Rapid echocardiographic assessment of left and right heart hemodynamics in critically ill obstetric patients

Maternal Hemodynamics from Preconception to Delivery: Research and Potential Diagnostic and Therapeutic Implications: Position Statement by Italian Association of Preeclampsia and Italian Society of Perinatal Medicine

OBJECTIVE

 The Italian Association of Preeclampsia (AIPE) and the Italian Society of Perinatal Medicine (SIMP) developed clinical questions on maternal hemodynamics state of the art.

STUDY DESIGN

 AIPE and SIMP experts were divided in small groups and were invited to propose an overview of the existing literature on specific topics related to the clinical questions proposed, developing, wherever possible, clinical and/or research recommendations based on available evidence, expert opinion, and clinical importance. Draft recommendations with a clinical rationale were submitted to 8th AIPE and SIMP Consensus Expert Panel for consideration and approval, with at least 75% agreement required for individual recommendations to be included in the final version.

RESULTS

 More and more evidence in literature underlines the relationship between maternal and fetal hemodynamics, as well as the relationship between maternal cardiovascular profile and fetal-maternal adverse outcomes such as fetal growth restriction and hypertensive disorders of pregnancy. Experts agreed on proposing a classification of pregnancy hypertension, complications, and cardiovascular states based on three different hemodynamic profiles depending on total peripheral vascular resistance values: hypodynamic (>1,300 dynes·s·cm-5), normo-dynamic, and hyperdynamic (<800 dynes·s·cm-5) circulation. This differentiation implies different therapeutical strategies, based drugs' characteristics, and maternal cardiovascular profile. Finally, the cardiovascular characteristics of the women may be useful for a rational approach to an appropriate follow-up, due to the increased cardiovascular risk later in life.

CONCLUSION

 Although the evidence might not be conclusive, given the lack of large randomized trials, maternal hemodynamics might have great importance in helping clinicians in understanding the pathophysiology and chose a rational treatment of patients with or at risk for pregnancy complications.

KEY POINTS

· Altered maternal hemodynamics is associated to fetal growth restriction.. · Altered maternal hemodynamics is associated to complicated hypertensive disorders of pregnancy.. · Maternal hemodynamics might help choosing a rational treatment during hypertensive disorders..

The role of point-of-care ultrasound to monitor response of fluid replacement therapy in pregnancy

Fluid management in obstetrical care is crucial because of the complex physiological conditions of pregnancy, which complicate clinical manifestations and fluid balance management. This expert review examined the use of point-of-care ultrasound to evaluate and monitor the response to fluid therapy in pregnant patients. Pregnancy induces substantial physiological changes, including increased cardiac output and glomerular filtration rate, decreased systemic vascular resistance, and decreased plasma oncotic pressure. Conditions, such as preeclampsia, further complicate fluid management because of decreased intravascular volume and increased capillary permeability. Traditional methods for assessing fluid volume status, such as physical examination and invasive monitoring, are often unreliable or inappropriate. Point-of-care ultrasound provides a noninvasive, rapid, and reliable means to assess fluid responsiveness, which is essential for managing fluid therapy in pregnant patients. This review details the various point-of-care ultrasound modalities used to measure dynamic changes in fluid status, focusing on the evaluation of the inferior vena cava, lung ultrasound, and left ventricular outflow tract. Inferior vena cava ultrasound in spontaneously breathing patients determines diameter variability, predicts fluid responsiveness, and is feasible even late in pregnancy. Lung ultrasound is crucial for detecting early signs of pulmonary edema before clinical symptoms arise and is more accurate than traditional radiography. The left ventricular outflow tract velocity time integral assesses stroke volume response to fluid challenges, providing a quantifiable measure of cardiac function, which is particularly beneficial in critical care settings where rapid and accurate fluid management is essential. This expert review synthesizes current evidence and practice guidelines, suggesting the integration of point-of-care ultrasound as a fundamental aspect of fluid management in obstetrics. It calls for ongoing research to enhance techniques and validate their use in broader clinical settings, aiming to improve outcomes for pregnant patients and their babies by preventing complications associated with both under- and overresuscitation.

Continuous non-invasive hemodynamic monitoring in early onset severe preeclampsia

OBJECTIVES

Continuous hemodynamic monitoring offers the opportunity to individualize management in severe preeclampsia (PEC). We compared cardiac output (CO) and total peripheral resistance (TPR) measured by bioreactance (NICOM), Clearsite™ Fingercuff [CS), and 3D-echocardiography (3DE).

STUDY DESIGN

This prospective observational study included 12 pregnant patients with early PEC. CO and TPR were measured simultaneously by NICOM, CS, and 3DE antepartum and 1-2 days postpartum. Using 3DE as the standard, CS and NICOM interchangeability, precision, accuracy, and correlation were assessed.

