G. Lyons

Assessment of platelet inhibition secondary to clopidogrel and aspirin therapy in preoperative acute surgical patients measured by Thrombelastography® Platelet Mapping™

BACKGROUND Increasing numbers of patients prescribed clopidogrel and aspirin are presenting for non-elective surgery. No consensus on the timing of surgery exists after withdrawal of antiplatelet and tests of platelet function are not routinely available. The Thrombelastography Platelet Mapping (TEG-PM) assay is designed to assess platelet inhibition secondary to antiplatelet therapy. We assessed its ability to detect platelet inhibition in preoperative acute surgical patients. METHODS We conducted a prospective observational study in three groups of preoperative patients: those taking clopidogrel or aspirin up to admission, and a control group. TEG-PM was performed on the day of admission and alternate days until surgery. RESULTS Mean (SD) platelet thromboxane A(2) receptor inhibition in the control group was 17.5% (23.8) (n=20), 52.6% (32.3) (n=18) in the aspirin group, and 31.9% (27.6) (n=21) in the clopidogrel group (P<0.01). Mean (SD) platelet adenosine diphosphate (ADP) receptor inhibition in the control group was 47.8% (18.9) (n=20), 52.6% (19.7) (n=18) in the aspirin group, and 71.5% (18.4) (n=21) in the clopidogrel group (P<0.01). Among the clopidogrel group awaiting surgery, mean platelet ADP channel inhibition decreased on day 3 to 67.1% (24.7) (n=11), 48.8% (24.4) (n=4) on day 5, and 36.1% (15.9) (n=2) on day 7 (P=0.57). CONCLUSIONS TEG-PM can identify statistically significant platelet inhibition after antiplatelet therapy; however, the overlap in platelet receptor inhibition between the three groups is likely to limit the clinical usefulness of this test.

Training in obstetric general anaesthesia: a vanishing art?

General anaesthesia in obstetric practice has largely been replaced by the use of regional techniques. We have studied this phenomenon and the subsequent impact on training in this technique both retrospectively and with a prospective audit. There has been a decline in the use of general anaesthesia for Caesarean section such that trainee anaesthetists are getting less practical exposure to this important procedure. Audit revealed a deficit with consultant involvement in training and heightened awareness has resulted in improved supervision. Possible implications for future consultant working practices are discussed.

An evaluation of a 30-gauge needle for spinal anaesthesia for caesarean section.

A 30‐gauge spinal needle was evaluated for Caesarean section, using a combined epidural/spinal technique, in 50 mothers. Spinal anaesthesia failed in six mothers and was inadequate in another six. General anaesthesia was required on one occasion. A 25% overall failure rate suggests that a 30‐gauge needle is not a practical proposition for routine clinical practice.

Role of prophylactic uterine artery balloon catheters in the management of women with suspected placenta accreta

BACKGROUND Placenta praevia and accreta are leading causes of major obstetric haemorrhage and peripartum hysterectomy. Detection is largely based on a high index of clinical suspicion, though the diagnostic accuracy of radiological imaging is improving. Interventional radiological techniques can reduce blood loss and the incidence of hysterectomy. METHODS We have reviewed our experience with bilateral prophylactic uterine artery balloon occlusion in the management of women with suspected placenta accreta. Thirteen women at high risk of major haemorrhage due to placenta praevia or suspected placenta accreta were retrospectively studied. Uterine artery balloons were placed prophylactically under neuraxial anaesthesia in the angiography suite followed by caesarean delivery in the obstetric operating theatre. RESULTS Intraoperative blood loss and transfusion requirements were low in our case series. There were no hysterectomies or admissions to the intensive care unit. Fetal bradycardia necessitating immediate caesarean delivery occurred in two women (15.4%). CONCLUSION In our case series in women with suspected placenta accreta, prophylactic use of uterine artery balloons was associated with a low requirement for blood transfusion but with possible increased risk of fetal compromise. Performing the interventional procedure at a different site from the operative room complicated management.

Diclofenac for analgesia after Caesarean section

The analgesic efficacy of a single intramuscular dose of 75 mg diclofenac given after elective Caesarean section was studied in 50 women in a double‐blind randomised manner using a patient‐controlled analgesia system. The mean 18 h papavaretum consumption of the placebo group was significantly greater (91.4 mg compared to 61.4 mg). Subjective experience of pain and observed sedation were significantly greater in the control group up to 6 h after operation.

