Patrick Belfrage

Neonatal depression after obstetrical analgesia with pethidine. the role of the injection-delivery time interval and of the plasma concentrations of pethidine and norpethidine

Pethidine (100 mg) was administered i.m. to women in labor at different times before delivery. The interval before respiration in the newborn became sustained was shorter if pethidine was given less than one hour before delivery. The respiratory rate of the newborn increased after naloxone injection in 40 per cent of the cases, mostly when intrauterine exposure to pethidine exceeded one hour. The plasma concentrations of pethidine and norpethidine were measured in mother and newborn. The concentrations in the umbilical vein and artery indicated a continuous net transfer of pethidine from mother to fetus for approximately two hours. This correlates with the clinical finding of maximal neonatal depression 2–3 hours after maternal injection. The concentrations of norpethidine increased with a longer time interval between injection and delivery, but were probably too low to have any effect on the newborn. Neonatal depression seems to be related to the amount of unmetabolized pethidine that has been transferred from mother to fetus but not to norpethidine as had been suspected earlier.

Lumbar Epidural Analgesia in Labour: I. Acid-base Balance and Clinical Condition of Mother, Fetus and Newborn Child

Abstract. Twenty‐four full‐term nulliparae and their babies were studied. Twelve received lumbar epidural analgesia with bupivacaine (Marcain‐adrenalin®) and twelve conventional obstetrical analgesia with meperidine (Petidin®), chlorpromazine (Hibernal®), nitrous oxide and a pudendal nerve block with prilocaine (Citanest®). The acid‐base balance was determined in fetal and maternal blood during labour and in neonatal blood after birth. The newborn infants were placed in incubators after birth and several clinical parameters were recorded during the first two hours. Epidural analgesia to the mothers resulted in a lower degree of metabolic acidosis than conventional obstetrical analgesia. The clinical and blood‐chemical parameters recorded in this study indicated no harmful effects on the newborn infants after epidural analgesia to the mothers.

Lumbar epidural analgesia with bupivacaine in labor

Abstract Lumbar epidural analgesia with bupivacaine was given to 37 women for uncomplicated labor. After the blockade serial determinations of pH and bupivacaine concentration were made in fetal scalp blood and maternal venous blood and there was continuous monitoring of the fetal heart rate. Fetal scalp blood pH was within normal limits and no pathologic FHR tracings were elicited by the blockade, although a temporary decrease of the baseline fetal heart rate irregularity was seen in about one-fifth of the cases. Fetal drug concentrations were low and about one-fourth of corresponding maternal values. After reinjection of bupivacaine the degree of drug accumulation was fairly similar in fetal and maternal blood.

Lumbar epidural analgesia in labour. II. Effects on glucose, lactate, sodium, chloride, total protein, haematocrit and haemoglobin in maternal, fetal and neonatal blood.

Abstract. Thirty‐three full‐term nulliparae and their babies were studied. Twenty‐one received lumbar epidural analgesia with bupivacaine (Marcain‐adrenalin®) and twelve conventional obstetrical analgesia with meperidine (Petidin®), chlorpromazine (Hibernal®), nitrous oxide and a pudendal nerve block with prilocaine (Citanest®). Glucose, lactate, potassium, sodium, chloride, total protein, haemoglobin and haematocrit were determined in fetal and maternal blood during labour and in neonatal blood after birth. This study revealed a high level of plasma sodium in scalp blood of both ‘epidural’ and ‘control’ series probably related to water loss during labour. Furthermore, administration of epidural analgesia to women in labour resulted in lower lactate concentrations in these women and their babies compared with those receiving conventional obstetric analgesia.

Influence of the Pelvic Outlet Capacity on Fetal Head Presentation at Delivery

The influence of pelvic outlet capacity on fetal head presentation in 1402 term primiparas with normal pregnancies was studied. In all cases radiological pelvimetry was carried out and labor started spontaneously. Occiput posterior (OP) delivery occurred in 5.1%. As pelvic outlet capacity decreased an increased frequency of OP presentations and need for epidural anesthesia (EDA) was found. With OP presentation the duration of labour was longer, the frequency of EDA, instrumental delivery, cesarean section and low Apgar score at 1 minute were all higher, all compared with occiput anterior (OA) presentation. No difference in fetal morbidity was found. When the influence of the pelvic outlet capacity was eliminated through comparison of matched groups, the course of delivery became more similar whether the presentation was OA or OP and the frequency of EDA became the same. Reduced pelvic outlet capacity seemed to be one cause of both OP presentation and the use of EDA.

