals. A stepwise reduction in the ocular perfusion pressure (OPP) was introduced by elevating the IOP manometrically. The AD was little affected by OPP change when OPP was above 40 mmHg, but with the OPP below 40 mmHg, a linear correlation was found between the AD and OPP.

Animals↗
PubMed1993

[An apparatus using laser speckle phenomenon for noninvasive 2-dimensional analysis of choroidal microcirculation].

A new instrument using the laser speckle phenomenon for noninvasive 2-dimensional analysis of the choroidal microcirculation was developed. The fundus was illuminated with a diode laser spot and its image speckle was detected with an area sensor. The difference between the average of the output data (I-mean) and the output data from successive scannings of the image speckles at the sensor plane was calculated and integrated to give as D-mean, and I-mean/D-mean was defined as normalized blur (NB), which is a quantitative index of blood flow velocity. The results were displayed in color graphics showing the 2-dimensional variation of the NB level in the area of interest. The NB had good correlation with the speed measured on ground glass in the range between 2 and 130mm/sec. Using this instrument, the effect of intraocular pressure on the chroidal circulation of the rabbit was studied. The coefficient of reproducibility was 6.9% when measured in the same area twice at 5-minute intervals. A stepwise reduction in the ocular perfusion pressure was introduced by elevating the intraocular pressure manometrically. A linear correlation was found between the NB and the ocular perfusion pressure.

Animals↗
PubMed1993

Effects of topical isoproterenol on bile acid-induced gastric mucosal injury.

Topical isoproterenol protects the gastric mucosa from the severe necrosis induced by 100 per cent ethanol. Its effect on gastric mucosal blood flow is unknown. The purpose of this study was to determine the effect of topical isoproterenol on gastric mucosal blood flow and on the less severe gastric mucosal injury caused by dilute bile acid. Prior to injury with topical 5 mM acidified taurocholate (pH 1.2), stomachs were pretreated with either saline or isoproterenol (low dose = 50 micrograms/kg; high dose = 500 micrograms/kg). Mucosal injury was assessed by measuring net transmucosal ion fluxes (H, K) and the appearance of DNA into the gastric lumen (DNAE). Gastric mucosal blood flow was determined by using laser doppler. Pretreatment with isoproterenol significantly decreased bile acid-induced net transmucosal ion fluxes and luminal accumulation of DNA, suggesting mucosal protection. Furthermore, this effect was dose-dependent on H and DNAE but not K. Pretreatment with topical high dose isoproterenol had no significant effect on gastric mucosal blood flow. Thus, topical pretreatment with isoproterenol dose dependently protects the gastric mucosa from the superficial injury caused by the application of dilute bile acid. This protective effect appears to be mediated by a mechanism other than augmentation of gastric mucosal blood flow.

Administration, Topical↗
PubMed1993

Soft tissue reconstruction. Monitoring.

Despite recent advances in technology, no safe and completely reliable monitoring device is available for clinical use. As a result, direct clinical evaluation remains the mainstay of post-operative monitoring efforts. Although we have found this technique to be reliable, we tend to supplement it with Doppler ultrasonography, particularly in those patients in whom the flap remains buried beneath the skin. In patients with replants, we use pulse oximetry as an adjunct to clinical findings. This has proved to be reliable in our experience. However, should any question arise concerning altered tissue perfusion, we remain liberal in our indications for reexploration. The old adage of "better safe than sorry" certainly applies, for it is much easier to reexplore a flap than to lose a potentially salvageable reconstruction. The future remains promising for techniques such as laser Doppler study and various methods of measuring transcutaneous oxygen. However, further experimental and clinical trials are necessary to determine the efficacy of these methods.

Blood Gas Monitoring, Transcutaneous↗
PubMedDate not supplied

[Measurement of cutaneous blood flow by laser Doppler velocimetry. Importance of probe effect and solvent effect after topical application].

A comparative methodological study of the probe and/or vehicle effects was performed in Human volunteers with two laser Doppler velocimeters (L.D.V.): Laserflo BPM 403, T.S.I., U.S.A. and Periflux PF2B, Perimed, Sweden. Individual variations of skin blood flow are great (up to 1,400%); this could be related to spontaneous variations and/or to the occlusive effect of the probe. Skin blood flow was significantly increased in 35% of the subjects after the application of the probe alone, and in 70 to 90% of the cases after topical application of water or ethanol (20 to 50 microliters). Lag times before vasodilatation measured only when the probe was applied on the skin were between 7.4 and 27 minutes, they were reduced between 5.2 and 8.3 minutes when the vehicles were applied. These data suggest that in any protocol for L.D.V. determination an absolute control and a vehicle control should be included to evaluate objectively topical vasoactive drugs.

