Search PubMed⌕ Search

Biomedical subjects

J A Thorp

Publications and source records attributed to J A Thorp.

48 records · Page 3Linked to original sources
PubMed1991

Epidural analgesia and cesarean section for dystocia: risk factors in nulliparas.

A retrospective study assessing the effect of epidural analgesia in labor on the incidence of cesarean section was performed. The first 500 consecutive nulliparas meeting the following criteria were included in this study: term (37 weeks or longer) and singleton gestation, cephalic presentation, spontaneous onset of labor, and 5 cm or less of cervical dilation on admission. Patients were grouped according to their rate of cervical dilation in early labor (greater than or equal to 1 cm/hr, and less than 1 cm/hr) and the timing of epidural placement (none, early, or late). There was no effect of epidural analgesia on the incidence of cesarean section for fetal distress. The incidence of cesarean section for dystocia was significantly greater (p greater than 0.000001) in the epidural group (15.6%) than in the nonepidural group (2.4%). The greatest effect of epidural analgesia on the incidence of cesarean section for dystocia was observed in nulliparas who dilated at slower rates (less than 1 cm/hr) in early labor and who had epidural analgesia placed at 5 cm or less of cervical dilation (20.6% versus 3.4%, relative risk of 6, p less than 0.0005). The increase of cesarean section for dystocia associated with epidural analgesia could not be accounted for when other possibly confounding variables were studied. Both the dilation rate prior to epidural placement and the cervical dilation at epidural placement were significantly correlated to frequency of cesarean section for dystocia (p less than 0.01). This study suggests that epidural analgesia in labor may increase the incidence of cesarean section for dystocia in nulliparas.

Adolescent↗
PubMed1990

Response of placental vasculature to high glucose levels in the isolated human placental cotyledon.

We report the effect of high glucose infusion on vascular resistance in isolated human placental cotyledons perfused with Krebs-Ringer-bicarbonate solution containing 80 mg/dl (4.4 mmol/L), 160 mg/dl (8.8 mmol/L), or 320 mg/dl (17.6 mmol/L) D-glucose (n = 6). Placental vascular resistance remained constant during 25-minute perfusion periods with 80 mg/dl followed by 160 mg/dl glucose solution. Subsequent perfusion with 320 mg/dl glucose produced a significant increase in placental vascular resistance. Placentas were also studied in which the placental cotyledon was sequentially perfused for 25-minute periods with solutions containing glucose at 80 mg/dl followed immediately by 320 mg/dl (n = 5). Placental vascular resistance remained constant throughout perfusion with 80 mg/dl glucose solution but increased significantly after beginning perfusion with 320 mg/dl glucose. We conclude that the increase in placental vascular resistance appears to be a function of the high glucose level rather than the duration of glucose perfusion.

Arteries↗
PubMed1990

Hyperkalemia after irradiation of packed red blood cells: possible effects with intravascular fetal transfusion.

Plasma potassium, calcium, and albumin concentrations in irradiated blood, and in fetal blood before and after transfusion, were measured. Dangerously high plasma potassium levels were observed in some units of irradiated packed red blood cells (range, 13.9 to 66.5 mEq/L; mean, 44.7 mEq/L) and could be one possible explanation for the high incidence of fetal arrhythmia associated with fetal intravascular transfusion. There are many factors operative in the preparation of irradiated packed red blood cells that may predispose to high potassium levels: the age of the red blood cells, the number of procedures used to concentrate the blood, the duration of time elapsed from concentration, the duration of time elapsed from irradiation, and the hematocrit. Use of fresh blood, avoidance of multiple packing procedures, limiting the hematocrit in the donor unit to less than or equal to 80%, and minimizing the time between concentration, irradiation and transfusion may minimize the potassium levels, and therefore making an additional washing procedure unnecessary.

Arrhythmias, Cardiac↗
PubMed1990

Effects of epidural analgesia: some questions and answers.

The effects of epidural analgesia on first labors have been studied by Thorp and colleagues. One study has been published and is the subject of a question-and-answer discussion, presented here. In this study 711 consecutive nulliparous women at term, with spontaneous onset of labor and cephalic presentation, were divided into one group (n = 447) who received epidural analgesia in labor and another group (n = 264) who received narcotics or no analgesia. The frequency of cesarean section for dystocia was significantly greater (p less than 0.005) in the epidural group (10.3%) than in the nonepidural group (3.8%), even after selection bias was corrected and the variables of maternal age and race; gestational age; cervical dilatation on admission; use, duration, and maximum infusion rate of oxytocin; labor duration; presence of meconium; and birth weight were controlled. For both groups the frequency of cesarean section for fetal distress was similar (p less than 0.20), and the frequency of low Apgar scores at 5 minutes and cord blood gas values showed no significant differences. The authors concluded that "epidural analgesia in labor may increase the incidence of cesarean section for dystocia in nulliparous women".

