Distribution of oxygenated blood flow at three different routes of extracorporeal membrane oxygenation in exteriorized fetal lambs

OBJECTIVE: The purpose of this study was to determine which extracorporeal membrane oxygenation (ECMO) route best approximates the normal physiologic pattern of oxygenated blood distribution in fetal lambs submerged in warm saline solution. STUDY DESIGN: Six fetal lambs ranging from 113 to 129 days of gestation were delivered by cesarean section and oxygenated with ECMO in a warm saline solution bath. We compared the distribution of oxygenated blood flow during intact placental circulation with 3 routes of ECMO, from the right atrium to the carotid artery (V-A), from the right atrium to umbilical vein (V-UV), and from the right atrium with umbilical artery to umbilical vein [(V + UA)-UV], in exteriorized fetal lambs. Distribution of oxygenated blood flow was determined by nonradioactive colored microspheres. RESULTS: The ECMO blood flow rate through the catheters during V-A, V-UV or (V + UA)-UV ECMO ranged at 150 to 300 ml/min. Among the 3 different routes of ECMO, the oxygenated blood distribution in (V + UA)-UV showed the best correlation with placental-fetal blood flow, particularly in the brain and heart. CONCLUSION: This study indicated that (V + UA)-UV ECMO most closely approximates normal intact placental-fetal blood flow distribution in fetal lambs.     

Effects of Extracorporeal Membrane Oxygenation (ECMO) on Fetal Lambs

The purpose of this study was to determine the applicability of using ECMO techniques to support fetal oxygenation while maintaining fetal circulation in utero. Extracorporeal membrane oxygenation (ECMO) was applied to four chronically instrumented fetal lambs with the placental circulation intact. Blood was obtained through a catheter (2.5 mm ID) inserted into the right atrium and was returned to the carotid artery after oxygenation (V-A ECMO). The rate of blood flow varied from 200 to 300 mL/min (80-100 mL/kg/min). Compressed air at 2 L/min was used to ventilate the membrane, achieving the mean pO₂ of 36.1 ± 9.5 torr in the blood after the membrane. A positive linear correlation was observed between pre-membrane and post-membrane pO₂. Despite maternal hypoxia experimentally produced by reducing FiO₂ of the mother for 15-35 min, V-A ECMO successfully maintained fetal blood pH and gases within the normal control range. These data indicate that V-A ECMO can effectively oxygenate lamb fetuses     

Effect of maternal oxygenation on fetal blood gas status in shiba goat fetuses

The purpose of this study is to investigate the effect of maternal oxygen administration on the fetal blood gas status. Five Shiba goat fetuses were used whose gestational days were 134 +/- 4 days. Maternal and fetal pH, pO2, pCO2, B.E., and hematocrit were measured every 30 minutes during 4 l/min oxygen administration for 60 minutes. Maternal arterial blood pO2 increased from 95.5 +/- 19.6 mmHg to 262.6 +/- 75.8 mmHg at 30 minutes and to 207.8 +/- 110.1 mmHg at 60 minutes. Fetal arterial blood pO2 increased significantly from 18.4 +/- 3.0 mmHg to 24.4 +/- 5.8 mmHg and 23.6 +/- 6.9 mmHg, respectively. There was a significant positive correlation between maternal pO2 and fetal pO2. The increase in fetal pO2 was small when the control pO2 was less than 17 mmHg. Although maternal pH did not change significantly, fetal pH decreased significantly from 7.29 +/- 0.07 to 7.25 +/- 0.07 at 60 minutes. Also fetal hematocrit decreased significantly from 33.9 +/- 5.2% to 32.8 +/- 5.4% at 60 minutes. Neither maternal nor fetal pCO2 and B.E. changed significantly. Therefore, we concluded that the effect of maternal oxygen administration on fetal pO2 was small when the fetus was already hypoxic. Also 60 minutes' oxygen administration may cause the decrease in fetal pH and hemodilution.     

The effects of isoproterenol on fetal oxygenation.

