This chapter should be cited as follows:
Rojas-Suarez J, Borré D, et al, Glob. libr. women's med.,
ISSN: 1756-2228; DOI 10.3843/GLOWM.414233
The Continuous Textbook of Women’s Medicine Series – Obstetrics Module
Volume 9
Principles and practice of obstetric high-dependency and critical care
Volume Editor: Professor Stephen Lapinsky, University of Toronto, Canada
Chapter
Hemodynamic Monitoring of the Critically Ill Obstetric Patient
First published: February 2021
Study Assessment Option
By completing 4 multiple-choice questions (randomly selected) after studying this chapter readers can qualify for Continuing Professional Development awards from FIGO plus a Study Completion Certificate from GLOWM
See end of chapter for details
INTRODUCTION
The cardiovascular system during pregnancy undergoes changes that ensure fetal growth.1 Understanding all the physiological changes of pregnancy to the cardiovascular system will allow a better interpretation of the hemodynamics in the obstetric patient. Hemodynamic monitoring involves the estimation of cardiac output (CO) and its variables: preload, contractility, and afterload,1,2,3,4 which enables selection of the most appropriate therapy (i.e. fluids or vasopressor). Currently, invasive and non-invasive monitoring systems are available. In the obstetric patient, non-invasive monitoring systems are preferred, and many of these have shown adequate correlation with invasive monitoring systems.
PHYSIOLOGICAL CHANGES IN THE CARDIOVASCULAR SYSTEM OF THE PREGNANT WOMAN
During pregnancy the cardiovascular system experiences changes to ensure fetal growth and to prepare the mother for childbirth and puerperium.1 Cardiac output is calculated as the result of stroke volume and heart rate. Stroke volume is defined as the amount of blood pumped into the aorta during each cardiac cycle and depends on preload and afterload.
During pregnancy, the blood volume increases, leading to an increment in the amount of blood returning to the heart (the preload). Also, afterload decreases due to vasodilation. The stroke volume, therefore, increases by 20–30% during pregnancy.5 Maternal heart rate increases at the beginning of pregnancy, reaching its peak and plateau in the third trimester, this increase ranges from 15 to 20 beats per minute. As a result of the increase in stroke volume and maternal heart rate, cardiac output increases by 30–50% during pregnancy (from about 4.6 L/min to 8.7 L/min).6
Hemodynamically, there are three physiological patterns during pregnancy:
- Continuous increase in cardiac output until term;7
- Constant increase in cardiac output, reached its peak at the last half of pregnancy, with subsequent decrease at term;8 or
- A constant increase in cardiac output, reaching a maximum in the second half of pregnancy, with a plateau near to term.6
Peripheral vascular resistance during pregnancy decreases. This decrease in systemic vascular resistance (SVR) is mediated by progesterone and nitric oxide, which relax the vascular smooth muscle. Nitric oxide is produced in the endothelium of blood vessels, and its production is regulated by estradiol during pregnancy.6 This reduction in SVR is more marked towards the 2nd trimester of pregnancy (nadir around 20 weeks of gestation), the uteroplacental circulation being responsible for 20–26% of the decrease in resistance. By the end of the third trimester, the systemic vascular resistance shows a plateau and then a slight increase towards delivery, returning to non-pregnant values at 2 weeks after delivery.8
Understanding the physiological changes of pregnancy on the cardiovascular system will allow a better interpretation of hemodynamic monitoring in the obstetric critically ill patient.1 Variations in these physiological changes seem to be related to a higher incidence of maternal and fetal complications (gestational hypertension, pre-eclampsia, and intrauterine growth restriction).9
Some hemodynamic subtypes have been proposed in preeclamptic patients. One is a hyperdynamic profile (high CO and low SVR) characteristic of near-term pre-eclampsia, and the other a hypodynamic profile (low CO and high SVR) in preterm and early-onset pre-eclampsia. The latter profile is a more dangerous condition, closely related with not only worse maternal outcomes, but also fetal impairment including Intrauterine growth restriction (IUGR) and fetal loss.10
INDICATIONS FOR MONITORING IN THE OBSTETRIC PATIENT
Traditionally, the main indication for hemodynamic monitoring in the general population is circulatory compromise due to shock or hypoperfusion; in the obstetric patient, hemodynamic compromise may be manifest as hypotension or hypertension, as the result of conditions such as postpartum hemorrhage and sepsis causing hypotension (Table 1), but also the hypertensive disorders of pregnancy.