RESULTS

Compared to 3DE-CO, CS-CO was highly correlated (R2 = 0.70, p = <0.0001) with low percentage error (PE 29%) which met criteria for interchangeablity. CS-TPR had strong correlation (R2 = 0.81, p = <0.0001) and low PE (29%). While CS tended to slightly overestimate CO (bias + 2.05 ±1.18 L/min, limit of agreement (LOA) -0.20 to 4.31) and underestimate TPR (bias -279 ±156 dyes/sec/cm5; LOA -580 to 18.4) these differences were unlikely to be clinically significant. Thus CS could be interchangeable with 3DE for CO and TPR. NICOM-CO had only moderate correlation with 3DE-CO (R2 = 0.29, p = 0.01) with high PE (52%) above threshold for interchangeability. NICOM-CO had low mean bias (-1.2 ±1.68 L/min) but wide 95% LOA (-4.41 to 2.14) suggesting adequate accuracy but low precision in relation to 3DE-CO. NICOM-TPR had poor correlation with 3DE-TPR (R2 = 0.32, p = 0.001) with high PE (67%), relatively low mean bias (238 ±256), and wide 95% LOA (-655 to 1131). NICOM did not meet the criteria for interchangeable with 3DE for CO and TPR.

CONCLUSIONS

Clearsite Fingercuff, but not NICOM, has potential to be clinically useful for CO and TPR monitoring in severe preeclampsia.

An update on maternal cardiac hemodynamics in fetal growth restriction and pre-eclampsia

Pre-eclampsia and fetal growth restriction (FGR) have been long related to primary placental dysfunction, caused by abnormal trophoblast invasion. Nevertheless, emerging evidence has led to a new hypothesis for the origin of pre-eclampsia and FGR. Suboptimal maternal cardiovascular adaptation has been shown to result in uteroplacental hypoperfusion, ultimately leading to placental hypoxic damage with secondary dysfunction. In this review, we summarize current evidence on maternal cardiac hemodynamics in FGR and pre-eclampsia. We also discuss the different approaches for antihypertensive treatment according to the hemodynamic phenotype observed in pre-eclampsia and FGR.

Accuracy and trending ability of finger plethysmographic cardiac output monitoring in late pregnancy

PURPOSE

Individuals in late pregnancy are at risk of significant hemodynamic variations, especially during Cesarean delivery. Although non-invasive monitoring might enable the early detection of variations in cardiac output (CO), clinical validation is lacking.

METHODS

In a prospective, single-center study, we measured CO simultaneously with finger plethysmography and transthoracic echocardiography in 100 third-trimester pregnant individuals in the supine and left lateral decubitus (LLD) positions.

RESULTS

A Bland-Altman analysis revealed a mean (standard deviation) bias of 1.36 (1.04) L·min-1 in the supine position (95% limits of agreement, -0.68 to 3.4 L·min-1; percent error, 26.6%), indicating overestimation by finger plethysmography. The intra-class correlation coefficient was 0.43 (95% confidence interval [CI], 0.33 to 0.51). Regarding the changes in CO induced by the supine-to-LLD transition, the concordance rate in a four-quadrant plot was 98.3% (95% CI, 91.1 to 99.9%).

CONCLUSION

Our study showed a poor reliability of finger plethysmography for static measurement of CO. Nevertheless, finger plethysmography had a reasonably high concordance rate for the detection of CO changes secondary to positional changes in late-pregnant individuals. STUDY REGISTRATION DATE: www.

CLINICALTRIALS

gov (NCT03735043); registered 8 November 2018.

Doppler trans-thoracic echocardiography for detection of pulmonary hypertension in adults

BACKGROUND

Pulmonary hypertension (PH) is an important cause of morbidity and mortality, which leads to a substantial loss of exercise capacity. PH ultimately leads to right ventricular overload and subsequent heart failure and early death. Although early detection and treatment of PH are recommended, due to the limited responsiveness to therapy at late disease stages, many patients are diagnosed at a later stage of the disease because symptoms and signs of PH are nonspecific at earlier stages. While direct pressure measurement with right-heart catheterisation is the clinical reference standard for PH, it is not routinely used due to its invasiveness and complications. Trans-thoracic Doppler echocardiography is less invasive, less expensive, and widely available compared to right-heart catheterisation; it is therefore recommended that echocardiography be used as an initial diagnosis method in guidelines. However, several studies have questioned the accuracy of noninvasively measured pulmonary artery pressure. There is substantial uncertainty about the diagnostic accuracy of echocardiography for the diagnosis of PH.

OBJECTIVES

To determine the diagnostic accuracy of trans-thoracic Doppler echocardiography for detecting PH.

SEARCH METHODS

We searched MEDLINE, Embase, Web of Science Core Collection, ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform from database inception to August 2021, reference lists of articles, and contacted study authors. We applied no restrictions on language or type of publication.

