Baseline haemoglobin variability by measurement technique in pregnant people on the day of childbirth.

Point-of-care haemoglobin measurement devices may play an important role in the antenatal detection of anaemia in pregnant people and may be useful in guiding blood transfusion during resuscitation in obstetric haemorrhage. We compared baseline haemoglobin variability of venous and capillary HemoCue® haemoglobin, and Masimo® Rad-67 Pulse CO-Oximeter haemoglobin with laboratory haemoglobin in people on the day of their planned vaginal birth. A total of 180 people undergoing planned vaginal birth were enrolled in this prospective observational study. Laboratory haemoglobin was compared with HemoCue and Masimo Rad-67 Pulse CO-Oximeter measurements using Bland-Altman analysis, calculating mean difference (bias) and limits of agreement. Five (2.8%) people had anaemia (haemoglobin < 110 g.l-1 ). Laboratory haemoglobin and HemoCue venous haemoglobin comparison showed an acceptable bias (SD) 0.7 (7.54) g.l-1 (95%CI -0.43-1.79), with limits of agreement -14.10-15.46 g.l-1 and acceptable agreement range of 29.6 g.l-1 . Laboratory and HemoCue capillary haemoglobin comparison showed an unacceptable bias (SD) 13.3 (14.12) g.l-1 (95%CI 11.17-15.34), with limits of agreement - 14.42-40.93 g.l-1 and unacceptable agreement range of 55.3 g.l-1 . Laboratory and Masimo haemoglobin comparison showed an unacceptable bias (SD) -14.0 (11.15) g.l-1 (95%CI -15.63 to -12.34), with limits of agreement to -35.85 to 7.87 g.l-1 and acceptable agreement range of 43.7 g.l-1 . Venous HemoCue, with its acceptable bias and limits of agreement, should be applied more widely in the antenatal setting to detect, manage and risk stratify pregnant people with anaemia. HemoCue capillary measurement under-estimated haemoglobin and Masimo haemoglobin measurement over-estimated, limiting their clinical use. Serial studies are needed to determine if the accuracy of venous HemoCue haemoglobin measurement is sustained in other obstetric settings.

High-flow humidified nasal preoxygenation in pregnant women: a prospective observational study.

BACKGROUND: Obstetric airway guidelines recommend preoxygenation in preparation for general anaesthesia to achieve end-tidal oxygen concentrations (etO2) of ≥90%, and mention the potential use of high-flow humidified nasal oxygen (HFNO). We investigated the new HFNO technique (Optiflow™) in term pregnant women. METHODS: Seventy-three term participants underwent a 3 min HFNO protocol (30 L min-1 for 30 s, and then 50 L min-1 for 150 s). The etO2 was assessed for the first four breaths after simulated preoxygenation. The primary outcome was the proportion who achieved etO2 ≥90% for the first expired breath. The secondary outcomes were the proportion who achieved etO2 ≥80%; fetal heart rate before and after the test; the association of body mass index (BMI) to etO2 achieved with preoxygenation; and comfort levels of, and preference for, nasal and face mask preoxygenation. RESULTS: The proportion with first expired breath etO2 ≥90% was 60% [95% confidence interval (CI): 54-66%] and etO2 ≥80% was 84% (95% CI: 80-88%). There was no change in fetal heart rate from before to after the test (P=0.34). There was a negative association of BMI to etO2 achieved with preoxygenation (Pearson correlation: -0.26; P=0.027). There was no difference in comfort scores between nasal cannula and face mask (P=0.40). Forty-one (56%; 95% CI: 35-47%) women preferred the nasal cannula to the face mask. CONCLUSIONS: HFNO using this protocol is inadequate to preoxygenate term pregnant women. Despite encouraging results in the literature reporting results in non-pregnant women, further work is required before justifying its use in pregnant women. CLINICAL TRIAL REGISTRATION: ACTRN 12616000531415p.

Defining peri-operative anaemia in pregnant women - challenging the status quo.

Peri-operative anaemia is a significant risk factor for morbidity and mortality. Anaemia during pregnancy is associated with adverse maternal and neonatal outcomes, and postpartum haemorrhage remains a leading cause of maternal mortality worldwide. Caesarean section is an operation incurring moderate risk of bleeding, and rates are rising globally. Recent international consensus guidelines recommend targeting a pre-operative haemoglobin > 130 g.l-1 for all patients having surgery with moderate-to-high risk of bleeding, regardless of sex. It is unclear how this recommendation translates to pregnant women, where anaemia is defined at a much lower haemoglobin level of < 110 g.l-1 . Long-standing definitions of anaemia during pregnancy are likely to be the result of flawed sampling of a so-called 'normal' but anaemic female population, given the high prevalence of iron deficiency and anaemia in healthy menstruating women. Contemporary data suggest that haemoglobin values in iron-replete pregnant women are higher than previously thought. The definition of anaemia has significant clinical implications, particularly for peri-operative management of women undergoing caesarean section. In addition, we should differentiate between lower reference values and optimal haemoglobin targets. The haemoglobin level associated with optimal obstetric and neonatal outcomes requires further investigation in pregnant women.

