Maternal Oxygen Research Articles

Fetal cerebral oxygenation and hemodynamics during labour measured by near‐infrared spectroscopy

The failure of modern fetal monitoring techniques to measure either oxygenation or perfusion within the fetal brain may underlie their poor specificity in the detection of intrapartum hypoxia-ischaemia. We have adapted the technique of near-infrared spectroscopy (NIRS) to obtain continuous, quantified measurements of changes in human fetal cerebral oxygenation and blood volume during labour. More than 140 fetuses have been studied at University College London for periods ranging from 10 to 765 minutes. Reciprocal changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin, indicating changing cerebral haemoglobin saturation, have been observed during uterine hyperstimulation with oxytocin, administration of maternal oxygen, changing maternal posture, and late fetal heart rate decelerations. Uterine contraction frequency greater than 1 every 2 minutes was associated with a fall in fetal cerebral oxygenation. A method for quantifying the oxygen saturation of hemoglobin derived from all vascular compartments (SmcO2) is described. There was a significant positive correlation between SmcO2 and umbilical artery pH. Conversely, the base deficit of blood from the umbilical artery showed a negative correlation with SmcO2. Changes in optical pathlength due to probe movement during uterine contractions are a potential source of error in the measurements. Preliminary data obtained using intensity modulated optical spectrometry, a technique that continuously measures optical pathlength, suggest that the maximum contribution of movement artifact to observed changes in chromophore concentration is 12%. These preliminary data demonstrate that NIRS is capable of measuring fetal cerebral oxygenation and blood volume during labour. However, because none of the fetuses in this study was born with evidence of intrapartum hypoxia-ischaemia, we cannot comment on the value of NIRS as a means of intrapartum surveillance. Further developments, including the routine use of IMOS and rigorous testing by randomized trials, will be required before this question is answered. MRDD Research Reviews 3:59–68, 1997. © 1997 Wiley-Liss, Inc.

Fetal cerebral oxygenation and hemodynamics during labour measured by near-infrared spectroscopy

The failure of modern fetal monitoring techniques to measure either oxygenation or perfusion within the fetal brain may underlie their poor specificity in the detection of intrapartum hypoxia-ischaemia. We have adapted the technique of near-infrared spectroscopy (NIRS) to obtain continuous, quantified measurements of changes in human fetal cerebral oxygenation and blood volume during labour. More than 140 fetuses have been studied at University College London for periods ranging from 10 to 765 minutes. Reciprocal changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin, indicating changing cerebral haemoglobin saturation, have been observed during uterine hyperstimulation with oxytocin, administration of maternal oxygen, changing maternal posture, and late fetal heart rate decelerations. Uterine contraction frequency greater than 1 every 2 minutes was associated with a fall in fetal cerebral oxygenation. A method for quantifying the oxygen saturation of hemoglobin derived from all vascular compartments (SmcO2) is described. There was a significant positive correlation between SmcO2 and umbilical artery pH. Conversely, the base deficit of blood from the umbilical artery showed a negative correlation with SmcO2. Changes in optical pathlength due to probe movement during uterine contractions are a potential source of error in the measurements. Preliminary data obtained using intensity modulated optical spectrometry, a technique that continuously measures optical pathlength, suggest that the maximum contribution of movement artifact to observed changes in chromophore concentration is 12%. These preliminary data demonstrate that NIRS is capable of measuring fetal cerebral oxygenation and blood volume during labour. However, because none of the fetuses in this study was born with evidence of intrapartum hypoxia-ischaemia, we cannot comment on the value of NIRS as a means of intrapartum surveillance. Further developments, including the routine use of IMOS and rigorous testing by randomized trials, will be required before this question is answered. MRDD Research Reviews 3:59–68, 1997. © 1997 Wiley-Liss, Inc.

Effect of pregnancy on maternal oxygen saturation values: use of reflectance pulse oximetry during pregnancy.