Regional blockade for delivery in women with scoliosis or previous spinal surgery

We conducted a prospective observational study between 1992 and 2001 identifying obstetric patients with untreated or surgically corrected scoliosis or lumbar-sacral fusion surgery. The regional techniques for labour and delivery that were offered were epidural analgesia, combined spinal epidural anaesthesia (CSE), single shot spinal or continuous spinal anaesthesia (CSA) depending on the degree of scoliosis, previous surgery, cardio-respiratory compromise and planned mode of delivery. Forty women were included in the study, one woman with two separate deliveries, giving 41 cases for analysis. Twenty-four women presented in labour: 11 required no regional technique, seven received effective epidural analgesia and six received CSA. Seventeen women presented for elective caesarean delivery: two received a CSE technique, two received single shot spinal and 13 had CSA. From a total of 19 CSA techniques attempted sixteen catheters were successfully inserted and produced good analgesia or anaesthesia for vaginal or operative delivery in 12 women (63%). There was one case of post dural puncture headache following a CSA for labour and delivery. We discuss the choices available for regional anaesthetic techniques in scoliotic women and the relative merits of each.

Vanishing experience in training for obstetric general anaesthesia: an observational study

BACKGROUND Changes in the delivery of anaesthesia for caesarean section have meant that trainee experience in obstetric general anaesthesia has steadily declined. In the UK, working patterns for trainees have changed significantly with the introduction of the New Deal in 2000 and the European Working Time Directive in 2004. Because of an impression that training opportunities had worsened during this period we have reviewed data in obstetric general anaesthesia at St Jamess University Hospital since 1998. METHODS Data were collected retrospectively from prospective audit information contained within annual reviews collated by the Department of Obstetric Anaesthesia, St Jamess University Hospital Leeds between 1998 and 2006. Results before and after the implementation of training changes in 2000 and 2004 were compared. RESULTS Since 1998 the total number of obstetric general anaesthetics given per year has continued to decline. The number of trainees increased from 23 in 1998 to 40 in 2006, with the main increase occurring between 2002 and 2003. The mean number of obstetric general anaesthetics given per trainee fell to 1 per year in 2006. CONCLUSION Since 1998 training opportunities in general anaesthesia for caesarean section at St Jamess Hospital have continued to decline. This reflects both changing trends in the delivery of anaesthesia for caesarean section and also changes in training hours and trainee numbers.

Anaesthesia for Caesarean section in a patient with Charcot-Marie-Tooth disease

We describe the management of a 25‐year‐old primigravida with severe respiratory insufficiency secondary to Charcot‐Marie‐Tooth disease type I scheduled for Caesarean section. Incremental subarachnoid anaesthesia via a microcatheter was utilised. Mother and baby made an uneventful recovery and were discharged home on the tenth postoperative day.

Lignocaine test dose to detect intravenous injection.

The accidental intravascular injection of bupivacaine or etidocaine epidurally has resulted in several maternal deaths. To be effective, a test dose must allow detection of intravenous catheter placement and prevent accidental intravenous injection. This study was designed to determine the dose of lignocaine required for this purpose. Sixty healthy gynaecological patients were allocated randomly to receive an intravenous dose of normal saline (group 1), lignocaine 0.5 mg.kg‐1 (group 2) or 1 mg.kg‐1 (group 3) 3 min prior to induction of anaesthesia. At 1 min intervals the patients were asked about subjective symptoms produced by this‘test dose’In group 2 only 50% of patients reported a positive test dose, whereas in the patients of group 3, a significantly greater percentage (95%) had a positive test dose (p < 0.01). This suggests that the use of 1 mg.kg‐1 lignocaine as a test dose would result in a significantly higher sensitivity for detecting intravascular injection than the use of 0.5 mg.kg‐1

Fetal effects of combined spinal-epidural vs epidural labour analgesia: a prospective, randomised double-blind study

We have compared fetal heart rate patterns, Apgar scores and umbilical cord gas values following initiation of labour analgesia using either combined spinal‐epidural or epidural. One hundred and fifteen healthy women requesting neuraxial analgesia in the first stage of labour were randomly assigned to receive either combined spinal‐epidural (n = 62) or epidural analgesia (n = 53). Fetal heart rate traces, recorded for 30 min before and 60 min after neuraxial block, were categorised as normal, suspicious or pathological according to national guidelines. Sixty‐one fetal heart rate tracings were analysed in the combined spinal‐epidural group and 52 in the epidural group. No significant differences were found in fetal heart rate patterns, Apgar scores or umbilical artery and vein acid‐base status between groups. However, in both combined spinal‐epidural and epidural groups, there was a significant increase in the incidence of abnormal fetal heart rate patterns following neuraxial analgesia (p < 0.0001); two before compared with eight after analgesia in the combined spinal‐epidural group and zero before compared with 11 after in the epidural group. These changes comprised increased decelerations (p = 0.0045) (combined spinal‐epidural group nine before and 14 after analgesia, epidural group four before and 16 after), increased late decelerations (p < 0.0001) (combined spinal‐epidural group zero before and seven after analgesia, epidural group zero before and eight after), and a reduction in acceleration rate (p = 0.034) (combined spinal‐epidural group mean (SD) 12.2 (6.7) h−1 before and 9.9 (6.1) h−1 after analgesia, epidural group 11.0 (7.3) h−1 before and 8.4 (5.9) h−1 after). These fetal heart rate changes did not affect neonatal outcome in this healthy population.