SELECTION CRITERIA

We included studies that evaluated the diagnostic accuracy of trans-thoracic Doppler echocardiography for detecting PH, where right-heart catheterisation was the reference standard. We excluded diagnostic case-control studies (two-gate design), studies where right-heart catheterisation was not the reference standard, and those in which the reference standard threshold differed from 25 mmHg. We also excluded studies that did not provide sufficient diagnostic test accuracy data (true-positive [TP], false-positive [FP], true-negative [TN], and false-negative [FN] values, based on the reference standard). We included studies that provided data from which we could extract TP, FP, TN, and FN values, based on the reference standard. Two authors independently screened and assessed the eligibility based on the titles and abstracts of records identified by the search. After the title and abstract screening, the full-text reports of all potentially eligible studies were obtained, and two authors independently assessed the eligibility of the full-text reports.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias and extracted data from each of the included studies. We contacted the authors of the included studies to obtain missing data. We assessed the methodological quality of studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. We estimated a summary receiver operating characteristic (SROC) curve by fitting a hierarchical summary ROC (HSROC) non-linear mixed model. We explored sources of heterogeneity regarding types of PH, methods to estimate the right atrial pressure, and threshold of index test to diagnose PH. All analyses were performed using the Review Manager 5, SAS and STATA statistical software.

MAIN RESULTS

We included 17 studies (comprising 3656 adult patients) assessing the diagnostic accuracy of Doppler trans-thoracic echocardiography for the diagnosis of PH. The included studies were heterogeneous in terms of patient distribution of age, sex, WHO classification, setting, country, positivity threshold, and year of publication. The prevalence of PH reported in the included studies varied widely (from 6% to 88%). The threshold of index test for PH diagnosis varied widely (from 30 mmHg to 47 mmHg) and was not always prespecified. No study was assigned low risk of bias or low concern in each QUADAS-2 domain assessed. Poor reporting, especially in the index test and reference standard domains, hampered conclusive judgement about the risk of bias. There was little consistency in the thresholds used in the included studies; therefore, common thresholds contained very sparse data, which prevented us from calculating summary points of accuracy estimates. With a fixed specificity of 86% (the median specificity), the estimated sensitivity derived from the median value of specificity using HSROC model was 87% (95% confidence interval [CI]: 78% to 96%). Using a prevalence of PH of 68%, which was the median among the included studies conducted mainly in tertiary hospitals, diagnosing a cohort of 1000 adult patients under suspicion of PH would result in 88 patients being undiagnosed with PH (false negatives) and 275 patients would avoid unnecessary referral for a right-heart catheterisation (true negatives). In addition, 592 of 1000 patients would receive an appropriate and timely referral for a right-heart catheterisation (true positives), while 45 patients would be wrongly considered to have PH (false positives). Conversely, when we assumed low prevalence of PH (10%), as in the case of preoperative examinations for liver transplantation, the number of false negatives and false positives would be 13 and 126, respectively.

AUTHORS' CONCLUSIONS

Our evidence assessment of echocardiography for the diagnosis of PH in adult patients revealed several limitations. We were unable to determine the average sensitivity and specificity at any particular index test threshold and to explain the observed variability in results. The high heterogeneity of the collected data and the poor methodological quality would constrain the implementation of this result into clinical practice. Further studies relative to the accuracy of Doppler trans-thoracic echocardiography for the diagnosis of PH in adults, that apply a rigorous methodology for conducting diagnostic test accuracy studies, are needed.

Methods and considerations concerning cardiac output measurement in pregnant women: recommendations of the International Working Group on Maternal Hemodynamics

Cardiac output (CO), along with blood pressure and vascular resistance, is one of the most important parameters of maternal hemodynamic function. Substantial changes in CO occur in normal pregnancy and in most obstetric complications. With the development of several non-invasive techniques for the measurement of CO, there is a growing interest in the determination of this parameter in pregnancy. These techniques were initially developed for use in critical-care settings and were subsequently adopted in obstetrics, often without appropriate validation for use in pregnancy. In this article, methods and devices for the measurement of CO are described and compared, and recommendations are formulated for their use in pregnancy, with the aim of standardizing the assessment of CO and peripheral vascular resistance in clinical practice and research studies on maternal hemodynamics. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Lung and cardiac ultrasound for hemodynamic monitoring of patients with severe pre-eclampsia

OBJECTIVE

To evaluate lung and cardiac ultrasound for the assessment of fluid tolerance and fluid responsiveness before and after delivery in pregnant women with severe pre-eclampsia (PE).

METHODS

This was a prospective observational study of singleton pregnant women with severe PE and healthy term controls. Lung ultrasound echo comet score (ECS), which denotes the amount of extravascular lung water, was obtained using the 28-rib interspaces technique. The echocardiographic E/e' ratio, measured by pulsed-wave and tissue Doppler, was used as a marker of diastolic left ventricular function. Fluid responsiveness was assessed by measuring changes in stroke volume (SV) with passive leg raising (PLR). SV was calculated from the left ventricular flow velocity-time integral measured by pulsed-wave Doppler at baseline and after PLR. Change in SV ≥ 12% was considered to indicate fluid responsiveness. Measurements obtained 1 day before delivery and 1 and 4 days after delivery were compared in the two groups (PE vs controls).

RESULTS

We included 21 women with severe PE and 12 healthy controls. ECS and E/e' ratio were higher in women with PE than in controls, both before delivery (P = 0.002 and P = 0.02) and 1 day postdelivery (P = 0.02 and P = 0.03); however there was no difference at 4 days postdelivery (P = 0.63 and P = 0.90). The change in SV with PLR before (P = 0.26) and after (P = 0.71) delivery did not differ between groups. An increase in SV ≥ 12% was observed in three (14%) women with PE and four (33%) controls before delivery and in four (19%) women with PE and two (17%) controls 1 day after delivery.

