Systematic review and meta-analysis of method comparison studies of Masimo pulse co-oximeters (Radical-7™ or Pronto-7™) and HemoCue® absorption spectrometers (B-Hemoglobin or 201+) with laboratory haemoglobin estimation.

We assessed agreement in haemoglobin measurement between Masimo pulse co-oximeters (Rad-7™ and Pronto-7™) and HemoCue® photometers (201+ or B-Hemoglobin) with laboratory-based determination and identified 39 relevant studies (2915 patients in Masimo group and 3084 patients in HemoCue group). In the Masimo group, the overall mean difference was -0.03 g/dl (95% prediction interval -0.30 to 0.23) and 95% limits of agreement -3.0 to 2.9 g/dl compared to 0.08 g/dl (95% prediction interval -0.04 to 0.20) and 95% limits of agreement -1.3 to 1.4 g/dl in the HemoCue group. Only B-Hemoglobin exhibited bias (0.53, 95% prediction interval 0.27 to 0.78). The overall standard deviation of difference was larger (1.42 g/dl versus 0.64 g/dl) for Masimo pulse co-oximeters compared to HemoCue photometers. Masimo devices and HemoCue 201+ both provide an unbiased, pooled estimate of laboratory haemoglobin. However, Masimo devices have lower precision and wider 95% limits of agreement than HemoCue devices. Clinicians should carefully consider these limits of agreement before basing transfusion or other clinical decisions on these point-of-care measurements alone.

Time to get comfortable with a labour epidural.

Women frequently request regional analgesia during labour, yet little is known about how long it takes before they become comfortable. This prospective observational study aimed to determine various time-points following maternal request for regional analgesia in labour until comfort was achieved. It was conducted in two tertiary referral centres for maternity care in Australia between December 2009 and May 2010.Midwives and anaesthetists recorded times of maternal request for regional analgesia, anaesthetist contact,anaesthetist's arrival in the labour room, local anaesthetic infiltration on starting the procedure, injection of neuraxial local anaesthetic and first report of maternal comfort. Composite median times and interquartile range were recorded for maternal request to anaesthetist arrival, anaesthetist arrival to maternal comfort and total time from request to comfort. Statistical modelling and regression analyses assessed possible factors associated with these time intervals. A P value <0.05 was considered significant. Of the 324 maternal requests, 244 out of 324 (75.3%, 95% confidence interval 70.2% to 79.9%) were recorded as having achieved satisfactory labour analgesia. Median interquartile range times observed were: maternal request to anaesthetist arrival: 20 (10 to 35) minutes; anaesthetist arrival to maternal comfort: 40 (30 to 50) minutes; and total time from request to comfort: 65 (50 to 85) minutes. We have shown that approximately one hour is required for a mother to achieve comfort following her request for epidural analgesia during labour. Our findings are likely to provide useful information for antenatal education, enhance informed consent and improve the provision of anaesthetic services for labour analgesia.

Peak plasma anti-Xa levels after first and third doses of enoxaparin in women receiving weight-based thromboprophylaxis following caesarean section: a prospective cohort study.

BACKGROUND: Women undergoing caesarean section are at higher risk for thromboembolic complications following delivery than other parturients. The aim of this study was to determine whether higher doses of enoxaparin based on body weight are safe and more likely to achieve plasma anti-Xa levels within the accepted thromboprophylactic range. METHODS: We undertook a prospective cohort study of 80 women undergoing caesarean section in a tertiary obstetric hospital with >6000 deliveries per year. Enoxaparin was administered after caesarean section using the Royal College of Obstetricians and Gynaecologists weight-adjusted dosing guidelines. Plasma anti-Xa levels were measured at baseline and 3-4 h after enoxaparin administration on days one and three postoperatively. The main outcomes of interest were plasma anti-Xa levels and the proportion of patients with plasma anti-Xa levels in the range of 0.2-0.4 IU/mL. RESULTS: The proportion of women with anti-Xa levels between 0.2 and 0.4 IU/mL was 72% (95% CI 60-81%). Unadjusted mean anti-Xa levels were 0.26 ± 0.09 IU/mL and 0.28 ± 0.08 IU/mL on day one and day three respectively. No woman had levels >0.48 IU/mL. CONCLUSION: The majority of women receiving weight-based enoxaparin thromboprophylaxis following caesarean section achieved plasma anti-Xa levels within the putative thromboprophylactic range. No woman achieved levels associated with an increased risk of bleeding (>0.8 IU/mL). These findings provide a safety basis for a large prospective study using this regimen.