1
Main causes of circulatory shock in the pregnant woman.
Hypovolemic shock | Ectopic pregnancy, placenta previa, postpartum hemorrhage, trauma, uterine rupture |
Shock classification | Causes |
Septic shock | Puerperal sepsis, septic abortion |
Cardiogenic shock | Pre-existing valvular heart disease, peripartum cardiomyopathy |
Obstructive shock | Pulmonary embolism, amniotic fluid embolism |
Hemodynamic monitoring in the pregnant woman might help to:
- Identify patients with the highest risk of maternal and fetal complications; and
- Once circulatory shock has been established, to identify the hemodynamic problem and establish a specific therapy.
A decrease in cardiac output and an increase in resistance in the first stage of labor has been described as a risk factor for maternal–fetal complications, such as fetal compromise/hypoxia, postpartum hemorrhage or uterine atony, as a consequence of a decrease in blood flow to the uterus.11
HOW TO MONITOR?
The monitoring can be divided into:
- Clinical monitoring: physical examination is essential (HR, respiratory rate, state of consciousness, urine output, skin perfusion, capillary refill time); however, changes in clinical variables appear late or may be attributed to physiological changes during pregnancy;
- Biochemical monitoring: through laboratory markers of tissue perfusion (lactate; mixed venous oxygen saturation, SvO2; veno-arterial blood CO2 concentration difference, DCO2; base deficit, BD); that establish the shock diagnosis without defining its etiology;
- Hemodynamic monitoring (cardiac index, CI; cardiac output, CO; systemic vascular resistance, SVR): Mainly focused on changes in the cardiovascular system.3
Blood pressure measurement during pregnancy should be standardized. However, in severe cases and cases of blood pressure measurement in association with CO monitoring, blood pressure should be taken as closely as possible and in the same position as the CO assessment, to allow a reliable calculation.12
Blood pressure can be obtained invasively using intraarterial catheters or non-invasively using either a sphygmomanometer or automated oscillometric devices validated for use in pregnancy, using an appropriately sized arm cuff.13
MONITORING SYSTEMS
A variety of monitoring systems have been developed to monitor the cardiovascular system; these can be classified into invasive, minimally invasive or less invasive and non-invasive systems.11
Invasive monitoring: pulmonary artery catheter
For decades, the pulmonary artery catheter (PAC) was used to measure cardiac output. It was first described in 1970, and for more than 20 years was considered the gold standard in terms of hemodynamic monitoring.14
Concerns regarding the risks of the pulmonary artery catheter in the non-pregnant as well as in obstetric patients has limited its use; however, usual complications (subclavian or jugular injury, pneumothorax, arrhythmias and cardiac trauma) are not greater in pregnant patients than in the general population.15 Currently, in most centers the use of pulmonary artery catheter in pregnancy is very limited.
Minimally or less invasively monitoring
Most of the minimally invasive monitoring systems are based on the arterial pressure waveform analysis, by integrating the area under the systolic part of the arterial curve. Some differences between the monitoring systems are the insertion site of the arterial line (central or peripheral), and the need for calibration. Currently, there are three such systems: PiCCO and LiDCO (calibrated) and Flotrac (not calibrated).16
LiDCO
This technique is simple, requires the presence of an arterial line and central or peripheral venous access. For calibration, a small dose of lithium 0.3 mmol/L is injected; A lithium sensor generates a concentration–time curve at the level of the arterial line. The CO is calculated using the lithium dose and the area under the curve, before recirculation. Recent measurements of serum hemoglobin and sodium chloride are also required for calibration purposes and indexed values such as maternal height and weight.
