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PubMed2001

Secretion of oxytocin in pregnant and parturient cows: corpus luteum may contribute to plasma oxytocin at term.

Plasma oxytocin (OT) concentrations were determined in 14 late-pregnant and parturient Angus-Hereford cows. Jugular and utero-ovarian veins were cannulated for simultaneous withdrawal of blood samples. Samples were collected at 10-min intervals for 6 h once weekly beginning 60-14 days before the date of expected delivery (group 1), or daily 3-7 days before the due date (group 2). In a third group, samples were collected at 15-min intervals every other day for 12 h beginning 1 wk before calving. Basal levels of OT were low, the overall mean for both veins was 0.46 +/- 0.03 microU/ml until a week before parturition, and then increased to 0.77 +/- 0.1 microU/ml (P < 0.02). Spurts of OT occurred intermittently on all days. Interpeak intervals averaged 71.0 +/- 10.7 min until Day -14, and from Day -14 to Day -1 the intervals were 44.0 +/- 5.3 min (P < 0.05). From Day -60 to Day -25 the amplitudes of OT peaks were low and similar in both veins (mean 1.37 +/- 0.1 microU/ml). From Day -14 to Day -1 the peak amplitudes were 3.6 +/- 0.4 microU/ml on average (P < 0.02). During the last 2 wk the utero-ovarian peak of OT was frequently higher than the peripheral peak. In addition, a number of spurts were observed in the utero-ovarian vein only (solo peaks). On the day of parturition during the first stage of labor, peak amplitudes had increased to 7.3 +/- 2.0 microU/ml, and the interpeak intervals had become shorter than before labor (mean 25.1 +/- 2.6 min). A large surge of OT initiated the expulsive stage of labor. Basal levels rose to 43.1 +/- 16 microU/ml and 38.7 +/- 12.6 microU/ml, and peak levels to 77.4 +/- 19.1 microU/ml and 91.6 +/- 21 microU/ml in the jugular and utero-ovarian veins, respectively. Interpeak intervals had decreased to 17.2 +/- 3.3 min (P < 0.05). Oxytocin levels remained high after delivery of the calf until the placenta was expelled. The posterior pituitary was the source of circulating OT during most of gestation and labor, but the solo peaks observed during late gestation in the utero-ovarian vein were probably of luteal origin or possibly of caruncular origin, because near term, both tissues express OT mRNA. Fetal posterior pituitary is another possible source for these peaks. Our conclusions are that during bovine pregnancy, low amplitude spurts of OT are secreted intermittently; near term, both the frequency and peak amplitude of the spurts increase; and during labor, a dramatic increase in plasma OT precedes the expulsion of the calf. The main source of OT is the posterior pituitary, but near term, a utero-ovarian source secretes additional OT into the systemic circulation.

Animals↗

PubMed2000

Comparison of epidural fentanyl versus epidural sufentanil for analgesia in ambulatory patients in early labor.

UNLABELLED: Epidural sufentanil, after a lidocaine and epinephrine test dose, provides adequate analgesia and allows for ambulation during early labor. Epidural fentanyl has not been evaluated in this setting. The current study was designed to determine whether there is an analgesic difference between epidural fentanyl and epidural sufentanil in laboring patients. Forty-six laboring nulliparous women, at <5-cm cervical dilation, who requested epidural analgesia were enrolled. After a 3-mL test dose of lidocaine with epinephrine, patients were randomized to receive either sufentanil 20 microg or fentanyl 100 microg. After administration of the analgesic, pain scores and side effects were recorded for each patient at 5, 10, 15, 20, and 30 min and every 30 min thereafter, by an observer blinded to the technique used. There were no demographic differences between the two groups. Pain relief was rapid for all patients. The mean durations of analgesia were similar between the sufentanil group (138 +/- 50 min) and the fentanyl group (124 +/- 42 min). Side effects were similar between the two groups. In early laboring patients, epidural fentanyl 100 microg, after a lidocaine and epinephrine test dose, provides analgesia comparable to that of sufentanil 20 microg. IMPLICATIONS: In early laboring patients, epidural fentanyl 100 microg, after a lidocaine and epinephrine test dose, provides analgesia comparable to that of sufentanil 20 microg.