Lumbar epidural analgesia with bupivacaine in labor: Drug concentration in maternal and neonatal blood at birth and during the first day of life

Lumbar epidural analgesia with bupivacaine was administered to 33 women for relief of pain during labor. At delivery blood samples were drawn from the umbilical cord vessels and from a maternal peripheral vein. Blood samples were also collected from the noenate and its mother, 1, 4, and 20 hours after delivery. Analyses of bupivaccaine concentrations were carried out in all samples with a gas-chromatographic technique. The drug concentration in the umbilical vein (UV) was usually higher than the corresponding umbilical artery value (UA), but with increasing time interval between the last bupivaccaine infection and delivery the UA/UV drug concentration ratio rose. After delivery the rate of drug decline in blood was similar in mother and newborn infant. The clinical condition of the infant was unrelated to the drug concentration in the umbilical cord vessels.

Epidural Analgesia in Labour: IV. Influence on Uterine Activity and Fetal Heart Rate

Abstract. The influence of epidural block with bupivacaine (Marcaine‐adrenalin®) on fetal heart rate, uterine activity, and the frequency and intensity of contractions was studied in twenty‐five nulliparae at term. Uterine activity was found to decrease during the first 30 minutes following epidural block. In the time interval 30 to 40 minutes after epidural block uterine activity increased again and attained the same level as during the last 10 minutes before analgesia. The frequency of uterine con‐tractious did not decrease after the block. The lower levels of uterine contractility were due only to a lower amplitude of the contractions. The regularizing effect of epidural analgesia on incoordinate uterine action was noted. The recording of fetal heart rate in the time interval studied revealed no pathological findings. Mode of delivery, mean labour duration and Apgar scores after epidural block were comparable with earlier studies of a larger patient population. This study suggest that epidural analgesia does not induce any important changes in fetal heart rate but temporarily decreases uterine activity.

Micromethod for the determination of bupivacaine in maternal and foetal blood during obstetric analgesia

A method for the determination of bupivacaine in maternal and foetal blood during obstetric analgesia is described. The drug and the internal standard, 1‐pentyl‐2‐(2,6‐xylylcarbamoyl)‐piperidine, are initially extracted into methylene chloride. Perchloric acid is added to retain bupivacaine and the standard as Perchlorates in the organic phase accomplishing a selective separation from less hydrophobic amines. Bupivacaine and the standard are then re‐extracted into sulphuric acid, followed by a purification with methylene chloride. The aqueous extract is finally made alkaline and the compounds extracted into 10 μl methylene chloride. This extract is analysed by gas chromatography using a 3% OV‐17 column. The standard deviation of the method at therapeutic concentrations is about 10% and the lowest level which can be determined with reasonable accuracy is 15 ng ml−1.

The term breech presentation. A retrospective study with regard to the planned mode of delivery

Background. To analyze retrospectively a large group of term breech and vertex deliveries, with regard to the influence of the mode of delivery on the frequency of fetal and maternal complications.

Hemodynamic measurements with Swan-Ganz catheter in women with severe proteinuric gestational hypertension (pre-eclampsia)

Ten women with severe pre‐eclampsia, i.e. a blood pressure ≥ 150/110 mmHg or 140/90 mmHg and proteinuria > 3 g/24 h were, after initial antihypertensive treatment, centrally monitored with a pulmonary artery catheter (Swan‐Ganz). All had been normotensive in early pregnancy. Mean age was 29 years (range 23–37). Mean gestational age upon admission was 29 weeks (range 23–36) and 7 of the women were nulliparous. Nine of the 10 patients had subjective symptoms, e.g headache and/or epigastric pain. All were considered in need of intensive care. Two patients were found to have an abnormal coagulation and liver function. All patients had normal serum creatinine values despite proteinuria. Hypertension was treated with dihydralazine and/or labetalol. Volume substitution was carried out with plasma and albumin. The women could be divided into two groups: 5 patients where progress of the disease despite therapy led to delivery within 24 h, and 5 patients whose diastolic blood pressure could be stabilized around 100 mmHg after treatment and pregnancy could be prolonged by 5‐13 days. Common for all patients was a hyperkinetic circulation with an increased cardiac output despite a variety of central pressures. Invasive monitoring of central pressures with a Swan‐Ganz catheter demonstrated that the clinical status could be stabilized and the pregnancy prolonged in 5 of the 10 women with severe pre‐eclampsia. The variety of the central hemodynamic values illustrates clearly that treatment has to be individualized regarding antihypertensive medication, fluids and diuretics. This can be done by means of the Swan‐Ganz catheter in order to optimize treatment and clinical status before delivery in these severely ill patients.