Infusion of isoproterenol (1 microgram/kg/min, i.v.) into the anesthetized pregnant rhesus monkey near term consistently reduced fetal oxygenation, despite diminishing myometrial activity. The decline in pO2 of fetal arterial blood (mean = 4.3 +/- 2.3 mmHg S.D.) was accompanied by an increase in pCO2 tension (mean = 4.6 +/- 2.7 mmHg) and a decline in pH (mean = 0.04 +/- 0.02 S.D.). There was an increase in heart rate and a widening of pulse pressure in the mother and also in the adequately oxygenated fetus providing evidence that the agent crosses the placenta. The poorly oxygenated fetuses developed bradycardia and hypotension. Administration of isoproterenol directly to the fetus elicited similar changes in the composition of blood, and in blood pressure and heart rate, to those observed after administration of the agent to the mother.     

Continuous monitoring of fetal pH, pO(2) and pCO(2) using a fiberoptic multiparameter sensor in animal models reproducing in utero conditions

OBJECTIVES: To evaluate the feasibility and accuracy of continuous fetal monitoring with a multiparameter intravascular sensor (MPIS) in animal models mimicking the fetal metabolic status. METHODS: First, the accuracy of the MPIS in hypoxic conditions was tested in adult rabbits (n = 6). The carotid artery (n = 4) or vein (n = 2) was catheterized with a 20-gauge cannula, housing a 500-microm Neotrend((R)) fiberoptic sensor for pCO(2), pO(2), pH and temperature. Fiberoptic readings were compared with arterial blood-gas (ABG) analyses. Secondly, the feasibility of continuous fetal fiberoptic sensing was tested during experimental fetoscopic surgery in lambs (n = 4). An identical sensor was introduced in a chorionic artery and readings were compared to ABG analyses of fetal blood samples. RESULTS: The overall bias and precision in the first experiment (147 measurement pairs) were -4.2 and 10.9 mm Hg for pO(2), +1.6 and 8.2 mm Hg for pCO(2) and -0.015 and 0.031 for pH, respectively. In the sheep experiments, continuous readings for all parameters were only available during 50% of the operation time, mainly due to disturbances induced by movement, contact with vessel wall and interference by endoscopic light. 20 sample pairs were obtained resulting in an overall bias and precision of -3.9 and 4.3 mm Hg for pO(2), -0.74 and 3.68 mm Hg for pCO(2) and -0.0032 and 0. 02 for pH. CONCLUSIONS: Fiberoptic microsensors are potentially useful for monitoring acid-base status in the low pO(2) range present in fetal life.     

Ovine hourly fetal urine production: relation to fetal electrocortical activity

OBJECTIVE: Ultrasound studies of hourly urine production rate in human fetuses have suggested that a fall in urine production occurs in state 2F (fetal quiet sleep) secondary to a state-dependent decrease in renal blood flow. We sought to ascertain the relationship between fetal hourly urine production rate and behavioral state in the near-term ovine fetus, a model in which urine production and fetal brain activity can be directly measured. METHODS: Six ewes with singleton pregnancies were prepared with vascular and amniotic fluid catheters. Fetuses were prepared with hindlimb vascular catheters, a bladder catheter, and biparietal ECoG electrodes. After at least 5 days of recovery (ga 130 +/- 2 days; term = 145-150 days), each animal was monitored for a 6-h period. Urine production was measured by draining the bladder catheter through a drop counter and fetal ECoG was continuously recorded (sampling rate of 50 Hz). ECoG activity was analyzed using power spectral analysis and periods of active and quiet sleep identified using both signal amplitude and corresponding 85% spectral edge frequency. RESULTS: Basal fetal arterial pH (7.36 +/- 0.01), pO2 (22.0 +/- 1.2 mmHg) and pCO2 (47.0 +/- 1.6 mmHg) and plasma (295 +/- 2 mOsm/kg) and urine (179 +/- 3 mOsm/kg) osmolalities were within normal ranges. Active and quiet sleep comprised 50 +/- 2 and 43 +/- 1% time, respectively. There was no difference in hourly urine production rate in active sleep (21.4 +/- 9.7 ml/h) and quiet sleep (18.8 +/- 7.7 ml/h). CONCLUSIONS: 1) Hourly fetal urine production rate is independent of ECoG activity state in the near-term ovine fetus. 2) Assuming only minor species differences, ultrasound measurement of human fetal hourly urine production rate can be performed without concern for fetal neurobehavioral state changes.     

