Characteristics of follicular evacuation during human ovulation.

Our objectives were to determine the rate and extent of follicular evacuation during human ovulation. Female volunteers were given 5000 or 10,000 IU human chorionic gonadotropin to induce ovulation when a follicle reached 18-20 mm. Ovulations were observed via transvaginal ultrasonography and recorded. Images were digitized for computer-assisted analysis. Areas of the follicles, taken to reflect follicular volume, were measured at specific time intervals from the moment of the first leakage of fluid until complete follicular evacuation. Twenty-five ovulations were visualized. In 23 cases (92%) all of the follicular fluid was expelled, but in two cases the follicle failed to empty completely. In all complete ovulations the initial fluid loss was rapid. The time to reach 70% evacuation was 0.9 +/- 0.3 min (+/- SEM). The remaining fluid leaked out more slowly; the mean time to complete follicular evacuation was 6.1 +/- 1.1 min. There was considerable variability in the rates of ovulation (range 6 s to 18.5 min). An association was observed between the type of stigma formed prior to ovulation and the initial rate of fluid loss. The data provide evidence of variability during follicular evacuation, which may in turn influence the successful expulsion of the oocyte from the follicle.     

Correlations in umbilical blood flow Doppler velocities in the human fetus during breathing.

We hypothesized that changes in intrathoracic pressure during fetal breathing episodes result in quantifiable variations in umbilical arterial and venous blood flow velocities, and that these variations are related to compliance properties of each system. We further hypothesized that these variations in velocities are different in fetuses with normal and abnormal umbilical arterial Doppler velocities. Umbilical arterial and venous Doppler velocities were measured simultaneously during breathing episodes in 15 normal fetuses and 14 fetuses with elevated systolic-to-diastolic (S/D) umbilical arterial Doppler velocity ratios. Umbilical arterial end-diastolic velocity changes were less than umbilical venous velocity changes in normal fetuses, but were significantly greater in four fetuses with elevated S/D ratios (p < 0.004). Furthermore, umbilical arterial diastolic velocity minima preceded umbilical venous velocity minima by a time lag that was greater in fetuses with elevated S/D ratios (p < 0.002). These results suggest that differences in umbilical arterial and venous velocity variation during fetal breathing episodes may be related in part to vascular compliance, which may be altered in fetuses with abnormal umbilical arterial Doppler velocity.     

Cerebral blood flow during propofol induced sedation.

PURPOSE: This work determined if 2, 6-diisopropylphenol (propofol) selectively affects cerebral blood flow in regions associated with wakefulness. PROCEDURES: Cerebral blood flow (CBF) was measured with positron emission tomography (PET) using the 15O-water bolus technique in 10 subjects while awake and during light and deep sedation. Arterial blood was sampled for CBF estimation, blood gases and propofol plasma concentrations. RESULTS: Global CBF decreased under deep sedation. A regression analysis of CBF vs. propofol concentration showed significant decreases in CBF in the thalamus and posterior cingulate and increases in the hippocampus and cerebellum. An ANCOVA analysis on condition (controlling for pCO(2) levels) showed mean CBF decreased in the thalamus and posterior cingulate cortex and increased in the primary motor and hippocampal areas during the light and deep sedation compared to awake conditions. CONCLUSIONS: These data support the hypothesis that propofol preferentially alters CBF in specific brain regions necessary to maintain wakefulness.     

Time domain measurement of blood flow in the human fetal aorta during normal pregnancy.

