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Biomedical subjects

M M Abitbol

Publications and source records attributed to M M Abitbol.

At least 37 records · Page 2Linked to original sources
PubMed1987

Umbilical flow in the normal and pre-eclamptic placenta. A study in vitro.

In order to develop a simple in vitro method for assessing adequacy of placental perfusion, umbilical flow was measured in placentae from 10 normal control women and from 10 women with pre-eclampsia, by infusing through the umbilical arteries a heparinized 0.9% saline solution. The average induced umbilical flow in placentae from uneventful pregnancies was 276 +/- 16 SE ml/min compared with 163 +/- 12 ml/min (p less than 0.001) in the pre-eclamptic group. In angiographic studies, 79 +/- 2 SE% of the cotyledons from the normal series, and only 56 +/- 3% (p less than 0.001) from the pre-eclamptic series were functional. Additionally, gross and histological examination revealed three distinct types of cotyledon. Placental areas that blanched following saline infusion showed no blood in the collapsed villi or in the intervillous space; areas distinguished by a ruddy appearance following perfusion showed blood trapped in the villi and in the intervillous space; in a third area, the findings were mixed. When compared with placental zones identified by perfusion with 5% Hypaque solution, these three anatomical regions corresponded to normal, reduced, or absent flow (blanched, intermediate, or ruddy regions, respectively). We conclude that under the conditions of this in vitro study, pre-eclamptic placentae had a greater proportion of umbilical perfusion deficits than had normal placentae.

Female↗
PubMed1986

Arterial PO2, PCO2, and pH versus transcutaneous PO2 and PCO2 and tissue pH in the fetal dog.

In the fetal dog, simultaneous recording by transcutaneous PO2 and PCO2 and tissue pH electrodes were compared to corresponding arterial values during hypoxic episodes produced by occlusion of the maternal abdominal aorta. Before occlusion, the differences between the paired values were minimal. Under anoxic conditions, expected changes in the peripheral circulation were observed. However, the transcutaneous PO2 was lower, the transcutaneous PCO2 much higher, and the tissue pH much lower than in blood. Continuous electrodes demonstrate changes resulting from gas and hydrogen ion coming from cells more readily than blood because they are closer to the former. Additionally, carbon dioxide and hydrogen ion are buffered to a greater degree in blood than in cells. Consequently, under conditions of stress and active metabolism, PCO2 is higher while PO2 and pH are lower in cells than in blood. When compared with monitoring of gases and acid-base balance through blood sampling, continuous transcutaneous and intracutaneous monitoring would seem to be more representative of the environment at the cellular level.

Animals↗
PubMed1986

Nonstress test and maternal position.

Antepartum evaluation of 225 low-risk primipara and 262 high-risk primipara and multipara using nonstress testing revealed 53 to be nonreactive when the test was performed in the supine position. When the test was repeated in the lateral decubitus position, it became reactive nonstress testing in 21 of these patients. This group of patients with a supine nonreactive nonstress test and a lateral reactive nonstress test demonstrated an associated compression of the abdominal aorta by the pregnant uterus in the supine, but not the lateral position. This study distinguishes three types of nonreactive nonstress tests: those due to placental insufficiency, those resulting from compression of the abdominal aorta by the pregnant uterus, and the falsely nonreactive. The percentage of false nonreactive nonstress tests results will be reduced by performing the test in the lateral decubitus position.

Aorta, Abdominal↗
PubMed1985

Supine position in labor and associated fetal heart rate changes.

Presented is an investigation of the relationship of fetal heart rate (FHR) deceleration and position of the patient in labor. In a group of 902 laboring patients, 126 (14%) demonstrated late decelerations. Of the 126, 24 (19%) patients demonstrated late decelerations in the supine position only. These occurred during uterine contractions and were associated with reduced femoral arterial blood pressure and amplitude of the capillary pulse of the big toe. A drop in capillary blood pH of the fetal scalp could also be demonstrated. These effects reproducibly appeared and disappeared when supine and lateral positions were alternated. These data would suggest that maternal aortic compression by the pregnant uterus plays a role in the etiology of fetal stress as expressed by changes in fetal heart rate and acid base balance. This effect can be evaluated and monitored simply by recording the pulse pressure of the big toe and femoral arterial pressure. These atraumatic procedures can be applied to any patient.

Aorta, Abdominal↗
PubMed1985

New multipronged fetal scalp electrode: a preliminary report.

Presented is a preliminary report of the use of a new type of scalp electrode (patent pending), which, because of its design, may have the advantage of improved safety. It was used on 40 patients in labor. To confirm the quality of the recording, in all cases, a fetal electrocardiogram was also obtained. Application was achieved on the first attempt in 37 cases in two additional cases on the second attempt. There were no reported cases of the electrode being dislodged during labor. The quality of the recording was reported to be good. There were no reported cases of trauma to the fetal scalp nor were there any cases of infection noted.

Electrodes↗
PubMed1984

Trends in continuous metabolic monitoring during experimental fetal distress.