CONCLUSIONS

Severe PE is associated with an increase in extravascular lung water, which could in part be caused by disturbed diastolic left ventricular function. Excess lung water can be identified by lung ultrasound assessment in women with severe PE before the appearance of clinical signs. Only a small proportion of these women are fluid responsive. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Validation of maternal cardiac output assessed by transthoracic echocardiography against pulmonary artery catheterization in severely ill pregnant women: prospective comparative study and systematic review

OBJECTIVE

Most severe pregnancy complications are characterized by profound hemodynamic disturbances, thus there is a need for validated hemodynamic monitoring systems for pregnant women. Pulmonary artery catheterization (PAC) using thermodilution is the clinical gold standard for the measurement of cardiac output (CO), however this reference method is rarely performed owing to its invasive nature. Transthoracic echocardiography (TTE) allows non-invasive determination of CO. We aimed to validate TTE against PAC for the determination of CO in severely ill pregnant women.

METHODS

This study consisted of a meta-analysis combining data from a prospective study and a systematic review. The prospective arm was conducted in Pretoria, South Africa, in 2003. Women with severe pregnancy complications requiring invasive monitoring with PAC according to contemporary guidelines were included. TTE was performed within 15 min of PAC and the investigator was blinded to the PAC measurements. Comparative measurements were extracted from similar studies retrieved from a systematic review of the literature and added to a database. Simultaneous CO measurements by TTE and PAC were compared. Agreement between methods was assessed using Bland-Altman statistics and intraclass correlation coefficients (ICC).

RESULTS

Thirty-four comparative measurements were included in the meta-analysis. Mean CO values obtained by PAC and TTE were 7.39 L/min and 7.18 L/min, respectively. The bias was 0.21 L/min with lower and upper limits of agreement of -1.18 L/min and 1.60 L/min, percentage error was 19.1%, and ICC between the two methods was 0.94.

CONCLUSIONS

CO measurements by TTE show excellent agreement with those obtained by PAC in pregnant women. Given its non-invasive nature and availability, TTE could be considered as a reference for the validation of other CO techniques in pregnant women. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

RESUMEN OBJETIVO

Las complicaciones del embarazo más graves se caracterizan por trastornos hemodinámicos serios, debido a los cuales existe la necesidad de sistemas validados de monitorización hemodinámica para mujeres embarazadas. Aunque la cateterización de la arteria pulmonar (CAP) mediante termodilución es el patrón de referencia clínico para la medición del gasto cardíaco (GC), este método se usa con poca frecuencia debido a su naturaleza invasiva. La ecocardiografía transtorácica (ETT) permite la determinación no invasiva del GC. El objetivo de este estudio fue validar la ETT frente al CAP para determinar el GC en mujeres embarazadas gravemente enfermas. MÉTODOS: Este estudio consistió en un metaanálisis que combinó datos de un estudio prospectivo y una revisión sistemática. El estudio prospectivo se llevó a cabo en Pretoria (Sudáfrica) en 2003. Se incluyeron mujeres con complicaciones graves en el embarazo que requerían una monitorización invasiva mediante CAP según las directrices de ese momento. Se realizó una ETT en un plazo de 15 minutos de haber realizado el CAP y el investigador no tuvo acceso a las mediciones del CAP. Las mediciones comparativas se extrajeron de estudios similares obtenidos a partir de una revisión sistemática de la literatura y se añadieron a una base de datos. Se compararon las mediciones simultáneas del GC mediante ETT y CAP. La concordancia entre métodos se evaluó a través del método estadístico de Bland-Altman y de coeficientes de correlación intraclase (CCI).

RESULTADOS

Se incluyeron treinta y cuatro mediciones comparativas en el metaanálisis. Los valores medios del GC obtenidos mediante CAP y ETT fueron de 7,39 l/min y 7.18 l/min, respectivamente. El sesgo fue de 0,21 l/min, siendo los límites inferior y superior de la concordancia de -1,18 l/min y 1.60 l/min; el error porcentual fue del 19,1%, y el CCI entre ambos métodos fue de 0,94.

CONCLUSIONES

Las mediciones del GC en mujeres embarazadas mediante ETT muestran una excelente concordancia con las obtenidas mediante CAP. Dada su naturaleza no invasiva y su disponibilidad, la ETT podría considerarse como referencia para la validación de otras técnicas relacionadas con el GC en mujeres embarazadas. : ,。(pulmonary artery catheterization,PAC)(cardiac output,CO),,。(transthoracic echocardiography,TTE)CO。PACTTECO。 : meta。2003。PAC。PAC 15 minTTE,PAC。,。TTEPACCO。Bland-Altman(intraclass correlation coefficients,ICC)。 : meta34。PACTTECO7.39 L/min7.18 L/min。-1.18 L/min、1.60 L/min0.21 L/min,19.1%,ICC0.94。 : TTECOPACCO。,TTECO。.

