Problems with general anaesthesia for Caesarean section

This has not been a comprehensive review of problems with general anaesthesia for Caesarean section, but major issues have been considered. The old problems are still with us, but their manifestations are perhaps more subtle as anaesthesia has become more sophisticated. Most of the problems are of our own making, but hindsight is only useful if we apply it to the future. Maternal safety is best served by a continuing expansion in the use of regional anaesthesia, but we must prepare for the problems that we create by ensuring that anaesthetists are adequately trained for the occasional general anaesthetic, possibly with more help from simulation.

Epidural test dose with levobupivacaine and ropivacaine: determination of ED 50 motor block after spinal administration

BACKGROUND

When a test is required to detect a possible intrathecal catheter, many would seek to use the same local anaesthetic as that used for epidural analgesia. The rapid onset of inappropriate motor block after a local anaesthetic administered epidurally implies intrathecal spread. Because of claims of greater sensory-motor separation, or because of reduced potency compared with bupivacaine, the efficacy of the new local anaesthetics in intrathecal testing has been questioned. The aim of this study was to establish the feasibility of a test dose for an inadvertent intrathecal catheter using ropivacaine and levobupivacaine, and to establish the dose required.

METHODS

Sixty women undergoing elective Caesarean section with a combined spinal- epidural technique were enrolled into this prospective, double-blind sequential allocation study. The women were randomized to receive plain levobupivacaine 0.5% or ropivacaine 0.5% intrathecally. The dose was determined according to up-down sequential allocation. The end-point was any evidence of lower limb motor block within 5 min of injection.

RESULTS

The ED(50) motor block at 5 min was 4.8 mg (95% CI, 4.49, 5.28) for levobupivacaine and 5.9 mg (95% CI, 4.82, 6.98) for ropivacaine (95% CI difference, 0.052, 1.98) (P=0.04). The estimated ED(95) motor block was 5.9 mg (95% CI 5.19, 6.71) for levobupivacaine and 8.3 mg (95% CI, 6.30, 10.44) for ropivacaine. The potency ratio between the two drugs was 0.83 (95% CI, 0.69, 0.99).

CONCLUSIONS

Both local anaesthetics produce evidence of motor block within 5 min of intrathecal injection and could serve as tests of intrathecal administration. Derived ED(95) values suggest 10 mg doses should be effective, but this study did not measure predictive value. Ropivacaine is less potent for motor block than levobupivacaine by a factor of 0.83 (P<0.04).

In vitro evidence of gender-related heparin resistance

Coagulability varies among men, women, and pregnant women, along a spectrum where the blood of men is the least and that of pregnant women the most coagulable. The effects of differences in coagulation status on the action of heparin cannot be measured by specific laboratory tests such as aPTT or anti-Factor Xa assay. Thromboelastography which measures whole blood coagulation can assess the effect of heparin against differing backgrounds of coagulation. The aim of this in vitro study was to explore differences in heparin effect between men, women and pregnant women. Fifteen male and female staff volunteers, and 15 pregnant women approaching term, donated venous blood, which was added to four cups in two TEG 5000 analysers. In the cups of the analysers was 0.03 mL of saline control, or heparin 0.4, 0.6 or 1 unit/mL. TEG variables r and k, angle and MA were compared across the groups using two way ANOVA. All subject groups demonstrated a significant heparin effect, which was least in the control group and greatest with 1 unit/mL (P < 0.0001). Across the subject groups, from men to pregnant women, increasing coagulability was seen, with shortening of r and k (P < 0.04), and increasing angle and MA (P < 0.0001). A relationship between gender and heparin was significant for r and k (P < 0.02) but not for angle and MA. This result assists the case against a one-size-fits-all approach to policies on heparinisation.

Supraventricular tachycardia in pregnancy

We present four cases of supraventricular tachycardia in pregnancy of varied aetiology. Risk factors for the development of supraventricular tachycardia and options for obstetric anaesthetic management, during pregnancy, labour, and at Caesarean section are discussed. We recommend the use of adenosine as first line therapy.

Risk management options for endocrine disruptors in national and international programs

This workshop was convened to address common issues and concerns associated with risk management of endocrine-disrupting chemicals (EDCs). The talks described the tools and policies for key Japanese, Australian, German, and U.S. regulatory agencies. The agencies participating in the workshop were responsible for the regulation of various substances including: chemicals, pesticides, environmental contamination, pharmaceuticals, and food additives. The panel also described the role of the Organization for Economic Cooperation and Development (OECD) in standardizing the tools and validation of testing and screening methods. The panel also included nongovernmental organizations presenting the views of the World Wildlife Fund, and the chemical industry from industrialized nations; each organization described its concerns and proposed approaches to risk management of EDCs. This summary highlights the most important areas of common points of view of government, industry, and environmentalists. We also try to identify issues upon which viewpoints diverge.