Unloading of baroreceptors by carotid occlusion does not increase heart rate in fetal sheep

Unloading of baroreceptors by carotid occlusion does not increase heart rate in fetal sheep; Objectives: To test the hypothesis that in fetal sheep reduction of carotid sinus pressure by carotid occlusion increases heart rate. Study design: Fetal sheep (gestational age 121-132 days) were chronically instrumented with bilateral carotid occluders, catheters and electrodes (ECG) to measure systemic arterial and carotid sinus (CSP) blood pressures, and fetal heart rate. Results: Bilateral carotid occlusion (BCO) increased mean arterial blood pressure from 46+/-7 mmHg to 53+/-8 mmHg (mean+/-S.D.) while CSP decreased from 44+/-7 mmHg to 17+/-7 mmHg. Fetal heart rate fell during occlusion significantly from 186+/-34 bpm to 159+/-26 bpm (n=20 animals). Infusion of phenylephrine (8.5-20 microg min(-1)kg(-1)) or methoxamine (60-200 microg min(-1)kg(-1)) increased mean blood pressure from 44+/-6 to 61+/-9 mmHg, and fetal heart rate decreased from 186+/-30 to 132+/-31 bpm (n=12). BCO increased systemic arterial pressure further to 70+/-11 mmHg whereas carotid sinus pressure was reduced to 31+/-13 mmHg. However, average heart rate did not increase significantly (136+/-28 bpm). Conclusion: We conclude that in contrast to adult animals, in fetal sheep carotid occlusion with subsequent unloading of baroreceptors does not increase heart rate even when the baroreflex had been activated by arterial hypertension. It seems likely that stimulation of carotid chemoreceptors prevents the expected baroreceptor mediated heart-rate response.     

Efficacy of carotid collateral perfusion in anaesthetized sheep fetuses

The purpose of this study was to learn to what extent carotid collateral circulation is efficient in maintaining cephalic blood flow in the sheep fetus. Under halothane anaesthesia six fetal sheep at 124-135 days of gestation were instrumented with inflatable occluders around both common carotid arteries, an inductive flow probe around one external carotid artery, and arterial catheters to measure carotid sinus and aortic pressure. In acute experiments, the occluders were inflated on one side, or the other, or both sides simultaneously, while carotid blood flow, driving pressures and fetal heart rate were determined. Ipsi- and bilateral occlusion reduced carotid blood flow from about 42 ml/min to 10-0 ml/min and decreased sinus pressure from 39 mmHg to 29.1+/-2.9 (mean+/-s.d.) and 16.7+/-3.7 mmHg, respectively. Occlusion of the contralateral carotid artery increased ipsilateral carotid blood flow from 45+/-10 ml/min to 64+/-14 ml/min within 0.2 sec. Heart rate and aortic and sinus pressures did not change appreciably. Analysis of an analogue resistance network demonstrated that the observed carotid flow increases (less than twice normal) do not require changes of vascular resistances.It is concluded that the fetal sheep, as in the adult of many species, possesses an efficient carotid collateral system.     