OBJECTIVE: To evaluate blood-volume flow-rate measurement in the fetal descending thoracic aorta using a non-invasive, non-Doppler, ultrasound technique. METHODS: This was a cross-sectional, observational study. Volume flow measurements were obtained from the descending thoracic aorta in 59 human fetuses between 20 and 40 weeks' gestation. These were uncomplicated pregnancies that resulted in the live births of appropriately grown infants. The measurements were obtained using a time domain processing technique: color velocity imaging quantification (CVI-Q). RESULTS: The blood-volume flow rate increased consistently from the second trimester until term. The mean values ranged between 100 mL/min at 20 weeks' gestation and approximately 350 mL/min at term. The normalized (weight-adjusted) volume flow rates decreased with increasing gestation, from a maximum of 626 mL/min/kg at 23 weeks to a minimum of 45.6 mL/min/kg at 37 weeks. CONCLUSIONS: The regular measurement of blood-volume flow in the descending fetal thoracic aorta is feasible using CVI-Q. Although there is a considerable learning curve, with adequate training there are potential clinical applications for this non-Doppler technique. However, limitations exist with the currently available technology for clinical use in fetal vascular studies.     

Influence of ovulation induction with human menopausal gonadotropin on uterine blood flow: comparison of unexplained and mechanical infertility

A prospective study in patients undergoing in vitro fertilization treatment was conducted to assess whether any difference may be present in uterine blood flow between unexplained and mechanical infertility, before and during ovulation induction. The ascending branch of the uterine artery, the arcuate arteries, and the radial arteries were examined by transvaginal, color pulsed Doppler sonography on day 3 and on the day of human chorionic gonadotropin administration. Patients with mechanical factor demonstrated a decrease in resistance to blood flow in all the examined vessels during ovulation induction. Patients with unexplained infertility showed a contrasting trend in changes of uterine blood flow (e.g., as the cycle progressed, the resistance index increased). Moreover, the resistive index values on the day of human chorionic gonadotropin administration were significantly higher in patients with unexplained infertility. It is quite possible that the rise in impedance to uterine blood flow during ovulation induction and the higher impedance on the day of human chorionic gonadotropin administration in patients with unexplained infertility may be one of the factors responsible for the lower conception rate in these patients.     

Systolic and diastolic changes in human coronary blood flow during Valsalva manoeuvre

Valsalva manoeuvre is reported to be sometimes successful for the relief of angina pectoris. The present study investigated how haemodynamic changes produced by Valsalva manoeuvre can interact to improve the relationship between cardiac work and coronary blood flow. Ten male subjects aged 53 ± 12 years (SD) were considered. Blood velocity in the internal mammary artery, previously anastomosed to the left descending coronary artery, was studied with Doppler technique. The subjects performed Valsalva manoeuvres by expiring into a tube connected to a mercury manometer, to develop a pressure of 40 mmHg. The arterial blood pressure curve was continuously monitored with a Finapres device from a finger of the left hand. During expiratory effort, an increase in heart rate and a decrease in arterial pulse pressure were followed by a more delayed and progressive increase in mean and diastolic pressures. Systolic blood velocity markedly decreased along with the reduction in pulse pressure and increase in heart rate. By contrast, diastolic and mean coronary blood velocities did not show any significant change. Since it is known that the Valsalva manoeuvre strongly reduces stroke volume and cardiac output, it is likely that a reduction in cardiac work also takes place. Since in diastole, i.e. when the myocardial wall is better perfused, coronary blood velocity did not show any significant reduction, it is likely that unchanged perfusion in the presence of reduced cardiac work is responsible for the relief from angina sometimes observed during Valsalva manoeuvre. It is also likely that the increase in heart rate prevents the diastolic and mean blood coronary velocity from decreasing during the expiratory strain, when an increased sympathetic discharge could cause vasoconstriction through the stimulation of the coronary α‐receptors.     

Development of hydrosalpinx during ovulation induction.

We have observed that hydrosalpinx develops in some patients undergoing ovulation induction as part of in vitro fertilization-embryo transfer and gamete intrafallopian transfer programs. Increased tubal secretions due to multihormonal stimulation causes a blocked tube to distend by the time of oocyte harvest. In a subset of women, hydrosalpinx was not identified on initial pelvic sonograms. Hydrosalpinx became apparent during serial sonography to monitor follicular development. We performed a retrospective chart review of these cases in order to confirm this finding with hysterosalpingography or laparoscopy. Nine of 316 women developed unilateral (eight cases) or bilateral hydrosalpinx (one case) during stimulation. Recognition of this sonographic finding is important to the referring physician because it has important therapeutic and outcome implications.     