Echocardiographic determination of resting haemodynamics and optimal positioning in term pregnant women.

Optimal positioning for anaesthesia in pregnant women involves balancing the need for ideal tracheal intubation conditions (achieved by the head elevated ramped position), with the prevention of reduced cardiac output from aortocaval compression (achieved by left lateral pelvic tilt). No studies have examined the effect on cardiac output of left lateral pelvic tilt in the ramped position. We studied non-labouring, non-anaesthetised healthy term pregnant women who underwent baseline (left lateral decubitus) cardiac assessment using transthoracic echocardiography. We then compared cardiac output, maternal physiological variables, fetal heart rate and comfort scores in three positions: left lateral decubitus; ramped position with wedge; and ramped position alone. Thirty women completed the study. Mean (SD) age, gestation and body mass index were 33.5 (3.93) years, 38.5 (0.94) weeks and 29.0 (4.0) kg.m-2 , respectively. Mean ejection fraction, left ventricular internal diameter and mitral valve E/e' were 55.2 (6.8) %, 4.70 (0.43) cm and 7.50 (1.82), respectively. There were no differences in cardiac output between the positions (p = 0.503). There were no differences in systolic (p = 0.955) or diastolic (p = 0.987) blood pressure, maternal heart rate (p = 0.133), oxygen saturation, respiratory rate (p = 0.964) or fetal heart rate (p = 0.361) between ramped with wedge and ramped alone positions. Left lateral decubitus was most comfortable (p = 0.001), however, there were no differences in comfort levels between ramped with wedge and ramped alone positions. The ramped position without left lateral tilt is safe and acceptable in non-labouring, non-anaesthetised, healthy term pregnant women. Left lateral pelvic tilt may be unnecessary in the head elevated ramped position in term pregnant women.

Transthoracic echocardiographic assessment of haemodynamics in severe pre-eclampsia and HIV in South Africa.

Haemodynamic and cardiac structural changes in severe pre-eclampsia and in pregnant women with human immunodeficiency virus (HIV) infection have not been clearly established. We performed transthoracic echocardiography on 105 women. Women with pre-eclampsia demonstrated (mean (SD), untreated vs treated) preserved fractional shortening (40 (7.1)% vs. 41 (8.6)%), a non-dilated left ventricle (4.5 (0.49) cm vs. 4.4 (0.44) cm), increased mitral valve E/septal e' (10.5 (3.3) vs. 10.6 (2.8)), and preserved tricuspid annular plane systolic exertion (2.6 (0.36) cm vs. 2.4 (0.51) cm). Women with HIV infection demonstrated (mean (SD), HIV-positive vs healthy) a reduced cardiac index (2.8 (0.64) ml.min(-1) .m(-2) vs. 3.1 (0.7) ml.min(-1) .m(-2) , p = 0.029), reduced septal s' tissue Doppler velocity (8.5 (1.5) cm.s(-1) vs. 9.3 (1.7) cm.s(-1) , p = 0.042), increased left ventricular end-diastolic area (7.6 (2.1) cm2 vs. 6.3 (1.7) cm2 , p = 0.004), and reduced right ventricular s' and e' velocity (s' velocity 14.7 (3.1) cm.s(-1) vs. 7.0 (2.9) cm.s(-1) p = 0.001, e' velocity 16.3 (4.1) cm.s(-1) vs. 18.7 (3.4) cm.s(-1) , p = 0.013). The mitral value E/septal e' was > 8 in 39% of patients with HIV. Fractional shortening (< 28%) was reduced in 10% of healthy women, and mitral valve E/septal e' ratios were > 8 in 38% of that group. Women with pre-eclampsia demonstrated preserved systolic function, with diastolic dysfunction. Women with HIV demonstrated reduced left and right ventricular systolic function, with increased ventricular dilatation.

Transthoracic echocardiography in women with treated severe pre-eclampsia.

The aim of this study was to investigate cardiac function and haemodynamic indices using transthoracic echocardiography in women with severe pre-eclampsia who had already received treatment interventions. Fifteen women with treated severe pre-eclampsia were studied using transthoracic echocardiography. Mean (SD) cardiac output in women with treated disease was 5690 (1708) ml.min(-1). Systolic function was preserved in women with treated disease evidenced by mean (SD) fractional shortening 41 (9)%, fractional area change 62 (12)% and septal s' velocities 9.0 (2.1) cm.s(-1). Left ventricle end-diastolic diameters were within healthy reference ranges at 4.7 (0.3) cm and the left ventricle was not dilated. Diastolic function was reduced, with a mean (SD) mitral valve E/septal e' ratio of 12.6 (4.1). Left ventricular mass was increased at 182.0 (44.4) g. There was large variability in haemodynamics in women with treated severe pre-eclampsia. Transthoracic echocardiography is acceptable and applicable and enables quantification of cardiac function in women with severe pre-eclampsia.