Combined spinal-epidural versus epidural analgesia in labour.

BACKGROUND: Traditional epidural techniques have been associated with prolonged labour, use of oxytocin augmentation, and increased incidence of instrumental vaginal delivery. The combined spinal-epidural (CSE) technique has been introduced in an attempt to reduce these adverse effects. CSE is believed to improve maternal mobility during labour and provide more rapid onset of analgesia than epidural analgesia, which could contribute to increased maternal satisfaction. OBJECTIVES: To assess the relative effects of CSE versus epidural analgesia during labour. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (December 2006). SELECTION CRITERIA: All published randomised controlled trials involving a comparison of CSE with epidural analgesia initiated for women in the first stage of labour. DATA COLLECTION AND ANALYSIS: Three review authors independently assessed the trials identified from the searches for inclusion and extracted the data. MAIN RESULTS: Nineteen trials (2658 women) met our inclusion criteria. Twenty-six outcomes in two sets of comparisons involving CSE versus traditional epidurals and CSE versus low-dose epidural techniques were analysed. Of the CSE versus traditional epidural analyses only three outcomes showed a difference. CSE was more favourable in relation to need for rescue analgesia and urinary retention, but associated with more pruritus. For CSE versus low-dose epidurals, four outcomes were statistically significant. CSE had a faster onset of effective analgesia from time of injection but was associated with more pruritus. CSE was also associated with a clinically non-significant lower umbilical arterial pH. No differences between CSE and epidural were seen for maternal satisfaction, mobilisation in labour, modes of birth, incidence of post dural puncture headache or blood patch and maternal hypotension. It was not possible to draw any conclusions with respect to maternal respiratory depression, maternal sedation and need for labour augmentation. AUTHORS' CONCLUSIONS: There appears to be little basis for offering CSE over epidurals in labour with no difference in overall maternal satisfaction despite a slightly faster onset with CSE and less pruritus with epidurals. There is no difference in ability to mobilise, obstetric outcome or neonatal outcome. However, the significantly higher incidence of urinary retention and rescue interventions with traditional techniques would favour the use of low-dose epidurals. It is not possible to draw any meaningful conclusions regarding rare complications such as nerve injury and meningitis.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section.

BACKGROUND: Maternal hypotension, the most frequent complication of spinal anaesthesia for caesarean section, can be associated with severe nausea or vomiting which can pose serious risks to the mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis and neurological injury). OBJECTIVES: To assess the effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2005). SELECTION CRITERIA: Randomised controlled trials comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section. DATA COLLECTION AND ANALYSIS: Three review authors independently assessed eligibility and methodological quality of studies, and extracted data. MAIN RESULTS: We included 75 trials (a total of 4624 women). Crystalloids were more effective than no fluids (relative risk (RR) 0.78, 95% confidence interval (CI) 0.60 to 1.00; one trial, 140 women, sequential analysis) and colloids were more effective than crystalloids (RR 0.68, 95% CI 0.52 to 0.89; 11 trials, 698 women) in preventing hypotension following spinal anaesthesia at caesarean section. No differences were detected for different doses, rates or methods of administering colloids or crystalloids. Ephedrine was significantly more effective than control (RR 0.51, 95% CI 0.33 to 0.78; seven trials, 470 women) or crystalloid (RR 0.70, 95% CI 0.50 to 0.96; four trials, 293 women) in preventing hypotension. No significant differences in hypotension were seen between ephedrine and phenylephrine (RR 0.95, 95% CI 0.37 to 2.44; three trials, 97 women) and phenylephrine was more effective than controls (RR 0.27, 95% CI 0.16 to 0.45; two trials, 110 women). High rates or doses of ephedrine may increase hypertension and tachycardia incidence. Lower limb compression was more effective than control (no leg compression) (RR 0.69, 95% CI 0.53 to 0.90; seven trials, 399 women) in preventing hypotension, although different methods of compression appeared to vary in their effectiveness. No other comparisons between different physical methods such as position were shown to be effective, but these trials were often small and thus underpowered to detect true effects should they exist. AUTHORS' CONCLUSIONS: While interventions such as colloids, ephedrine, phenylephrine or lower leg compression can reduce the incidence of hypotension, none have been shown to eliminate the need to treat maternal hypotension during spinal anaesthesia for caesarean section. No conclusions can be drawn regarding rare adverse effects due to the relatively small numbers of women studied.

