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.

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.

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.

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.

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.

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.

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.

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.

Blood pressure assessment and first-line pharmacological agents in women with eclampsia.

BACKGROUND: Eclampsia is a life-threatening complication of pregnancy. Timely blood pressure assessment and administration of magnesium sulphate are essential management. In this retrospective single-centre study we examined the timing and magnitude of maternal blood pressure before eclampsia, and whether magnesium sulphate was administered as the first agent for treatment. METHODS: We conducted a five-year review of eclampsia in a tertiary referral obstetric hospital. Using data from electronic birthing records and hospital coding (ICD-10AM) we identified patients with the diagnostic criteria for eclampsia and assessed patient characteristics, blood pressure and pharmacological treatment. RESULTS: There were 33812 births from July 2008 to June 2013 with 19 cases of eclampsia (1:1780). Patients were 32±5.9years of age, 36±3.9weeks of gestation, 63% were nulliparous and all had a singleton pregnancy. Antepartum eclampsia occurred in 74%. In the four hours before a fit, 47% of patients had blood pressure recorded, of whom 78% were hypertensive. Magnesium sulphate was administered as first therapy in 47% of patients but it was not given to any patient transferred to hospital by ambulance. Of the patients who fitted antenatally, 86% underwent caesarean section, of whom 25% received neuraxial anaesthesia. CONCLUSIONS: Our study highlights the need for vigilance when managing pregnant women with hypertension, especially in the third trimester as eclampsia is most likely preceded by raised blood pressure. It also highlights the need for timely commencement of magnesium sulphate in the community and during transfer to hospital for the treatment of eclampsia, and for prevention of eclampsia in hospital when thresholds for severe preeclampsia are met.

Echocardiographic differences between preeclampsia and peripartum cardiomyopathy.

Peripartum heart failure due to preeclampsia or peripartum cardiomyopathy represents a significant global health issue. Transthoracic echocardiography enables differentiation of heart failure with preserved ejection fraction, commonly observed in women with preeclampsia, from that with peripartum cardiomyopathy in which a reduced ejection fraction is more common. An understanding of the different definitions and diagnostic features of these two diseases, as well as accurate characterisation of the haemodynamics in preeclampsia and peripartum cardiomyopathy, allows clinicians to manage these conditions appropriately. This article outlines the echocardiographic differences between preeclampsia and peripartum cardiomyopathy, the likely mechanisms for heart failure in preeclampsia and the relevance of these differences to clinicians in relation to prevention and treatment. It also emphasises the importance of disease definitions as a key framework for the more consistent classification of the two diseases.

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.