Feature discovery and classification of Doppler umbilical artery blood flow velocity waveforms

Doppler umbilical artery blood flow velocity waveform measurements are used in perinatal surveillance for the evaluation of fetal condition. There is an ongoing debate on the predictive value of Doppler measurements concerning the critical effect of the selection of parameters for the interpretation of Doppler waveforms. In this paper, we describe how neural network methods can be used both to discover relevant classification features and subsequently to classify Doppler umbilical artery blood flow velocity waveforms. Results obtained from 199 normal and high risk patients' umbilical artery waveforms highlighted a classification concordance varying from 90 to 98% accuracy.     

Doppler flow velocity waveforms of human fetal ductus arteriosus and branch pulmonary artery.

Doppler waveforms of the human fetal ductus arteriosus and the branch pulmonary artery are distinct in their shape and might reflect fetal cardiovascular hemodynamics and vessel wall characteristics. The waveform of ductus arteriosus had two peaks, a higher one in systole and a lower one in diastole. Both peaks had slow acceleration and deceleration and looked like two narrow base isosceles triangles. This unique waveform might be due to vessel wall characteristics and an instantaneous pressure gradient between the main pulmonary artery and descending aorta. The waveform of the branch pulmonary artery showed very steep acceleration with the onset of ejection followed by steep decline, then low velocity flow during diastole. The characteristic shape of the branch pulmonary artery might be related to high vascular resistance, decreased capacitance and the earlier reflection wave of pulmonary vessels.     

Measurement of blood flow through AV-fistulae by means of Doppler sonography in regularly haemodialysed patients

In regularly dialyzed patients a variety of pathological events can negatively influence haemodynamics and blood flow through arterio-venous fistula, leading to inadequate blood flow through the dialyzer or disturbances in hemodynamics of the whole body. It therefore appears important to quantify flow velocity and volume flow through the arteriovenous fistula in such cases. We used a Vasoview computer controlled system for noninvasive vascular diagnostics based on B-scan "real-time" ultrasound for imaging the structure of tissue, combined with pulsed Doppler ultrasound for determination of hemodynamics. Thirty patients (16 males and 14 females, aged 45 +/- 10 years; range 23 to 61 years), with different periods spent on hemodialysis (5.5 +/- 3.1 years, range 1 to 11 years) were included in this study. The average systolic, diastolic and mean blood volume flows were 2131.8 +/- 565.8, 972.0 +/- 309.6 and 728.4 +/- 287.4 ml/min, respectively. The mean blood volume flow was calculated by integration of the area under curve of blood flow in one heart cycle on the Doppler signal. It is calculated by the apparatus and displayed on the screen during measurement. The average blood vessel diameter was 9.1 +/- 1.3 mm (mu +/- omega). The results revealed a marked inter-individual variation in volume flow through arteriovenous fistulae of dialyzed uremics (range 240.0 to 1200.0 ml/min). Doppler ultrasound thus appears to be a valuable method for determination of blood flow through arteriovenous fistula of dialyzed uremics as well as for detection of hemodynamics disturbances of interest, such as turbulent blood flow.     

兔急性颅内高压时,颅内压及血压对眼内压的影响

本文以颅内压、血压与眼内压之间的病理生理为基础,应用通经分析方法,分析实验兔急性颅内压增高时,眼内压上升的机理。结果提示急性颅内高压时,不仅颅内高压本身直接引起眼内压上升,同时,颅内高压所导致的血压增高亦可间接地促使眼内压上升。     

Similarity of fingertip skin blood flow patterns recorded by the model-based thermal clearance and large area laser Doppler probes.