Uterine artery blood flow velocity waveforms during uterine contractions.

OBJECTIVE: No quantitative or qualitative Doppler velocimetry classification of vascular flow resistance covering all stages of forward and reversed flows exists. The objective of this study was to characterize uterine artery (UtA) flow velocity waveforms (FVWs) obtained during an oxytocin challenge test (OCT) and compare them to FVWs in spontaneous normal labor. METHODS: Uterine artery Doppler velocimetry was performed during and between uterine contractions in 61 high-risk pregnancies subjected to an OCT and in 20 normal pregnancies undergoing spontaneous labor. FVWs were classified relative to the presence of forward/absent/reversed flow during systole and diastole, and the time-averaged flow velocity over the heart cycle. RESULTS: Eleven different FVW classes were identified. No relationship between FVWs recorded during uterine inertia and contractions was found (P >/= 0.2). In both groups, only forward FVWs were recorded between contractions, whereas during contractions flow reversal was more common in the OCT group (P 相似文献   

Correlation between ventilation and brain blood flow during sleep.

The relationships between brain blood flow (BBF) and ventilation (VI) were studied during sleep in 13 goats. Unilateral BBF was continuously measured with an electromagnetic flow probe; total and regional BBF were assessed by the radioactive microsphere technique in four animals. Interacting changes in VI and BBF occurred during both slow wave (SWS) and rapid eye movement (REM) sleep. During SWS, significant decreases in VI and increases in arterial PCO2 occurred compared to wakefulness. BBF during SWS correlated linearly with arterial CO2 tension (PaCO2); nd the relationship was similar to that for awake goats breathing CO2. During REM sleep, VI was significantly less than both the awake (W) and SWS states due principally to a decrease in tidal volume. BBF during REM sleep was significantly and substantially increased compared with both the W and SWS states; this increase was shared by all brain areas. The increase in BBF during REM sleep was greater than that predicted from changes in PaCO2. In five goats provided with chronic sagittal sinus fistulae, arteriovenous oxygen difference was measured in separate studies and found to be significantly lower during REM sleep compared with W; brain O2 consumption was similar in magnitude in the REM and W states. Thus, the high BBF of REM sleep was also unexplained by an increase of brain metabolic activity. We conclude that, during SWS, increases in BBF are explained by hypoventilation and hypercapnia. In contrast, during REM sleep, BBF is substantially in excess of that expected from PaCO2 or brain metabolism. It is postulated that this excess of BBF during REM sleep could reduce the central chemoreceptor pH relative to that present in SWS. The combination of reduction of sensitivity to CO2 and lower tissue PCO2 during REM sleep makes it likely that the output of the central chemoreceptors during this state is less than that during SWS and wakefulness. This may contribute to the low tidal volume and respiratory irregularities of this sleep period.     

The fetal portal vein: normal blood flow development during the second half of human pregnancy.