The influence of maternal oxygen inhalation for 30 to 60 minutes on fetal oxygenation

Healthy parturients with uterine displacement received oxygen inhalation before and during spinal anesthesia for elective cesarean section. Oxygen was administered through a mask (group OH2 : 20 cases) or via a nasal cannula (group OH1: 20 cases) for 33 to 69 minutes. All patients were in the right lateral position prior to spinal block and were in the left tilt after the anesthesia. The fetal blood-gas values were relatively evaluated among the OH2, OH1 and OH groups which received oxygen via a cannula for 9 to 17 minutes. The maternal artery PO2 values for the OH2 group (the mean: 491.7 +/- 61.4mmHg) were significantly higher than those for the OH1 and OH groups (244.5 +/- 28.0 and 225.0 +/- 62.9mmHg, respectively). The umbilical vein PO2 (46.1 +/- 7.5mmHg) and SO2 (87.6 +/- 6.3%) of the OH2 group were also significantly greater than those of the other groups (PO2: 36.1 +/- 4.1mmHg, SO2: 77.3 +/- 6.0% in the OH1 group and PO2: 37.5 +/- 6.4mmHg, SO2: 77.6 +/- 10. 3% in the OH group, respectively). The Apgar scores and both the maternal and fetal acid-base values for all groups were excellent. The umbilical vein to artery PO2 and SO2 gradients of the OH2 group were significantly greater than those of the other groups. It is emphasized that maternal hyperoxia with uterine displacement improves fetal oxygenation without adversely affecting the fetal acid-base state, even if it is excessive and maintained for 60 minutes.     

Effect of hypoxia on the auditory system of goat fetuses during extrauterine incubation

AIM: To investigate the effect of hypoxia on the auditory system in fetuses, we attempted to analyze the auditory brainstem response, the middle latency response, and changes of several physiological parameters of goat fetuses during extrauterine incubation. METHODS: We conducted extrauterine incubation of five goat fetuses at around 127days of gestation (term = 148 days). Their physiological parameters, such as fetal heart rate, mean blood pressure, flow rate of carotid artery, as well as the auditory brainstem response and middle latency response, were recorded prior to and during hypoxia, and the two sets of data were compared with each other. RESULTS: In all five cases, the fetal heart rate decreased from 178 +/- 12.2 b.p.m. to 144 +/- 15.2 b.p.m. during hypoxia, while mean blood pressure and flow rate of carotid artery increased from 37.3 +/- 3.7 mmHg to 43.2 +/- 5.1 mmHg, and from 38.5 +/- 5.5mL/min to 47.0 +/- 5.1 mL/min, respectively. The latency of the auditory brainstem response's wave V and of the middle latency response's Pa wave elongated from 5.24 +/- 0.24 ms to 5.69 +/- 0.20 ms, and from 19.2 +/- 1.6 ms to 20.9 +/- 1.4 ms, respectively. CONCLUSIONS: Although fetal compensatory reactions, such as increases in mean blood pressure and flow rate of carotid artery during hypoxia were recognized, elongation of latency, and decrement of amplitude were observed in the auditory brainstem response and middle latency response. These results suggest that hypoxia itself influences the auditory system of the fetus.     

Contribution of the Bohr effect to the fall in fetal PO2 caused by maternal alkalosis

A decrease in the PO2 of fetal arterial blood is observed in maternal alkalosis caused by hyperventilation in labour or exercise. The contribution of altered blood oxygen affinity to this effect was studied experimentally and by computer simulation of placental gas exchange. Thirteen guinea pigs near term of pregnancy were anesthetized and the right atrium of the fetus was catheterized to enable continuous and simultaneous measurement of PO2 and PCO2 by mass spectrometry. An infusion of base was given through a catheter in the descending aorta of the dam and the effect on fetal respiratory gas tensions observed. The mean change in maternal arterial pH measured in blood taken from a femoral artery was 0.07 +/- 0.04 (mean +/- S. D.). There was an immediate decrease in PO2 in the right atrium of the fetus, but no consistent alteration in PCO2. Two minutes after the start of the infusion, PO2 had fallen by 3.2 +/- 1.6 Torr (p less than 0.001) and PCO2 had risen by 1.7 +/- 1.8 Torr (not significant). The experiments were simulated using a mathematical model of placental gas exchange in the guinea pig. The model was able to predict the change in fetal arterial PO2, given numerical values for the pH, PO2 and PCO2 of fetal and maternal arterial blood prior to infusion of base and for maternal blood during the infusion of base. These values were obtained from the experimental data. Other input variables of the model were maternal and fetal hematocrit and DPG concentration, and the rates of blood flow on the two sides of the placenta.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of a systemic arteriovenous fistula on the pulmonary arterial blood pressure in the fetal sheep.