We compared two different techniques for non-invasive registration of fingertip skin blood flow patterns in 15 healthy volunteers during a rest at room temperature 26-28 degrees C. The large area probes of a two-channel laser Doppler flowmeter (LDF) and an experimental probe of a thermal clearance (TC) instrument provided approximately the same sample volume of the studied tissue. The laser Doppler probes were attached to the pulp of the index (LDF1) and ring (LDF2) fingers, while the TC probe to the pulp of the middle finger. A computer simulation method, provided by the MATLAB package, was introduced to speed up the frequency response of the TC probe. By calculating the correlation coefficients and applying the least squares criterion, we evaluated the similarity of the 3-min samples having time resolution of 1 s. The group-averaged value of the correlation coefficient (median with a 99% confidence interval) for LDF2 versus LDF1 equalled 0.95 (0.92-0.97). After an introduction of the computer-based frequency correction, the correlation coefficient for TC versus LDF1 increased from 0.81 (0.61-0.85) till 0.92 (0.84-0.95), while the root mean squared error between TC and LDF1 diminished by 33% (p<0.001).     

彩色多普勒超声测定胎儿大脑中动脉血流速度与围产儿预后的相关性研究

目的探讨应用彩色多普勒超声测定孕晚期胎儿大脑中动脉（MCA）血流参数与围产儿预后的相关性。方法通过运用彩色多普勒超声测定晚孕期胎儿MCA血流速度,并对胎儿预后进行随访观察。结果异常组胎儿MCA—ED显著高于正常组胎儿、MCA—PI、MCA—RI、MCA—S／D均显著低于正常组胎儿;以MCA—ED大于其正常值2个标准差、MCA—PI〈1．4、MCA—RI〈0．6、MCA—S／D值〈4．0为血流异常,预测胎儿预后不良的敏感性及特异性分别为26．39％和97．33％、62．50％和56．00％、12．50％和98．67％、65．28％和52．00％。结论彩色多普勒超声测定胎儿大脑中动脉血速度对预测围产儿预后具有一定的临床价值。     

Methods of preventing vinorelbine-induced phlebitis: an experimental study in rabbits

Purpose: In order to identify methods for preventing phlebitis caused by intravenous administration of vinorelbine (VNR), we established a procedure for estimating the severity of phlebitis in an animal model.Methods: Four different factors (administration rate, dilution, flushing, and infusion of fat emulsion) were evaluated for alleviation of phlebitis caused by VNR infusion. VNR was diluted with normal saline to prepare test solutions with concentrations of 0.6 mg/mL or 0.3 mg/mL for infusion into the auricular veins of rabbits. Two days after VNR infusion, the veins were subjected to histopathological examination.Results: VNR did not cause obvious loss of venous endothelial cells, the most sensitive and common feature of phlebitis, but VNR infusion led to inflammatory cell infiltration, edema, and epidermal degeneration.Tissue damage was significantly decreased by shortening the administration time and by diluting the VNR solution for infusion from 0.6 mg/mL to 0.3 mg/mL. However, there was no effect of flushing with normal saline after VNR infusion, while treatment with fat emulsion before and after VNR infusion only had a minimal effect.Conclusion: Rapid infusion and dilution are effective methods of reducing phlebitis caused by the infusion of VNR, but the efficacy of flushing with normal saline or infusion of fat emulsion was not confirmed.     

Basilar artery blood flow velocity and the ventilatory response to acute hypoxia in mountaineers

Hypoxic ventilatory response is higher in successful extreme-altitude climbers than in controls. We hypothesized that these climbers have lower brainstem blood flow secondary to hypoxia which may possibly cause retention of medullary CO(2) and greater ventilatory drive. Using transcranial Doppler, basilar artery blood flow velocity (Vba) was measured at sea level in 7 extreme-altitude climbers and 10 controls in response to 10 min sequential exposures to inspired oxygen fractions (FI(O(2))) of 0.21 (baseline), 0.13, 0.11, 0.10, 0.09, 0.08 and 0.07. Sa(O(2)) was higher in climbers at FI(O(2)) of 0.11 (P<0.05), 0.08 and 0.07 (both P<0.0001). Expired ventilation (VE) increased more (n.s.), and PET(CO(2)) decreased more (n.s.) in the climbers than in controls. Vba did not significantly change in both groups at FI(O(2)) of 0.13-0.09. At FI(O(2)) of 0.08 and 0.07, Vba decreased 21% (P<0.03) and 27% (P<0.01), respectively, in climbers, and increased 29% (P<0.01) and 27% (P<0.01), respectively, in controls. The conflicting effects of hypoxia and hypocapnia on both medullary blood flow and ventilatory drive thus balance out, giving climbers a greater drive and higher Sa(O(2)), despite lower PET(CO(2)) and lower brain stem blood flow.     