OBJECTIVES: The umbilical vein is the major source of blood for the fetal liver, but portal blood, which has not been measured directly in human fetuses, probably constitutes a physiologically important contribution. We aimed to establish a method for measuring blood flow in the fetal portal vein and to produce longitudinal reference ranges for diameter, blood flow velocities and volume blood flow during the second half of pregnancy. METHODS: After a pilot project to develop the measuring technique, 160 low-risk pregnant women were recruited to a longitudinal study that included ultrasound examinations at 4-5-week intervals starting at 20-22 weeks of gestation. The inner diameter (D) of the vessel was measured with a perpendicular insonation angle, and the time-averaged maximum blood velocity (TAMXV) and weighted mean velocity (VWMEAN) were recorded with an insonation directed along the long axis of the vessel. Portal flow was calculated as: Q = pi(D/2)(2) x h x TAMXV (where h is a velocity profile parameter and equals 0.5). Portal flow was normalized for estimated fetal weight based on birth-weight percentiles. RESULTS: The portal vein could be visualized and measured in 558/593 (94%) cases. Blood flow was pulsatile. D and TAMXV doubled during the second half of pregnancy (21-39 weeks), from 1.5 to 3.4 mm and from 8.4 to 14.9 cm/s, respectively. Correspondingly, the portal flow increased from 5 to 41 mL/min, and from 10 to 13 mL/min/kg when normalized for fetal weight. Similar results were achieved for VWMEAN. CONCLUSION: Portal flow can be measured with a standardized technique. It increases during the second half of pregnancy, even when normalized for fetal weight, suggesting that it has increasing importance in the fetal liver circulation.     

Liver blood flow during cardiac surgery

OBJECTIVE: Impairment of liver blood flow and, therefore, potentially liver function, has important short-term consequences because of the liver's key metabolic importance and role in drug metabolism. The objective of this study was to quantify the effect of cardiac surgery on liver blood flow from before the induction of anaesthesia to 24 hours postoperatively. METHOD: Ten patients with no history of liver impairment, moderate or good left ventricular function, and undergoing routine hypothermic coronary artery bypass graft surgery, were entered into the study. Liver blood flow was determined by the clearance of indocyanine green (ICG), expressed as a percentage disappearance rate (PDR). RESULTS: The mean baseline percentage disappearence rate (PDR) of indocyanine green (ICG) was 19.84 +/- 4.47%/min. This increased marginally to 20.42 +/- 6.67%/min following the induction of anaesthesia, but after 15 min of cardiopulmonary bypass, the PDR fell to 13.51 +/- 3.69%/min; this was significantly lower than all other PDRs measured throughout the study. Prior to extubation, the PDR increased again to 20.01 +/- 3.72%/ min, and this level was maintained at 12 hours (PDR 20.32 +/- 3.53%min) and 24 hours (PDR 20.51 +/- 2.27%/min). CONCLUSION: The induction of anaesthesia and positive pressure ventilation do not affect liver blood flow. Cardiopulmonary bypass at 30 degrees C is associated with a significant reduction in liver blood flow, which returns to normal within 4-6 hours of surgery and remains normal for up to 24 hours after surgery.     

Regional blood flow during hyperoxic haemodilution

BACKGROUND: Ventilation with pure oxygen (hyperoxic ventilation, HV) increases arterial oxygen content (CaO(2)). However HV induces arteriolar constriction and thus potentially affects O(2) supply. We therefore investigated the effects of HV on regional blood flow (RBF) and O(2) supply of different vital organs during moderate normovolaemic anaemia. METHODS: Twenty-two anaesthetized dogs were haemodiluted under normoxia (i.e. FiO(2) = 0.21) to a target haemoglobin concentration (Hb) of 7 g dl(-1) and were subsequently ventilated with pure O(2). RBF was determined by use of the radioactive microspheres method in the myocardium, kidney, skeletal muscle, liver, intestine, stomach, and pancreas at Hb = 7 g dl(-1) and after subsequent initiation of HV. RBF in proportion to cardiac output (RBF(relative)), the variation coefficient of RBF (VC) and regional O(2) supply (rDO(2)) were calculated. RESULTS: Initiation of HV at Hb = 7.0 +/- 0.3 g dl(-1) reduced cardiac index (-17%) as well as RBF within the myocardium (-21%), pancreas (-25%), and skeletal muscle (-25%), whereas renal, hepatic, and intestinal RBF remained unchanged. Consequently RBF(relative) of the latter organs increased. Heterogeneity of RBF was marginally affected by HV. CONCLUSION: The initiation of HV during moderate normovolaemic anaemia (Hb =7 g dl(-1)) was accompanied by RBF redistribution with preference for renal, hepatic and intestinal O(2) supply. Cardiac, pancreatic and muscular O(2) supply decreased, however without any critical restriction of organ function.     