Analgesia, Epidural↗
PubMed1990

Maternal lithium therapy and polyhydramnios.

Lithium is widely used in the treatment of bipolar affective disorders, and teratogenic effects include cardiovascular abnormalities, notably Ebstein anomaly. The most common side effect in the patient taking lithium is polyuria, a form of nephrogenic diabetes insipidus. We report the case of a manic-depressive gravida on lithium therapy who developed polyhydramnios in her last trimester. Because lithium crosses the placenta, we postulate that, by a similar mechanism, lithium may cause fetal polyuria which results in polyhydramnios.

Adult↗
PubMed1989

Routine umbilical cord blood gas determinations?

Between 1986 and 1988, 1924 term nulliparous patients with spontaneous onset of labor were studied to assess the importance of obtaining umbilical cord blood gas levels on all deliveries. The umbilical cord arterial and venous pH values (expressed as mean +/- 2 SD) were 7.24 +/- 0.14 (n = 1694) and 7.32 +/- 0.12 (n = 1820), respectively. The incidence of newborn depression (1- or 5-minute Apgar score less than 7) was 14.1%; of these depressed newborns, the incidence of normal umbilical cord arterial pH values (greater than or equal to -2 SD) was 77.8%. Of the vigorous newborns, there was a 2.1% incidence of umbilical cord arterial blood acidemia. Umbilical cord arterial blood acidemia in vigorous newborns was not highly predictive of specific morbidity in the immediate newborn period. Regression analysis demonstrated the umbilical cord arterial pH to correlate best with the Apgar scores when compared with all other arterial or venous blood gas measurements. We reached the following conclusions: (1) that obtaining cord arterial pH values in vigorous newborns should be considered since the values will provide objective documentation or normal fetal acid base balance in 98% of infants. (2) Only a cord arterial pH determination is recommended since it reflects fetal or newborn status more accurately than all other measurements. Additional measurements increase the likelihood of abnormal results and do not contribute to neonatal management. (3) An umbilical cord blood pH value is extremely useful in ruling out the diagnosis of birth asphyxia in the depressed newborn.

Acid-Base Equilibrium↗
PubMed1989

The effect of continuous epidural analgesia on cesarean section for dystocia in nulliparous women.

Epidural analgesia in labor is generally accepted as safe and effective and therefore has become increasingly popular. However, little is known regarding the effect of epidural analgesia on the incidence of cesarean section for dystocia in nulliparous women. During the first 6 months of 1987 we studied 711 consecutive nulliparous women at term, with cephalic fetal presentations and spontaneous onset of labor. Comparison of 447 patients who received epidural analgesia in labor with 264 patients who received either narcotics or no analgesia was performed. The incidence of cesarean section for dystocia was significantly greater (p less than 0.005) in the epidural group (10.3%) than in the nonepidural group (3.8%). There remained a significantly increased incidence (p less than 0.005) of cesarean section for dystocia in the epidural group after selection bias was corrected and the following confounding variables were controlled by multivariate analysis: maternal age, race, gestational age, cervical dilatation on admission, use of oxytocin, duration of oxytocin use, maximum infusion rate of oxytocin, duration of labor, presence of meconium, and birth weight. The incidence of cesarean section for fetal distress was similar (p greater than 0.20) in both groups. There were no clinically significant differences in frequency of low Apgar scores at 5 minutes or cord arterial and venous blood gas parameters between the two groups. This study suggests that epidural analgesia in labor may increase the incidence of cesarean section for dystocia in nulliparous women.

Analgesia, Epidural↗
PubMed1989

The effect of magnesium sulfate tocolysis on the fetal biophysical profile.