Changes in Sonographically Measured Inferior Vena Caval Diameter in Response to Fluid Loading in Term Pregnancy

OBJECTIVES

The purpose of this study was to determine whether the inferior vena caval (IVC) diameter is influenced by intravascular volume changes in pregnancy.

METHODS

A prospective observational study was done on 2 groups of normal term gravidas. In 24 patients, we measured the IVC diameter, blood pressure, and heart rate (HR) before and after a 1-L fluid infusion in preparation for regional anesthesia, after initiation of an epidural block, and within 24 hours postpartum. In a second group of 15 women, we measured the IVC diameter sequentially during a 1-L crystalloid infusion.

RESULTS

In the first group, the mean baseline IVC diameter ± SD at end-inspiration was 1.45 ± 0.32 cm, which was 19% smaller than at end-expiration (1.73 ± 0.31 cm; P= .003). This respiratory cycle variation remained significant at each measurement epoch. The mean caval diameter at end-inspiration increased by 23% after the fluid bolus (P = .012). Hydration was not, however, accompanied by any significant change in the HR, mean arterial pressure, or collapsibility index of the inferior vena cava. With epidural anesthesia, the mean arterial pressure decreased from 88 ± 9 to 80 ± 7 mm Hg (P= .018), but the HR and collapsibility index remained unchanged. Postpartum values were not significantly different from their baseline measurements, except for the mean arterial pressure, which was lower by about 6 mm Hg (P = .042). In the second group, the IVC diameter at end-inspiration increased by 31% after the 1-L infusion, and there was a positive correlation between the volume infused and the IVC diameter (r= 0.67; P< .0001).

CONCLUSIONS

Measurable variations in the IVC diameter occur in response to volume changes in normal term pregnancy and postpartum.

Pulmonary hypertension and pregnancy: the experience of a tertiary institution over 15 years

Background:

Pulmonary hypertension (PH) in pregnancy is associated with a high maternal mortality and morbidity and has been found to be as high as 30-56%.

Aim:

To review the management of such patients in a tertiary center over a 15 year period, as the current literature consists of a few case reports, a few small case series and 2 meta-analyses.

Materials and Methods:

A review of all patients admitted to our institution for management of PH in pregnancy between 1994 and February 2009 was undertaken. Cases were identified from the high-risk pregnancy database within the department of anesthesia and from the hospital medical records. Severity of PH, type of PH, NYHA functional status at presentation and delivery, mode of delivery, peripartum monitoring and APGAR scores were noted. Patients were reviewed by a multidisciplinary team and management planned accordingly.

Results:

19 eligible patients were identified. Patients who were significantly sick due to their PH were aggressively managed during pregnancy. Overall there was an improvement in NYHA functional status at the time of delivery. Epidural analgesia and anesthesia for labor and operatively delivery seem to be the ideal choice.

Conclusion:

Multidisciplinary approach is a key to the successful management of these patients. Secondary PH results in higher morbidity and mortality, in particular, older the age higher the maternal morbidity and mortality.

Haemodynamic assessment in pregnancy and pre-eclampsia: A Guytonian approach

OBJECTIVES

Hypertensive disorders of pregnancy continue to be amongst the leading causes of maternal morbidity and mortality. There is debate about the optimal monitoring and treatment for these women, particularly in regard to circulatory and fluid management. A restrictive fluid strategy is advocated, which conflicts with the prevailing view that the circulating volume is contracted in pre-eclampsia. This belief has been erroneously reinforced by use of the central venous pressure (CVP) as a measure of the volume state.

METHODS

We used a Guytonian model of the circulation involving the mean systemic filling pressure (Pms) to review published data using a cohort of normal pregnant/post partum women and a pre-eclamptic cohort. The Pms is the pressure left in the circulation when the heart is stopped, arguably the true volume state measure. An analogue of the Pms (Pmsa) can be calculated using commonly measured haemodynamic variables.

RESULTS

Our results show the Pmsa to be elevated in normal pregnancy versus post partum (10.79 vs. 9.58, a 12.6% difference) and elevated further in pre-eclamptic pregnancy (13.86, 29% higher than the normal pregnant group).

CONCLUSIONS

There is scope to challenge the long held belief that the volume state is contracted in pre-eclampsia. This approach indicates that the maternal volume state in pre-eclampsia is often elevated. When viewed in combination with recent echocardiographic insights this model helps to explain some of the haemodynamic management paradoxes that these women present. Most importantly, it provides a sound physiological basis for the restrictive fluid strategy that is currently recommended.

Critical care in pregnancy--is it different?

In the first part of this review, the epidemiology of obstetric critical care is discussed. This includes the incidence of severe morbidity in pregnancy, identification of critically ill and potentially critically ill patients, the incidence of obstetric ICU admissions, the type of critical illness by stage of pregnancy, ICU admission diagnoses, the severity of illness in obstetric ICU patients compared to non-obstetric patients, ICU mortality of obstetric patients, the ICU proportion of total maternal mortality, and the causes of death for obstetric patients in ICU. In the second part, the management of obstetric patients who happen to be admitted to a general ICU is discussed. Rather than focusing on the management of particular obstetric conditions, general principles of ICU management will be discussed as applied to obstetric ICU patients. These include drug safety, monitoring the fetus, management of the airway, sedation, muscle relaxation, ventilation, cardiovascular support, thromboprophylaxis, and radiology and ethical issues.

