R.A. Dyer

The use of uterotonic drugs during caesarean section.

The administration of oxytocic drugs during caesarean section is an important intervention to prevent uterine atony or treat established postpartum haemorrhage. Considerable past and current research has shown that these agents have a narrow therapeutic range. A detailed knowledge by anaesthetists of optimal doses and side effects is therefore required. Oxytocin remains the first line agent. In view of receptor desensitisation, second line agents may be required, namely ergot alkaloids and prostaglandins. This review examines the adverse haemodynamic and side effects, and methods for their limitation. An approach to dosing and choices of agent for the limitation of postpartum haemorrhage is suggested.

Knowledge and expectations of labour among primigravid women in the public health sector

OBJECTIVES We analysed knowledge and expectations of the process and pain of labour in primigravidas attending a local midwifery obstetric unit (MOU). It was anticipated that the results of this study could inform the development of interventions aimed at improving the analgesic care of women delivering at primary health care obstetric units. DESIGN Qualitative analysis of data obtained from in-depth semi-structured interviews. SETTING A Cape Town MOU. SUBJECTS 30 black African, Xhosa-speaking primigravidas. OUTCOME MEASURES An open-ended interview guide was developed. The themes explored included previous painful experiences, knowledge of labour, expectations of and attitudes towards labour pain, and knowledge of biomedical analgesia. RESULTS Patients were poorly informed about the process and pain of labour. Most women appeared highly motivated concerning their ability to cope with labour. Most expected pain, but had no concept of the severity or duration of the pain, and knew very little concerning methods available for pain relief in labour. CONCLUSION Women at this MOU were poorly prepared for the experience of delivery. Antenatal programmes should incorporate sensitive education concerning the process and pain of labour and the methods available to alleviate pain.

A randomised comparison of bolus phenylephrine and ephedrine for the management of spinal hypotension in patients with severe preeclampsia and fetal compromise

BACKGROUND Studies in healthy patients undergoing elective caesarean delivery show that, compared with phenylephrine, ephedrine used to treat spinal hypotension is associated with increased fetal acidosis. This has not been investigated prospectively in women with severe preeclampsia. METHODS Patients with preeclampsia requiring caesarean delivery for a non-reassuring fetal heart tracing were randomised to receive either bolus ephedrine (7.5-15mg) or phenylephrine (50-100µg), to treat spinal hypotension. The primary outcome was umbilical arterial base excess. Secondary outcomes were umbilical arterial and venous pH and lactate concentration, venous base excess, and Apgar scores. RESULTS Among 133 women, 64 who required vasopressor treatment were randomised into groups of 32 with similar patient characteristics. Pre-delivery blood pressure changes were similar. There was no difference in mean [standard deviation] umbilical artery base excess (-4.9 [3.7] vs -6.0 [4.6] mmol/L for ephedrine and phenylephrine respectively; P=0.29). Mean umbilical arterial and venous pH and lactate concentrations did not significantly differ between groups (7.25 [0.08] vs 7.22 [0.10], 7.28 [0.07] vs 7.27 [0.10], and 3.41 [2.18] vs 3.28 [2.44] mmol/L respectively). Umbilical venous oxygen tension was higher in the ephedrine group (2.8 [0.7] vs 2.4 [0.62]) kPa, P=0.02). There was no difference in 1- or 5-min Apgar scores, numbers of neonates with 1-min Apgar scores <7 or with a pH <7.2. CONCLUSIONS In patients with severe preeclampsia and fetal compromise, fetal acid-base status is independent of the use of bolus ephedrine versus phenylephrine to treat spinal hypotension.

The use of phenylephrine to obtund oxytocin-induced hypotension and tachycardia during caesarean section

BACKGROUND Oxytocin causes clinically significant hypotension and tachycardia. This study examined whether prior administration of phenylephrine obtunds these unwanted haemodynamic effects. METHODS Forty pregnant women undergoing elective caesarean section under spinal anaesthesia were randomised to receive either an intravenous 50 μg bolus of phenylephrine (Group P) or saline (Group S) immediately before oxytocin (3U over 15s). Systolic blood pressure, diastolic blood pressure, mean arterial pressure and heart rate were recorded using a continuous non-invasive arterial pressure device. Baseline values were averaged for 20s post-delivery. Between-group comparisons were made of the mean peak changes in blood pressure and heart rate, and the mean percentage changes from baseline, during the 150s after oxytocin administration. RESULTS The mean ± SD peak percentage change in systolic blood pressure was -16.9 ± 2% in Group P, and -19.0 ± 1.9% in Group S and the estimated mean difference was 2.1% (95% CI -3.5% to 7.8%; P=0.44); corresponding changes in heart rate were 13.5 ± 2.3% and 14.0±1.5% and the mean estimated difference was 0.5% (95% CI -6.0% to 5%; P=0.87). The mean percentage change from the baseline measurements during the 150s period of measurement was greater for Group S than Group P: systolic blood pressure -5.9% vs -3.4% (P=0.149); diastolic blood pressure -7.2% vs -1.5% (P=0.014); mean arterial pressure -6.8% vs -1.5% (P=0.007); heart rate 2.1% vs -2.4% (P=0.033). CONCLUSION Intravenous phenylephrine 50 μg immediately before 3U oxytocin during elective caesarean section does not prevent maternal hypotension and tachycardia.

