Validation of a new transit time ultrasound flowmeter for measuring blood flow in colonic mesenteric arteries

OBJECTIVE: To validate a transit time ultrasound flowmeter (CardioMed CM 4000) for measuring blood flow in isolated colonic mesenteric arteries. DESIGN: Experimental and clinical study. SETTING: Teaching hospital, Denmark. ANIMALS AND SUBJECTS: One female pig, and 6 patients being operated on for carcinoma of the sigmoid colon and rectum. INTERVENTIONS: Volume blood flow measured by Cardiomed CM 4000 and pump withdrawal flow recordings. MAIN OUTCOME MEASURES: Correlation between the two methods. RESULTS: There was good agreement between transit time flow recordings and pump withdrawal flow recordings (correlation coefficient of 1.0). Of the differences between the two methods, 95% were between -0.16 ml min(-1) and 1.29 ml min(-1), mean 0.57 ml min(-1), or (in percentages) 105, 95% lying between 97-115. There was also good reproducibility in transit time flow recordings, the mean difference between repeated measurements being 0.06 ml min(-1), 95% lying between -0.66 ml min(-1) and 0.78 ml min(-1). CONCLUSION: Ultrasound transit time flow recordings gave precise measurements of blood flow in isolated colonic mesenteric arteries.     

Intravascular measurements of the blood flow in rats

The blood flow velocity in aorta was measured in rats with intravascular probes. Ultrasonic probes was fixed at the end of polyethylene tubing 0.6 mm in diameter. Miniature piezoelectric crystal worked on 33 MHz frequency. Simultaneously cardiac output were measured with cuff probes placed on ascending aorta. Correlative coefficient between them was 0.96 in static experiments. Dynamics of cardiac output process was caused by injection of vasoactive agents and asphyxia. The difference between intravascular probes and cuff probes blood flow parameters were 6-9%, strike volume 4-6%, cardiac output 5-7%. In ten cases intravascular probes was implanted in ascending aorta for hemodynamics study on conscious rats.     

Tissue blood flow distribution and the effect of chronic vascular catheterization in the hind limb of the fetal lamb

In six chronically instrumented fetal lambs, hind-limb skin, bone, and muscle comprised 22.5 +/- 1.3, 35.3 +/- 1.6, and 42.3 +/- 1.1% of total limb weight, respectively. As estimated using radionuclide-labeled microspheres, blood flow to these tissues averaged 30.4 +/- 4.9, 30.1 +/- 3.3, and 14.0 +/- 3.1 mL.min-1.100 g-1, respectively, and they received 29.5 +/- 3.3, 45.3 +/- 3.6, and 25.2 +/- 4.5% of total limb blood flow. Thus, muscle has a lower blood flow in relation to its weight in comparison with the other tissues, while bone receives the largest fraction of hind-limb blood flow. The higher perfusion rate to bone may by due to a high rate of hematopoiesis in late gestation, whereas muscle flow may be lower than that reported immediately after birth because of limited limb movement and lack of shivering thermogenesis. There were no significant differences in tissue weights between the limb in which femoral arterial and lateral tarsal venous catheters were implanted (nonstudy limb) and the leg that had smaller diameter catheters placed in the pudendoepigastric artery and vein (study limb). However, nonstudy limb blood flow was 13.4 +/- 1.8% less than in the study limb, although the flow distribution to hind-limb tissues was not different between the two limbs. This suggests that the longer, larger diameter catheters inserted into the nonstudy limb had an adverse effect on hind-limb blood flow but not on overall limb growth or blood flow distribution. More attention should be paid to the effects of chronic fetal vascular catheterization on the tissues or organs normally perfused by the catheterized vessel.     

Estimation of blood flow in transcutaneous PO2 measurements

A method for estimation of the cutaneous blood flow in transcutaneous PO2 measurements is presented. Recordings of electrode and skin temperature make it possible to compute the effect dissipated to the circulating blood. Eighteen measurements were performed on three healthy volunteers at electrode temperature settings from 37.0 degrees C to 45.0 degrees C. The blood-flow estimates ranged from 0.07 to 0.19 ml . cm-2 . min-1. At an electrode temperature of 45.0 degrees C the investigations showed a tc-PO2 value as low as 7 mmHg (0.9 kPa) which, however, corresponded well to the lowest blood-flow estimate determined. The temperature-corrected (37 degrees C) a-PO2-tc-PO2 gradient ranged from 50 mmHg to 95 mmHg (6.7-12.6 kPa). The investigations confirm the importance of simultaneous determinations of cutaneous blood flow, capillary temperature and cutaneous oxygen consumption in order to describe the connection between arterial and cutaneous oxygen tension. The cutaneous blood flow seems in this connection to be the most important parameter.     