Lithium is perfect for dilution of the indicator because it has no significant first-pass metabolism or loss in the pulmonary circulation and is rapidly redistributed. Lithium dose has no pharmacological or toxic effect.17
PiCCO system (Pulsion Medical Systems)
This system uses a traditional transpulmonary thermodilution method to measure CO and pulse wave contour analysis to generate a continuous beat-to-beat measurement of the CO; it requires a central venous catheter and a central arterial line. PiCCO also provides valuable information about intrathoracic lung volumes and extracellular lung volumes, including intra thoracic blood volume (ITBV) and extravascular lung water (EVLW).18
FloTrac sensor and Vigileo monitor
This system uses a blood pressure wave analysis based on the principle that the aortic pulse pressure is proportional to the stroke volume and inversely proportional to the aortic compliance. This system has some limitation compared to LiDCO and PiCCO since it does not provide truly continuous data in real-time, analyzing a 20 second window of pressure waveforms.16
None of these systems has been validated in pregnancy, with few articles published in this population. Recently the LiDCO plus monitoring system was evaluated in normal pregnancy, providing high-quality information, and found to be easy to use and safe. The LiDCO plus system can guide fluid therapy without potential risks to the mother and the newborn.19
Hemodynamic parameters of minimally invasive monitoring systems (PiCCO)(Table 2) generated by these hemodynamic systems
- Preload parameters:
- Global volume at the end of diastole (GEDV)
- Intrathoracic blood volume (ITBV)
- Stroke volume variation (SVV)
- Pulse pressure variation (PPV)
- Afterload parameter:
- Systemic vascular resistance (SVR)
- Contractility variables:
- Global ejection fraction (GEF)
- Cardiac function index (CFI)
- Maximum left ventricular contractility (dPmax)
- Excess lung water parameter:
- Extravascular lung water (EVLW)
- Pulmonary vascular permeability index (PVPi)
2
Hemodynamic parameters of the transpulmonary thermodilution system.
Variable | Definition | Reference range |
Cardiac function index | The CFI is the ratio of the index of cardiac output to the index of the GEDV. A measure of how well the CO is doing in relation to its preload | CI = CO/CS (normal value: 3.0–5.0 l/min/m2) CFI = CI/GEDV (normal value: 4.5–6.5 l/min) |
Global end diastolic index | Is the volume of blood contained in the 4 chambers of the heart | GEDI – global end diastolic index: |
Intra thoracic blood volume index | Is the volume of the 4 chambers of the heart plus the blood volume in the pulmonary vessels | ITBVI – intra thoracic blood volume index: 850–1000 ml/m2 |
Stroke volume variation | Reflects the sensitivity of the heart to the cyclic changes in cardiac preload induced by mechanical ventilation. Can predict whether stroke volume will increase with volume expansion | SVV – stroke volume variation: <13% |
Pulse pressure variation | The physiological principle is the same as in the SVV, but in this case the measure is the quotient between the difference of the maximum and minimum value of the pulse pressure by the average of the two values, expressed as a percentage, in the same respiratory cycle | PPV – pulse pressure variation: <13% |
Systemic vascular resistance index | The systemic vascular resistance index (SVRI) represents the peripheral vascular resistance. It is calculated as the difference in gradient from the aorta to the right atrium and is inversely related to blood flow (IC) | SVRI – systemic vascular resistance index: 1700–2400 dyn/s/cm5/m2 |
Extravascular lung water index | Is the amount of water content in the lungs or degree of pulmonary edema | ELWI – extravascular lung water index: |
Pulmonary vascular permeability index | Indication of pulmonary edema in relation to preload. This helps to differentiate if an increase in ELWI is due to an increase in hydrostatic pressure or a consequence of alveolar–capillary membrane damage | PVPI 1–3 |
Adapted from reference16
Variables such as SVV and PPV (dynamic variables), have a greater capacity to discriminate between fluids responder or non-responder patients; however, these have been validated mainly in patients receiving mechanical ventilation.20
Non-invasive monitoring
The non-invasive monitoring systems can be classified into three groups:
- Cardiac output monitoring based on measures of aortic blood flow:
- Transthoracic echocardiography (TTE);
- Transesophageal echocardiography (TEE);
- Transesophageal Doppler;
- Suprasternal Doppler.
- Cardiac output monitoring based on changes in electrical resistance induced by vascular flow:
- Bioimpedance and Bioreactance.