Update on general anaesthesia for Caesarean section

The increased use of regional anaesthesia for Caesarean section (CS) has been a consequence of the risk of failed intubation associated with general anaesthesia (GA) for CS, as well as the provision of an improved birth experience and quality of postoperative analgesia. This trend has led to a lack of experience in the practice of rapid sequence intubation and GA in trainee anaesthetists, 1 prompting the suggestion that simulators may become an essential part of anaesthesia training in this scenario. 2 In the USA during the period 1984-2002, the case fatality rate for general anaesthesia decreased from 32.3 to 6.5 per million, while the rate of regional anaesthesia was lower, but increased from 1.9 to 3.8 per million. 3

Maternal cardiac output response to colloid preload and vasopressor therapy during spinal anaesthesia for caesarean section in patients with severe pre‐eclampsia: a randomised, controlled trial

We examined the haemodynamic effects of colloid preload, and phenylephrine and ephedrine administered for spinal hypotension, during caesarean section in 42 women with severe early onset pre‐eclampsia. Twenty patients with pre‐delivery spinal hypotension were randomly allocated to receive an initial dose of either 50 μg phenylephrine or 7.5 mg ephedrine; the primary outcome was percentage change in cardiac index. After a 300‐ml colloid preload, mean (SD) cardiac index increased from 4.9 (1.1) to 5.6 (1.2) l.min−1.m−2 (p < 0.01), resulting from an increase in both heart rate, from 81.3 (17.2) to 86.3 (16.5) beats.min−1 (p = 0.2), and stroke volume, from 111.8 (19.0) to 119.8 (17.9) ml (p = 0.049). Fourteen (33%) and 23 (54.8%) patients exhibited a stroke volume response > 10% and > 5%, respectively; a significant negative correlation was found between heart rate and stroke volume changes. Spinal hypotension in 20 patients was associated with an increase from baseline in cardiac index of 0.6 l.min−1.m−2 (mean difference 11.5%; p < 0.0001). After a median [range] dose of 50 [50–150] μg phenylephrine or 15 [7.5–37.5] mg ephedrine, the percentage change in cardiac index during the measurement period of 150 s was greater, and negative, in patients receiving phenylephrine vs. ephedrine, at −12.0 (7.3)% vs. 2.6 (6.0)%, respectively (p = 0.0001). The percentage change in heart rate after vasopressor was higher in patients receiving phenylephrine, at −9.1 (3.4)% vs. 5.3 (12.6)% (p = 0.0027), as was the change in systemic vascular resistance, at 22.3 (7.5) vs. −1.9 (10.5)% (p < 0.0001). Phenylephrine effectively reverses spinal anaesthesia‐induced haemodynamic changes in severe pre‐eclampsia, if left ventricular systolic function is preserved.

Qualitative study of the knowledge and expectations of the pain of labour, in urban Xhosa primigravidae

No Abstract Available Southern African Journal of Anaesthetics and Analgesia Vol.11(1) 2005: 23

New trends in the management of postpartum haemorrhage

If the World Health Organization (WHO) global maternal mortality by cause is examined for the period 1997-2007, haemorrhage constitutes 35% of deaths. Published data from the triennium 2008-2010 in South Africa indicate that if non-pregnancy-related sepsis is excluded, haemorrhage still ranks with hypertension as the most common cause of maternal deaths (24%). So how can anaesthetists improve this situation and save lives? Sadly, the main reason for the appalling figures in respect of maternal deaths in sub-Saharan Africa is poor access to basic obstetric care, blood products and basic commodities, such as electricity, for the refrigeration of blood and drugs such as oxytocin.1 Nevertheless, there are many areas where management, and hence outcomes, could be improved. This article addresses the crucial issues of predicting haemorrhage, assessing blood loss, point-of-care monitoring and transfusion protocols. Surgical techniques and oxytocic therapy are equally important, and are the subject of many other reviews. Keywords : postpartum haemorrhage; management; new trends

Informed consent for epidural analgesia in labour

ABSTRACT Consent for epidural analgesia for labour is unique. The issues of patient autonomy and competence are controversial because of the limited antenatal education that most South African patients receive, and the absence of a culture of structured birth planning. Frequently, such patients are first encountered by the anaesthetist when in advanced labour and limited time is available for explanation. Overall, this represents the most extreme example of obtaining consent in compromised circumstances.

Incidence of myocardial injury after non-cardiac surgery: Experience at Groote Schuur Hospital, Cape Town, South Africa

BACKGROUND Myocardial injury after non-cardiac surgery (MINS) is a newly recognised entity identified as an independent risk factor associated with increased 30-day all-cause mortality. MINS increases the risk of death in the perioperative period by ~10-fold. More than 80% of patients with MINS are asymptomatic, so the majority of diagnoses are missed. Awareness of MINS is therefore important for perioperative physicians. OBJECTIVES To investigate the incidence of MINS after elective elevated-risk non-cardiac surgery at Groote Schuur Hospital, Cape Town, South Africa (SA). METHODS Patients aged ≥45 years undergoing elective elevated-risk non-cardiac surgery were enrolled via convenience sampling. The new fifth-generation high-sensitivity cardiac troponin T blood test was used postoperatively to identify MINS. Preoperative troponin levels were not measured. RESULTS Among 244 patients included in the study, the incidence of MINS was 4.9% (95% confidence interval (CI) 2.8 - 8.5), which was not significantly different from that in a major international prospective observational study (VISION) (8.0% (95% CI 7.5 - 8.4)); p=0.080. CONCLUSIONS Our SA cohort had a lower cardiovascular risk profile but a similar incidence of MINS to that described in international literature. The impact of MINS on morbidity and mortality is therefore likely to be proportionally higher in SA than in published international studies. The limited sample size and lower event rate weaken our conclusions. Larger studies are required to establish patient and surgical risk factors for MINS, allowing for revision of cardiovascular risk prediction models in SA.