Laser Doppler flowmetry and bone blood flow in an isolated perfused preparation

A preparation of an isolated bovine forefoot was established which could be perfused with blood at variable rates. A laser Doppler flowmeter probe inserted into the cancellous bone of the metatarsal produced a signal which varied with changes in perfusion rate and oscillated in synchrony with the peristaltic perfusion pump. A stronger laser Doppler signal was obtained when the probe was inserted into a drill hole than when inserted into a hole bored with a guide wire. It appears that laser Doppler flowmetry has potential intraoperative use when the viability of bone is in question.     

Haemodynamic changes in IUGR fetus with chronic hypoxia evaluated by fetal heart-rate monitoring and Doppler measurement of blood flow velocity

The measurement of fetal blood flow velocity and 24 h monitoring of fetal heart-rate (FHR) using a computer were performed to clarify the haemodynamics of growth-retarded fetuses with chronic hypoxia. One hundred normal-growth and 18 growth-retarded fetuses were analysed. All the growth-retarded fetuses with chronic hypoxia were characterised by abnormal blood flow velocity waveforms (with the pulsatility index in the descending aorta below the −1·0 SD and in the middle cerebral artery above the +1·0 SD for our reference range, from 100 normal-growth fetuses). In the latter, the incidence of accelerations of defined size and variability in FHR patterns showed a diurnal variation after 30 weeks' gestation. The initial change in FHR patterns during hypoxia in 11 growth-retarded fetuses, resulting in fetal distress, was a derangement of diurnal variations in FHR patterns, followed by a decrease in variability. A rapid increase in blood flow velocity in the middle cerebral artery with the advance of hypoxia was observed before the onset of distress. Maternal low-dose oxygen inhalation elicited a temporary increase in FHR variability in the growth-retarded but not in normal fetuses. Re-inhalation after 1 h elicited a similar change, suggesting that intermittent rather than continuous, oxygen inhalation may be more effective.     

Enzyme histochemical reactions at the demarcation line in frostbite: an experimental study on rabbits.

Eleven frostbites were induced on the ears of seven New Zealand White rabbits and specimens were taken from the lesion after 1, 4 and 8 hours, and from ten further frostbites on the ears of six rabbits for examination 1, 3 and 7 days later. The specimens were taken at the border between the frozen and non-frozen skin. NADH-diaphorase, alkaline phosphatase and esterase were demonstrated histochemically in the sample, which was also studied by haematoxylin and eosin staining. Five ears served as controls. Some granulocytes could be seen accumulating in the vessels and in the dermis at the border of the frostbite area after only 1 hour, and other enzyme rich cells (macrophages) also began to appear. After 4 hours the inflammation was quite obvious with the enzyme reactions clearly observable in the sections. After 8 hours there was no marked difference compared with the 4-hour picture. It was only after 3 days that the line of demarcation between the normal and frostbite tissue could be seen clearly. This was oblique in some specimens and vertical in others. The degeneration in the lesion could best be demonstrated by the NADH-diaphorase and esterase reactions and the early inflammation by the alkaline phosphatase reaction.     