- Cardiac output monitoring based on non-invasive blood pressure monitoring.6
Cardiac output monitoring based on measures of aortic blood flow
Transthoracic echocardiography
Transthoracic echocardiography (TTE) allows the calculation of cardiac output and the cardiac index. This evaluation is made with the patient in the supine position at 45°, in a slightly lateral left position. In the parasternal long axis (PLAX), cardiac output can be determined by the product of heart rate, the pulsed Doppler velocity time integral (VTI) and aortic cross-sectional area (AoCSA) or m-mode left ventricular dimensions during systole and diastole (LVED and LVES, respectively) and heart rate.4
The hemodynamic monitoring by transthoracic echocardiography has been compared with the reference standard (pulmonary artery catheter) in obstetric patients with sepsis, acute respiratory distress syndrome (ARDS) and pre-eclampsia, with an adequate correlation between the two methods.21 The response to fluids is evaluated by a 10–15% increase in cardiac output after a volume challenge, or by passive leg elevation.22
Some authors suggest measurements of the inferior vena cava (IVC) to identify fluids responders and non-responders in spontaneous breathing patients. An IVC diameter <2.1 cm or a collapse >50% during inspiration suggests a right atrium pressure approximately of 3 mmHg (0–5 mmHg), suggesting fluid responsiveness, while an IVC diameter >2.1 cm or a collapse <50% suggests a right atrium pressure of 10–20 mmHg.23
TTE in conjunction with pulmonary ultrasound in severe pre-eclamptic patients, may help to guide therapy. This allows the identification of volume responsiveness (changes in stroke volume >10%) after a passive leg raising test, diastolic dysfunction (E/e′ ratio), and increased extravascular lung water (B lines).24
Also, echo allows a rapid and reliable hemodynamic evaluation of obstetric patients in critical condition, with a valuable information for an appropriate management.
Transesophageal echocardiography (TEE)
The value of transesophageal echocardiography (TEE) lies in its ability to visualize the heart and obtain information on filling pressures, ventricular and valvular dysfunction. Currently, obstetric patients often have a large number of comorbidities (morbid obesity, hypertension, coronary heart disease, diabetes, and liver dysfunction), that increase the risk of cardiovascular complications.21
TEE is useful for hemodynamic monitoring and management of refractory shock, even in maternal cardiac arrest, by accurately reflecting the direction and magnitude of changes in cardiac output in real time. TTE has been validated versus invasive monitoring in not only healthy, but also in critically ill, pregnant women with hypertensive disorders. However, evidence regarding TEE in pregnancy is limited. TEE has been used to determine not only the etiology, but also to guide resuscitation, impacting on survival.
TEE is valuable to determine the etiology and to address the therapy in refractory hypotension or cardiac arrest in obstetric patients.25,26 The cardiac output is calculated based on the aortic flow; the aortic diameter has been established from anthropometric measurements (weight, height, and age), with high accuracy in most cases.27
Echocardiography is an excellent hemodynamic system, given its non-invasive nature and immediate availability. For this, echocardiography should be considered as the reference for the validation of other hemodynamic methods in pregnant women.28
Ultrasonic Cardiac Output Monitor (USCOM)
The Ultrasonic Cardiac Output Monitor (USCOM, USCOM Ltd, NSW, Australia) monitoring system applies a continuous Doppler system through the suprasternal notch to obtain the integral trans-aortic or transpulmonary time velocity. The transducer is placed in the suprasternal notch or the parasternal interspace, and the Doppler transducer is directed towards the aortic outflow tract to acquire a spectral Doppler flow. Once the optimal flow profile is obtained, the screen freezes and the flow profiles are automatically tracked allowing the stroke volume to be calculated as the product of the integral velocity-time and the cross-sectional area of the chosen valve. The area of the aortic valve is determined from indexed regression equations based on anthropometric measurements. The cardiac output is calculated from the product of the heart rate and the stroke volume.29
The USCOM monitoring system accurately measures blood flow, stroke volume, and cardiac output, regardless of whether the patient has sinus rhythm, atrial fibrillation, vasopressors, or intermittent ventilation. The hemodynamic monitoring by USCOM has been compared with the NICOM monitoring, showing an excellent correlation not only in normal pregnant woman, but also in the group of hypertensive patients.30
Cardiac output monitoring based on changes in electrical resistance induced by vascular flow
Bioimpedance and bioreactance
Transthoracic bioimpedance was the first non-invasive method used to monitor cardiac output and has been used in various obstetric conditions, with the advantage of being independent of the operator. However, bioimpedance is inaccurate in intensive care units (ICUs) and other settings where significant electrical noise and body motion exist, thus, it is not widely used.
On the other hand, bioreactance is a user-friendly and straightforward non-invasive monitoring system, which has solved bioimpedance issues and is currently used to evaluate maternal hemodynamics, even in the outpatient setting.31 The use of bioreactance has gained considerable interest recently, and its use in the obstetric population is growing.