Administration, Topical↗
PubMed1993

Effects of oxygen and carbon dioxide on human retinal circulation.

PURPOSE: Carbogen, a gas mixture of 95% O2 and 5% CO2, is given to patients with retinal artery obstruction in an attempt to improve retinal oxygenation. The purpose of this study was to compare the effects of carbogen and 100% O2 breathing on retinal blood flow. METHODS: On two separate occasions, 12 normal, healthy volunteers breathed air and then either 100% O2 or carbogen while laser Doppler velocimetry measurements and monochromatic fundus photographs were taken. Retinal vessel diameter, maximum velocity of red blood cells, and volumetric blood flow rate were determined in a main temporal vein. RESULTS: Both 100% O2 and carbogen caused significant average reductions in vessel diameter (14.1% and 10.6%, respectively), maximum red blood cell velocity (42.1% and 27.3%, respectively), and blood flow (56.4% and 42.2%, respectively). The average vasoconstriction of the large retinal veins caused by carbogen was not significantly smaller than that caused by 100% O2. The average reductions in maximum red blood cell velocity and blood flow caused by carbogen were significantly smaller than those caused by 100% O2 (P < .001 and P < .01, respectively). CONCLUSIONS: In normal subjects, inhalation of carbogen leads to less reduction in blood flow than inhalation of 100% O2, presumably by reducing the vasoconstriction of small arterioles induced by elevated oxygen levels.

Adult↗
PubMedDate not supplied

[Instrumental research of the functional character of the skin adnexa and microcirculation during chronic venous insufficiency].

We have led a microcirculatory and functional research of skin adnexa over 3 groups of 20 people each, who were affected with IVC at different grades and we have compared them to another group of 20 normal people. The microcirculatory researches (laser-Doppler, skin oximetry and thermometry) and functional ones of skin adnexa (sebometry and skin hydration) allowed us to get a nonunivocal behaviour between normal subjects and phlebopathies of I degree. For this reason, it is possible to consider these exams as screenings tests to determine the starting phases of phlebopathy, failing any skin marks. The reduced fluximetrical response taken by laser Doppler after postural variation and the reduction of hydration degree have been considered particularly significant.

Blood Gas Monitoring, Transcutaneous↗
PubMed1993

Sequential measurements of cerebral blood flow in the acute phase of subarachnoid hemorrhage.

Cerebral blood flow (CBF) measurements were made at predetermined intervals over the first 20 days after a subarachnoid hemorrhage (SAH) by the method of 133Xe inhalation clearance in 39 patients, Hunt and Hess degrees I, II or III. Mean hemispheral and regional blood flow showed a similar pattern of behavior over time: namely an initial hypoperfusion, being more marked in patients with consistent or thick blood deposition at CT scanning, followed by transient improvement and subsequent deterioration in the second week, this being especially conspicuous in patients who developed vasospasm; deterioration, at any rate, was distributed widely regardless of the initial CBF readings or magnitude of bleeding. Patients developing later neurological deficit (23% of the total) were those who showed a statistically significant increase of hemispheric asymmetries and regional hypoperfusion at the time when deterioration occurred. Accordingly, the Author calls attention to the practical value of CBF measurements in SAH patients, in view of the relationships that obtain between certain CBF patterns and the emergence of late neurologic deficits.

Acute Disease↗
PubMed1993

[Effect of hydralazine on the blood flow of normal and tumor tissues in hyperthermia].

We examined changes in blood flow in normal muscle and SCC-VII tumors of C 3 H/He mice following hyperthermia (HT) combined with the vasodilator hydralazine (Hyd) and compared them with similar changes after Hyd treatment or HT alone. Blood flow was measured by the Laser Doppler method, and oxygen tension was evaluated by polarography. The mean blood flow for the tumors in the Hyd group decreased. After HT treatment, it decreased to a low level. The largest decrease in tumor blood flow was observed after HT combined with Hyd administration. In normal muscle, no decrease in blood flow was induced by HT, Hyd or their combination. The magnitude of action of Hyd on the heat-induced changes in tumor blood flow and on damage to tumor vessels is considered to depend on the initial perfusion level. Therefore, we tried to clarify how this parameter was correlated with Hyd and/or HT-induced changes. In the HT and combined groups, the higher the temperature, the more significant the decrease in blood flow. In conclusion, these results suggest that the decrease in blood flow inside the tumor caused by Hyd plays an important role in enhancement of the hyperthermic anti-tumor effect.

Animals↗