Adult↗

PubMed2001

Minimum local anesthetic volume blocking the femoral nerve in 50% of cases: a double-blinded comparison between 0.5% ropivacaine and 0.5% bupivacaine.

UNLABELLED: Recent studies demonstrated that ropivacaine was nearly 40% less potent than bupivacaine in the first stage of labor, but contrasting results have been reported. We, therefore, conducted a prospective, randomized, double-blinded study to determine the effects of the ropivacaine/bupivacaine potency ratio on the minimum volume of local anesthetic required to produce effective block of the femoral nerve in 50% of patients. Fifty adults premedicated with IV midazolam, 0.05 mg/kg, undergoing elective knee arthroscopy received femoral nerve blocks with a multiple-injection technique with a nerve stimulator (contractions of vastus medialis, vastus intermedius, and vastus lateralis were elicited with a 0.5-mA stimulating current). Patients randomly received either 0.5% ropivacaine (n = 25) or 0.5% bupivacaine (n = 25). The anesthetic volume was decided according to Dixon's up-and-down method, starting from 12 mL and being equally divided among the three elicited twitches. Successful nerve block was loss of pinprick sensation in the femoral nerve distribution with concomitant block of the quadriceps muscle within 20 min after injection, as assessed by a blinded observer. Positive or negative responses determined a 3-mL decrease or increase for the next patient, respectively. According to the up-and-down sequences, the minimum local anesthetic volume providing successful nerve block in 50% of cases was 14 +/- 2 mL in the ropivacaine group (95% CI: 12-16 mL) and 15 +/- 2 mL (95% CI: 13-17 mL) in the bupivacaine group (P: = 0.155). We conclude that the volume of 0.5% ropivacaine required to produce effective block of the femoral nerve in 50% of patients is similar to that required when using 0.5% bupivacaine. IMPLICATIONS: Considering the risk for drug-related systemic toxicity, the equipotency ratio between ropivacaine and bupivacaine is crucial for daily practice. Despite the 40% reduction in the analgesic potency of ropivacaine reported during epidural analgesia for labor pain, results of this prospective, randomized, double-blinded study demonstrated that the same volume of 0.5% ropivacaine or 0.5% bupivacaine is required to produce an effective block of the femoral nerve in 50% of cases.

Amides↗

PubMed2001

The influence of a bupivacaine and fentanyl epidural infusion after epidural fentanyl in patients allowed to ambulate in early labor.

UNLABELLED: Epidural fentanyl after a lidocaine and epinephrine test dose provides adequate analgesia and allows for ambulation during early labor. This study was designed to determine the influence of an epidural infusion of bupivacaine plus fentanyl administered after initiation of epidural labor analgesia with fentanyl. Specifically, we evaluated whether there is an increase in motor block or an increased time to request for further analgesic medication. Fifty-one laboring primigravid women at <5 cm cervical dilation who requested epidural analgesia were enrolled. After a 3-mL epidural test dose of 1.5% lidocaine with epinephrine (5 microg/mL), patients received fentanyl 100 microg via the epidural catheter. They then randomly received either an infusion (10 mL/h) of 0.0625% bupivacaine with fentanyl (3 microg/mL) or an infusion of preservative-free saline. After the administration of the initial analgesic, pain scores and side effects were recorded for each patient at 10, 20, and 30 min, every 30 min thereafter, and at the time of request for additional analgesic medication, by an observer blinded to the technique used. There were no demographic differences between the two groups. The mean duration of analgesia (time from initial dose to request for additional analgesia) was increased in the group that received a continuous infusion of bupivacaine and fentanyl compared with the Saline group (198 +/- 86 vs 145 +/- 50 min; P < 0.009). Side effects were similar between the two groups. No patient in either group experienced any detectable motor block. Fourteen patients chose to ambulate in the Saline group, and 12 patients chose to ambulate in the Infusion group. In early laboring patients, a continuous infusion of 0.0625% bupivacaine infusion with fentanyl (3 microg/mL) prolonged the duration until top-up was required, after epidural fentanyl 100 microg after a lidocaine and epinephrine test dose, and did not cause any clinically detectable motor block. IMPLICATIONS: A 0.0625% bupivacaine and fentanyl (3 microg/mL) infusion, when added to epidural fentanyl (100 microg), prolongs the analgesic duration without increasing motor block in women in early labor.

Adjuvants, Anesthesia↗

PubMed1994

Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are in spontaneous labor?