Our objective was to evaluate the usefulness of pulse oximetry monitoring in a large population of pregnant patients. We designed our study to measure pulse oximetry saturation in a cross section of 952 obstetric inpatients and outpatients. A group of 366 patients identified as normal were compared with abnormal subgroups. A subgroup of 64 patients with saturation measurements less than 96% were further evaluated. Our results indicated that oxygen saturation values did not change appreciably during the course of pregnancy in normal patients. Hypoxemia (saturation measurement less than 96%) was associated with smoking, and hypoxemia with preterm labor occurred more frequently in patients who smoked. Obesity and magnesium sulfate use appeared to be synergistic in the presence of hypoxemia. We concluded that the routine use of pulse oximetry during pregnancy may not be justified. Smoking, obesity, and magnesium sulfate use have some effect on oximetry in pregnant patients.

Fetal and maternal blood oxygen affinity: A comparative study in llamas and sheep

We compared blood oxygen affinity (P50) and hemoglobin concentration among fetal and maternal llamas and sheep, as respective examples of species native to high and low altitudes. P50, hemoglobin concentration and blood oxygen content were determined at sea level in 16 pregnant llamas, 6 pregnant sheep and their respective fetuses. P50 was similar in fetal llamas and sheep, but maternal llamas had higher blood oxygen affinity than maternal sheep. As a consequence, the P50 difference between mother and fetus was less in llamas than in sheep. Fetal llamas had higher hemoglobin concentrations than fetal sheep. In contrast, the maternal hemoglobin concentrations were similar. The blood oxygen content was higher in fetal and maternal llamas than in fetal and maternal sheep. We conclude that the llama, a species native to the altiplano, has a higher blood oxygen content than the sheep, as determined in the fetus by a high hemoglobin concentration and in the mother by a low P50.

Comparison of angiotensin II type 1 receptor blockade and angiotensin‐converting enzyme inhibition in pregnant sheep during late gestation

1. The effects of antagonism of the maternal renin-angiotensin system (RAS) with either an angiotensin II type 1-(AT1) specific receptor blocker (GR138950) or an angiotensin-converting enzyme (ACE) inhibitor (captopril) were compared in chronically-catheterised ewes and their foetuses during late gestation. 2. Daily from 127 +/- 1 days of gestation until parturition at 145 +/- 2 days, each ewe received i.v. either GR138950 (3 mg kg-1; n = 10), captopril (3 mg kg-1; n = 6) or an equivalent volume of vehicle solution (0.9% w/v saline; n = 10). 3. Within 2 h of drug administration, GR138950 abolished the maternal, but not the foetal, pressor responses to angiotensin II (AII; 100-188 ng kg-1, i.v.; P < 0.05), whereas captopril abolished both the maternal and foetal pressor responses to angiotensin I (AI; 400-750 ng kg-1, i.v.; P < 0.05). 4. On the first day of treatment, maternal blood pressure decreased in all GR138950-treated (-21 +/- 4 mmHg; P < 0.05) and captopril-treated (-13 +/- 5 mmHg; P > 0.05) ewes at 2 h after drug administration. Captopril also significantly decreased foetal blood pressure by 5 +/- 1 mmHg (P < 0.05). However, foetal blood pressure in the GR138950-treated animals remained unchanged. Maternal and foetal heart rates were unaffected by any treatment. Uterine blood flow was significantly reduced within 2 h of both GR138950 (-130 +/- 20 ml min-1; P < 0.05) and captopril (-72 +/- 16 ml min-1; P < 0.05) administration. 5. On the first day of treatment, maternal arterial haemoglobin (Hb) concentration and oxygen (O2) content increased at 2 h in all GR138950-treated and captopril-treated ewes. Foetal arterial pH and oxygenation (O2 content, O2 saturation and Pao2) were reduced by a similar extent in both groups of drug-treated ewes. 6. After one week of daily GR138950 administration, maternal blood pressure decreased from a pretreatment value of 96 +/- 5 mmHg on day 1 to 79 +/- 2 mmHg by day 7 (P < 0.05). Captopril treatment had no long-term effect on maternal blood pressure. Although foetal blood pressure increased by 3 +/- 1 mmHg over a week of vehicle treatment (P < 0.05), no significant differences were observed between the long-term changes in foetal blood pressure in all three groups of animals. 7. There were no long-term effects of drug administration on maternal Hb concentration or oxygenation, or on the foetal haematological parameters. However, changes in maternal PaCo2 observed in the GR138950-treated (+1.4 +/- 0.5 mmHg; P < 0.05) and captopril-treated (+3.3 +/- 1.1 mmHg; P > 0.05) ewes were significantly different from those seen in the vehicle-treated animals (P < 0.05). 8. There were no apparent adverse effects of maternal GR138950 or captopril treatment on foetal viability. 9. The present study demonstrated that administration of either GR138950 or captopril to pregnant ewes effectively blocked the maternal RAS, and caused hypotension and a decrease in uterine blood flow. However, only captopril appeared to cross the placenta to influence directly the RAS of the sheep foetus. This suggests that the fall in foetal oxygenation observed after AT1-specific receptor blockade and ACE inhibition originates primarily from changes in the maternal and/or placental vasculature. Despite these changes, neither GR138950 nor captopril were detrimental to the outcome of pregnancy when foetal blood loss was kept to a minimum.