Preeclampsia complicated by placental abruption, HELLP, coagulopathy and renal failure – further lessons

We present a case of preeclampsia complicated by HELLP (haemolysis, elevated liver enzymes and low platelets) syndrome and marked coagulopathy. The severity of the coagulopathy and haemolysis made renal failure and pulmonary oedema inevitable. We identified a number of discussion points in this case. These were the delay to appreciate the haemolysis, the severity of the haemolysis and its interaction with the treatment of coagulopathy and the conservative management of pulmonary oedema. At these points there were shortcomings in our management of this complex case that merit further discussion.

Endocrine active substances and the need to improve environmental protection: An environmentalist's perspective

This paper reviews the existing concerns and presents conclusions and recommendations for action.

The first section outlines an environmentalist's perspective and predicts that endocrine active substances (EASs) pose a high risk for wildlife populations. The second section explains that risk assessment, as currently practiced for individual chemicals, does not adequately protect the environment, and suggests several improvements that should be made. However, it is argued that the properties of endocrine disruption lead to increased uncertainty in the risk assessment, such that countries wishing to achieve a high level of protection would be justified in implementing precautionary controls.

The third section outlines some conclusions and additionally provides an appraisal of the responses of governments and industry. Furthermore, several recommendations are made, particularly the imperative for research funding to be substantially increased and guaranteed for many years to come. Also highlighted is the need to hasten the development of screens and tests for ecotoxicity, and for governments to commit to a comprehensive sorting, screening, and toxicity testing program for all chemicals to which significant exposure occurs.

Peripartum management of a patient with Glanzmann's thrombasthenia using Thrombelastograph

We describe the perioperative management of a 31-yr-old primipara with Glanzmann's thrombasthenia, who required urgent Caesarean delivery at 33 weeks' gestation. Peripartum haemorrhage was inevitable and was pre-empted by transfusion of multiple blood products, the effects of which were monitored by Thrombelastograph. The blood products given are discussed.

Postpartum neurological symptoms following regional blockade: a prospective study with case controls

We undertook a 12-month prospective study to establish the incidence, nature and significance of postpartum neurological symptoms. To explore the effects of regional blockade, obstetric intervention and neurological examination, women with symptoms after regional blockade were matched with two asymptomatic case controls, one with similar regional blockade and obstetric intervention and another without either regional blockade or obstetric intervention. Twenty-two of 2615 women who had received regional blockade and one of 1376 who had not, presented with postpartum neurological symptoms (incidence 5.8:1000). Presentation with symptoms was associated with regional blockade (P = 0.003) but may reflect reporting bias. Sixty-three women were recruited and examined in a standardised manner. Neurological deficits were identified in all groups. Twelve women were readily diagnosed with obstetric palsies, all of which were associated with vaginal rather than caesarean delivery (P = 0.003). Four of these women had not volunteered symptoms before examination. Six women reported lower sacral dermatome numbness of unknown aetiology but associated with caesarean delivery (P = 0.002). Non-anatomical sensory loss in four of 21 women with symptoms was also noted in 10% of the controls and is likely to be of little clinical significance. Sixteen women who had presented with symptoms completed a 6-month follow-up interview. Thirteen had no symptoms and three had residual sensory symptoms but no functional impairment. These results confirm that postpartum neurological dysfunction is more frequent if specifically sought, and support the clinical impression that significant neurological deficits occur irrespective of the use of regional anaesthesia.

Advancing health promotion in Australian general practice

Health promotion activities, while having the potential to prevent disease and decrease the burden of ill health, often play a minor role in the health care offered by general practitioners. There are several identified barriers to the involvement of Australian general practitioners in health promotion. These include structural barriers and barriers within the practice setting, individual practitioner and patient factors, and difficulties in evaluating the outcomes of health promotion activities. This article explores the barriers to the engagement of Australian general practice with health promotion and reviews several recent initiatives that have the potential to increase the health promotion activities of general practitioners. These initiatives act at the level of the individual practitioner, the practice, and in the community. Despite the lack of a coordinated national approach, these strategies form an important development in general practice.

Minimum analgesic dose of epidural sufentanil for first-stage labor analgesia: a comparison between spontaneous and prostaglandin-induced labors in nulliparous women

BACKGROUND

The aim of this prospective, double-blind, sequential allocation study was to compare the effects of spontaneous and prostaglandin-induced labor on the minimum analgesic dose of epidural sufentanil in the first stage of labor.