Fluid management in pre-eclampsia

Intravenous fluid given to women with pre-eclampsia may be a necessary form of treatment; however, intravenous fluid therapy can also cause iatrogenic pulmonary oedema. The indications for the use of intravenous fluids, the titration of the amount of fluid given and the use of invasive monitoring have not been subject to adequate examination in randomised studies. Clinical experience, combined with available evidence and a reasoned approach are the basis for a suggested management algorithm.

Predicting fluid responsiveness with transthoracic echocardiography is not yet evidence based

An essential part of intensive care is to accurately identify fluid responders among patients with circulatory failure. Over the past few years, new techniques have been assessed for rapid and non-invasive prediction of fluid responsiveness. As transthoracic echocardiography (TTE) is becoming an integrated tool in the intensive care unit, this systematic review examined studies evaluating the predictive value of TTE for fluid responsiveness. In October 2012, we searched Pubmed, EMBASE and Web of Science for studies evaluating the predictive value of TTE-derived variables for fluid responsiveness defined as change in thermodilution cardiac output or stroke volume after a fluid challenge or a passive leg raising test. The use of thermodilution was used as inclusion criterion because it is the only method validated to show the change in cardiac output or stroke volume, which defines fluid responsiveness. Of the 4294 evaluated citations, only one study fully met our inclusion criteria. In this study, the predictive value of variations in inferior vena cava diameter (> 16%) for fluid responsiveness was moderate with sensitivity of 71% [95% confidence interval (CI) 44-90], specificity of 100% (95% CI 73-100) and an area under the receiver operating curve of 0.90 (95% CI 0.73-0.98). Only one study of TTE-based methods fulfilled the criteria for valid assessment of fluid responsiveness. Before recommending the use of TTE in predicting fluid responsiveness, proper evaluation including thermodilution technique as the gold standard is needed.

The critically ill obstetric patient - Recent concepts

Obstetric patients admitted to an Intensive Care Unit (ICU) present a challenge to an intensivist because of normal physiological changes associated with pregnancy and puerperium, the specific medical diseases peculiar to pregnancy and the need to take care of both the mother and the foetus. Most common causes of admission to an ICU for obstetric patients are eclampsia, severe preeclampsia, haemorrhage, congenital and valvular heart disease, septic abortions, severe anemia, cardiomyopathy and non-obstetric sepsis. The purpose of this review is to present the recent concepts in critical care management of obstetric patients with special focus mainly on ventilatory strategies, treatment of shock and nutrition. The details regarding management of individual diseases would not be discussed as these would be beyond the purview of this article. In addition, some specific issues of importance while managing such patients would also be highlighted.

Transesophageal echocardiography and noncardiac surgery

The use of transesophageal echocardiography (TEE) for monitoring during cardiac and noncardiac surgery has increased exponentially over the past few decades. TEE has evolved from a diagnostic tool to a monitoring device and a procedural adjunct. The close proximity of the TEE transducer to the heart generates high-quality images of the intracardiac structures and their spatial orientation. The use of TEE in noncardiac and critical care settings is not well studied, and the evidence of the benefits of its use in these settings is lacking. Despite the widespread availability of TEE equipment in US hospitals, less than 30% of anesthesiologists are formally trained in the use of perioperative TEE. In this review, the safety and indications of TEE are reviewed and detailed analysis of the best available evidence in this regard is presented. Landmark trials evaluating the use of TEE and its therapeutic impact in noncardiac surgical setting are critically reviewed. This article details recommendations to familiarize anesthesiologists with TEE technology to exploit it to its fullest potential to achieve better patient monitoring standards and eventually improve outcome. Training of greater numbers of anesthesiologists in TEE is needed to increase awareness of the indications and contraindications. Until relatively inexpensive TEE equipment is available, the initial cost of equipment acquisition remains a significant prohibitive factor limiting its widespread use.

Physiological changes of pregnancy and monitoring

Advances in medical care have led to increasing numbers of complex, high-risk obstetric patients. Specialist training and a sound knowledge of normal maternal physiology are essential to optimize outcomes. One of the earliest observed changes is peripheral vasodilatation; this causes a fall in systemic vascular resistance and triggers physiological changes in the cardiovascular and renal systems, with 40-50% increases in cardiac output and glomerular filtration rates. Safety concerns over Swan Ganz catheters have driven the increasing interest in alternative techniques, such as echocardiography, thoracic bioimpedance and pulse contour analysis, although their exact roles in future obstetric high-dependency care have yet to be established. Analysis of arterial blood gases is fundamental to the management of sick patients, and correct interpretation can be aided by a systematic approach. Observation charts are almost ubiquitous in all aspects of medicine, but little evidence exists to support their use in the high-dependency setting.