Lack of a critical cardiac output and critical systemic oxygen delivery during low cardiac output in the third trimester in the pregnant sheep

OBJECTIVE: We sought to determine whether a critical cardiac output and oxygen delivery exist in normal pregnancy. We also sought to determine the role of fetoplacental oxygen demand on maternal oxygen transport variables in response to decreased maternal cardiac output. STUDY DESIGN: We studied 10 adult female sheep, 5 nonpregnant and 5 pregnant. We placed a flow-directed thermodilution catheter in the pulmonary artery and a balloon-tipped catheter in the right atrium of the sheep. We also placed a catheter for pressure monitoring and blood sampling in the descending thoracic aorta in both the mother and fetus. We decreased maternal cardiac output by incremental inflation of the right atrial balloon. We measured maternal cardiac output by intravenous bolus thermodilution technique. We also measured maternal and fetal acid-base status and serum lactate concentrations. We calculated a variety of maternal cardiorespiratory variables, including systemic oxygen delivery, systemic oxygen consumption, and fractional whole body tissue oxygen extraction. RESULTS: The nonpregnant sheep displayed a critical cardiac output below which there was an abrupt decrease in oxygen consumption. In contrast, there was no critical level of cardiac output in the pregnant sheep. Maternal oxygen consumption was linearly dependent on cardiac output. Maximum fractional oxygen extraction was significantly lower in the pregnant sheep than in the nonpregnant sheep. CONCLUSION: States of low cardiac output in the pregnant sheep are associated with a lack of a critical cardiac output; the flow-dependent oxygen consumption observed is the result of either an impairment in tissue oxygen extraction or some degree of metabolic arrest or a combination of both. If this unique cardiac output - oxygen consumption relationship is seen in human pregnancy, it could have significant implications in the care of the critically ill obstetric patient. (Am J Obstet Gynecol 1996;175:222-8.)

Base deficit and oxygen transport in severe preeclampsia

To evaluate the relationship of anaerobic metabolism, as reflected by the calculated base deficit, with oxygen transport and left ventricular function in women with severe preeclampsia. Forty women with singleton pregnancies and severe preeclampsia who met prescribed criteria for invasive hemodynamic monitoring had arterial blood gas and hemodynamic values obtained immediately after placement of a pulmonary artery catheter. Oxygen transport indices were stratified according to the admission base deficit. Linear regression analysis demonstrated a strong negative correlation between the calculated base deficit and the oxygen delivery index (r = -0.64), cardiac index (r = -0.62), and left ventricular stroke work index (r = -0.58). A baseline maternal base deficit exceeding -8.0 mEq/L consistently predicted fetal acidosis, fetal death, and maternal end-organ ischemic injury. The calculated base deficit reliably reflects maternal oxygen transport dynamics and identifies patients at risk for end-organ injury. Ventricular contractility and oxygen delivery decline with mounting oxygen debt.

