Normal cardiopulmonary physiology during pregnancy

A Study of Fluid Intake, Hydration Status, and Body Composition of Pregnant Women in Their Third Trimester, and Relationships with Their Infant's Birth Weight in China: A Prospective Cohort Study

BACKGROUND

Water intake and hydration status may potentially influence maternal and child health. However, there is little research regarding this topic.

OBJECTIVES

This study aimed to investigate pregnant women's total fluid intake (TFI) levels, hydration status, and body composition and further explore their relationship with infant birth weight.

METHODS

A 7-day, 24 h fluid intake recorded was applied to determine participants' TFI levels. Morning urine samples were collected and tested to evaluate their hydration status. Maternal body compositions in their third trimester and infant birth weights were measured.

RESULTS

A total of 380 participants completed the study. The TFI was insufficient for pregnant women during their third trimester (median = 1574 mL), with only 12.1% of participants meeting the recommended adequate fluid intake level for pregnant women living in China (1.7 L per day). With the increasing TFI values, the urine osmolality decreased, which showed statistical significance among the four groups (χ2 = 22.637, p < 0.05). The participants displayed a poor hydration status. Meanwhile, the percentage of participants who were in dehydrated status decreased (χ2 = 67.618, p < 0.05), while body water content and basal metabolic rate increased with the increase in TFI levels (χ2 = 20.784, p < 0.05; χ2 = 14.026, p < 0.05). There were positive linear relationships between plain water intake, the basal metabolic rate of pregnant women and their infant birth weight (SE = 0.153, p < 0.05; SE = 0.076, p < 0.05).

CONCLUSIONS

Water intake was insufficient, and poor hydration status was common among pregnant women in China. There may be potential relationships between plain water intake, basal metabolic rate, and infant birth weight.

Pulmonary Arteriovenous Malformation Unmasked by Pregnancy: A Review of Pulmonary Arteriovenous Malformations and Cardiovascular and Respiratory Changes in Pregnancy

Pulmonary arteriovenous malformations are abnormal, direct communications between the branches of the pulmonary artery and pulmonary veins, but without pulmonary capillaries between them. During pregnancy, PAVMs can enlarge and become symptomatic, causing even serious complications like haematothorax. To recognize the PAVM that becomes symptomatic in pregnancy, one must be able to distinguish the patient’s symptoms caused by developing complications of PAVM, as in the case we present, from physiological changes accompanying a healthy pregnancy, including their degree in relation to the stage of pregnancy. The modified early obstetric warning score charts are a very helpful tool in the assessment of (ab)normal signs and symptoms in pregnant women, especially for physicians who rarely manage pregnant women.

Asthma in pregnancy

Background: Asthma is a frequent and potentially life-threatening disease that complicates many pregnancies. There are extensive data with regard to the diagnosis and treatment of asthma during pregnancy. Medical providers require an up-to-date summary of the critical aspects of asthma management during pregnancy. Objective: This review aimed to summarize the available data from clinical trials, cohort studies, expert opinions, and guideline recommendations with regard to asthma in pregnancy. Methods: A search through PubMed was conducted by using keywords previously mentioned and MeSH (Medical Subject Headings) terminology. Clinical trials, observational studies, expert opinions, guidelines, and other reviews were included. The quality of the studies was assessed, and data were extracted and summarized. Results: Asthma worsens in ∼40% of pregnant women, which can be associated with maternal and fetal complications. Physiologic changes in the respiratory, cardiovascular, and immune systems during pregnancy play a critical role in the manifestations of asthma. The diagnosis and the treatment of asthma are similar to that of patients who are not pregnant. Nonetheless, concern for fetal malformations, preterm birth, and low birth weight must be considered when managing pregnant patients with asthma. Importantly, cornerstones of the pharmacotherapy of asthma seem to be safe during pregnancy. Conclusion: Asthma in pregnancy is associated with adverse outcomes. Roadblocks to management include associated comorbidities, medication nonadherence, atopy, lack of education, and smoking habits. These need to be acknowledged and addressed for successful asthma management during pregnancy.

Pregnancy Considerations for Patients With Interstitial Lung Disease

Advances in our understanding of interstitial lung disease (ILD) pathophysiology and natural history have led to the development of guidelines for the diagnosis and management of several of these complex diseases. The demographics of patients with ILD indicate the disease is not restricted to older adults. Connective tissue disease-associated ILD, familial pulmonary fibrosis, and post-COVID-19 fibrosis may affect women of child-bearing age. Recent trials have excluded pregnant women, thereby limiting the applicability of contemporary therapeutic advances to these patients. This review synthesizes the current knowledge of pregnancy outcomes in those with ILD, with a focus on connective tissue disease-associated ILD, and potential treatment implications for patients with ILD who are pregnant or considering pregnancy. Pregnancy considerations for patients with ILD include the need for preconception counseling and planning to ensure disease stability, medication and vaccination optimization, and multidisciplinary involvement of a patient's pulmonologist, obstetrician, and, when indicated, rheumatologist and genetic counselor. Evidence to date suggests that women with ILD can have safe and healthy pregnancies but that complications may occur in those with severe ILD.