Correlation of transthoracic echocardiography and right heart catheterization in pregnancy

OBJECTIVES

To correlate estimated pulmonary artery pressures (PAP) by echocardiography with right heart catheterization (RHC) measurements and to correlate estimated left ventricular ejection fraction (EF) by echocardiography with cardiac output (CO) measurements by RHC.

STUDY DESIGN

All women who had echocardiography at a single institution during a 6-year period and underwent RHC during pregnancy were included. Echocardiography estimates of right ventricular systolic pressure (RVSP) and EF were correlated with measured RHC PAP and CO, respectively.

RESULTS

Eighteen patients underwent 21 RHCs, 10 antepartum at the catheterization laboratory and the remaining 11 intrapartum, performed with the use of a pulmonary artery catheter placed prior to the onset or induction of labor. Correlation between RVSP and PAP was good (rho=0.79, P<0.0001); nonetheless, in 30% of cases RHC eliminated the concern for pulmonary hypertension (PHTN). There was minimal correlation between EF and CO.

CONCLUSION

Despite good statistical correlation between echocardiography and RHC for determining pulmonary artery pressure, RHC should be considered for major decisions such as pregnancy interruption or preterm delivery given the proportion of cases where concern for PHTN was excluded by RHC. EF provides a poor proxy for CO.

The role of the anaesthetist in the management of the pre-eclamptic patient

PURPOSE OF REVIEW

Recent literature on the anaesthetist's role in the management of the patient with severe pre-eclampsia is reviewed, with particular emphasis on the role of regional anaesthesia.

RECENT FINDINGS

Laboratory findings in pre-eclamptic women include increased levels of markers of oxidative stress and circulating tyrosine kinase 1, and inflammatory activation of leucocytes. Magnesium sulphate is the most effective agent for seizure prophylaxis. The optimal pharmacological agents for acute control of blood pressure remain controversial. The benefits of epidural analgesia in labour are well established. Single-shot spinal anaesthesia for caesarean section is safe in the absence of contraindications. Successful use of combined spinal-epidural anaesthesia has been described. Most studies on maternal haemodynamics have employed heart rate and blood pressure data as surrogate measures of cardiac output. Noninvasive cardiac output studies provide further insight into the haemodynamic response during neuraxial techniques for caesarean section.

SUMMARY

The value of regional anaesthesia cannot be over-emphasized. Recent research into spinal anaesthesia for caesarean section suggests a lower susceptibility to hypotension and probably less impairment of cardiac output than in healthy parturients. Noninvasive cardiac output measurement may also have advantages in critical care management.

Hemodynamic assessment in a pregnant and peripartum patient

PATHOPHYSIOLOGY

Critical care in obstetrics has many similarities in pathophysiology to the care of nonpregnant women. However, changes in the physiology of pregnant woman necessary to maintain homeostasis for both mother and fetus, especially during critical illness, result in complex pathophysiology. Understanding the normal physiologic changes during pregnancy, intrapartum, and postpartum is the key to managing critically ill obstetric patients with underlying medical diseases and pregnancy-related complications.

HEMODYNAMIC MONITORING

When the pathophysiology of critically ill obstetric patients cannot be explained by noninvasive hemodynamic monitoring and the patient fails to respond to conservative medical management, invasive hemodynamic monitoring may be helpful in guiding management. Most important, the proper interpretation of hemodynamic data is predicated on knowledge of normal values during pregnancy and immediately postpartum. Invasive hemodynamic monitoring with pulmonary artery catherization has been used in the obstetric population, particularly in patients with severe preeclampsia associated with pulmonary edema and renal failure.

Maternal diastolic dysfunction and left ventricular geometry in gestational hypertension

The objective of this study was to evaluate diastolic parameters and left ventricular geometry in gestational hypertension. Twenty-one consecutive pregnant women with gestational hypertension and 21 normotensive women matched for age and gestational age were enrolled in the third trimester of gestation. Echocardiographic and uterine color Doppler evaluations were performed. Systolic, diastolic, and mean blood pressure, total vascular resistance (TVR), and uterine resistance index were higher in hypertensive women than in control subjects (P<0.01). Left atrial function and cardiac output were significantly lower in gestational hypertension (P<0.01). Patients with gestational hypertension had longer left ventricular isovolumetric relaxation time (IVRT) (P<0.0001); lower velocity-time integral of the A wave (P<0.05) and of the diastolic pulmonary vein flow (P<0.05); and higher velocity-time integral of the reverse pulmonary vein flow (P<0.05). Systolic fraction of the pulmonary vein flow was higher in women with gestational hypertension than in control subjects (P<0.01); the difference in duration of pulmonary vein flow and A wave was closer to 0 in gestational hypertension (P<0.0001). Altered left ventricular geometry was found in 100% of hypertensive patients and in 19.05% of normotensive patients (P<0.001). IVRT, left ventricular end-systolic volume, atrial function, and uterine resistance index were directly related to TVR (P<0.01); deceleration time of the E wave showed a quadratic correlation with TVR (P<0.01). Gestational hypertension is characterized by an altered cardiac geometric pattern of concentric hypertrophy. The altered geometric pattern assessed during gestational hypertension is associated, in our study, with depressed systolic function, high TVR, altered diastolic function, and left atrial dysfunction. Deceleration time of the E wave, IVRT, and left atrial fractional area change, found in concomitance with the highest TVR, may be useful in the evaluation of cardiac function and hemodynamics present in pregnancy-induced hypertension.