Management of pre-eclampsia: issues for anaesthetists.

Pre-eclampsia is a leading cause of maternal morbidity and mortality. Substandard care is often present and many deaths are preventable. The aim of this review is to summarise the key management issues for anaesthetists in the light of the current literature. A systematic literature search of electronic databases was undertaken including MEDLINE, EMBASE and the Cochrane Library using the key words obstetrics, pregnancy, pregnancy complications, maternal, pre-eclampsia, preeclampsia, cardiac function, haemodynamics, haemolysis, elevated liver enzymes, low platelets (HELLP), eclampsia, anaesthesia, anesthesia, neuraxial. Relevant Colleges and Societies websites were examined for pertinent guidelines. The disease is defined within the context of hypertensive diseases, and early recognition of pre-eclampsia and its complications, as well as multidisciplinary expert team management is highlighted. Accurate monitoring and recording of observations including the use of transthoracic echocardiography is discussed. The importance of the treatment of systolic blood pressure>180 mmHg and the use of intravenous antihypertensive medication as well as the use of parenteral magnesium sulphate for the treatment and prevention of eclampsia is emphasised . Restricted intravenous fluid therapy and avoidance of ergometrine is discussed. Neuraxial analgesia and anaesthesia, and general anaesthesia for birth is summarised as well as postpartum management including analgesia, thromboprophylaxis, management of acute pulmonary oedema and the use of pharmacological agents in the setting of breastfeeding.

Acute pulmonary oedema in pregnant women.

Acute pulmonary oedema in pregnant women is an uncommon but life-threatening event. The aims of this review are to address why pulmonary oedema occurs in pregnant women and to discuss immediate management. We performed a systematic literature search of electronic databases including MEDLINE, EMBASE and the Cochrane Library, using the key words obstetrics, pregnancy, acute pulmonary oedema, pregnancy complications, maternal, cardiac function and haemodynamics. We present a simple clinical classification of acute pulmonary oedema in pregnancy into pulmonary oedema occurring in normotensive or hypotensive women (i.e. without hypertension), and acute pulmonary oedema occurring in hypertensive women, which allows focused management. Pre-eclampsia remains an important cause of hypertensive acute pulmonary oedema in pregnancy and preventive strategies include close clinical monitoring and restricted fluid administration. Immediate management of acute pulmonary oedema includes oxygenation, ventilation and circulation control with venodilators. Pregnancy-specific issues include consideration of the physiological changes of pregnancy, the risk of aspiration and difficult airway, reduced respiratory and metabolic reserve, avoidance of aortocaval compression and delivery of the fetus.

Haemodynamics in women with untreated pre-eclampsia.

This study aimed to compare the haemodynamics in healthy pregnant women with the haemodynamics in women with untreated pre-eclampsia, to determine the cardiovascular reason for hypertension in pre-eclampsia. 40 women with untreated pre-eclampsia, 40 matched healthy pregnant women and 20 non-pregnant women were studied using transthoracic echocardiography. Untreated pre-eclampsia demonstrated (mean (SD), healthy non-pregnant vs healthy pregnant vs untreated pre-eclampsia) increased cardiac output (3400 (752) vs 4109 (595) vs 4789 (1416) ml.min(-1), p=0.002), increased stroke volume (53 (10) vs 53 (8) vs 59 (13) ml, p=0.04), increased fractional shortening (35 (5) vs 35 (7) vs 41 (8) %, p=0.006), increased fractional area change (57 (7) vs 57 (9) vs 65 (9)%, p=0.002) and increased systemic vascular resistance (2116 (457) vs 1613 (315) vs 2016 (625) dyne.s.cm(-5), p=0.001). Mitral E/septal e' was higher (6.0 (1.1) vs 6.7 (1.3) vs 10.4 (2.4), p=0.002) and left atrial size increased (3.2 (0.3) vs 3.8 (0.4) vs 4.0 (0.4) cm, p=0.002). Hypertension in untreated pre-eclampsia is due to increased cardiac output and mild vasoconstriction, with increased inotropy and reduced diastolic function.

High flow humidified nasal oxygen in pregnant women.