In order to investigate whether systemic arteriovenous fistula occurring during the fetal period could induce pulmonary hypertension at birth, a fistula was surgically created between the carotid artery and jugular vein of fetal lambs at 120 days' gestation. Mean pressures in the left pulmonary artery, aorta, atrium and ventricles were measured at birth in seven experimental animals and in five control animals. Mean left pulmonary pressure was significantly higher in the lambs with fistula as compared with the control group, suggesting that prenatal occurrence of systemic arteriovenous fistula may induce fetal pulmonary hypertension. The present study provides a new animal model that could be relevant for the study of mechanisms regulating pulmonary vascular tone in the perinatal period.     

Effects of fetal breathing movements on umbilical venous blood flow in fetal lambs

The effects of fetal breathing movements on the blood flow pattern in the common umbilical vein were studied in six chronically instrumented fetal lambs between 106 and 143 days gestation. Umbilical venous blood flow was measured with an electromagnetic flow transducer around the intra-abdominal common umbilical vein. Fetal breathing movements were recorded by means of an intratracheal catheter. During rapid irregular breathing movements instantaneous umbilical venous blood flow showed undulations with the frequency of the breathing movements. An inspiratory movement, characterized by a fall in tracheal pressure (mean +/- S.D. = 5.3 +/- 1.7 mmHg) was accompanied by a decrease in instantaneous umbilical venous blood flow (mean +/- S.D. = 10.5 +/- 2.8%). This decrease in umbilical blood flow during inspiration was accompanied by an increase in intra-abdominal pressure. A much greater decrease (mean +/- S.D. = 40.6 +/- 18.4%) in instantaneous umbilical venous blood flow occurred during deep inspiratory efforts (mean pressure drop +/- S.D. = 15.5 +/- 4.3 mmHg), accompanied by marked increases in intra-abdominal pressure. Isolated expiratory efforts resulted in an increase in both tracheal (mean +/- S.D. = 6.3 +/- 2.6 mmHg) and intra-abdominal pressure, while umbilical venous blood flow decreased (mean +/- S.D. = 33.5 +/- 21.3%). These observations show the great influence of fetal respiratory movements on the blood flow pattern in the common umbilical vein. The changes in instantaneous umbilical venous blood flow are possibly brought about by changes in intra-abdominal pressure.     

Plasma endothelin-1 and atrial natriuretic peptide levels during prolonged (24-h) non-acidemic hypoxemia in fetal goats.

OBJECTIVE: The purpose of this study was to investigate the effects of prolonged (24-h) non-acidemic hypoxemia on plasma endothelin-1 and atrial natriuretic peptide (ANP) in fetal goats. METHODS: During continuous infusion of nitrogen into the maternal trachea, fetal plasma endothelin-1 and ANP levels were measured in nine chronically instrumented goat fetuses at 117-129 days' gestation. Endothelin-1 and ANP were measured by radioimmunoassay. RESULTS: Fetal arterial pO(2) decreased significantly from 23.1 +/- 1.0 mmHg (control) to 15.2 +/- 0.9 mmHg during the first 2 h of hypoxemia and to 15.7 +/- 1.1 mmHg at the end of the experimental period of hypoxemia. The plasma endothelin-1 concentration increased from 10.6 +/- 1.9 pg/ml to 20.4 +/- 4.3 pg/ml (p < 0.05) during the first 2 h and was 19.7 +/- 2.4 pg/ml (p < 0.01) at the end of the experimental period. The plasma ANP concentration also increased, from 20.3 +/- 5.5 pg/ml to 23.0 +/- 4.7 pg/ml in the first 2 h and then to 58.0 +/- 8.8 pg/ml (p < 0.05) at the end of the experimental period. There was a significant negative correlation between fetal plasma endothelin-1 and pO(2), but no significant correlation was found between fetal plasma ANP and pO(2). CONCLUSIONS: Prolonged non-acidemic hypoxemia induces a continuous increase in fetal plasma endothelin-1 and ANP levels. Fetal plasma ANP increases time-dependently but endothelin-1 remains constant during hypoxemia.     