Regional blood flow during periodic acceleration

OBJECTIVE: To determine whether a motion platform that imparts noninvasive periodic acceleration (pGz) forces to the body causes systemic vasodilation and changes local organ blood flow. DESIGN: Prospective paired blocked design. SETTING: Medical center research laboratory. SUBJECTS: Juvenile Yorkshire pigs. INTERVENTIONS: Juvenile pigs (12 kg) were anesthetized, paralyzed, and placed on a motion platform that oscillated at a frequency of 4 Hz and a force of approximately 0.4 G. MEASUREMENTS AND MAIN RESULTS: Regional blood flows, as assessed by colored microspheres, increased during pGz relative to values obtained before pGz. Blood flow (mL.min-1.100 g-1) significantly increased to the epicardium (71%), endocardium (93%), cerebrum (183%), brain stem (177%), renal cortex (53%), ileal mucosa (69%), gastric antral mucosa (72%), and liver (86%). Spleen and skeletal muscle blood flow increased without statistical significance, 38% and 158% with pGz, relative to paired control values. Regional blood flows returned to baseline 10 mins after discontinuation of pGz, except in the myocardial layers, where blood flow remained significantly elevated. There was no difference compared with baseline in heart rate, arterial blood gases, and blood pressure, but serum nitrite concentration was significantly higher (58%) during pGz. In another series of animals, pGz increased pulmonary artery blood flow directly proportional to the magnitude of the applied acceleration force with frequency held constant. CONCLUSIONS: Periodic sinusoidal inertial forces in the spinal axis increase blood flow to tissues. The increased blood flow is reversible and may be caused by vasodilation secondary to local mediator release. These effects may be desirable in clinical conditions of low tissue oxygen delivery and perfusion.     

Changes in inferior vena cava blood flow velocity and diameter during breathing movements in the human fetus.

Breathing movements in the human fetus cause distinct changes in Doppler flow velocity measurements at arterial, venous and cardiac levels. In adults, breathing movements result in a momentary inspiratory collapse of the inferior vena cava vessel wall. The study objective was to quantify the inferior vena cava flow velocity modulation during fetal breathing movements and to evaluate possible inferior vena cava vessel diameter changes in normal third-trimester pregnancies.We studied 57 women after oral administration of dextrose (50 g). In 40 fetuses (n = 19, 27-32 weeks and n = 21, 36-39 weeks), fetal inferior vena cava waveforms were obtained during apnea and fetal breathing activity. In 30 fetuses (27-39 weeks) inferior vena cava vessel diameter changes were studied using the M-mode during apnea and breathing movements. Peak and time-averaged velocities of inferior vena cava flow velocity waveforms showed a gestational age-independent increase of 60-160% during breathing activity. A temporary inferior vena cava vessel wall collapse (range, 50-83%) was recorded, which was significantly different from vessel diameter changes during apnea (range, 11-19%). The marked increase of inferior vena cava flow velocities is due to a raised thoraco-abdominal pressure gradient, which may cause a reduction in vessel size and additional volume flow into the right atrium. The significance of the caval index for recognition of elevated right atrial pressure in abnormal human fetal development needs further investigation.     

Monitoring blood flow responses during topical ALA-PDT

Photodynamic therapy (PDT) using topical 5-aminolevulinic acid (ALA) is currently used as a clinical treatment for nonmelanoma skin cancers. In order to optimize PDT treatment, vascular disruption early in treatment must be identified and prevented. We present blood flow responses to topical ALA-PDT in a preclinical model and basal cell carcinoma patients assessed by diffuse correlation spectroscopy (DCS). Our results show that ALA-PDT induced early blood flow changes and these changes were irradiance dependent. It is clear that there exists considerable variation in the blood flow responses in patients from lesion to lesion. Monitoring blood flow parameter may be useful for assessing ALA-PDT response and planning.     

