Randomized trial of anaesthetic interventions in external cephalic version for breech presentation.

BACKGROUND: Successful external cephalic version (ECV) for breech presenting fetus reduces the need for Caesarean section (CS). We aimed to compare the success rate of ECV with either spinal anaesthesia (SA) or i.v. analgesia using remifentanil. METHODS: In a double-phased, stratified randomized blinded controlled study we compared the success rates of ECV, performed under spinal anaesthesia (SA), i.v. analgesia (IVA) using remifentanil or no anaesthetic interventions. In phase I, 189 patients were stratified by parity before randomization to ECV, performed by blinded operators, under SA using either hyperbaric bupivacaine 9 mg with fentanyl 15 µg, i.v. remifentanil infusion 0.1 µg kg min(-1), or Control (no anaesthetic intervention). Operators performing ECV were blinded to the treatment allocation. In phase 2, patients in the Control group in whom the initial ECV failed were further randomized to receive either SA (n=9) or IVA (n=9) for a re-attempt. The primary outcome was the incidence of successful ECV. RESULTS: The success rate in Phase 1 was greatest using SA [52/63 (83%)], compared with IVA [40/63 (64%)] and Control [40/63 (64%)], (P=0.027). Median [IQR] pain scores on a visual analogue scale (range 0-100), were 0 [0-0] with SA, 35 [0-60] with IVA and 50 [30-75] in the Control group (P<0.001). Median [IQR] VAS sedation scores were highest with IVA [75 (50-80)], followed by SA, [0 (0-50)] and Control [0 (0-0)]. In phase 2, 7/9 (78%) of ECV re-attempts were successful with SA, whereas all re-attempts using IVA failed (P=0.0007). The incidence of fetal bradycardia necessitating emergency CS within 30 min, was similar among groups; 1.6% (1/63) in the SA and IVA groups and 3.2% (2/63) in the Control group. CONCLUSIONS: SA increased the success rate and reduced pain for both primary and re-attempts of ECV, whereas IVA using remifentanil infusion only reduced the pain. There was no significant increase in the incidence of fetal bradycardia or emergency CS, with ECV performed under anaesthetic interventions. Relaxation of the abdominal muscles from SA appears to underlie the improved outcomes for ECV.

Randomized comparison of closed-loop feedback computer-controlled with manual-controlled infusion of phenylephrine for maintaining arterial pressure during spinal anaesthesia for caesarean delivery.

BACKGROUND: Closed-loop feedback computer-controlled infusion has not been described for administering phenylephrine to maintain arterial pressure (AP) during spinal anaesthesia for caesarean delivery. We aimed to compare AP control using this automated system with a previously described manual infusion system. METHODS: We randomly allocated 222 healthy subjects having spinal anaesthesia for scheduled caesarean delivery to have systolic AP maintained near baseline with phenylephrine (100 µg ml(-1)) by computer-controlled infusion utilizing a proportional algorithm or manual-controlled infusion utilizing an on-off algorithm. AP control was assessed by comparing the proportion of systolic AP measurements within ±20% of baseline and by performance error (PE) calculations. RESULTS: A total of 212 subjects finished the study. In the computer-control group, 97% of systolic AP recordings fell within ±20% of baseline compared with 95% in the manual-control group (P=0.0004). For computer-control compared with manual-control, wobble was smaller [median 3.5 (inter-quartile range 2.5-4.8)% vs 4.2 (3.3-5.9)%, P=0.003], but there was no difference in the median PE [2.9 (0.3-4.7)% vs 1.9 (0-4.2)%], median absolute PE [4.7 (3.5-5.6)% vs 4.7 (3.8-6.7)%], or divergence [-0.01 (-0.03-0)% vs -0.06 (-0.26-0.08)%]. Fewer interventions per subject for controlling AP were required in the computer-control group [2 (2-2) vs 10 (8-13), P<0.001]. There were no differences in measured clinical outcomes. CONCLUSIONS: Within the constraints of the studied algorithms, closed-loop feedback computer-controlled phenylephrine infusion provided better AP control with fewer interventions required compared with manual-controlled infusion.

Multi-dimensional response-probability-dose curves for bupivacaine and ropivacaine epidural labour analgesia.

