Uteroplacental and fetal haemodynamics and cardiac function of the fetus and newborn after crystalloid and colloid preloading for extradural Caesarean section anaesthesia

We have studied the effects of randomized preloading with eithera crystalloid (lactated Ringer's) 15 ml kg^–1 or colloid(hydroxyethyl starch) 7.5 ml kg^–1 solution in 20 parturientsundergoing elective Caesarean section under extradural anaesthesia,on blood flow in maternal placental and non-placental uterineand placental arcuate arteries and in fetal umbilical, renaland middle cerebral arteries, using a pulsed colour Dopplertechnique. Simultaneously, fetal and neonatal myocardial functionwere investigated by pulsed Doppler and M mode echocardiography.We found no changes in maternal or fetal blood velocity waveformindices after crystalloid preloading, but the pulsatility indexof the maternal non-placental uterine artery in creased significantlyafter colloid preloading. Fetal heart rate decreased after preloadingwith crystalloid solution. There were no differences in fetalor neonatal myocardial function between the groups, and theoutcome of the newborn infants were uneventful in all cases.These results suggest that preloading with either a crystalloidor colloid solution may lead to different uterine and fetalhaemodynamics but these solutions had only minimal effects onfetal and neonatal myocardial performance and no effect on theclinical condition of newborns in uncomplicated pregnancies.     

EFFECT OF SEGMENTAL EXTRADURAL ANALGESIA ON PLACENTAL BLOOD FLOW DURING NORMAL LABOUR

Placental blood flow was measured during the first stage ofnormal labour using a xenon-133 clearance technique before andafter segmental extradural analgesia. Analgesia was producedwith 0.5% plain bupivacaine in eight patients and with 0.5%bupivacaine-adrenaline in 10 patients. Segmental extraduralanalgesia with a small dose (20 mg) of bupivacaine did not changeplacental blood flow significantly. The addition of adrenaline20 µg produced no effect.     

Labetalol does not alter the placental and fetal blood flow or maternal prostanoids in pre-eclampsia

Summary. The effect of intravenously administered labetalol (1 mg/kg) on placental and fetal blood flow was studied in 13 pre-eclamptic women. Although the maternal blood pressure decreased, no changes occurred in the blood flows in the intervillous space, the umbilical vein or the fetal descending aorta, nor did the indices of peripheral vascular resistance in the fetal aorta change, but the placental vascular resistance did decrease. Labetalol had no effect on prostacyclin or thromboxane A₂ as measured by urinary 6-keto-prostaglandin F_1α and serum thromboxane B₂ respectively. These findings are clinically relevant since they suggest that labetalol reduces maternal blood pressure without interfering with the placental or fetal blood flow.     

PLACENTAL BLOOD FLOW DURING CAESAREAN SECTION PERFORMED UNDER SUBARACHNOID BLOCKADE

Subarachnoid blockade using 0.5% bupivacine after a "preload"of Ringer's lactate solution 1500–2000 ml i.v. was studiedin nine patients undergoing elective Caesarean section. Ephedrineinfusion 50 mg in 500 ml was instituted at the first signs ofmaternal hypotension in seven patients. Although significantdecreases in mean maternal systolic, mean and diastolic arterialpressures were recorded, the individual decreases in pressurewere less than 30 mm Hg in all except two patients. In generalplacental blood flow did not change, although there was a markedincrease in one patient with toxaemia and a decrease in onewoman with diabetes mellitus. The babies were unaffected atdelivery. Preventive measures, especially the "preload" infusion,are important in the maintenance of adequate placental perfusionin patients undergoing Caesarean section under subarachnoidblockade.     

UTEROPLACENTAL AND FETAL CIRCULATION DURING EXTRADURAL BUPIVACAINE-ADRENALINE AND BUPIVACAINE FOR CAESAREAN SECTION IN HYPERTENSIVE PREGNANCIES WITH CHRONIC FETAL ASPHYXIA