The biophysical profile has proved to be a valuable tool for the assessment of fetal well-being, independent of gestational age. Magnesium sulfate is commonly used as a tocolytic agent, yet relatively little is known about its effects on the biophysical activities of the fetus. To investigate the effects of magnesium sulfate on the biophysical profile, we performed serial studies on patients who received tocolytic therapy with this agent because of preterm labor. A total of 16 women with 22 fetuses at 26 to 34 weeks' gestation in spontaneous preterm labor were studied. An initial biophysical profile was performed at the time of admission, and a second examination was performed when maternal serum magnesium levels reached 6 to 8 mg/dl. On admission all fetuses had reactive nonstress test results and 21 of 22 (95%) demonstrated sustained fetal breathing movements. With magnesium sulfate tocolysis, 50% of fetuses had nonreactive nonstress test results, and only 4 of 22 (18%) demonstrated sustained fetal breathing movements. Fetal tone, gross body movements, and amniotic fluid volume were found to be unaffected by magnesium sulfate tocolysis.

Adult↗
PubMed1988

Comparison of the vasoactive effects of leukotrienes with thromboxane mimic in the perfused human placenta.

Vasoactive effects of leukotrienes and thromboxane mimic were tested in the perfused human placental cotyledon. Tissue viability was demonstrated by oxygen consumption and by carbon dioxide and lactate production. Vasoconstrictive effects of leukotrienes B4, C4, and D4 were compared with those of a known potent vasoconstrictor, thromboxane mimic (U 46619). The leukotrienes and thromboxane mimic were administered as bolus injections into a chorionic plate artery in doses ranging from 10(-6) to 25 micrograms. In each placenta only one leukotriene was compared with thromboxane mimic. Vasoconstrictive effects were determined by maximum increases in resistance occurring after each injection. Thromboxane mimic caused significantly greater increases in resistance than any of the leukotrienes (p less than 0.001). Thromboxane mimic and leukotriene D4 had significantly lower threshold doses than leukotriene B4 or C4 (p less than 0.001). We concluded: (1) Thromboxane mimic is a potent vasoconstrictor in the human placental vasculature; (2) leukotrienes also cause vasoconstriction but are much less potent than thromboxane; (3) thromboxane mimic and leukotriene D4 have vasoconstrictor effects at significantly lower (p less than 0.001) concentrations than leukotriene B4 or C4.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1988

Low-dose aspirin inhibits thromboxane, but not prostacyclin, production by human placental arteries.

Preeclampsia is associated with increased thromboxane and decreased prostacyclin production by the placenta. Low-dose aspirin can selectively inhibit thromboxane production in the adult circulation, but its effects on placental vascular production of thromboxane and prostacyclin are incompletely understood. We therefore studied the effects of low-dose aspirin on the production rates of prostacyclin and thromboxane, with and without vasoconstricting doses of angiotensin II, in human placental arteries. Chorionic plate arteries were incubated and samples were assayed for thromboxane and prostacyclin by radioimmunoassay of their stable metabolites. Production rates for prostacyclin were similar in the control, aspirin, angiotensin II, and angiotensin II plus aspirin groups. Mean (+/- SEM; n = 8) thromboxane production rates in the aspirin (1.4 +/- 0.5 pg/mg/hr) and angiotensin II plus aspirin (2.9 +/- 0.6 pg/mg/hr) groups were significantly lower (p less than 0.05) than values in the control (8.6 +/- 2.7 pg/mg/hr) and angiotensin II (6.7 +/- 1.3 pg/mg/hr) groups. We conclude that low-dose aspirin significantly decreases production of thromboxane in placental arteries both with and without vasoconstricting doses of angiotensin II.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Effects of high-dose oxytocin augmentation on umbilical cord blood gas values in primigravid women.

Active management of labor for term primigravid women with singleton, vertex presentations is associated with significant decreases in incidence of cesarean section and duration of labor, without adversely affecting major perinatal outcome variables. Concern has been expressed that high-dose oxytocin augmentation may increase the incidence of fetal compromise. With active management of labor, 43% of 1423 primigravid women received high-dose oxytocin augmentation during an 11-month period. Umbilical cord blood gas values from those who received high-dose oxytocin augmentation were compared with values in those who received no oxytocin. The mean arterial pH value in the no oxytocin group was 7.24 +/- 0.07, which is not significantly different (p greater than 0.10) from that of the oxytocin-augmented group, 7.23 +/- 0.07. Similarly, all other arterial and venous umbilical cord gas parameters were unaffected by high-dose oxytocin augmentation (p greater than 0.10). Our values were compared with other published values where labor was not managed according to the principles of active management of labor, and no differences were found. We report the largest series of cord blood pH values in primigravid women and conclude that there is no adverse effect of high-dose oxytocin augmentation or active management of labor on umbilical cord blood gas values at delivery.

Adult↗