The effects of xylazine on intrauterine pressure, uterine blood flow, maternal and fetal cardiovascular and pulmonary function in pregnant goats.

To investigate the effects of xylazine on pregnant goats, xylazine induced changes in heart rate (HR), arterial blood pressure (ABP) and arterial blood pH and gases in the mother and fetus, as well as changes in intrauterine pressure (IUP) and uterine blood flow (UBF), were studied using a chronic preparation model of pregnant goats. Intramuscular administration of xylazine (0.2 mg/kg b.w.) caused a marked decrease in HR and ABP of the mother, which remained significantly reduced up to 120 min. In the fetus, a significant decrease in HR and a significant increase in ABP were recorded after only 5 min. Significant decreases of maternal arterial blood pH and oxygen partial pressure (Po2) were observed up to 120 and 30 min after the injection, respectively. Fetal arterial blood pH and Po2 also decreased, but these changes were milder and less persistent than those of the mother. Within 2 to 5 min after the administration of xylazine, IUP began to increase and remained high for about 15 min. Thereafter, there was a frequent periodic increase in IUP. After 5 min, UBF decreased significantly and remained low up to 120 min. A fall in UBF was associated with a rise in IUP. These findings suggested that administration of xylazine to pregnant goats results in a decrease in UBF arising from the induction of uterine contractions, a decrease in circulating blood volume, hypoxemia and acidosis in the mother.

The hemodynamic effects of maternal hypo and hyperoxygenation in healthy term pregnancies

To evaluate the hemodynamic effects of maternal hypo- and hyperoxygenation in normal term pregnancy. Ten healthy women between 35-41 weeks' gestation were exposed to 10% oxygen in inspired air for 10 minutes and, after a 5-minute recovery period, to a stepwise increase in oxygenation with 50 and 100% oxygen for 10 minutes. Maternal ventilation, hemodynamics, and oxygenation were assessed noninvasively, and maternal and fetal vascular responses were assessed with pulsed-wave color Doppler velocimetry. Computerized cardiotocography was used for fetal heart rate (FHR) analysis. Substantial maternal hypoxia was achieved and accompanied by a statistically significant rise in the maternal heart rate (from 89 +/- 11 to 104 +/- 16 beats per minute) and systolic blood pressure (from 123 +/- 13 to 131 +/- 13 mmHg). Doppler measurements demonstrated a statistically significant decline in the pulsatility index (PI) of the maternal internal carotid artery (from 1.8 +/- 0.3 to 1.5 +/- 0.4) and an increase in the uterine artery PI (from 0.60 +/- 0.12 to 0.72 +/- 0.13). Baseline FHR, heart rate variability, and Doppler velocimetry in the umbilical artery and the middle cerebral artery showed no statistically significant changes. Hyperoxia did not cause changes in the maternal circulation, but the FHR decreased significantly (from 142 +/- 12 to 133 +/- 11 beats per minute). Acute short-term hypoxia modifies the maternal circulation, suggesting redistribution of maternal blood flow, but exerts no detectable effects on the healthy fetus. Maternal hyperoxygenation induces no apparent adverse effects.

