The past two decades have witnessed some controversy on the ideal anaesthesia for Caesarean section for women with pre-eclampsia. In the 1980s, many obstetricians recommended avoiding regional anaesthesia because of concern for sudden hypotension and the risks associated with pressor agents and large volumes of fluid, given to correct hypotension [1-3]. Currently, many obstetricians and anaesthetists have changed their opinions. Epidural anaesthesia is the preferred technique of anaesthesia for Caesarean section in pre-eclamptic pregnancies as well as in severe pre-eclampsia [4,5]. This form of anaesthesia improves utero-placental perfusion and avoids some of the risks associated with general anaesthesia (awareness, intubation problems, aspiration pneumonia and hypertensive crises). In emergency situations, such as fetal distress, rapid anaesthesia is required and epidural anaesthesia may be inappropriate. One alternative to general anaesthesia for urgent Caesarean sections is spinal anaesthesia, where appropriate levels of anaesthesia can be obtained within 5-10 min.
In normal pregnancy, spinal anaesthesia is associated with a high incidence of hypotension [6,7]. In both pre-eclamptic patients and severely pre-eclamptic parturients, Chiu and colleagues and Hood and colleagues concluded that spinal anaesthesia did not result in more severe hypotension compared to standard epidural anaesthesia [8,9]. However, mean arterial pressure declined more than 25% in both the epidural and spinal groups in the study by Hood and Curry and by 20% in the study by Chiu and colleagues. Recently, Vercauteren and colleagues demonstrated that a low-dose combined spinal-epidural (CSE) technique combined with small prophylactic doses ephedrine, prevented hypotension in normal parturients .
For more than 4 yr, we have used a low-dose CSE technique for Caesarean section in normal and pre-eclamptic patients. To evaluate the effect of a low-dose CSE on maternal haemodynamics, maternal outcome and neonatal outcome, we performed a retrospective analysis of patients' charts comparing conventional epidural anaesthesia with low-dose CSE anaesthesia for Caesarean section in pre-eclamptic mothers. The objective of the present retrospective patient chart analysis was to assess haemodynamic changes associated with either epidural or CSE anaesthesia in both mild and severe pre-eclampsia. We postulated that no significant differences would be identified.
Following institutional review board approval, all charts of pre-eclamptic patients who underwent Caesarean delivery between 1 January 1998 and 31 December 2001 were analysed retrospectively. Data were compared according to the anaesthetic technique used: conventional epidural anaesthesia (EPI-group) vs. low-dose CSE anaesthesia (CSE-group).
Pre-eclampsia is defined as sustained values of arterial pressure of at least 140 mmHg systolic and 90 mmHg diastolic combined with proteinuria. Proteinuria is defined as the excretion of more than 300 mg of protein in a 24 h urine collection or the finding of + or 2+ on dipstick urine testing in two clean samples taken more than 6 h apart. Severe pre-eclampsia is defined as pre-eclampsia combined with one of the following conditions : severe hypertension (sustained arterial pressure of at least 160 mmHg systolic or at least 110 mmHg diastolic on at least two occasions 6 h apart), severe proteinuria (>5 g proteinuria in a 24 h specimen or 3+ or 4+ on semi quantitative analysis), oliguria (<400 mL over 24 h), cerebral or visual disturbances, pulmonary oedema, epigastric pain, hepatic rupture, impaired liver function, thrombocytopenia, HELLP (haemolysis, elevated liver, low platelet) syndrome and evidence of fetal compromise.
Combined spinal-epidural and epidural anaesthesia were performed in the sitting position at the L3-L4 or L4-L5 interspace. The attending anaesthetist determined at his or her own discretion the choice of regional anaesthetic technique. However, many patients received epidural anaesthesia because a functioning epidural catheter was already in place during labour. Epidural anaesthesia was induced with incremental boluses of bupivacaine or ropivacaine 0.5% combined with sufentanil 1 μg mL−1 with the patient in the supine position with left lateral tilt. This was done in patients having an epidural catheter in situ or those who did not have a catheter in situ prior to operative delivery. The total volume of the anaesthetic mixture administered was at the discretion of the attending anaesthetist.
Combined spinal-epidural anaesthesia was performed using a mixture of hyperbaric bupivacaine 7.5 mg combined with sufentanil 2.5 μg dissolved in NaCl 0.9% 2 mL (physiological saline). Of this mixture 0.1 mL per 10 cm of the patient's height was given intrathecally. Additional epidural 'top-ups' were administered using bupivacaine or ropivacaine 0.5% according to the wishes of the attending anaesthetist. In both regional techniques patients were preloaded with lactated Ringer's solution 500-1000 mL. In the CSE-group, prophylactic ephedrine 10-15 mg could be given according to written protocols at our department.