Acute Respiratory Distress Syndrome in Pregnancy

Acute respiratory distress syndrome (ARDS) is a clinical syndrome characterized by several clinical features and pathological responses involving the respiratory system primarily. Infections (viral), sepsis, and massive transfusion are the commonest causes of ARDS during pregnancy. The majority of them recover with noninvasive ventilatory (NIV) support. NIV is safe in pregnancy provided the center is experienced and has a protocolized patient care pathway. Parturients requiring invasive mechanical ventilation are best managed in experienced centers. PaO₂/FiO₂ targets are higher in parturients compared to nonpregnant patients. Permissive hypercapnia is not a safe option in pregnancy. In severe ARDS with refractory hypoxemia, prone ventilation is a safe option. However, it has to be done in experienced centers. Venovenous ECMO is a safe alternative option in pregnant women with refractory hypoxemia, and delivery has been prolonged to a safe viable age on ECMO. The decision to deliver and the mode of delivery have to be a multidisciplinary decision; primary criterion is maternal survival. Postdelivery, establishing maternal bonding while in ventilatory support facilitates early weaning and minimizes lactation failure.

Perinatal COVID-19 outcomes: evaluating the strength of current evidence

Purpose of the Study: Viral respiratory diseases, like those caused by novel strains of influenza and Coronaviridae, have historically disproportionately affected pregnant women and conferred increased risk of adverse perinatal outcomes. Initial reports published from Wuhan, China identified only limited symptoms in pregnant women and no cases of mortality, but more recent reports from other regions of the world have reported contrasting information. The purpose of the study was to evaluate initially published cases of SARS-CoV-2 infection in pregnant women in China and compare them to subsequently published studies from the remainder of the world. Materials and Methods: This review curates 199 maternal published cases of SARS-CoV-2 infection and COVID-19 initially reported in the literature from China and contrasts them to more recent literature reporting clinical findings and outcomes of 729 selected cases from the rest of the world, including the United States. Results: Overall, initial case reports and series from China reported no cases of maternal mortality, which contrasts with subsequent reports from other regions of the world demonstrating significant morbidity and mortality can and does occur in pregnant women infected with SARS-CoV-2. Conclusion: While initial reports suggest limited risks of infection in pregnancy with SARS-CoV-2, subsequent findings have demonstrated pregnant women are at risk for severe morbidity and mortality. Case studies and series that are imperative in the early stages of a pandemic to provide data on a novel pathogen cannot be used to provide generalizable information predicting group risks.

Anatomical and physiological alterations of pregnancy

The extensive metabolic demands of pregnancy require specific physiological and anatomical changes. These changes affect almost all organ systems, including the cardiovascular, respiratory, renal, gastrointestinal, and hematologic system. The placenta adds another layer of complexity. These changes make it challenging for clinicians to understand presenting signs and symptoms, or to interpret laboratory and radiological tests. Furthermore, these physiological alterations can affect the pharmacokinetics and pharmacodynamics of drugs. Drug safety in lactation is only supported by limited evidence. In addition, the teratogenic effects of medications are often extrapolated from animals, which further adds uncertainties. Unfortunately, pregnant women are only rarely included in clinical drug trials, while doses, regimens, and side effects are often extrapolated from studies conducted in non-pregnant populations. In this comprehensive review, we present the changes occurring in each system with its effects on the pharmacokinetic variables. Understanding these physiological changes throughout normal pregnancy helps clinicians to optimize the health of pregnant women and their fetuses. Furthermore, the information on pregnancy-related physiology is also critical to guide study design in this vulnerable 'orphan' population, and provides a framework to explore pregnancy-related pathophysiology such as pre-eclampsia.

Pregnancy-induced Cardiovascular Pathologies: Importance of Structural Components and Lipids

Pregnancy leads to adaptations for maternal and fetal energy needs. The cardiovascular system bears the brunt of the adaptations as the heart and vessels enable nutrient supply to maternal organs facilitated by the placenta to the fetus. The components of the cardiovascular system are critical in the balance between maternal homeostatic and fetus driven homeorhetic regulation. Since lipids intersect maternal cardiovascular function and fetal needs with growth and in stress, factors affecting lipid deposition and mobilization impact risk outcomes. Here, the cardiovascular components and functional derangements associated with cardiovascular pathology in pregnancy, vis-à-vis lipid deposition, mobilization and maternal and/or cardiac and fetal energy needs are detailed. Most reports on the components and associated pathology in pregnancy, are on derangements affecting the extracellular matrix and epicardial fat, followed by the endothelium, vascular smooth muscle, pericytes and myocytes. Targeted studies on all cardiovascular components and pathological outcomes in pregnancy will enhance targeted interventions.