Bioreactance (Starling SV, former NICOM device, Cheetah Medical) uses four double electrode stickers placed around the thorax. A high-frequency current is passed between the four outer electrodes, and the resulting voltages are recorded between the four inner electrodes. The relative phase shift and rate of change of phase between these signals are determined and used in the calculations of stroke volume. The phase shift in the detected signal is proportional to the pulsatile blood flow in the thorax and is highly correlated with the volume of aortic blood.
The stroke volume is calculated with the following formula: stroke volume = d X/d t × VET, where d X/d t the maximum flow and VET the ventricular ejection time. The heart rate is obtained from an electrocardiography (ECG) signal detected from the electrodes, finally calculating the cardiac output by the formula: CO = stroke volume × heart rate.2,3
While echocardiography is a low-risk and non-invasive method of assessing CO and stroke volume, it requires expert training to acquire appropriate images and reading experience to estimate stroke volume and CO. In contrast, bioreactance requires minimum training to obtain these data; in addition, there are device-specific reference ranges for stroke volume, cardiac output and SVR for the NICOM device in healthy pregnancy.2,8 A recent study compared bioreactance and echocardiography in pregnant patients in three trimesters and found an adequate correlation only during the third trimester.32
Cardiac output monitoring based on non-invasive blood pressure monitoring
A large number of undetectable episodes of hypotension can only be recognized with continuous monitoring of arterial blood pressure, and non-invasive systems such as the continuous non-invasive arterial pressure (CNAP) can be used. This system is a non-invasive method for measuring the continuous blood pressure waveform. The patient’s blood pressure is recorded by the CNAP module using a double finger cuff with an integrated infrared (IR) light sensor and air chambers. This system allows continuous non-invasive monitoring of blood pressure with high reliability compared with an intra-arterial waveform analysis.33
The CNAP monitor includes an application for pregnant women, including patients with pre-eclampsia. However, in some instances the continuous measurement of blood pressure is not reliable and/or is not possible, e.g. reduced peripheral blood flow (shock, hypothermia) or presence of arterial vascular diseases (arteriosclerosis, Raynaud's syndrome, endarteritis obliterans, advanced vascular diseases), among others.34
CLINICAL CASE
A 22-year-old woman, with a 41-week pregnancy, without comorbidities, was admitted to the emergency department with cough and dyspnea; heart rate of 160/min, blood pressure of 140/90 mmHg, respiratory rate of 28/min and oxygen saturation of 79%. Thorax auscultation revealed bilateral crackles and wheezing, fetal heart rate was 141 bpm, arterial blood gases showed severe hypoxemia. Her oxygen saturation was <90% using a face mask with FiO2 of 80%. The patient was intubated and transferred to the intensive care unit and invasive ventilation initiated. She developed hypotension, and vasopressors were infused. A minimally invasive monitoring (FloTracä, Edward lifescience), was initiated with the findings in Table 3.
3
Case study – findings of minimally invasive monitoring
Variable | Reference range | Results |
Cardiac index | 3.0–5.0 l/min/m2 | CI 1.7 l/min/m2 |
Global end diastolic index | 680–800 ml/m2 | GEDI 950 ml/m2 |
Stroke volume variation | ≤13% | SVV 7% |
Pulse pressure variation | ≤13% | PPV 8% |
Systemic vascular resistance index | 1700–2400 dyn/s/cm5/m2 | SVRI 3770 dyn/s/cm5/m2 |
Extravascular lung water index | 3.0–7.0 ml/kg | ELWI 17.2 ml/kg |
Pulmonary vascular permeability index | 1.0–3.0% | PVPI 2.0% |
PRACTICE RECOMMENDATIONS
- Hemodynamic monitoring in pregnant women can be performed at three levels: clinical monitoring, biochemical monitoring, and hemodynamic monitoring.
- Traditionally, non-invasive hemodynamic monitoring systems are preferred in pregnant women, demonstrating adequate correlation with invasive monitoring systems such as pulmonary artery catheters.
- Non-invasive monitoring of cardiac output is potentially useful in the obstetric patient to define the most appropriate therapy: administration of fluids, giving a vasopressor medication or an inotropic drug.