Combined spinal-epidural versus epidural analgesia in labour.

BACKGROUND: Traditional epidural techniques have been associated with prolonged labour, use of oxytocin augmentation, and increased incidence of instrumental vaginal delivery. The combined spinal-epidural (CSE) technique has been introduced in an attempt to reduce these adverse effects. CSE is believed to improve maternal mobility during labour and provide more rapid onset of analgesia than epidural analgesia. OBJECTIVES: To assess the relative effects of combined spinal-epidural versus epidural analgesia during labour. SEARCH STRATEGY: The Cochrane Pregnancy and Childbirth Group Trials Register (July 2002), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 to June 2002) and EMBASE (1974 to June 2002). SELECTION CRITERIA: All published randomised controlled trials involving a comparison of CSE with epidural analgesia initiated for women in the first stage of labour. DATA COLLECTION AND ANALYSIS: Trials identified from searching were assessed for inclusion by the same two reviewers independently. Review Manager software was used for calculation of the treatment effect represented by odds ratios (OR) and weighted mean difference (WMD) using a fixed effects model with 95% confidence intervals (CI). MAIN RESULTS: Fourteen trials (2047 women) met our inclusion criteria. Of the 25 outcomes analysed from these studies CSE shows a reduced time from first injection to effective maternal analgesia WMD -5.50 minutes (95% CI -6.47 to -4.52; four trials), an increased incidence of maternal satisfaction OR 4.69 (95% CI 1.27 to 17.29; three trials), and an increased incidence of pruritus OR 2.79 (95% CI 1.87 to 4.18; nine trials). No difference was found between CSE and epidural techniques with regards to maternal mobility, rescue analgesia requirements, the incidence of post dural puncture headache (PDPH) or blood patch, hypotension, urinary retention, mode of delivery, or admission of the baby to the neonatal unit. REVIEWER'S CONCLUSIONS: There is no standard CSE or epidural technique. Compared with epidural, CSE provides faster onset of effective pain relief from the time of injection, and increases the incidence of maternal satisfaction. However, CSE women experience more itch. There is no difference between CSE and epidural techniques with respect to: the incidence of forceps delivery, maternal mobility, PDPH, caesarean section rates or admission of babies to the neonatal unit. It is not possible to draw any meaningful conclusions regarding rare complications such as nerve injury and meningitis.

Avoiding inadvertent epidural injection of drugs intended for non-epidural use.

Inadvertent administration of non-epidural medications into the epidural space has the potential for serious morbidity and mortality. The aim of this study was to collate reported incidents of this type, describe the potential mechanisms of occurrence and identify possible solutions. We searched medical databases and reviewed reference lists of papers retrieved, covering a period of 35 years, regarding this type of medication incident. The 31 reports of 37 cases found is likely to represent a gross underestimation of the actual number of incidents that occur. "Syringe swap", "ampoule error", and epidural/intravenous line confusion were the main sources of error in 36/37 cases (97%). Given that no effective treatment for such errors has been identified, prevention should be the main defence strategy. Despite all the precautions that are currently undertaken, accidents will inevitably occur. We have identified areas for systemwide change that may prevent these types of incidents from occurring in future.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section.