Effect of chronic hypoxemia on the regulation of nitric-oxide synthase in the fetal sheep brain

We undertook a prospective study to determine the type and distribution of foot and ankle snowboarding injuries. Reports of 3213 snowboarding injuries were collected from 12 Colorado ski resorts between 1988 and 1995. Of these, 491 (15.3%) were ankle injuries and 58 (1.8%) were foot injuries. Ankle injuries included 216 (44%) fractures and 255 (52%) sprains. Thirty-three (57%) of the foot injuries were fractures and 16 (28%) were sprains. The remaining injuries were soft tissue injuries, contusions, or abrasions. There was no significant correlation between boot type (soft, hybrid, or hard) and overall foot or ankle injury rate. There were significantly fewer ankle sprains in patients wearing hybrid boots and fewer fractures of the lateral process of the talus in patients wearing soft boots. An unexpectedly high number of fractures of the lateral process of the talus were noted. These 74 fractures represented 2.3% of all snowboarding injuries, 15% of all ankle injuries, and 34% of the ankle fractures. Many of these fractures are not visible on plain radiographs and require computed tomography imaging to be diagnosed. Diagnosis of this fracture pattern is paramount; the physician should be very suspicious of anterolateral ankle pain in the snowboarder, where subtle fractures that may require surgical intervention can be confused with anterior talofibular ligament sprains.     

The effect of diazoxide on uterine blood flow in pregnant sheep

Diazoxide, a labor inhibiting agent, was administered intravenously at various rates to seven pregnant, near-term sheep to evaluate its effect on cardiovascular and uterine hemodynamics. Uterine blood flow was measured with electromagnetic flow transducers. Rapid administration of diazoxide resulted in a profound maternal tachycardia with hypotension, an increase in uterine vascular resistance, and a significant decrease in uterine blood flow. With slow infusion of the drug, the changes in heart rate and blood pressure were minimized, uterine vascular resistance was decreased, and uterine blood flow was maintained. Therefore, slow infusion appears to be the preferred method for inhibiting labor with diazoxide.     

Treatment of chronic myeloid leukemia in relapse after umbilical cord blood transplantation

Umbilical cord blood (UCB) is increasingly used as a source of hematopoietic progenitor cells for allotransplantation. Donor-derived buffy coat cells are considered optimal treatment for leukemia relapses after transplantation of allogeneic bone marrow. Experience with relapses after UCB transplants are sparse. Here we report a girl who received an UCB transplant for chronic myeloid leukemia, relapsed after three years, failed to respond to donor buffy coat cells, but achieved a complete hematologic, cytogenetic, and molecular remission on interferon-alpha.     

Doppler flow velocity waveforms of the umbilical arteries correlate with intravillous blood volume

OBJECTIVE: My purpose was to measure the volume of the fetoplacental vessel tree and to relate findings to Doppler flow patterns of the umbilical arteries. STUDY DESIGN: One hundred sixty placentas were examined by means of standardized random block placental histomorphometry after delivery and the results were compared with antenatal Doppler findings. RESULTS: There was a high correlation (r = -0.703) between the intravillous blood volume obtained from measurements of intermediate and terminal villi and the Doppler flow velocity waveforms detected within the last week before delivery. Moreover, the reduced size of a vessel tree less than 85 mL is highly predictive of perinatal complications, such as fetal growth restriction, low umbilical artery pH values after birth, reduced Apgar scores, and cesarean section for fetal distress. CONCLUSION: These data suggest that reduced end-diastolic flow velocities in the umbilical arteries are associated with elevated fetoplacental impedance owing to reduced vascularization of intermediate and terminal villi.     