BACKGROUND: Some studies suggest that epidural analgesia prolongs labor and increases the incidence of cesarean section, especially if it is administered before 5 cm cervical dilation. The purpose of the current study was to determine whether early administration of epidural analgesia affects obstetric outcome in nulliparous women who are in spontaneous labor. METHODS: Informed consent was obtained from 344 healthy nulliparous women with a singleton fetus in a vertex presentation, who requested epidural analgesia during spontaneous labor at at least 36 weeks' gestation. Each patient was randomized to receive either early or late epidural analgesia. Randomization occurred only after the following conditions were met: (1) the patient requested pain relief at that moment, (2) a lumbar epidural catheter had been placed, and (3) the cervix was at least 3 cm but less than 5 cm dilated. Patients in the early group immediately received epidural bupivacaine analgesia. Patients in the late group received 10 mg nalbuphine intravenously. Late-group patients did not receive epidural analgesia until they achieved a cervical dilation of at least 5 cm or until at least 1 h had elapsed after a second dose of nalbuphine. Ten of the 344 patients were excluded because of a protocol violation or voluntary withdrawal from the study. RESULTS: Early administration of epidural analgesia did not increase the incidence of oxytocin augmentation, prolong the interval between randomization and the diagnosis of complete cervical dilation, or increase the incidence of malposition of the vertex at delivery. Also, early administration of epidural analgesia did not result in an increased incidence of cesarean section or instrumental vaginal delivery. Seventeen (10%) of 172 women in the early group and 13 (8%) of 162 women in the late group underwent cesarean section (relative risk for the early group 1.22; 95% confidence interval 0.62-2.40). Patients in the early group had lower pain scores between 30 and 150 min after randomization. Infants in the late group had lower umbilical arterial and venous blood pH and higher umbilical venous blood carbon dioxide tension measurements at delivery. CONCLUSIONS: Early administration of epidural analgesia did not prolong labor, increase the incidence of oxytocin augmentation, or increase the incidence of operative delivery, when compared with intravenous nalbuphine followed by late administration of epidural analgesia, in nulliparous women who were in spontaneous labor at term.

Adult↗

PubMed1980

Influence of occiput posterior position on the fetal heart rate pattern.

Fetal heart rate (FHR) recordings of 138 deliveries with the fetus in the occiput posterior position (OPP) are compared with recordings of 138 control fetuses in the occiput anterior position (OAP). The 2 groups are comparable in maternal age, parity, duration of first stage of labor, frequency of nerve blocks for analgesia, and incidence of cord complications. Variable decelerations were significantly more frequent and more pronounced in the OPP group than in the controls. The number of newborns with low Apgar scores was similar in both groups, despite a large number of pronounced decelerations in the OPP group. Possible mechanisms for the origin of variable decelerations in the occiput posterior position are discussed.

Female↗

PubMed1975

Posture and epidural block in pregnant women at term. Effects on arterial blood pressure and limb blood flow.

Upper and lower limb blood flow was measured in 4 fullterm pregnant women in the left lateral and supine positions before and after epidural block. Radial artery mean blood pressure was recorded in 6 full term pregnant women under the same conditions. Before epidural block there was a much greater reduction in lower limb blood flow (39-1%) than in upper limb blood flow (13-5%) when women moved from the lateral to the supine position; this was probably the result of aortic compression. Mean radial artery pressure increased slightly by 4-6% due to maternal overcompensation in the upper part of the body. After epidural block, patients in the lateral position had a mean rise in lower limb blood flow of 25% and a reduction in upper limb blood flow of 37-2%. The mean arterial pressure remained unchanged. In the supine position there was no further reduction of upper limb blood flow; this was accompanied on average by a 9% fall in mean radial arterial pressure indicating decompensation in the mother. The leg blood flow fell less, 26-9% than before epidural block. In the supine position, a greater flow to the legs, associated with a decreased mean arterial pressure, would be expected to lead to a diminution in placental perfusion, which is the probable mechanism for foetal decompensation. Therefore the supine position should be avoided with an epidural block. In other patients it would be wise not to rely upon maternal compensatory mechanisms.

Anesthesia, Epidural↗

PubMed1978

Entonox analgesia in labour. A pilot study to reduce the delay between demand and supply.