We have studied the effects of an extradural block during Caesareansection using either bupivacaine plain or with adrenaline 85–100µg on blood velocity waveforms of maternal uterine andplacental arcuate arteries and fetal umbilical, renal and middlecerebral arteries, in 20 hypertensive parturients with chronicfetal asphyxia. Fetal myocardial function was investigated atthe same time by M-mode echocardiography. Extradural anaesthesiaresulted in a significant decrease in maternal mean systolicand diastolic arterial pressures in both groups, but this wasmore marked after plain bupivacaine. There were no significantdifferences in any of the Doppler recordings relative to baselinevalues after plain bupivacaine, but after bupivacaine with adrenalinethere were significantly increased blood flow velocity indicesfor the maternal uterine and placental arcuate arteries andsignificantly decreased indices in the fetal renal and middlecerebral arteries. Neonatal outcome as evaluated by Apgar scoresand acid-base values in the umbilical cord were similar in thetwo groups. The results suggest that adrenaline added to thesolution of bupivacaine increased vascular resistance in theuteroplacental circulation, indicating impaired blood flow.     

UTEROPLACENTAL AND FETAL HAEMODYNAMICS DURING EXTRADURAL ANAESTHESIA FOR CAESAREAN SECTION

We have studied the effects of extradural anaesthesia with bupivacaine(plain) in eight healthy parturients undergoing elective Caesareansection, on blood flow in maternal uterine and placental arcuatearteries and in fetal umbilical, renal and middle cerebral arteries,using a colour Doppler technique. Simultaneously, fetal myocardialfunction was investigated by M-mode echocardiography. Maternaland fetal blood velocity waveform indices did not change significantly.We found no changes in fetal myocardial function with extraduralanaesthesia, except for an increase in the right ventricularinner end-diastolic dimensions. These results suggest that extraduralanaesthesia has no detrimental effects on uteroplacental andfetal circulations in the uncomplicated pregnancy when maternalhypotension is avoided with rapid prehydration.     

EFFECTS OF EXTRADURAL BUPIVACAINE WITH ADRENALINE FOR CAESAREAN SECTION ON UTEROPLACENTAL AND FETAL CIRCULATION

We have studied the effects of an extradural block using bupivacainewith adrenaline 90–100 µg on blood flow in the maternaluterine and placental arcuate arteries and the fetal umbilical,renal and middle cerebral arteries, using a colour Doppler techniquein eight healthy parturients undergoing elective Caesarean section.Fetal myocardial function was investigated simultaneously byM-mode echocardiography. Maternal heart rate increased and diastolicarterial pressure decreased after extradural administrationof bupivacaine with adrenaline. The latter effect was relievedby increasing the infusion rate in every case and none of thepatients required vaso-pressors. There were no significant differencesin maternal or fetal blood velocity waveforms, and no significantchanges were found in any of the fetal myocardial measurementsrelative to control values. These observations suggest thatextradural anaesthesia using bupivacaine with adrenaline doesnot have an adverse effect on vascular resistance in the uteroplacentalor fetal circulations or on fetal myocardial function in normalpregnancy when bupivacaine-adrenaline is administered fractionallyand maternal hypotension is prevented by rapid crystalloid volumeloading.     

EFFECT OF EXTRADURAL ANALGESIA USING BUPIVACAINE AND 2-CHLOROPROCAINE ON INTERVILLOUS BLOOD FLOW DURING NORMAL LABOUR

The effect of lumbar extradural analgmig on intervillous bloodflow (IBF) during labour was studied in 26 healthy parturientsusing an i. v. bolus injection of xenon-133. There was a 19%decrease (n.s.) in mean IBF in six parturients (non-extraduralcontrol group). Mean IBF increased by 37.5% when 0.25% bupivacaine10 ml was used and by 35.2% when 2% 2-chloroprocaine 10 ml wasused (n.s.). When the two extradural groups were combined, themean difference between IBFi and IBF2 was 45± 112 mlmin dl^–1. This increase is statistically significant (P<0.05). The improvement in IBF after extradural block was consideredto be a result of the decreased uterine vascular resistance,as no significant changes were observed in arterial pressure,utenne activity or uterine tone.     

ETHANOL IN THE PREVENTION OF NEONATAL HYPERBILIRUBINAEMIA

Seventy-four pregnant women were given 80 g of ethanol orally or 63, 94 or 102 g intravenously the day prior to delivery. Nineteen mothers and their offspring served as controls. The effect on the bilirubin values of the newborn was studied. The bilirubin levels of the newborn were not significantly lower during the first six days of life compared with the controls. The results differ from those reported earlier. The reasons for this are discussed.