METHODS

Seventy healthy, nulliparous women, at more than 37 weeks' gestation with cervical dilatation from 2 to 4 cm, requesting epidural pain relief in labor were enrolled. The subjects were assigned to two different groups according to whether labor was spontaneous or induced with dinoprostone 0.5 mg. Parturients received 10 ml of the study solution through a lumbar epidural catheter. The initial dose was sufentanil 25 microg, and subsequent doses were determined by the response of the previous patient in the same group using up-down sequential allocation. The analgesic effectiveness was assessed using 100-mm visual analog pain scores. The up-down sequences were analyzed using the method of independent paired reversals and probit regression.

RESULTS

The minimum analgesic dose of sufentanil in spontaneous labor was 22.2 microg (95% CI: 19.6, 22.8) and 27.3 microg (95% CI: 23.8, 30.9) in induced labor. The minimum analgesic dose of sufentanil in induced labor was significantly greater (P = 0.0014) than that in spontaneous labor (95% CI difference: 2.9, 9.3) by a factor of 1.3 (95% CI: 1.1, 1.5).

CONCLUSION

Prostaglandin induction of labor produces a significantly greater analgesic requirement than does spontaneous labor.

Minimum local analgesic dose of intrathecal bupivacaine in labor and the effect of intrathecal fentanyl

BACKGROUND

Combining bupivacaine with fentanyl for intrathecal analgesia in labor is well recognized, but dosages commonly used are arbitrarily chosen and may be excessive. This study aimed to determine the median effective dose (ED50) of intrathecal bupivacaine, defined as the minimum local analgesic dose (MLAD), and then use this to assess the effect of different doses of fentanyl.

METHODS

In this double-blind, randomized, prospective study, 124 parturients receiving combined spinal epidural analgesia at 2-6-cm cervical dilatation were allocated to one of four groups to receive bupivacaine alone or with 5, 15, or 25 microg fentanyl, using the technique of up-down sequential allocation. Analgesic effectiveness was assessed using 100-mm visual analog pain scores, with less than or equal to 10 mm within 15 min defined as effective. MLAD was calculated using the formula of Dixon and Massey. Pruritus and duration of spinal analgesia were also recorded.

RESULTS

Minimum local analgesic dose of intrathecal bupivacaine was 1.99 mg (95% confidence interval, 1.71, 2.27). There were similar significant reductions in MLAD (P < 0.001) for all bupivacaine-fentanyl groups compared with bupivacaine control. There was a dose-dependent increase in both pruritus and duration of spinal analgesia with increasing fentanyl (P < 0.0001).

CONCLUSION

Under the conditions of this study, the addition of intrathecal fentanyl 5 microg offers a similar significant bupivacaine dose-sparing effect as 15 and 25 microg. Analgesia in the first stage of labor can be achieved using lower doses of fentanyl, resulting in less pruritus but with a shortening of duration of action.

Survivors of childhood cancers: implications for obstetric anaesthesia

Treatment of many childhood malignancies involves surgery, radiotherapy and chemotherapy. If the child survives, normal physical development can be impaired and abnormalities with anaesthetic implications may be present. We discuss two women with a range of problems who presented for obstetric anaesthesia, having survived childhood malignancies. Common features included anthracycline cardiotoxicity and short stature. Both patients received incremental spinal anaesthesia in order to titrate the dose of local anaesthetic required to produce an adequate block height and to minimize cardiovascular instability.

An environmentalist's vision of operationalizing the precautionary principle in the management of chemicals

In Europe and elsewhere, there is compelling evidence that humans, wildlife, and the environment are being damaged by man-made chemicals. Recognizing that regulatory initiatives are needed to try to prevent harm before it occurs in the future, the precautionary principle has become a focus of attention on both sides of the Atlantic. The authors suggest a way to implement the precautionary principle in the management of chemicals, outlining how this guiding principle can be given a practical relevance within regulatory initiatives to reduce the risks posed by chemicals currently traded in the European Union and elsewhere.

Preparation for regional anaesthesia induces changes in thrombelastography

The effects of crystalloid and colloid infusions on coagulation measured by thrombelastography (TEG) present a confused picture. The influence of environmental factors may explain the disparity between previous studies. We studied two groups of 20 women presenting at term for elective Caesarean section. In the first group, TEG analysis was performed before and after infusion of Gelofusine 500 ml over 15 min. The second group was treated in the same way except that subjects did not receive fluid. We found significant changes in r and k values in both groups, suggesting enhanced coagulation. As hypercoagulable changes were also seen in the group that did not receive fluid preload, the hypothesis that moderate haemodilution causes hypercoagulability must be questioned. The influence of environmental factors can explain differences reported between in vivo and in vitro studies.