Describing the relationship between magnitude of response, probability of response, dose and time is difficult using traditional two-dimensional dose-response curves. We devised a novel way of presentation in four dimensions. Data from a previous study of epidural bupivacaine and ropivacaine given for labour analgesia were re-analysed. For a range of response magnitudes (5-95% reduction in pain score), estimates of doses associated with probabilities of response 0.05-0.95 were calculated using probit analysis. Three dimensional surface plots were constructed with axes x = magnitude of response, y = probability of response and z = log(dose) at intervals for 30 min. Arithmetic interpolation was used to assemble an animation depicting temporal changes in relationship between variables (fourth dimension). Response-probability-dose curves in three and four dimensions were constructed and presented for both drugs. We believe that this model is more aligned with the logic of clinical dose selection compared with traditional two-dimensional curves.

Haemodynamic effects from aortocaval compression at different angles of lateral tilt in non-labouring term pregnant women.

BACKGROUND: Aortocaval compression (ACC) can result in haemodynamic disturbances and uteroplacental hypoperfusion in parturients. Its detection is difficult because in most patients, sympathetic compensation results in no signs or symptoms. However, profound hypotension may develop after sympathectomy during regional anaesthesia. In this prospective observational study, we aimed to detect ACC by analysing haemodynamic changes in term parturients who were positioned sequentially at different angles of lateral tilt. METHODS: We studied haemodynamic changes in 157 non-labouring term parturients who were positioned in random order at 0°, 7.5°, 15°, and full left lateral tilt. Cardiac output (CO), stroke volume, and systemic vascular resistance were derived using suprasternal Doppler. Non-invasive arterial pressure (AP) measured in the upper and lower limbs was analysed to detect aortic compression. RESULTS: CO was on average 5% higher when patients were tilted at ≥15° compared with <15°. In a subgroup of patients (n=11), CO decreased by more than 20%, without changes in systolic AP, when they were tilted to <15° which was considered attributable to severe inferior vena caval compression. Only one patient in the supine position had aortic compression with the systolic AP in the upper limb 25 mm Hg higher than the lower limb. CONCLUSIONS: Patients with ACC can be identified by the CO changes from serial measurements between supine, 15°, or full lateral tilt. Our findings suggest that in non-labouring parturients, ACC is asymptomatic and can be effectively minimized by the use of a left lateral tilt of 15° or greater.

Effects of different inspired oxygen fractions on lipid peroxidation during general anaesthesia for elective Caesarean section.

BACKGROUND: During general anaesthesia (GA) for Caesarean section (CS), fetal oxygenation is increased by administering an inspired oxygen fraction (Fi(o(2))) of 1.0. However, it is unclear whether such high Fi(o(2)) will increase oxygen free radical activity. METHODS: We randomized 39 ASA I-II parturients undergoing elective CS under GA to receive 30% (Gp 30), 50% (Gp 50), or 100% (Gp 100) oxygen with nitrous oxide and sevoflurane adjusted to provide equivalent minimum alveolar concentration. Baseline maternal arterial blood before preoxygenation and maternal arterial, umbilical arterial and venous blood at delivery were sampled for assays of the by-product of lipid peroxidation, isoprostane, and for measurement of blood gases and oxygen content. RESULTS: Maternal and umbilical isoprostane concentrations were similar among the three groups at delivery, despite significantly increased maternal and fetal oxygenation in Gp 100. However, paired comparisons of maternal delivery vs baseline concentration of isoprostane showed an increase at delivery for all groups [Gp 30: mean 342 (sd 210) vs 154 (65) pg ml(-1), P=0.016; Gp 50: 284 (129) vs 156 (79) pg ml(-1), P=0.009; Gp 100: 332 (126) vs 158 (68) pg ml(-1), P<0.001]. The magnitude of increase was similar in all three groups and independent of the Fi(o(2)) or duration after induction. CONCLUSIONS: GA for CS is associated with a marked increase in free radical activity in the mother and baby. The mechanism is unclear but it is independent of the inspired oxygen in the anaesthetic mixture. Therefore, when 100% oxygen is administered with sevoflurane for GA, fetal oxygenation can be increased, without inducing an increase in lipid peroxidation.

Supplementary oxygen for emergency Caesarean section under regional anaesthesia.