BACKGROUND: Maternal hypotension is the most frequent complication of spinal anaesthesia for caesarean section. Most workers define hypotension as a maternal systolic blood pressure below 70-80% of baseline recordings and/or an absolute value of < 90 - 100mmHg. Hypotension is often associated with nausea and vomiting and, if severe, poses serious risks to mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis and neurological injury). Several strategies are currently used to prevent or minimise hypotension but there is no established ideal technique. OBJECTIVES: To assess the relative efficacy and side effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section. SEARCH STRATEGY: The Cochrane Pregnancy and Childbirth Group Trials Register (January 2002) and the Cochrane Controlled Trials Register (Cochrane Library, Issue 4, 2001). SELECTION CRITERIA: All published or unpublished randomised controlled trials comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section. DATA COLLECTION AND ANALYSIS: Trials identified from searching are assessed for inclusion by the same two reviewers independently. Studies are excluded from review where: hypotension is not an outcome measure or clearly defined prior to administering a rescue treatment; randomisation is unsatisfactory; the spinal anaesthetic technique or dose of local anaesthetic is not controlled-for; and the intervention is implemented in response to a fall in blood pressure rather than for prevention. Review Manager software is used for calculation of the treatment effect, represented by relative risks and proportional and absolute risk reductions. MAIN RESULTS: Twenty-five trials (1477 women) meet our inclusion criteria. Four of fifteen interventions reviewed reduce the incidence of hypotension under spinal anaesthesia for caesarean section: (1) crystalloid versus control, relative risk (RR) 0.78 (95% confidence interval (CI) 0.63, 0.98); (2) pre-emptive colloid administration versus crystalloid, RR 0.54 (95% CI 0.37, 0.78); (3) ephedrine versus control, RR 0.69 (95% CI 0.57, 0.84); and (4) lower limb compression versus control, RR 0.70 (95% CI 0.59, 0.83). Ephedrine is associated with dose-related maternal hypertension and tachycardia, and fetal acidosis of uncertain clinical significance. REVIEWER'S CONCLUSIONS: No intervention reliably prevents hypotension during spinal anaesthesia for caesarean section. No conclusions are drawn regarding rare adverse effects of interventions due to their probable low incidence and the small numbers of women studied. Further trials are recommended, in particular assessing a combination of the beneficial interventions, ie colloid or crystalloid preloading, ephedrine administration and leg compression with bandages, stockings or inflatable boots.

Aseptic precautions for inserting an epidural catheter: a survey of obstetric anaesthetists.

We performed a postal survey of Fellows of the Australian and New Zealand College of Anaesthetists with a special interest in obstetric practice, about their beliefs regarding aseptic precautions for insertion of an epidural catheter in the labour ward. Of the 435 consultant anaesthetists surveyed, 367 responded (84%), revealing a wide variation in practice. It was not thought to be essential practice to remove a watch before washing hands by 51 respondents (14%), to wear a facemask by 105 (29%) or to wear a sterile gown by 45 (12%). Three anaesthetists (1%) did not believe sterile gloves were essential. However, all respondents indicated that an antiseptic skin preparation was essential. Our results raise questions regarding an acceptable standard of aseptic practice for the insertion of an epidural catheter in labour and we propose a minimal standard of essential precautions.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section.