Umbilical artery pulsatility index and placental vascular resistance during acute hypoxemia in fetal lambs

The effect of hypoxemia on the pulsatility index (PI) of the umbilical artery flow velocity waveform and placental vascular resistance was studied. Fetal hypoxemia was induced by maternal breathing of a low-oxygen gas mixture. Umbilical venous blood flow was measured with an electromagnetic flowmeter. Placental vascular resistance (PVR) was defined as the ratio perfusion pressure (mean arterial pressure minus umbilical venous pressure) and umbilical blood flow. Umbilical artery velocity waveforms were obtained by a 5-MHz pulsed Doppler device around one umbilical artery in 4 lambs and by a transcutaneous 4-MHz continuous wave Doppler transducer in 3 lambs. Fetal arterial oxygen content was lowered from 2.28 +/- 0.18 to 0.93 +/- 0.15 mM (p less than 0.05), while pCO2 and pH remained unchanged. Control values of the hemodynamic variables were compared with values during deepest hypoxemia. Fetal heart rate, mean arterial and umbilical venous pressure, PVR and the umbilical artery PI did not significantly change, whereas umbilical blood flow increased from 436 +/- 64.7 to 491 +/- 65.9 ml/min (p less than 0.05) during deepest hypoxemia. Individual regression analysis, however, showed a significant inverse correlation of umbilical venous pressure whereas PVR had a positive correlation with actual oxygen content. It is concluded that acute fetal hypoxemia slightly decreases PVR, but does not affect the umbilical artery PI in sheep. Decreasing fetal oxygenation is associated with an increase in pressure in the umbilical vein.     

Effect of arginine vasopressin on arterial oxygen partial pressure in the chronically catheterized fetal lamb

Fetal plasma 2,3-Diphosphoglycerate (2,3-DPG) and glucose levels were observed during infusion of arginine vasopressin into 6 chronically catheterized fetal lambs. Low dose infusion of arginine vasopressin (5-10 mIU/min.) did not change fetal arterial blood gases significantly. At a high concentration of vasopressin (20-40 mIU/min.), infusion for 60 minutes increased fetal arterial pO2 by approximately 5 mmHg (p less than 0.005 by paired t-test), and decreased pCO2 by approximately 2 mmHg (p less than 0.005 by paired t-test) without significant changes in pH. Neither low nor high dose infusion of arginine vasopressin was accompanied by significant changes in 2,3-DPG or the glucose level.     

Perinatal adaptive response of the adrenal and carotid blood flow in sheep fetuses subjected to total cord occlusion.