The effect of epidural opioids on maternal oxygenation during labour and delivery

The effect of epidural opioids on maternal oxygenation during labour and delivery

Fetal endoscopic (‘Fetendo’) surgery: The relationship between insufflating pressure and the fetoplacental circulation

Application of video-endoscopic surgery to the gravid uterus provides a new treatment option for the fetus with a correctable congenital anomaly. “Fetendo” surgery requires temporary enlargement of the uterine cavity to create a working space. Volume expansion of the amniotic space raises intrauterine pressure, which could increase placental vascular resistance and thereby reduce placental blood flow. To test this hypothesis, the authors developed a fetal sheep model to examine the relationship between insufflating pressure and flow in the placental circulation. Fetoplacental blood flow was measured via ultrasonic flow probes placed around the fetal common umbilical artery and the maternal uterine artery in five anesthetized 120-day-gestation ewes. Invasive feto-maternal monitoring permitted synchronous measurement of fetal mean arterial pressure, fetal central venous pressure, maternal mean arterial pressure, amniotic pressure, and fetal oxygen saturation, with calculated values for fetal and maternal placental vascular resistance. Amniotic pressure was raised from 10 mm Hg to 40 mm Hg in 5-mm Hg increments by a combination of saline amnioinfusion and external uterine compression. At amniotic pressures of 20 mm Hg or less, placental blood flow was preserved; however, elevation of amniotic pressure above 20 mm Hg resulted in a significant decrease in placental flow, with concomitant fetal hypoxia. The authors conclude that the relationship between intrauterine pressure, flow in the placental circulation, and fetal oxygen delivery must be considered when selecting intrauterine insufflation pressures for hysteroscopic intervention.

Acute tocolysis for suspected intrapartum fetal distress: maternal effects of terbutaline versus magnesium sulfate

This study was undertaken to determine the maternal hemodynamic impact of terbutaline versus magnesium sulfate in the acute treatment of fetal distress prior to cesarean delivery. Forty-six women were prospectively randomized to receive 0.25 mg subcutaneous terbutaline or 4.0 g intravenous magnesium sulfate for in utero fetal resuscitation before cesarean delivery. There were no significant differences between groups in baseline mean arterial pressure, arterial pressure before and after induction of anesthesia, maternal heart rate, maternal oxygen saturation, estimated blood loss, and pre- and postoperative hematocrits. Magnesium sulfate-treated women received significantly more intraoperative intravenous fluids (2365 +/- 877 ml) than the terbutaline group (1624 +/- 564 ml; P < 0.001). However, mean urine output was significantly greater in the terbutaline group (88 +/- 42 ml/h) than in those treated with magnesium sulfate (61 +/- 26 ml/h; P < 0.03). Terbutaline, the superior agent for acute tocolysis, is not associated with an increase in maternal cardiovascular side effects during anesthesia.

Metabolic costs of viviparity in yellowtail rockfish,Sebastes flavidus

We estimated the energy utilized by developing embryos and larvae of yellowtail rockfish,Sebastes flavidus, by determining the routine metabolic rate of adult females throughout gestation and subtracting the mean metabolic rate of non-gestating fish. The pattern of maternal oxygen consumption during gestation was such that metabolic demands did not become significantly elevated until intra-ovarian embryos had hatched and larvae were being incubated (i.e. 24–28 d post-fertilization). Metabolic rates of females in this latter stage of gestation were 82% higher than spent females and 101% higher than those of non-reproductive males. We determined that 0.08996 cal embryo-1 was consumed during gestation as compared to the change in energy content of embryos from fertilization to birth which was 0.08690 cal embryo-1. The difference between the energy consumed and the energy lost during the 29 d gestation period indicated that extra embryonic sources contributed only 3.4% or 0.00306 cal embryo-1 of the energy utilized after fertilization. Our observations agree with previous work which determined that embryos and larvae ofS. flavidus are primarily lecithotrophic and that the relatively high fecundity ofS. flavidus coupled with a small egg size, rapid embryogenesis and brief gestation period characterize this species as a relative r-strategist within a genus whose species range broadly over the ‘K end’ of the r-K continuum.

Effect of maternal oxygen therapy on placental calcium transport in intrauterine growth retarded rats.