BACKGROUND: Controversy still exists if the administration of supplementary oxygen to patients having emergency Caesarean section (CS) under regional anaesthesia is beneficial or potentially harmful. Therefore, in a prospective double-blinded study, we randomized patients having emergency CS under regional anaesthesia to receive either air or 60% oxygen until delivery and compared the effects on fetal oxygenation and lipid-peroxidation in the mother and baby. METHODS: We recruited 131 women having emergency CS under regional anaesthesia. Either 21% (air group) or 60% oxygen (oxygen group) was administered using a Venturi-type facemask until delivery. We compared the oxygen exposure duration, umbilical arterial (UA) and venous (UV) blood gases and oxygen content, and plasma concentration of 8-isoprostane. Subanalysis was performed according to whether or not fetal compromise was considered present. RESULTS: Data from 125 patients were analysed. For the oxygen group vs the air group, there were greater values for UA PO(2) [mean 2.2 (SD 0.5) vs 1.9 (0.6) kPa, P=0.01], UA O(2) content [6.6 (2.5) vs 4.9 (2.8) ml dl(-1), P=0.006], UV PO(2) [3.8 (0.8) vs 3.2 (0.8) kPa, P<0.0001], and UV O(2) content [12.9 (3.5) vs 10.4 (3.8) ml dl(-1), P=0.001]. There was no difference between the groups in maternal, UA, or UV 8-isoprostane concentration. Apgar scores and UA pH were similar between the groups. Similar changes were observed regardless of whether fetal compromise was considered present (n=37) or not (n=88). CONCLUSIONS: Breathing 60% oxygen during emergency CS under regional anaesthesia increased fetal oxygenation with no associated increase in lipid-peroxidation in the mother or fetus.

Ephedrine versus phenylephrine as a vasopressor for spinal anaesthesia-induced hypotension in parturients undergoing high-risk caesarean section: meta-analysis, meta-regression and trial sequential analysis.

BACKGROUND: Phenylephrine is the preferred vasopressor for the prevention and treatment of spinal anaesthesia-induced hypotension during caesarean section, because studies on low-risk elective patients found it to have a less detrimental effect on umbilical artery pH compared with ephedrine. However, limited data exist from high-risk parturients and parturients with uteroplacental insufficiency. METHODS: We systematically searched for randomised, controlled, double-blinded trials of these two vasopressors in high-risk caesarean sections. We applied conventional meta-analysis, trial sequential analysis, computing the required information size that would exclude type I and II errors, contour-enhanced funnel plot testing for publication bias, meta-regression to assess the dose-response relationship, and the Grading of Recommendations Assessment, Development, and Evaluation system (GRADE). The incidence of fetal acidosis (umbilical arterial pH <7.2) was the primary outcome. RESULTS: Eight trials (712 patients) with low risk of bias were identified. Pooling six studies of patients with preeclampsia and other reasons for fetal compromise, as well as subgroup analysis of the preeclampsia studies, revealed no significant differences in the incidence of fetal acidosis. Trial sequential analysis showed that the required information size was not reached. The funnel plot was not suggestive of publication bias. Meta-regression showed no dose-response relationship. The GRADE score was moderate quality. CONCLUSIONS: Despite several studies and a large number of patients there was insufficient evidence to make a recommendation for choice of vasopressor in high-risk caesarean section. Trials with adequate power to detect differences in the incidence of fetal acidosis between ephedrine and phenylephrine are required to provide evidence-based guidance.

Ultrasound-guided lumbar plexus block through the acoustic window of the lumbar ultrasound trident.

Lumbar plexus block (LPB) is frequently used in combination with an ipsilateral sacral plexus or sciatic nerve block for lower limb surgery. This is traditionally performed using surface anatomical landmarks, and the site for local anaesthetic injection is confirmed by observing quadriceps muscle contraction to peripheral nerve stimulation. In this report, we describe a technique of ultrasound-guided LPB that was successfully used, in conjunction with a sciatic nerve block, for anaesthesia during emergency lower limb surgery. The anatomy, sonographic features, technique of identifying the lumbar plexus, and the potential benefits of using this approach are discussed.

Randomised double-blinded comparison of phenylephrine vs ephedrine for maintaining blood pressure during spinal anaesthesia for non-elective Caesarean section*.

SUMMARY: In a randomised, double-blinded study, we compared boluses of phenylephrine 100 microg with ephedrine 10 mg for treating hypotension (systolic blood pressure < 100 mmHg) in 204 patients having non-elective Caesarean section under spinal anaesthesia. Umbilical arterial (UA) and venous (UV) pH and base excess were similar between groups. In the ephedrine group, UA lactate concentration was higher (median 2.6 [interquartile range 2.3-3.3] vs 2.4 [1.9-3.0] mmolxl(-1), p = 0.002) and UV lactate concentration was higher (2.5 [2.2-3.2] vs 2.3 [1.9-2.8] mmolxl(-1), p = 0.016) and more patients had nausea or vomiting (12.7% vs 3.9%, p = 0.02). Clinical neonatal outcome was similar. Of the protocol-compliant patients (n = 148), UA Po(2) and UV Po(2) were lower in the phenylephrine group although oxygen content was similar. We conclude that phenylephrine and ephedrine are both suitable vasopressors for use in non-elective Caesarean sections.