- In the obstetric patient hemodynamic compromise can manifest as hypotension or hypertension.
- The leading causes of hemodynamic instability in pregnant women are postpartum hemorrhage, sepsis, and hypertensive disorders.
- Most minimally invasive monitoring systems are based on the analysis of the arterial blood pressure waveform, and others use calibration by transpulmonary thermodilution.
- Minimally invasive monitoring systems analyze preload, afterload, and contractility parameters, as well as valuable information on intrathoracic lung volumes and extravascular pulmonary water (EVLW).
- The transthoracic echocardiogram allows a rapid and reliable hemodynamic evaluation of the obstetric patient in critical condition. However, it requires expert training to obtain images and to estimate the systolic volume and cardiac output.
- Bioreactance requires minimal training to obtain systolic volume, cardiac output and systemic vascular resistance (SVR).
CONFLICTS OF INTEREST
The author(s) declare the receipt of grants from Sanofi and Baxter.
Feedback
Publishers’ note: We are constantly trying to update and enhance chapters in this Series. So if you have any constructive comments about this chapter please provide them to us by selecting the "Your Feedback" link in the left-hand column.
REFERENCES
Bijl RC, Valensise H, Novelli GP, et al. Methods and considerations concerning cardiac output measurement in pregnant women: recommendations of the International Working Group on Maternal Hemodynamics. Ultrasound Obstet Gynecol 2019;54(1):35–50. | |
Doherty A, El-Khuffash A, Monteith C, et al. Comparison of bioreactance and echocardiographic non-invasive cardiac output monitoring and myocardial function assessment in primagravida women. Br J Anaesth 2017;118(4):527–32. | |
Vincent JL, Ince C, Bakker J. Clinical review: Circulatory shock – an update: a tribute to Professor Max Harry Weil. Crit Care 2012;16(6):1–5. | |
Cecconi M, De Backer D, Antonelli M, et al. Consensus on circulatory shock and hemodynamic monitoring. Task force of the European Society of Intensive Care Medicine. Intensive Care Med 2014;40(12):1795–815. | |
Kolovetsiou-Kreiner V, Moertl MG, Papousek I, et al. Maternal cardiovascular and endothelial function from first trimester to postpartum. PLoS One 2018;13(5):1–13. | |
Sanghavi M, Rutherford JD. Cardiovascular physiology of pregnancy. Circulation 2014;130(12):1003–8. | |
Melchiorre K, Sharma R, Khalil A, et al. Maternal cardiovascular function in normal pregnancy: Evidence of maladaptation to chronic volume overload. Hypertension 2016;67(4):754–62. | |
Perry H, Stirrup O, Gutierrez J, et al. Influence of maternal characteristics and gestational age on hemodynamic indices: NICOM device‐specific reference ranges. Ultrasound Obstet Gynecol 2019. | |
Thilaganathan B, Kalafat E. Cardiovascular system in preeclampsia and beyond. Vol. 73, Hypertension. Lippincott Williams and Wilkins, 2019:522–31. | |
Perry H, Lehmann H, Mantovani E, et al. Correlation between central and uterine hemodynamics in hypertensive disorders of pregnancy. Ultrasound Obstet Gynecol 2019;54(1):58–63. | |
Valensise H, Tiralongo GM, Pisani I, et al. Maternal hemodynamics early in labor: a possible link with obstetric risk? Ultrasound Obstet Gynecol 2018;51(4):509–13. | |
Roberts L, Chaemsaithong P, Sahota DS, et al. Protocol for measurement of mean arterial pressure at 10–40 weeks’ gestation. Pregnancy Hypertens 2017;10:155–60. | |
Bello NA, Woolley JJ, Cleary KL, et al. Accuracy of blood pressure measurement devices in pregnancy: A systematic review of validation studies. Hypertension 2018;71(2):326–35. | |
Marik PE. Obituary-pulmonary artery catheter 1970 to 2013. Ann Intensive Care 2013;3(1):38. | |
Clark SL, Horenstein JM, Phelan JP, et al. Experience with the pulmonary artery catheter in obstetrics and gynecology. | |