Capillary recruitment and transit time in the rat lung

Increasing pulmonary blood flow and the associated rise in capillary perfusion pressure cause capillary recruitment. The resulting increase in capillary volume limits the decrease in capillary transit time. We hypothesize that small species with relatively high resting metabolic rates are more likely to utilize a larger fraction of gas-exchange reserve at rest. Without reserve, we anticipate that capillary transit time will decrease rapidly as pulmonary blood flow rises. To test this hypothesis, we measured capillary recruitment and transit time in isolated rat lungs. As flow increased, transit time decreased, and capillaries were recruited. The decrease in transit time was limited by an increase in the homogeneity of the transit time distribution and an increased capillary volume due, in part, to recruitment. The recruitable capillaries, however, were nearly completely perfused at flow rates and pressures that were less than basal for the intact animal. This suggests that a limited reserve of recruitable capillaries in the lungs of species with high resting metabolic rates may contribute to their inability to raise O2 consumption manyfold above basal values.     

Evaluation of an ultrasonic method applied to the measurement of blood coagulation time

The separation of dilute protein mixtures was achieved using simple monovalent buffering species to form retained, internally produced pH gradients on a strong-basic anion-exchange column. Highly focused proteins bands localized on stepwise pH transitions were produced experimentally under trace and volume overloaded feed conditions. Numerical simulations were performed that accurately predict the pH profile and protein band shapes in the column effluent. Experimental results were combined with numerical investigations to explore strategies for designing efficient preparative-scale chromatofocusing systems using simple, inexpensive buffers and adsorbents.     

Effect of umbilical artery catheters on blood flow and oxygen supply to extremities

The effect of catheter placement in the abdominal aorta on the blood flow and oxygenation of lower extremities was evaluated in 30 New Zealand rabbits, weighing 0.55-3.5 kg, by inserting 3.5 and 5.0 French polyvinyl chloride catheters, of the type commonly used for umbilical artery catheterization, through the femoral artery, advancing 15-20 cm, and leaving in place for 10-30 min. Arterial blood pressure (BP), common iliac artery blood flow (BF), gracilis muscle tissue oxygen availability (O2a), and subcutaneous temperature (T) in the foot were continuously monitored before and during catheter placement and after withdrawal. There were no changes in the physiologic variables measured in the contralateral leg when the catheter remained below the aortic bifurcation; however, when the catheter was advanced 15-20 cm into the abdominal aorta, a decrease in lower extremity BF, O2a, and T occurred. Because the length of catheter insertion was maintained constant in each animal, the decreases in BF, O2a, and T are related to the relative dimensions of the vessel and the catheter. The ratio of catheter to vessel diamter, in addition to the site of catheter placement, should be considered during the clinical application of arterial catheters. Reduction in blood flow could be detected by continuous differential monitoring of core and extremity temperature or extremity muscle oxygen availability.     

Comparison of retroviral-mediated gene transfer into cultured human CD34+ hematopoietic progenitor cells derived from peripheral blood, bone marrow, and fetal umbilical cord blood

Genetic alteration of stem cells ex vivo followed by bone marrow transplantation could potentially be used in the treatment of numerous diseases and malignancies. However, there are many unanswered questions as to the best source of hematopoietic cells for long-term reengraftment and the most effective way to introduce foreign genes into this target cell. We have compared retroviral-mediated gene transfer into CD34+-enriched cells derived from peripheral blood (PB), bone marrow (BM), or fetal umbilical cord blood (CB). Cells from all three sources that had been expanded ex vivo in the presence of stem cell factor (SCF), interleukin-3 (IL-3), IL-6, and granulocyte colony-stimulating factor (G-CSF) showed transduction efficiencies ranging from 5-45%, as measured by acquisition of G418 resistance. The average efficiencies of gene transfer from multiple experiments for PB, BM, and CB were not statistically different. To determine the effect of ex vivo expansion on gene transfer into CB CD34+ cells, we compared the transduction efficiencies of cells exposed to virus immediately after harvest and CD34 selection or after 6 days of culture CD34+ CB cells were more effectively transduced after expansion in culture, showing gene transfer efficiencies 3- to 5-fold higher on day 6 compared with day 0. Last, we examined retroviral transduction via spinoculation of CB CD34+ cells and found it to be approximately as effective as our standard transduction with no significant loss of cell viability as measured by colony formation in semi-solid medium.     