Closed-loop feedback computer-controlled infusion of phenylephrine for maintaining blood pressure during spinal anaesthesia for caesarean section: a preliminary descriptive study.

We describe the novel use of a closed-loop feedback computer-controlled infusion of phenylephrine for maintaining blood pressure in 53 patients having spinal anaesthesia for elective caesarean section. A simple on-off algorithm was used that activated an intravenous phenylephrine infusion at 100 microg.min(-1) when systolic blood pressure was less than or equal to baseline and stopped the infusion when systolic blood pressure exceeded baseline. Up to uterine incision, 94.6% of all systolic blood pressure measurements were within the range (baseline +/- 20%). Seven patients (13.2%) had one or more episodes of hypotension (systolic blood pressure < 80% of baseline) and 23 patients (37.7%) had one or more episodes of hypertension (systolic blood pressure > 120% of baseline). No patient had nausea or vomiting and in no case was umbilical arterial blood pH < 7.2. Calculated system performance parameters were comparable with those of previously published closed-loop systems and provide a reference for the potential development and comparison of more advanced algorithms.

A randomised double-blinded controlled trial of the effect of diluent volume on the efficacy of a single dose of epidural ropivacaine for labour analgesia.

BACKGROUND: Few studies have systematically investigated the effect of diluent volume on the efficacy of epidural local anaesthetics for labour analgesia and no data are available for ropivacaine. Our aim was to compare epidural ropivacaine given in three different volumes for labour analgesia. METHODS: In a double-blinded study, we randomly assigned 60 labouring parturients with cervical dilatation <5 cm to receive epidural ropivacaine 30 mg diluted to 5 mL (group 5, n=20), 10 mL (group 10, n=20) or 20 mL (group 20, n=20) for analgesia. We measured visual analogue scale pain scores at the peak of contraction for 30 min plus onset and duration of analgesia. RESULTS: Pain scores at 30 min were similar among group 5 (median 22 [interquartile range 0-44] mm), group 10 (9 [0-21] mm) and group 20 (37 [0-51] mm), P=0.35. The number of patients who achieved a decrease in pain score to < or =30% of baseline was similar among group 5 (12/20 (60%)), group 10 (17/20 (85%)) and group 20 (11/19 (58%)), P=0.13. Onset and duration of analgesia, the incidence of motor block and patient satisfaction were similar among groups. CONCLUSIONS: Under the conditions of this study, within the range of 5-20 mL, the volume and concentration were not significant factors influencing the efficacy of a single 30-mg bolus of epidural ropivacaine given for labour analgesia. This suggests that the most important factor influencing analgesic efficacy was drug mass.

Gabapentin for the treatment and prophylaxis of cluster headache.

BACKGROUND AND OBJECTIVES: Cluster headache is an uncommon debilitating condition for which effective management remains a challenge. We describe the use of gabapentin in the treatment and prophylaxis of cluster headache in a patient who was refractory to other treatments. CASE REPORT: A 38-year-old man had a history of intermittent right-side headaches for 24 years, diagnosed as cluster headache. He received only partial relief from a range of conventional treatments. A trial with gabapentin 300 mg twice daily was tried and found to be effective in treatment and prophylaxis of his headaches. CONCLUSION: Gabapentin was effective in the treatment of a patient with cluster headache. Further investigation of gabapentin compared with conventional treatments and placebo is warranted.

Status of obstetric epidural analgesia services in Hong Kong public hospitals: postal questionnaire survey.