Intermittent, progressive maternal aortic occlusions were used to produce fetal distress in the fetuses of six pregnant dogs at term. Fetal heart rate and fetal tissue surface pH were continuously recorded and were compared to fetal blood pH, pCO2, pO2 and lactic acid values determined from intermittent sampling. Baseline fetal heart rate was an insensitive indicator of fetal blood pH, tissue surface pH, or of fetal blood lactic acid concentrations. "Delayed" decelerations in fetal heart rate following an occlusive episode were uniformly produced after minimal stress and also did not correlate well with these variables. On the other hand, fetal blood lactic acid concentrations remained elevated even after occlusive episodes were discontinued and other variables had returned to baseline values.

Animals↗
PubMed1982

Fetal heart rate and tissue pH changes associated with repetitive aortic occlusion in the pregnant dog.

Variations in fetal heart rate (FHR) and tissue pH (tpH) were studied simultaneously in 10 pregnant dogs at term during experimental fetal distress produced by subjecting the fetuses to short episodes of acute anoxia, which was produced by occlusion of thr maternal aorta. The fetal response to these anoxic episodes dependent on the initial value of the tpH. With tpH higher than or equal to 7.20, the tpH and FHR showed minimal or no response. With tpH between 7.20 and 7.10, the FHR showed a "delayed" deceleration and there was a sharp decline in tpH. With lower tpH, the variations in FHR and tpH were less accentuated. Also noted were unusual variations, such as "transient" or "irregular" FHR decelerations, and tpH "reactive alkalosis." In this acute experimental situation, tpH seemed to be a very sensitive indicator of fetal anoxia. The combined continuous monitoring of FHR and tpH for the diagnosis of fetal distress deserves further investigation.

Animals↗
PubMed1982

Simplified technique to produce toxemia in the rat: considerations on cause of toxemia.

Under ether anesthesia a silver clip was placed around the abdominal aorta of pregnant rats, thus reducing the uterine blood flow by 35-45%. This resulted in a toxemia-like syndrome comparable to the one previously produced in other animal species. Consideration is given to the hypothesis that, in a similar way, compression of the abdominal aorta by the pregnant uterus in humans produces uterine ischemia leading to toxemia.

Animals↗
PubMed1981

A simplified technique to produce toxemia in the pregnant dog.

In 39 pregnant and six nonpregnant dogs the abdominal aorta was exposed extraperitoneally through a left paralumbar incision, and a vascular occluder and a flow transducer were placed around it. The tubing of the occluder and the wiring of the flow transducer were slipped under the skin and advanced to the back of the neck of the animal. Thus, the aortic blood flow could be progressively reduced and continuously monitored. After 4 to 20 days of blood flow reduction of 35% to 75%, the picture of a moderately severe toxemia appeared in 10 dogs and that of a mild toxemia was seen in the 11 others. Nine animals were eliminated because of premature labor and three were eliminated for surgical complications. The control group (six pregnant animals with a sham operation and six nonpregnant animals with a severe aortic constriction) presented no abnormalities.

Animals↗
PubMed1980

Uterine and ovarian artery blood flow in the rhesus monkey near term.

Uterine and ovarian artery blood flow (UABF and OABF) were measured in six pregnant monkeys near term by means of the electromagnetic flowmeter. The average UABF was 21.4 ml/min and OABF was 1.9 ml/min. Complete aortic occlusion reduced UABF from 21.4 to 2.4 ml/min, while OABF increased from 1.9 to only 2.1 ml/min. In six pregnant monkeys near term, chronic partial constriction of the abdominal aorta for an average of 10 days produced a parallel reduction in UABF but no increased circulation through the ovarian or round ligament arteries. The ovarian arteries were not visualized on angiography in these pregnant monkeys even when the abdominal aorta was acutely or chronically constricted; the uterine arteries were readily seen. The authors concluded that acute or chronic aortic constriction in the pregnant monkey at term results in a noncompensated uterine blood flow (UBF) reduction. The possible implications in pregnant women are discussed.

Animals↗
PubMed1980

Uterine and ovarian artery blood flow in the pregnant dog. Attempt at comparative study in pregnant women.

UABF and OABF were measured in dogs with the electromagnetic flowmeter. In eight nonpregnant animals, UABF was on the average 3.2 ml/min and OABF 0.4 ml/min. In 10 pregnant bitches near term UABF was 27.3 ml/min and OABF 1.3 ml/min. Complete aortic occlusion in the pregnant bitch at term reduces UABF to 2.4 ml/min (loss of 24.9 ml/min) and increases OABF to only 1.6 ml/min (gain of 0.3 ml/min). The conclusion is that most of the blood flow to the uteroplacental unit in the pregnant bitch is channelled through the uterine artery and the marked drop in UABF produced by acute aortic occlusion is not compensated by an increase in OABF. The conditions are different in human pregnancy where the progressive nature of the aortic compression by the pregnant uterus allows, under the most favorable circumstances, the gradual development of a collateral circulation mostly through the ovarian arteries. However, this does not occur all the time as demonstrated by angiographic studies in a series of 12 patients and in similar studies reported in the literature. This could result in a placental insufficiency.