BACKGROUND: Maternal hypotension is the most frequent complication of a spinal anaesthetic for caesarean section with an incidence approaching 100%. Most workers define hypotension as a maternal systolic blood pressure below 70-80% of baseline recordings and/or an absolute value of < 90 -100mmHg. The frequent occurrence and rapid onset of hypotension during spinal anaesthesia has encouraged anaesthetists to try and prevent or minimise the associated maternal symptoms of nausea and vomiting during the establishment of the block. Untreated, severe hypotension can also pose serious risks to both mother (unconsciousness, pulmonary aspiration, apnoea or even cardiac arrest) and baby (impaired placental perfusion leading to hypoxia, fetal acidosis and neurological injury). A range of strategies is currently used to prevent or minimise hypotension but there is no established ideal technique. OBJECTIVES: To assess the relative efficacy and side effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section. SEARCH STRATEGY: The Cochrane Pregnancy and Childbirth Group Trials Register, the Cochrane Controlled Trials Register, other databases and bibliographies of relevant papers are searched according to the strategy developed for the Pregnancy and Childbirth Group as a whole. Date of last search: May 2001. SELECTION CRITERIA: All published or unpublished randomised controlled trials that compare use of an intervention to prevent hypotension with placebo or alternative treatment in patients having spinal anaesthesia for caesarean section. DATA COLLECTION AND ANALYSIS: Trials identified from searching are assessed for inclusion by the same two reviewers independently. Studies are excluded from review for the following reasons: hypotension is not an outcome measure or clearly defined prior to administering a rescue treatment; randomisation is unsatisfactory; the spinal anaesthetic technique or dose of local anaesthetic is not controlled-for; and the intervention is implemented in response to a fall in blood pressure rather than for prevention. Statistical analyses use the Review Manager software for calculation of the treatment effect as represented by the relative risks and proportional and absolute risk reductions. MAIN RESULTS: Twenty trials meet the criteria for inclusion. Four of the twelve interventions reviewed are shown to reduce the incidence of hypotension under spinal anaesthesia for caesarean section: (1) crystalloid 20ml/kg vs control, Relative Risk (RR) 0.78 (95% confidence interval (CI) 0.6, 1.0); (2) pre-emptive colloid administration vs crystalloid, (RR) 0.54 (95% CI 0.37, 0.78); (3) ephedrine vs control, RR 0.70 (95% CI 0.57, 0.85); and (4) lower limb compression vs control, RR 0.75 (95% CI 0.59, 0.94). There are no significant differences in maternal or neonatal side effects in any of the comparisons studied. REVIEWER'S CONCLUSIONS: No studied intervention has been shown to eliminate the need to treat maternal hypotension during spinal anaesthesia for caesarean section. We are unable to draw any conclusions regarding adverse effects of the studied interventions, due to their probable low incidence and the small number of women studied. Further randomised controlled trials are recommended, in particular assessing a combination of the beneficial interventions, i.e. colloid or crystalloid preloading, parenteral ephedrine administration and leg compression with bandages, stockings or inflatable boots.

A survey of Australasian obstetric anaesthesia audit.

In order to develop a minimal obstetric anaesthesia dataset based on current Australasian clinical audit best practice, we carried out a postal survey of 69 Australasian anaesthetic departments covering an obstetric service. We asked about data being collected, specifically concerning the high risk obstetric patient, epidural analgesia and postoperative anaesthetic review. Examples of any data collection forms were requested. Of the 66 responses, 35 departments (53%) were not collecting any audit data. Twenty-six of the 31 departments (84%) performing obstetric anaesthesia audit responded to our follow-up telephone survey. Eighteen departments believed that there had been an improvement in patient care as a result of their audit and 13 felt that the benefits outweighed the costs involved. However, only six departments (9%) had performed an audit cycle. The importance of feedback to patients or hospital staff and the incidence of post dural puncture headache (PDPH) were cited by some as priorities for obstetric anaesthesia audit. There was however no consistency as to what data should be collected. Many responses suggested a perceived need to collect clinical data without knowing what to do with it. Our survey has highlighted confusion between three distinct objectives; a dataset for obstetric anaesthesia record keeping, data required for continuing patient management in hospital and, a specific minimal dataset for clinical audit purposes. We conclude that current Australasian obstetric anaesthesia audit strategies are inadequate to develop a minimal dataset for cost-effective clinical audit.