OBJECTIVE: To examine the status of obstetric epidural analgesia services in Hong Kong public hospitals in 2001, and to compare findings with those from a similar survey conducted in 1995. DESIGN: Postal questionnaire survey. SETTING: Hospital Authority hospitals in Hong Kong offering an obstetric and delivery service. PARTICIPANTS: Chiefs of Service of departments of anaesthesia and coordinators of obstetric anaesthesia and analgesia service. MAIN OUTCOME MEASURES: The availability of an obstetric epidural analgesia service, specialist staff allocation to the service, existence of clinical protocols, rate of epidural analgesia, techniques of epidural administration, obstetric outcome or mode of delivery, and the incidence of adverse events associated with the use of epidural analgesia. RESULTS: Between 1 January and 31 December 2001, all eight Hospital Authority hospitals with an obstetric service provided epidural analgesia for labour pain relief, but only six (75%) offered a 24-hour service. A dedicated anaesthetist provided obstetric anaesthesia and analgesia during office hours in all units, but after hours in only three. This level of service provision compared favourably with that available in 1995, when only 82% of public maternity units provided epidural analgesia and only 36% offered a 24-hour service. The median epidural analgesia rate was 15% (range, 8%-20%) compared with 10% in 1995. The incidence of adverse events and complications was very low. Formal written protocols for the conduct of epidural analgesia for labour were used in six units. All units used mixtures of local anaesthetic combined with opioid, administered as intermittent boluses, continuous epidural infusion, or patient-controlled epidural analgesia. CONCLUSIONS: Although there has been progress and improvement in the provision of obstetric epidural analgesia services in our public hospitals, the rate is still relatively low and the provision of services after hours is limited. Further progress will likely be hindered by current or future cutbacks in public hospital budgets.

The accuracy of references in the Hong Kong Medical Journal.

We have reviewed the reference citations in volume 1 (1995) and volume 2 (1996) of the Hong Kong Medical Journal to determine their accuracy. One hundred references were randomly selected from each volume. After excluding references not from indexed journals, all citations were examined in detail by dividing them into six component elements and comparing them with the original. We found that 61% of references in volume 1 and 51% of references in volume 2 contained inaccuracies, giving an overall error rate of 56%. Thirty-eight percent of references contained errors in one element, 16% contained errors in two elements, and 2% contained errors in three or more elements. The most common errors were those of the title or authors' names. The rate of citation errors in the Hong Kong Medical Journal is at the high end of the range compared with other medical journals. Contributors to this journal need to take more care in checking their references before publication.

Patient-controlled epidural analgesia in a parturient with hypertrophic obstructive cardiomyopathy.

We describe the use of patient-controlled epidural analgesia (PCEA) using fentanyl in the management of a labouring parturient with hypertrophic obstructive cardiomyopathy (HOCM). With non-invasive monitoring, PCEA was started in the early first stage of labour with a bolus dose of fentanyl 20 microg, lockout 5 min and 4-h maximum dose of 500 microg. Analgesia was satisfactory during the early first stage but was poor subsequently, despite a total fentanyl consumption of 760 microg during the 6-h labour. The maternal cardiovascular condition was stable throughout labour and delivery and the baby was born in good condition without subsequent respiratory depression. Opioid-based PCEA is an alternative to systemic analgesia in labouring parturients with HOCM. However, although its use avoids the potential adverse effects of sympathetic block associated with conventional epidural analgesia, our regimen had limited analgesic efficacy in the latter stage of labour.

Anesthetic management of renal cell carcinoma with inferior vena caval extension.

We present a case of a patient with renal cell carcinoma extending into the inferior vena cava. Preoperative diagnosis was facilitated by transthoracic and transesophageal echocardiography (TEE), and inferior venacavography. Intraoperatively, monitoring with continuous TEE was used. Preparation was made for cardiopulmonary bypass but surgery was successfully completed using extracorporeal venous shunting. We discuss the important aspects of preoperative diagnosis and the intraoperative anesthetic management of this case.

Structured preoperative patient education for patient-controlled analgesia.

STUDY OBJECTIVE: To investigate the effectiveness of a structured preoperative education program in patients receiving patient-controlled analgesia (PCA). DESIGN: Randomized controlled trial. SETTING: University-affiliated hospital. PATIENTS: 60 ASA physical status I and II women undergoing major gynecologic surgery. INTERVENTIONS: Patients were randomly allocated to receive either standard information given during routine preanesthetic assessment (n = 30) or additional structured preoperative education on the use of PCA (n = 30). MEASUREMENTS: All patients received standard anesthesia and PCA was provided for postoperative analgesia. Patients were reviewed bid by an independent team of pain specialists and nurses. Patient satisfaction, severity of postoperative pain, nausea, dizziness, and morphine consumption were measured at discharge from recovery room, 24, and 48 hours after operation. Recovery characteristics of patients were also measured. MAIN RESULTS: Pain scores and morphine consumption decreased over time (p < 0.01), but there was no significant difference between groups. The overall analgesic efficacy, side effects, and recovery times was not affected by the education program. Patient satisfaction in the education group was better than control during early recovery (p= 0.03), but there was no additional benefit in the remaining postoperative period. CONCLUSIONS: Structured preoperative PCA education did not affect patient outcome. The early improvement in patient satisfaction was minimized by continued education and pain team supervision during the rest of the postoperative period.