Jozwiak M, Monnet X, Teboul JL. Less or more hemodynamic monitoring in critically ill patients. Vol. 24, Current Opinion in Critical Care. Lippincott Williams and Wilkins, 2018:309–15. | |
Poels EMP, Bijma HH, Galbally M, et al. Lithium during pregnancy and after delivery: a review. Vol. 6, International Journal of Bipolar Disorders. SpringerOpen, 2018. | |
Monnet X, Teboul JL. Transpulmonary thermodilution: Advantages and limits. Vol. 21, Critical Care. BioMed Central Ltd., 2017. | |
Xiao W, Duan Q, Zhao L, et al. Goal-directed Fluid Therapy May Improve Hemodynamic Stability of Parturient with Hypertensive Disorders of Pregnancy Under Combined Spinal Epidural Anesthesia for Cesarean Delivery and the Well-being of Newborns. J Obs Gynaecol Res 2015;41:1547–55. | |
Monnet X, Teboul JL. Minimally invasive monitoring. Vol. 31, Critical Care Clinics. W.B. Saunders, 2015:25–42. | |
Rokey R, Belfort MA SG. Quantitative echocardiographic assessmentof left ventricular function in critically ill obstetric patients- A comparative study. Am J Obs Gynecol 1995;173(4):1148–52. | |
Miller A, Mandeville J. Predicting and measuring fluid responsiveness with echocardiography. Vol. 3, Echo Research and Practice. BioScientifica Ltd., 2016:G1–12. | |
Bentzer P, Griesdale DE, Boyd J, et al. Will this hemodynamically unstable patient respond to a bolus of intravenous fluids? Vol. 316, JAMA – Journal of the American Medical Association. American Medical Association, 2016:1298–309. | |
Ambrozic J, Brzan Simenc G, Prokselj K, et al. Lung and cardiac ultrasound for hemodynamic monitoring of patients with severe pre-eclampsia. Ultrasound Obstet Gynecol 2017;49(1):104–9. | |
Burrage PS, Shernan SK, Tsen LC, et al. Emergent transesophageal echocardiography in hemodynamically unstable obstetric patients. Int J Obstet Anesth 2015;24(2):131–6. | |
Penny JA, Anthony J, Shennan AH, et al. A comparison of hemodynamic data derived by pulmonary artery flotation catheter and the esophageal Doppler monitor in preeclampsia. Am J Obstet Gynecol 2000;183(3):658–61. | |
Mercado P, Maizel J, Beyls C, et al. Transthoracic echocardiography: An accurate and precise method for estimating cardiac output in the critically ill patient. Crit Care 2017;21(1). | |
Ghossein-Doha C, Khalil A, Lees CC. Maternal hemodynamics: a 2017 update. Ultrasound in Obstetrics and Gynecology 2017;49(1):10–4. | |
Vinayagam D, Thilaganathan B, Stirrup O, et al. Maternal hemodynamics in normal pregnancy: reference ranges and role of maternal characteristics. Ultrasound Obstet Gynecol 2018;51(5):665–71. | |
Vinayagam D, Bowe S, Sheehan E, et al. Non-Invasive Haemodynamic Monitoring in Pregnancy: A Comparative Study Using Ultrasound and Bioreactance. Fetal Diagn Ther 2017;41(4):273–82. | |
Carvalho JCA, Ohashi Y, Ibrahim H, et al. Non-Invasive Hemodynamic Assessment of Non-pregnant, Healthy Pregnant and Preeclamptic Women using Bio-Reactance. | |
Vinayagam D, Patey O, Thilaganathan B, et al. Cardiac output assessment in pregnancy: comparison of two automated monitors with echocardiography. Ultrasound Obstet Gynecol 2017;49(1):32–8. | |
Stenglova A, Benes J. Continuous non-invasive arterial pressure assessment during surgery to improve outcome. Vol. 4, Frontiers in Medicine. Frontiers Media S.A., 2017. | |
Ilies C, Kiskalt H, Siedenhans D, et al. Detection of hypotension during Caesarean section with continuous non-invasive arterial pressure device or intermittent oscillometric arterial pressure measurement. Br J Anaesth 2012;109(3):413–9. |
Online Study Assessment Option
All readers who are qualified doctors or allied medical professionals can now automatically receive 2 Continuing Professional Development credits from FIGO plus a Study Completion Certificate from GLOWM for successfully answering 4 multiple choice questions (randomly selected) based on the study of this chapter.
Medical students can receive the Study Completion Certificate only.
(To find out more about FIGO’s Continuing Professional Development awards programme CLICK HERE)