We tested the hypothesis that continuous maternal oxygen (O2) therapy leads to an increase in fetal survival, improvement in fetal growth, and correction of decreased placental calcium (Ca) transport, in pregnant rats who underwent uterine artery ligation. We measured on Day 21 of pregnancy, the unidirectional maternofetal clearance of 45Ca (Kmf45Ca) and 51Cr-EDTA (Kmf51Cr-EDTA) across in-situ perfused placentas of rats randomized on Day 17 to a modified Wigglesworth (bilateral uterine artery ligation) procedure (group WW, n = 8), to modified Wigglesworth and supplemental maternal O2 treatment (FiO2 0.40) (group WWO2, n = 8), or to a sham operation (group Sh, n = 8). Kmf51Cr-EDTA provides a measure of placental "porosity" or passive permeability. Maternal O2 therapy did not improve fetal survival, fetal growth, or placental Ca transport. CONCLUSION AND SPECULATION: Bilateral uterine ligation in the pregnant rat leads to IUGR and decreased placental Ca transport which cannot be corrected by maternal O2 therapy.

Growth deficient fetuses with absent or reversed umbilical artery end-diastolic flow are metabolically compromised.

Controversy continues regarding the clinical relevance of absent or reversed umbilical artery blood flow during diastole. The purpose of this study was to characterize the blood gas and lactate measurements of growth deficient fetuses with absent (ADF) or reversed (RDF) umbilical artery (UA) diastolic flow. In a descriptive study from February 1988 through October 1991, 42 consecutive structurally and karyotypically normal growth deficient fetuses identified to have either ADF or RDF diastolic flow in the UA were studied. Heparinized blood specimens were obtained from them and the pH, PCO2, PO2 and lactate measured. Fourteen of these specimens were obtained from the umbilical vein by cordocentesis and 28 at the caesarean delivery of non-labouring patients. Statistical analyses were performed using Fisher's exact test, Student t-test and linear correlation. All measured parameters in fetuses with ADF or RDF undergoing cordocentesis were significantly abnormal compared to gestational age corrected norms. Both the mean venous and arterial pH of fetuses with RDF were significantly lower than that of fetuses with ADF. With few exceptions, preoperative maternal oxygenation failed to correct the fetal hypoxaemia associated with either ADF or RDF. In the setting of severe fetal growth deficiency secondary to uteroplacental dysfunction, ADF and RDF are clinically reliable indicators of fetal compromise as determined by the umbilical blood gases. RDF is associated with a greater impairment of placental gas exchange than ADF.

Maternal hypoxaemia during labour and delivery: the influence of analgesia and effect on neonatal outcome

The effect of analgesia on the incidence of hypoxaemia was assessed in an unrandomised trial in 51 parturients from the last hour of the first stage of labour until delivery. Women were retrospectively divided into four groups: no analgesia, pethidine with intermittent Entonox, extradural bupivacaine (either infusion of 0.125% or top-ups of 10 ml of 0.25%): and extradural infusion of 0.1% bupivacaine with 2 micrograms.ml-1 fentanyl. The lowest median incidence of desaturation (SpO2 < 94%) was in the extradural bupivacaine group: 0 min.h-1 in the last hour of the first stage and 0.1 min.h-1 in the second stage. The incidence was significantly lower than in the pethidine/Entonox group (1.4 min.h-1) in the last hour of the first stage (p < 0.001) and the extradural bupivacaine/fentanyl group (0.9 min.h-1) and no analgesia group (3 min.h-1) in the second stage (p < 0.05 in both cases). There was no correlation between maternal oxygenation during the second stage and measures of neonatal outcome including Apgar score and umbilical artery and vein blood gases.