In a pilot study in six mothers using 50% nitrous oxide and 50% oxygen (Entonox) as an intermittent self-administered analgesic during labour, a significant reduction in the mean times to attain specified end-tidal nitrous oxide concentrations was obtained by a continuous nasal supplement of Entonox. The method proved acceptable in this small number of patients and there were no demonstrable effects upon fetal heart rate.

Anesthesia, Inhalation↗

PubMed1994

Comparison of the addition of three different doses of sufentanil to 0.125% bupivacaine given epidurally during labour.

In a double-blind, randomised, prospective study 150 women in labour received intermittent epidural injections of 10 ml 0.125% bupivacaine with adrenaline (1:800,000) with 5, 7.5 or 10 micrograms of sufentanil added. The onset, duration, and quality of analgesia were compared. Motor block, type of delivery and neonatal Apgar scores were noted. The onset, duration, and quality of analgesia were generally similar in the three groups, except following the second injection when the quality of analgesia was significantly superior in the sufentanil 7.5 and 10 micrograms groups. Motor blockade and type of delivery did not differ between the groups and there were no differences in neonatal Apgar scores. No patient required more than three injections. We conclude that 7.5 micrograms sufentanil is the optimal dose to add to intermittent epidural injections of 10 ml 0.125% bupivacaine with adrenaline (1:800,000) for pain relief in labour.

Adult↗

PubMed2004

Interleukin-8 is involved in cervical dilatation but not in prelabour cervical ripening.

Our aim was to determine the amount and source of interleukin (IL)-8 and to study IL-8 receptor expression in the human cervix during pregnancy and after labour. Cervical biopsies were obtained from six non-pregnant women, eight women undergoing pregnancy termination, 17 women undergoing elective caesarean section and 11 women after vaginal delivery. IL-8 levels were compared in women with and without a ripe cervix, as determined by cervical Bishop score and cervicovaginal fetal fibronectin levels. Levels of IL-8 and IL-1beta, a regulator of IL-8 expression, were determined by enzyme-linked immunosorbent assay (ELISA). IL-8, IL-1beta and IL-8 receptor proteins were localized by immunohistochemistry. Compared with late pregnancy, IL-8 levels increased after labour and vaginal delivery (P < 0.01) but there was no correlation with cervical ripening. IL-8 was localized to stromal cells, macrophages and granulocytes. There were no significant differences in IL-1beta levels between groups. IL-8 receptors were expressed primarily on granulocytes and macrophages after vaginal delivery. We conclude that IL-8 is involved in cervical dilatation but not in cervical ripening.

Cervical Ripening↗

PubMed2006

Making the diagnosis of labour: midwives' diagnostic judgement and management decisions.

AIM: This paper reports a study examining midwives' perceptions of the way in which they diagnose labour. BACKGROUND: Diagnosis of active labour is often problematic. A midwifery workforce planning tool identified that up to 30% of women admitted to United Kingdom labour wards subsequently turned out not to have been in labour. There is evidence that if a woman is admitted to a labour ward in early labour, she is more likely to have some form of medical intervention. However, despite the impact of misdiagnosis, there is little research on the process of decision-making by midwives in relation to diagnosis of labour. METHODS: This was a qualitative study, employing focus group methods. Participants were a convenience sample of midwives working in a maternity unit in the North of England during 2002. They were asked to discuss their experience of admission of women in labour. Data were analysed using latent content analysis. FINDINGS: Thirteen midwives participated in one of two groups. They described using information cues, which could be separated into two categories: those arising from the woman (Physical signs, Distress and coping, Woman's expectations and Social factors) and those from the institution (Midwifery care, Organizational factors and Justifying actions). Midwives' decision-making process could be divided into two stages. The diagnostic judgement was based on the physical signs of labour: the management decision would then be made by considering the diagnostic judgement as well as cues such as how the woman was coping, her expectations and those of her family and the requirements of the institution. CONCLUSIONS: Midwives may experience more difficulty with the management decision than with the initial diagnosis. It may be that the number of inappropriate admissions to labour wards could be reduced by supporting midwives to negotiate the complex management hurdles, which accompany diagnosis of labour.

Adaptation, Psychological↗

PubMed1992

Effects of nitrous oxide/oxygen inhalation on the maternal circulation during vaginal delivery.