Multicenter study of obstetric admissions to 14 intensive care units in southern England

OBJECTIVES

To identify pregnant and postpartum patients admitted to intensive care units (ICUs), the cause for their admission, and the proportion that might be appropriately managed in a high-dependency environment (HDU) by using an existing database. To estimate the goodness-of-fit for the Simplified Acute Physiology Score II, the Acute Physiology and Chronic Health Evaluation (APACHE) II, and the APACHE III scoring systems in the obstetrical population.

DESIGN

Retrospective analysis of demographic, diagnostic, treatment, and severity of illness data.

SETTING

Fourteen ICUs in Southern England.

PATIENTS

Pregnant or postpartum (<42 days) admissions between January 1, 1994, and December 31, 1996.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We identified 210 patients, constituting 1.84% (210 of 11,385) of all ICU admissions and 0.17% (210 of 122,850) of all deliveries. Most admissions followed postpartum complications (hypertensive disease of pregnancy [39.5%] and major hemorrhage [33.3%]). Seven women were transferred to specialist ICUs. There was considerable variation between ICUs with respect to the number and type of interventions required by patients. Some 35.7% of patients stayed in ICU for <2 days and received no specific ICU interventions; these patients might have been safely managed in an HDU. There were seven maternal deaths (3.3%); fetal mortality rate was 20%. The area under the receiver operator characteristic curve and the standardized mortality ratio were 0.92 (confidence interval [CI], 0.85-0.99) and 0.43 for the Simplified Acute Physiology Score II, 0.94 (CI, 0.86-1.0) and 0.24 for APACHE II, and 0.98 (CI, 0.96-1.0) and 0.43 for APACHE III, respectively.

CONCLUSIONS

Existing databases can both identify critically ill obstetrical patients and provide important information about them. Obstetrical ICU admissions often require minimal intervention and are associated with low mortality rates. Many might be more appropriately managed in an HDU. The commonly used severity of illness scoring systems are good discriminators of outcome from intensive care admission in this group but may overestimate mortality rates. Severity of illness scoring systems may require modification in obstetrical patients to adjust for the normal physiologic responses to pregnancy.

Cardio-respiratory physiological adaptation of pregnancy

Significant physiological adaptations during pregnancy contribute to its successful outcome. These occur early in the pregnancy and continue throughout gestation, with complete reversal after delivery. Many changes that are normal during pregnancy are pathological should they occur in the nonpregnant woman. Adequate understanding of these normal changes is essential in the assessment of all pregnancies and in the management of those with complications. This article reviews the cardiovascular and pulmonary changes that occur during a normal gestation.

Quantitative echocardiographic assessment of left ventricular function in critically ill obstetric patients: a comparative study

OBJECTIVE

Our purpose was to compare different echocardiographic methods to quantitate maternal ventricular function.

STUDY DESIGN

Eleven critically ill obstetric patients requiring invasive monitoring and M-mode and two-dimensional Doppler echocardiographic studies were retrospectively studied. Ventricular volumes and ejection fraction derived from multiple methods were computed and compared with analysis of variance and Newman-Keuls tests.

RESULTS

Two M-mode studies could not be analyzed. M-mode and two-dimensional estimates of stroke volume were similar to the previously validated Doppler stroke volume values of these 11 patients. End-diastolic volume estimates were similar. There was no difference in ejection fraction for the five different two-dimensional Doppler methods used (66%, 66%, 67%, 63%, and 63%).

CONCLUSION

Left ventricular function is reliably calculated in pregnant women by a number of different echocardiographic techniques. The ability to combine echocardiographic techniques is helpful when any single method does not provide all of the information required.

Use of cardiac index in pregnancy: is it justified?

OBJECTIVE

The aim of this study was to test the hypothesis that standardization of cardiac output in pregnancy by correcting for body surface area, and thus obtaining cardiac index, is justified.

STUDY DESIGN

Cardiac output was determined by thoracic electrical bioimpedance monitoring in 78 pregnant women; recordings were made at 1-month intervals from the first antenatal visit and a further two were made during the sixth and twelfth weeks after delivery. In a separate group of 10 pregnant women, cardiac output was determined by Doppler echocardiography at 5, 10, 14, 25, and 35 weeks and at 12 weeks post partum.

RESULTS

Irrespective of gestational age, the correlation between cardiac output and body surface area was poor, by either thoracic electrical bioimpedance monitoring (r = 0.15 to 0.39) or Doppler echocardiography (r = 0.00 to 0.29). Furthermore, strict proportionality between cardiac output and body surface area was in general not the best way of describing the (poor) relation between these two.

CONCLUSION

Standardization of cardiac output in pregnancy by correcting for body surface area to compare cardiac performance between individuals and between groups of individuals is not justified.