Additional preloading and prophylactic or therapeutic ephedrine were given at the discretion of the attending anaesthetist. A block to a level of T2 using cold discrimination, or a block to T4 using pinprick, is typically used as the block height at our unit to perform Caesarean section.
The following data were retrieved from the anaesthesia charts: patient characteristic variables; method of anaesthesia; use of: anti-hypertensive therapy, magnesium sulphate, intraoperative infused volume, prophylactic or therapeutic ephedrine; Apgar scores and umbilical artery blood-gases. The following maternal arterial pressures were recorded: the baseline pressure during the first antenatal visit in the first trimester; the highest arterial pressure during pregnancy prior to the day of delivery and prior to anti-hypertensive treatment; the arterial pressure just prior to the Caesarean section; the lowest arterial pressure during Caesarean section after initiation of regional anaesthesia and prior to delivery of the baby and the lowest arterial pressure intraoperatively after delivery of the baby.
Continuous data, such as arterial pressure, were analysed using analysis of variance and Scheffe's post hoc test where appropriate. Categorical data were analysed using Fisher's exact test and χ2-analysis. P < 0.05 was considered to be significant.
Total study population
During the 4 yr period of analysis, 106 pre-eclamptic patients, who underwent Caesarean section were identified. In 11 patients, the medical records were incomplete. Eighteen patients underwent general anaesthesia. Four of these patients were scheduled for regional anaesthesia, but were converted to general anaesthesia because of inadequate anaesthesia. These patients were excluded from further analysis. Therefore, a total of 77 patients remained for final analysis. In 62 patients conventional epidural anaesthesia was performed. In 15 patients CSE anaesthesia was performed. In 51 patients pre-eclampsia was diagnosed and in a further 26 severe pre-eclampsia was noted. In seven of these severely pre-eclamptic patients a CSE was performed and in 19 epidural anaesthesia was given.
Age, height, weight and gestational age were comparable between the two treatment modalities (Table 1). In both groups a similar prevalence of severe pre-eclampsia was observed (Table 2). Proteinuria was comparable between the groups (Table 2). A similar number of women received anti-hypertensive treatment before initiation of regional anaesthesia (Table 2).
Mean, systolic and diastolic arterial pressures during the first trimester of pregnancy were similar between the two groups. The highest mean, systolic and diastolic arterial pressures during pregnancy, and just prior to anaesthesia for Caesarean section, were comparable between the EPI- and CSE-groups. Lowest intraoperative mean, systolic and diastolic arterial pressures prior and after delivery of the fetus were similar between EPI- and CSE-groups (Table 3, Fig. 1). Significantly more ephedrine was used in the CSE-group compared to the EPI-group. More intravenous (i.v.) lactated Ringer's was used in the EPI-group. Blood loss was comparable between the treatment groups (Table 3).
Neonatal weight was similar between the groups. Apgar scores did not differ between the groups. Umbilical artery pH was less in the EPI-group. In none of the patients in the CSE-group was an umbilical artery pH <7.2 observed, while this occurred in 16% of parturients treated with epidural anaesthesia (Table 4). Maternal intensive care admission was never required.
Results severe pre-eclampsia population
Twenty-six patients were diagnosed with severe pre-eclampsia. No differences in patient characteristics data and gestational age were identified. Proteinuria was similar between CSE- and EPI-groups.
Arterial pressure profile was similar in severe pre-eclamptic patients in the two groups (Table 5, Fig. 2). Mean, systolic and diastolic arterial pressures during the first trimester of pregnancy were similar between the two groups. Highest mean, systolic and diastolic arterial pressures during pregnancy, and just prior to anaesthesia for Caesarean section, were comparable between the EPI- and CSE-groups. Lowest intraoperative mean, systolic and diastolic arterial pressures prior and after delivery of the fetus were similar between EPI- and CSE-groups (Table 5, Fig. 2). Significantly more ephedrine was used in the CSE-group compared to the EPI-group. More i.v. lactated Ringer's was used in the EPI-group. Blood loss was comparable between the treatment groups (Table 5).
Neonatal weight was similar between the groups. Apgar scores did not differ between the groups. Umbilical artery pH was comparable between the two groups (Table 6). Maternal intensive care admission was never required. No cases of maternal pulmonary oedema were noted (Table 6).