Cardiac flow after fetal blood sampling in normally grown and growth-retarded fetuses

The objective of this study was to evaluate the effect of fetal blood sampling on cardiac flow velocity waveforms. Flow velocity waveforms were measured from the ascending aorta and pulmonary artery immediately before and after fetal blood sampling in 29 normally grown and 12 growth-retarded fetuses. The latter group was characterized by abnormal Doppler indices in the umbilical artery and middle cerebral artery suggestive of uteroplacental insufficiency as the causative factor of the impaired growth. The flow velocity parameters studied were the peak velocity, the time to peak velocity, and the left and right cardiac output and their ratio. In normally grown fetuses, the peak velocity and right and left cardiac output values increased significantly after fetal blood sampling, while no significant changes were observed in the other indices considered. The gestational age at the time of the procedure was positively related to the amplitude of these changes. In growth-retarded fetuses, fetal blood sampling did not induce any significant increase in cardiac output or peak velocities, while in more than 50 per cent of the fetuses these Doppler indices decreased. The amplitude of the decrease was significantly related to the severity of acidosis in the umbilical vein. In conclusion, the cardiac haemodynamic response to fetal blood sampling differs between normally grown and growth-retarded fetuses. This difference may explain the higher rate of complications occurring in the latter group of fetuses after blood sampling.     

Effect of ethyl alcohol on maternal and fetal acid-base balance and cardiovascular status in chronic sheep preparations

Thirteen chronically catheterized pregnant sheep were given intravenous infusions of 10 per cent ethyl alcohol in 5 per cent dextrose solution (15 mg/kg over two hours). Samples of blood from maternal femoral artery, uterine vein, and fetal brachiocephalic artery were drawn at hourly intervals before, during and after the infusions. Plasma was analyzed for alcohol concentration, protein concentration, haematocrit, PCO2 and pH. Maternal and fetal arterial blood pressures were monitored continuously. There were no significant differences between maternal and fetal arterial blood alcohol levels at any sampling interval nor was there any difference in elimination constants. Alcohol infusion did not produce any significant change in plasma protein concentration, haematocrit, PCO2 and pH, and mean arterial blood pressure in either mother or fetus. However, both maternal and fetal heart rate increased significantly following alcohol infusion.     

The relation between indirect fetal electrocardiogram and blood gas analysis of umbilical cord artery during labor

OBJECTIVE: To observe the relation between indirect fetal electrocardiogram (FECG) and blood gas analysis of umbilical cord artery blood during labor and discuss the possibility of using FECG for labor monitoring. METHODS: Indirect FECG was used for fetal monitoring in 80 cases during the second stage of labor and cord umbilical artery blood was taken immediately after delivery for blood gas analysis. Cases were retrospectively divided into normal and abnormal groups according to the results of FECG. RESULTS: The success rate of FECG test was 91.95%. Significant differences were noted in mean values of pH, PCO2, PO2, actual base excess (ABE) and standard base excess (SBE) of umbilical artery between the 2 groups, so were the percentages of cases with pH < 7.20, PCO2 > 8.00 kPa, PO2 < 2.10 kPa. CONCLUSIONS: Indirect FECG can be used for fetal monitoring during labor. FECG is obviously correlated with acid-base equilibrium and blood gas concentration of umbilical cord artery blood, it is a sensitive index of fetal and neonatal hypoxia.     

Carotid-vertebral artery blood transit time: results in healthy subjects and patients with schizophrenia and brain disease

Estimation of blood transit time in the neck and the extension of this into the head was made by a method of electrical impedance, over a wide age range, in 159 healthy subjects, 160 schizophrenic patients, and 199 patients with organic brain disease. In each case, the distance between the electrocardiogram and the next succeeding pulse-volume impedance wave was measured and averaged over 30 serial wave forms. Chronological age proved a significant variable, transit times lengthening progressively with the age, but only for measurements extending into the head. Sex and hemispheric laterality played no significant role. With age held constant, mean transit times into the head were significantly prolonged in both groups of patients as compared with controls. No significant differences were found however between means of psychiatric andneurological patients. It is suggested that these results reinforce the organic etiology of schizophrenia.