The hemodynamic changes occurring during the first stage of labor were studied in 24 healthy pregnant women during inhalation of different nitrous oxide/oxygen (N2O/O2) gas mixtures (intermittent 70/30, 40/60, 0/100 and continuous 40/60). Cardiac output increased (P less than 0.01) from 6.6 +/- 0.2 l/min between uterine contractions to 8.5 +/- 0.3 l/min during contractions. Heart rate, stroke volume, systolic, diastolic and mean arterial pressures were increased (P less than 0.01) and total peripheral vascular resistance was reduced (P less than 0.01) during contractions compared to measurements performed between contractions. The maternal circulation was influenced by the use of N2O/O2. During intermittent inhalation, higher concentrations of N2O were associated with a decrease (P less than 0.01) in heart rate, cardiac output and arterial pressure as well as an increase (P less than 0.01) in stroke volume. The degree of pain relief also increased (P less than 0.01) with increasing concentrations of inhaled nitrous oxide. The circulatory influence of intermittent inhalation given during uterine contractions was also apparent during the interval between contractions when N2O/O2 was not administered. The most obvious effects on both circulation and pain were demonstrated during continuous inhalation of N2O/O2. There was a close association between analgetic and cardiovascular effects indicating that the latter, at least partly, were due to pain relief. However, it was not possible to exclude or confirm possible direct pharmacological effects of N2O/O2 on maternal circulation.

Adult↗

PubMed2004

Vaginal and cervical dilatation intrapartum is associated with eosinophilic infiltration in the cow but not in the sheep.

During parturition maximal dilatation of the vagina and cervix is necessary for expulsion of the neonate. The aim of the present study was to characterize the cell infiltration of the vagina and cervix that is associated with this event in cows and sheep. For this purpose, vaginal and cervical tissue were removed from four pluriparous cows and four sheep immediately after delivery of the neonate by biopsy under visual control (group 1), and the eosinophilic granulocytes were stained selectively. Four cows that were in interoestrus were used for control (group 2). In a third group of cows (n=10), blood samples were taken to determine the concentration of eosinophilic granulocytes from the fifth day antepartum up to the sixth day postpartum (group 3). A high degree of infiltration with eosinophilic granulocytes was detected in the bovine vagina and cervix intrapartum but not during interoestrus and in the ovine tissue intrapartum (p <0.001). In the bovine tissue, the cell density was higher in the vagina than in the cervix (p <0.05). The intrapartal tissue infiltration was associated with a short-term blood eosinopenia. In conclusion, this investigation demonstrates eosinophilic infiltration in the bovine vagina and cervix intrapartum, which differs from the situation in sheep. We suggest that this difference can be explained by the fact that cows deliver at high oestrogen and low progesterone values, but sheep show relatively high intrapartal P4 levels, which might suppress tissue infiltration with eosinophilic granulocytes.

Animals↗

PubMed1993

Cervical contractions: the response of the cervix to oxytocic stimulation in the latent phase of labour.

OBJECTIVE: To assess the cervical response to myometrial activity in early labour. DESIGN: Prospective observational study. SUBJECTS: Women requiring oxytocin stimulation in induced and spontaneous labours. SETTING: A teaching hospital in Birmingham. MAIN OUTCOME MEASURES: Simultaneous comparison of the cervical response to myometrial contractions was made on a cycle by cycle basis to deduce the properties of the cervix in early labour. RESULTS: Sixty-seven patients have been monitored, of whom 63 had satisfactory cervimetry data. Thirty (47.6%) women exhibited cervical contractions in response to myometrial activity. This response was only observed at dilatations up to 4 cm. The change in behaviour coincides with the transition from latent to active phases of dilatation. The length of the latent phase of labour was significantly longer in those women who exhibited cervical contractions (P < 0.001), although the active phase was similar in the two groups (P > 0.1). The group without cervical contractions exhibited a greater degree of effacement (P < 0.05) and tended to have more dilated cervices (P < 0.01) than those who showed cervical contractions. CONCLUSIONS: It is possible for the cervix to contract in early labour. This response may be the result of incomplete preparation of the cervix for the process of dilatation, and is seen during what is recognised as the latent phase in those women in whom the cervix is unaffected and undilated. These properties of the cervix may explain the poor results obtained from oxytocin stimulation of labour in the latent phase.

Adult↗

PubMed1994