Spinal anaesthesia is probably the most widespread anaesthetic technique used for routine Caesarean section. In pre-eclampsia, many obstetric anaesthetists avoid the technique fearing sudden sympathetic blockade, resulting in a high number of patients experiencing severe hypotension which could also detrimentally affect neonatal outcome . Additionally, the rapid infusion of i.v. fluids could favour the development to pulmonary oedema . Although the use of i.v. pressor agents may be dangerous because of increased sensitivity to these agents in pre-eclampsia , several prospective and retrospective trials do not support this fear [8,9,12-14]. Spinal anaesthesia was not associated with more pronounced hypotension and worse neonatal or maternal outcome compared to epidural anaesthesia.
In normal pregnancy CSE anaesthesia, using a low dose of bupivacaine combined with opioids, produces very limited hypotension . The results of the present retrospective chart analysis provide evidence that also in pre-eclampsia and severe pre-eclampsia, CSE does not result in more pronounced hypotension than conventional epidural anaesthesia. This is in agreement with Ramanathan and colleagues views where no differences in haemodynamics and neonatal outcome were observed between EPI- and CSE-groups .
Some authorities suggest that a low-dose CSE is superior to single shot spinal anaesthesia because fewer haemodynamic changes occur. Chiu and colleagues , Wallace and colleagues  and Hood and Curry  demonstrate that on average arterial pressure is reduced by 15-25% in severe pre-eclamptic patients receiving either epidural or spinal anaesthesia. The present investigation shows that CSE reduces arterial pressure by 10-15%. It appears, from the available retrospective and limited prospective literature data, that low-dose opioids with CSE produces less hypotension than single shot spinal anaesthesia. However this assumption warrants further randomized prospective trials.
In the CSE-group more ephedrine was used. Written departmental protocols allow for prophylactic ephedrine (10-15 mg) in patients undergoing CSE anaesthesia in normal and pre-eclamptic pregnancy. Probably the observed differences in ephedrine use between the CSE- and EPI-groups could be explained by these written protocols. However, this is hard to demonstrate due to the retrospective study design. Alternatively, the increased use of ephedrine could also reflect increased haemodynamic instability in the CSE-group. In any case, the use of ephedrine probably influenced maternal arterial pressure. However, CSE combined with small doses of ephedrine, whether prophylactic or therapeutic, resulted in haemodynamic stability and good neonatal outcome compared to the EPI-group.
Significantly more Ringer's lactate was given in the EPI-group. In this group the prolonged duration of the procedure due to slower onset of anaesthesia and the increased use of prophylactic i.v. fluids, compared to the CSE-group, might explain these differences. Again, the retrospective study design does not allow for definitive conclusions.
Interestingly, umbilical artery pH was lower in pre-eclamptic patients undergoing epidural anaesthesia compared to those undergoing CSE, despite similar haemodynamics and increased use of ephedrine in the CSE-group. High doses of ephedrine, used for the prevention or treatment of hypotension during Caesarean section, have been associated with deleterious umbilical artery blood-gas status compared to other strategies of prevention of hypotension . Low umbilical artery pH in the EPI-group can be a reflection of worse pre-eclamptic disease in these patients compared to CSE-group. However, this is speculation and requires prospective randomized trials.
Emergency Caesarean delivery is performed under low-dose CSE anaesthesia at our institution in practically all cases, except when contraindications to regional anaesthesia, such as coagulation disorders, are present. In experienced hands, low-dose CSE anaesthesia allows for good surgical conditions within 5 min from the start of the spinal injection. Additionally it offers the advantage of additional top-ups and post-operative patient controlled epidural anaesthesia. It is important however to stress that experience in both epidural and spinal anaesthesia, does not suffice to successfully perform CSE anaesthesia.
A limitation of the present study is the low number of parturients receiving CSE anaesthesia compared to the number of parturients receiving epidural anaesthesia. This was mainly due to the fact that many pre-eclamptic patients were initially in labour and had labour epidurals in place before Caesarean section was eventually performed. Of course the present study design suffers from all limitations of other retrospective studies. We are well aware that interpretation of these results requires caution. However, these data have allowed us to initiate a randomized trial comparing epidural and CSE anaesthesia in severely pre-eclamptic patients undergoing semi-elective Caesarean section.
In conclusion, the present retrospective chart analysis provides further evidence that spinal anaesthesia - and more particularly CSE anaesthesia - is a safe and valuable alternative to epidural and general anaesthesia for Caesarean delivery in (severe) pre-eclampsia. Combined spinal-epidural anaesthesia is associated with relatively mild changes in haemodynamics and good maternal and neonatal outcome.
The authors wish to thank the midwifery staff of the University Hospitals for excellent record keeping and assistance in retrieving vital information.
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