The effect of maternal oxygen administration during the second stage of labor on umbilical cord blood gas values: A randomized controlled prospective trial

OBJECTIVE: Our aim was to determine whether supplemental oxygen during the second stage of normal labor affects cord blood gas and cooximetry values. STUDY DESIGN: Patients at term pregnancy were prospectively randomized to the control or treatment group at the onset of the second stage of labor. The treatment group received 10 L/min oxygen by face mask, which result in a mean fractional inspired oxygen concentration of 0.81. RESULTS: There were 86 patients randomized into the study. In the oxygen group there were significantly more cord arterial pH values < 7.20 ( 9 41 vs. 2 44 , p < 0.05). The control group was compared with two subgroups of patients receiving oxygen: those receiving oxygen therapy for ≤ 10 minutes and those receiving oxygen for >10 minutes. Analysis of variance demonstrated significant differences (7.285 ± 0.058, 7.312 ± 0.056, 7.237 ± 0.064; F test 8.3, p = 0.0005). Among several independent vriables, regression analysis demonstrated that only duration of oxygen therapy had a significant inverse relation to cord arterialpH ( F test = 15.6, p = 0.0002). CONCLUSIONS: Prolonged oxygen treatment during the second stage of normal labor resulted in a deterioration of cord blood gas values at birth.

Maternal oxygen consumption and CO 2 production during the peripartum period in normal gestation : [formula omitted], x G. Saade, x B. Leibman, x B. Kirshon, K. Adam, W Baker, x M. Balfort, x Dept. of OB/GYN, Baylor College of Medicine, Houston, TX

Maternal oxygen consumption and CO 2 production during the peripartum period in normal gestation : [formula omitted], x G. Saade, x B. Leibman, x B. Kirshon, K. Adam, W Baker, x M. Balfort, x Dept. of OB/GYN, Baylor College of Medicine, Houston, TX

Maternal oxygen transport, hemodynamic and metabolic variables as predictors of fetal acidemia in the unanesthetized pregnant sheep: [formula omitted], S. C. Capelle x, D. I. Edelstone x. Univ. of Pittsburgh/Magee-Womens Hospital, Dept. of OB/GYN and Reprod. Sci., Div. of Maternal Fetal Medicine, Pittsburgh, PA

Maternal oxygen transport, hemodynamic and metabolic variables as predictors of fetal acidemia in the unanesthetized pregnant sheep: [formula omitted], S. C. Capelle x, D. I. Edelstone x. Univ. of Pittsburgh/Magee-Womens Hospital, Dept. of OB/GYN and Reprod. Sci., Div. of Maternal Fetal Medicine, Pittsburgh, PA

A prospective, double-blind, randomized comparison of prophylactic intramyometrial 15-methyl prostaglandin F2α, 125 micrograms, and intravenous oxytocin, 20 units, for the control of blood loss at elective cesarean section

Our purpose was to compare intramyometrial 15-methyl prostaglandin F2 alpha with intravenous oxytocin for controlling blood loss at elective cesarean section. A double-blind, randomized trial was performed with intramyometrial 15-methyl prostaglandin F2 alpha, 125 micrograms, or intravenous oxytocin, 20 U, in 60 women undergoing elective lower segment cesarean section at 36 to 41 weeks' gestation. Subjective assessment of the operative blood loss and early lochial discharge and objective change in hemoglobin and hematocrit before and 24 hours after delivery and the incidence of side effects were compared by nonparametric statistical tests. The mean estimated blood loss was similar in both groups, with 645 ml (SD 278, range 400 to 1500) in the 15-methyl prostaglandin F2 alpha group compared with 605 ml (SD 303, range 200 to 1750) in the oxytocin group. The mean fall in hemoglobin and hematocrit was greater in the 15-methyl prostaglandin F2 alpha group than in the oxytocin group, 0.98 gm/dl (SD 0.95) versus 0.65 gm/dl (SD 0.79) for hemoglobin and 2.58% (SD 2.96) versus 2% (SD 2.96) for hematocrit. None of these differences reached statistical significance. There were no differences in side effects and lochial discharge between the treatment groups. In both groups there was a decrease of approximately 1% in maternal arterial oxygen saturation. Routine intramyometrial 15-methyl prostaglandin F2 alpha, 125 micrograms, does not offer any obvious advantage over intravenous oxytocin, 20 U, in reducing operative blood loss at elective lower-segment cesarean section.