Failed airway management in the obstetric patient undergoing general anaesthesia is associated with major sequelae for the mother and/or fetus. Effective and adequate pre-oxygenation is an important safety strategy and a recommendation in all current major airway guidelines. Pre-oxygenation practice in the obstetric population may be suboptimal based on current literature. Recently, clinical applications for high flow nasal oxygen, also known as transnasal humidified rapid insufflation ventilatory exchange or THRIVE, are expanding in the non-obstetric population and may have theoretical benefits if used for pre-oxygenation and apnoeic oxygenation in the obstetric population. We review the current literature surrounding high flow nasal oxygen relevant to the pregnant woman. We also propose a basis for potential advantages and complications for its use in this context.

Immediate birth - an analysis of women and their babies undergoing time critical birth in a tertiary referral obstetric hospital.

BACKGROUND: At our institution, the emergency obstetric 'code green' activates the system for immediate birth, usually by caesarean section. This study aimed to determine the incidence of immediate birth, indications, modes of anaesthesia, and short-term neonatal and maternal outcomes. METHOD: A review was performed for all women at the Royal Women's Hospital, Parkville, Australia who underwent immediate birth over a two-year period: January 1, 2013 to December 31, 2014. RESULTS: Within the study period 14,115 women gave birth, of which 387 women underwent an immediate birth, the majority (83%) by caesarean section. The commonest indication for immediate birth was prolonged fetal bradycardia (53%), however cord prolapse (4%) produced the most rapid decision-to-delivery interval, with a median [IQR] time of 14 [13-16] min versus 18 [14-23] min for all immediate births (P<0.01). Epidural top-up was the most common anaesthesia method. Conversion to general anaesthesia following inadequate neuraxial anaesthesia occurred in 6.2% of women. Among 103 general anaesthetics, there was one failed intubation (successful ventilation) and one dental injury. Nine women (2.3%) were admitted to the high dependency or intensive care units, and there were no maternal deaths. Babies born by caesarean section with a decision-to-delivery interval of less than 30min were more likely to have longer times to establish respiration (22.6% vs 16.7%, P<0.001). CONCLUSION: Request for immediate delivery is a common obstetric emergency. Epidural top-up has become the most common anaesthetic technique. Rapid delivery times can be achieved with an integrated emergency response system.

Myocardial tissue characterisation and detection of myocardial oedema by cardiovascular magnetic resonance in women with pre-eclampsia: a pilot study.

BACKGROUND: Pre-eclampsia is characterised by increased left ventricular wall thickness on transthoracic echocardiography (TTE). This is assumed to be myocardial hypertrophy, however TTE cannot determine myocardial structure which may be muscle, oedema or fibrosis. Given the high incidence of peripheral oedema in pre-eclampsia, we hypothesised that increased thickness could represent oedema. Cardiovascular magnetic resonance (CMR) characterises myocardial tissue, differentiating between hypertrophy, oedema and fibrosis. This pilot study was designed to characterise myocardial composition using CMR in pregnant women (healthy or with pre-eclampsia) and to compare cardiac output and left ventricular mass using TTE and CMR. METHODS: Thirty-six women (31 healthy, five with pre-eclampsia) underwent TTE and CMR and left ventricular mass was assessed applying standard definitions. Myocardial signal intensities were measured from left ventricular segments and compared to serratus anterior muscle to determine global myocardial signal intensity. Myocardial oedema was defined as a myocardial:skeletal signal intensity ratio >1.9. Agreement between devices for cardiac output and left ventricular mass, and inter- and intra-observer measurements used Bland Altman methodology, calculating the agreement tolerable interval: >1.5 is unacceptable, 1.0-1.5 is marginal and <1.0 is acceptable agreement. RESULTS: Myocardial oedema was present in two (40%) pre-eclamptic women but no healthy women (P=0.017). Agreement for cardiac output was acceptable, for left ventricular mass marginal, and for inter- and intra-observer measurements acceptable. CONCLUSIONS: Cardiovascular magnetic resonance was used to characterise the myocardial tissue in women with pre-eclampsia. Data suggest that some women with pre-eclampsia have myocardial oedema rather than hypertrophy.

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.

Analgesic requirements and pain experience after caesarean section under neuraxial anesthesia in women with preeclampsia.

OBJECTIVE: We determined pain experience and analgesic usage in women with preeclampsia (PE) after caesarean section (CS). METHOD: We conducted a one-year retrospective case (PE), control (healthy pregnancy HP) study in women undergoing CS. RESULTS: Sixty-two women were included. Cases received more intrathecal bupivacaine (mean difference 0.4 mg) and in the first six hours postoperatively received (mean ± SD, % or median (interquartile range, IQR)), less oxycodone (11.5 ± 3.9 mg versus 14.3 ± 5.1 mg, p < 0.031), less often received parecoxib (43% versus 100%, p < 0.001), and reported less maximum pain scores (0 (0,5) versus 4 (3,6), p < 0.005). CONCLUSION: Women with PE received less analgesia and experienced less pain compared to controls.