OBJECTIVE: To investigate the perinatal adaptive response of the adrenal blood flow/adrenal fractional moving blood volume (AFMBV) and carotid blood flow (CBF), in sheep fetuses subjected to severe acute intrauterine hypoxia/asphyxia induced by total cord occlusion. METHODS: Adrenal blood flow velocity, AFMBV and CBF were measured in 13 exteriorized fetal sheep; eight of them underwent total umbilical cord occlusion to induce severe acute hypoxia/asphyxia. Five lambs were used as sham controls. Middle adrenal artery pulsatility index (MAAPI) and mean velocity (MAAMV) were recorded with pulsed Doppler ultrasound. AFMBV was estimated using power Doppler ultrasound. CBF was recorded with a transonic flowmeter. In the neonatal period, after resuscitation all lambs were followed for a 4-hour period and AFMBV and CBF were recorded. Mean arterial blood pressure (MABP) and fetal heart rate were recorded continuously. Arterial cortisol levels were measured at the beginning and at the end of the fetal and neonatal periods. RESULTS: Following the total cord occlusion, there was a significant reduction in the CBF, MABP, and heart rate and adrenal flow/AFMBV after 2, 4 and 5 min, respectively. Cortisol levels in the asphyctic lambs at the end of the cord occlusion were significantly lower than those in controls. After resuscitation, the asphyctic lambs showed increased AFMBV and cortisol levels, and reduced MABP as compared to control lambs. No differences were found in CBF, MAAPI and MAAMV. Thereafter, no differences were observed between the two groups in any of the studied parameters. At the end of the cord occlusion period, there was a significant correlation between AFMBV and MABP (r=0.69), between AFMBV and CBF (r =0.65) and between CBF and MABP (r=0.89). CONCLUSION: During severe acute intrauterine hypoxia, the fetal lamb is able to maintain the blood flow to the brain and the adrenal gland for 3-5 min. Changes in the AFMBV and the CBF were highly correlated to the changes in MABP. Adrenal FMBV and cortisol levels were higher in lamb neonates exposed to severe intrauterine asphyxia.     

Diameters of the common carotid artery and aorta change in different directions during acute asphyxia in the fetal lamb

The aim of this experimental ultrasound study on six fetal lambs was to evaluate how blood flow variables and vessel diameters of the descending aorta and the common carotid artery change during fetal asphyxia in the acute preparation. When acute asphyxia was induced by obstructing the maternal aortic blood flow all fetuses reacted with significant decrease in the aortic diameter and blood flow. In the common carotid artery vessel diameter and the blood flow increased significantly. The results support the theory of a brain sparing effect during fetal distress with significant changes of blood vessel diameters occurring in opposite directions in the aorta and the common carotid artery, thereby contributing to the centralisation of circulation.     

Oxygenation status of primary and recurrent squamous cell carcinomas of the vulva

INTRODUCTION: Cancers of the vulva are relatively rare and, therefore, little is known about the pathophysiological role of tumor oxygenation in this entity. METHODS: Data are presented on the oxygenation status of primary (n = 15) and recurrent (n = 19) cancers of the vulva, as measured by the Eppendorf pO2 histography system. RESULTS: Contrary to other tumor entities, no significant differences in the oxygenation status between primary (median pO2 = 13 mmHg; hypoxic fraction < or = 5 mmHg = 37%) and recurrent (median pO2 = 11 mmHg; hypoxic fraction < or = 5 mmHg = 45%) tumors were found. Oxygenation was significantly lower in cancers of the vulva than in the subcutis. Anemic patients had significantly poorer tumor oxygenation compared with patients whose cHb values were within the normal range (p = 0.02). CONCLUSIONS: The oxygenation of vulvar cancers is similar to other tumor entities, but does not show more severe hypoxia in recurrent cases. Anemia is associated with a poorer oxygenation status in vulvar cancers, whereas in the normal tissue no impact of cHb values on the median pO2 was observed.     

Evaluation of fetal right coronary artery blood flow velocimetry

OBJECTIVES: In the present study fetal right coronary artery blood flow velocimetry was assessed. DESIGN: The prognostic value of the fetal right coronary artery blood flow velocimetry was evaluated in relationship with parameters of newborn's condition after birth. MATERIAL AND METHODS: The study was performed in 102 cases of pregnancies complicated by pregnancy induced hypertension. Blood flow velocimetry was visualized from fetal right coronary artery and correlated with perinatal outcome parameters. RESULTS: Fetal coronary blood flow velocimetry was visualized only in 11 cases. Coronary blood flow velocimetry visualisation correlated with each parameter of after-birth evaluation. The method has the highest specificity (97.7%) and positive prognostic value (85%) concerning evaluation of newborn's condition. CONCLUSIONS: Fetal right coronary artery blood flow velocimetry visualisation is a late sign of chronic fetal hypoxia. This seems to be a factor which causes maximal coronary vessels dilatation and allows oxygenation of fetal heart muscle.