Monitoring blood flow responses during topical ALA-PDT

Photodynamic therapy (PDT) using topical 5-aminolevulinic acid (ALA) is currently used as a clinical treatment for nonmelanoma skin cancers. In order to optimize PDT treatment, vascular disruption early in treatment must be identified and prevented. We present blood flow responses to topical ALA-PDT in a preclinical model and basal cell carcinoma patients assessed by diffuse correlation spectroscopy (DCS). Our results show that ALA-PDT induced early blood flow changes and these changes were irradiance dependent. It is clear that there exists considerable variation in the blood flow responses in patients from lesion to lesion. Monitoring blood flow parameter may be useful for assessing ALA-PDT response and planning.OCIS codes: (170.0170) Medical optics and biotechnology, (170.3660) Light propagation in tissues, (170.6480) Spectroscopy, speckle, (170.3880) Medical and biological imaging     

Carotid artery blood flow during premanipulative testing

BACKGROUND: Cervical manipulation is used millions of times every year. Concern about cerebrovascular accidents (CVAs) is common, but actual cases are rarely reported. Premanipulative tests are presumed to identify patients at risk of CVA. In an earlier study we found no significant changes in the vertebral artery blood flow of patients with a positive premanipulative test with different head positions. Consequently, we questioned whether there is a role for premanipulative testing to identify patients at risk of CVAs. OBJECTIVE: The aim of this study was to examine whether instead, blood flow velocity in the internal carotid arteries changes with head position in patients with a positive premanipulative test, potentially giving contraindication to cervical manipulation. METHODS: In a prospective study private practicing chiropractors from 3 Danish counties referred patients with a positive premanipulative test for an examination of cervical artery blood flow. Premanipulative testing was performed by an experienced chiropractor, and flow velocities were measured in both vertebral and internal carotid arteries by color duplex sonography at a university hospital vascular laboratory. RESULTS: A total of 11 consecutive patients with a positive premanipulative test were referred. Two of these were excluded because we could not reproduce any symptoms at repeat premanipulative testing before the vascular examination. In the remaining 9 patients we found no significant difference with different head positions in peak flow velocity or time-averaged mean flow velocity in the internal carotid arteries. Blood flow did not cease in 1 single patient despite a positive premanipulative test in all. CONCLUSION: It appears that a positive premanipulative test is not associated with a change in peak flow velocity or time-averaged mean flow velocity in either the carotid or the vertebral arteries. If premanipulative testing is used solely for the detection of vascular insufficiency as a potential substrate for CVAs after cervical manipulation, we believe that premanipulative testing is of little clinical value.     

Pharmacological manipulation of human gastrointestinal blood flow

Summary— The splanchnic circulation is one of the largest vascular regions in man. In the past, this has been difficult to study because of methodological problems. The adapting of noninvasive Doppler techniques has made it possible to develop reproducible measurements of coeliac and superior mesenteric artery blood flow, which are the main contributors to the gastrointestinal vasculature. This has resulted in the further understanding of neurogenic and humoral control of this region in a number of physiological and pathophysiological states, and has contributed towards the knowledge of its pharmacological control. These studies are of relevance to cardiovascular homeostasis and, in particular, systemic blood pressure control which depends upon various factors including responses in different vascular regions. In this review the key physiological factors which influence pharmacological studies on this circulation will be discussed. Examples will be provided, in subjects with cardiovascular and neurological disorders, of how administration of endogenous and exogenous substances, including drugs with specific pharmacological effects, alter human gastrointestinal blood flow. These will include insulin, alcohol, the somatostatin analogue octreotide, the central acting sympatholytic clonidine and the angiotensin H-converting inhibitor captopril. The relevance of these studies to subjects with postural hypotension due to sympathetic denervation and to primary hypertension, in particular, will be discussed.