Relationship of blood pressure and pump flow in an implantable centrifugal blood pump during hypertension

The purpose of this study was to evaluate the real time relationship between pump flow and pump differential pressure (D-P) during experimentally induced hypertension (HT). Two calves (80 and 68 kg) were implanted with the EVA-HEART centrifugal blood pump (SunMedical Technology Research Corp., Nagano, Japan) under general anesthesia. Blood pressure (BP) in diastole was increased to 100 mm Hg by norepinephrine to simulate HT. Pump flow, D-P, ECG, and BP were measured at pump speeds of 1,800, 2,100, and 2,300 rpm. All data were separated into systole and diastole, and pump flow during HT was compared with normotensive (NT) conditions at respective pump speeds. Diastolic BP was increased to 99.3+/-4.1 mm Hg from 66.5+/-4.4 mm Hg (p<0.01). D-P in systole was under 40 mm Hg (range of change was 10 to 40 mm Hg) even during HT. During NT, the average systolic pump flow volume was 60% of the total pump flow. However, during HT, the average systolic pump flow was 100% of total pump flow volume, although the pump flow volume in systole during HT decreased (33.1+/-5.7 vs. 25.9+/-4.0 ml/systole, p<0.01). In diastole, the average flow volume through the pump was 19.6+/-6.9 ml/diastole during NT and -2.2+/-11.1 ml/diastole during HT (p<0.01). The change in pump flow volume due to HT, in diastole, was greater than the change in pump flow in systole at each pump speed (p<0.001). This study suggests that the decrease of mean pump flow during HT is mainly due to the decrease of the diastolic pump flow and, to a much lesser degree, systolic pump flow.     

Role of the periosteal flap in chondrocyte transplantation: an experimental study in rabbits

To determine the role of the periosteal flap in chondrocyte transplantation for the treatment of articular cartilage defects, a cartilage defect was created on the patellar groove of the rabbit knee. The defect was filled with chondrocytes cultured in collagen gel, and was covered with a periosteal flap the cambial layer of which was facing the patella (P group), or facing down against the bone marrow (M group). The same defect was covered with a periosteal flap that was frozen and thawed three times (F group), and an artificial collagen film (C group). At 3 and 6 months, the defects were filled with reparative tissues that showed a smooth surface and resembled hyaline cartilage in the P, M, and F groups. There were no significant differences between the reparative tissues in the three groups histologically, immunohistochemically, biochemically, and biomechanically, although the collagen film fell down into the defect and the reparative tissue had a fibrous tissue-like appearance. These results showed that the periosteal flap does not have a beneficial humoral or cellular effect on the formation of reparative tissue, suggesting that the periosteal flap might act as a mechanical barrier to prevent leakage of grafted chondrocytes.     

Distribution of cardiac output and nutritional blood flow in the unanesthetized rat: alterations during experimental renal hypertension

Summary Fractional distribution of⁸⁶Rb injected intravenously was used to determine the distribution of cardiac output in unanesthetized, unrestrained rats. Renal hypertension was induced by two different methods: severe hypertension was produced by bilateral clamping of the renal arteries (Goldblatt hypertension) and moderate hypertension by kidney encapsulation with collodion followed by contralateral nephrectomy. The distribution of cardiac output was determined 5 or 10 weeks after the production of hypertension. In Goldblatt hypertensive rats the pattern of distribution was very similar after 5 or 10 weeks. On the average fractions of cardiac output were increased by 70% in heart and aorta, by 60% in the colon, by 20–30% in bronchial arteries. A 20–30% reduction was observed in the skin and a 10–20% in the liver. In collodion hypertensive rats similar directional changes were observed but they were of smaller importance. In hypertensive animals the relative enhancement of myocardial blood flow, which reflects the enlarged nutritional demand of the heart, was partly due to cardiac hypertrophy. Nevertheless, the fraction of cardiac output received by 1g of myocardium was increased by 25%. The pattern of redistribution of blood flow indicates that changes in peripheral resistances induced by hypertension are of unequal importance in the different regional beds.The investigation was supported by grants of the Institut National de la Santé et de la Recherche Médicale (No. 7111799).