Adult↗
PubMed1978

Inferior vena cava compression in the pregnant dog.

Attempts were made to produce inferior vena cava (IVC) compression in 14 pregnant and 12 nonpregnant bitches. Ligation of the iliac veins, the IVC below the renal veins, or the left renal vein separately produced minimal hemodynamic disturbances. Only ligation of the two renal veins or of the IVC above the renal veins produced a moderate drop in blood pressure and blood flow. Shock and bradycardia, characteristic of the supine hypotension syndrome (SHS) as observed in human subjects, were never observed. Satisfactory collateral circulation was demonstrated radiologically. Since human SHS was not reproduced in the pregnant bitch by compression of the IVC alone, one may conclude that the SHS is not solely caused by the compression.

Animals↗
PubMed1977

Experimental toxemia of pregnancy in the monkey, with a preliminary report on renin and aldosterone.

Experimental toxemia of pregnancy was induced in 8 pregnant monkeys (Macacamulatta) by reducing the abdomiinal aorta to one-third of its original diameter during the last month of gestation. It was characterized by hypertension and proteinuria. In the kidney, light and electron microscopy and immunofluorescence revealed findings similar to those in human toxemia. Focal necrosis in the liver and diffuse hemorrhagic infarctions in the placenta were also observed. Plasma renin activity and aldosterone levels, as determined in blood from the uterine vein, were elevated. None of these changes were found in 4 control animals.

Aldosterone↗
PubMed1977

Aortic compression and uterine blood flow during pregnancy.

To understand the effects of uterine compression on the abdominal aorta in pregnant women, the abdominal aorta in pregnant animals was experimentally constricted. This procedure produced symptoms identical to toxemia in humans. A physical model simulating the human aorta with blood flowing under physiologic pressure, and a "term uterus" pressing on it showed that blood flow reduction thus produced easily could be within the range observed in the toxemic human. Experimental constriction or compression of the abdominal aorta in pregnant animals produced a parallel drop in the femoral artery pulse pressure and uterine artery blood flow. This observation is applicable to pregnant women in the supine position. When the pregnant uterus presses on the abdominal aorta, reduced uterine artery blood flow was noted by following femoral or popliteal artery pulse pressure reduction. In 379 pregnant patients studied, 40% showed a drop in popliteal artery pulse pressure during uterine contraction and 11% during uterine relaxation. During relaxation, this was observed in 16% of primiparous patients and in 6% of multiparious patients.

Animals↗
PubMed1977

Hemodynamic studies in experimental toxemia of the dog.

The following experiments demonstrate that the severity of toxemia is proportional to the degree of reduction in blood flow to the pregnant uterus. Blood pressure and blood flow variations were studied in 21 nonpregnant and pregnant dogs following the placement of a progressive stricture on the abdominal aorta below the renal arteries. The immediate effect of the stricture was a mild hypertension in half of the pregnant dogs; in addition, in all the dogs, the blood flow progressively dropped in the arteries below the stricture (femoral and uterine) while it remained constant in the arteries above (ovarian and renal). In 3 of 5 pregnant dogs the delayed effect of the aortic stricture was hypertension associated with all the other signs of experimental toxemia. Removal of the aortic stricture after 10 days immediately improved the blood flow below the stricture. No noticeable preferential distribution of blood toward the pregnant uterus was noted during the constriction.

Animals↗
PubMed1976

Placental lesions in experimental toxemia in the rabbit.

Unlike the normal human placenta, the normal rabbit placenta, near term, is essentially free of such stigmas of aging as infarcts and syncytial knots. When experimental toxemia is produced in the pregnant rabbit by ligating the terminal aorta to a specific degree of stricture, placental lesions resembling those found in human toxemia are observed; namely, diffuse congestion, old and recent infarcts, and syncytial knots. All the treated animals who exhibited anatomical and clinical signs of toxemia presented, in association, obvious placental lesions; there were, however, some animals which showed infarct but no other signs of toxemia.

Animals↗
PubMed1976

Production of experimental toxemia in the pregnant rabbit.

Experimental toxemia of pregnancy was induced in 51 of 122 rabbits by constriction of the aorta below the renal arteries. The approach was extraperitoneal and dependent on the accuracy in calibrating this stricture between 0.6 and 1.0 mm. Experimental toxemia in the rabbit was characterized by hypertension, proteinuria, weight gain, and reduced weight of the fetus. Blood pressure and blood flow studies distal to the aortic constriction demonstrated a marked diminution of blood supply below the constriction. The light microscopic changes in the kidneys and in the liver were similar to those of human toxemia. The electron microscopic changes consisted of endothelial swelling and subendothelial deposits. In a separate experiment, 22 pregnant rabbits near term had an aortic constriction varying between 0.6 and 1.0 mm. This constriction lasted 4 to 12 days. Glomerular deposits of fibrinogen were demonstrated by immunofluorescence in 20 of 22 animals. The intensity of the immunofluorescence was related to the severity and duration of the aortic stricture.

Animals↗