Respiratory Diseases of Pregnancy

Pregnant patients can suffer from the same respiratory diseases as the general population in addition to unique syndromes of pregnancy (such as pre-eclampsia and tocolytic induced pulmonary edema, and pregnancy induced cardiomyopathy). Pregnancy by itself may add certain challenges such as difficult intubation. The critically ill pregnant patient requires a multidisciplinary approach and early inclusion of obstetrical expertise is paramount in managing these patients especially in the third trimester.

Pneumothorax: A Rare Entity During Pregnancy

Pneumothorax is a rarely seen condition during pregnancy, when changes in the respiratory physiology can sensitize the mother and fetus to the signs of hypoxia. Symptoms of pneumothorax, such as dyspnea, tachypnea, and chest pain, can also be attributed to pregnancy and complications with pregnancy and this can lead to misdiagnoses. The limitations in the use of diagnostic tests, such as chest X-ray and computed tomography, make treatment more difficult. Here, we report of two cases admitted to our hospital due to spontaneous pneumothorax during pregnancy. The diagnosis of pneumothorax was made based on a thorax ultrasonography in both patients, whereas a chest X-ray was used in the follow-up period, without the need for a thorax tomography. While one patient was treated via a tube thoracostomy, the other was treated via video-assisted thoracoscopic surgery.

Pulmonary Edema in Obstetrics: Essential Facts for Critical Care Nurses

Pulmonary edema is an acute pregnancy complication that, if uncorrected, can result in increased maternal and fetal morbidity and mortality. Although pulmonary edema is relatively rare in the general obstetrics population, pregnant patients are at increased risk for pulmonary edema because of the physiologic changes of pregnancy. The risk may be exacerbated by certain pregnancy-related diseases, such as preeclampsia. Prompt identification and appropriate clinical management of pulmonary complications is critical to prevent adverse outcomes in pregnant patients. This article reviews the collaborative treatment of pulmonary edema in pregnant women with complex critical illnesses.

Preventing shivering with adjuvant low dose intrathecal meperidine: A meta-analysis of randomized controlled trials with trial sequential analysis

The aim of this systematic review and meta-analysis is to evaluate the pros and cons of adjuvant low dose intrathecal meperidine for spinal anaesthesia. We searched electronic databases for randomized controlled trials using trial sequential analysis (TSA) to evaluate the incidence of reduced rescue analgesics, shivering, pruritus, nausea and vomiting when applying adjuvant intrathecal meperidine. Twenty-eight trials with 2216 patients were included. Adjuvant intrathecal meperidine, 0.05-0.5 mg kg-1, significantly reduced incidence of shivering (relative risk, RR, 0.31, 95% confidence interval, CI, 0.24 to 0.40; TSA-adjusted RR, 0.32, 95% CI, 0.25 to 0.41). Intrathecal meperidine also effectively reduced need for intraoperative rescue analgesics (RR, 0.27, 95% CI, 0.12 to 0.64; TSA-adjusted RR, 0.27, 95% CI, 0.08 to 0.91) and the incidence of pruritus was unaffected (RR, 2.31, 95% CI, 0.94 to 5.70; TSA-adjusted RR, 1.42, 95% CI, 0.87 to 2.34). However, nausea and vomiting increased (RR, 1.84, 95% CI, 1.29 to 2.64; TSA-adjusted RR, 1.72, 95% CI, 1.33 to 2.23; RR, 2.23, 95% CI, 1.23 to 4.02; TSA-adjusted RR,1.96, 95% CI, 1.20 to 3.21). Under TSA, these results provided a sufficient level of evidence. In conclusion, adjuvant low dose intrathecal meperidine effectively attenuates spinal anaesthesia-associated shivering and reduces rescue analgesics with residual concerns for the nausea and vomiting.

Síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) y embarazo

El embarazo es una condición temporal de la vida en la que ocurren importantes cambios en la fisiología de la mujer, los cuales se resuelven, en gran medida, después del parto. Hay cambios físicos, hormonales y psicológicos, con un aumento progresivo de peso. Estos factores pueden predisponer a un trastorno respiratorio del sueño o a exacerbar alguno ya existente. La literatura científica sugiere una mayor prevalencia de ronquido en las mujeres embarazadas. Las bases de datos demuestran que en menos del 1% de los embarazos aparece el código del diagnóstico de apnea de sueño. Se ha relacionado la presencia tanto de ronquido como de apnea durante el embarazo con algunos desenlaces adversos que se tratan en este artículo, el cual busca sensibilizar a los médicos para que consideren este diagnóstico durante el embarazo.

Hypercapnic respiratory failure during pregnancy due to polymyositis-related respiratory muscle weakness: a case report

Background

Polymyositis is a rare medical disorder complicating pregnancy. Ventilatory muscle weakness leading to respiratory failure is an uncommon manifestation of this autoimmune disease. We report a case of life-threatening hypercapnic respiratory failure due to polymyositis-related respiratory muscle weakness in a pregnant woman.

Case presentation

A 31-year-old, African woman in her second trimester of pregnancy presented to the emergency department with fever, shortness of breath and muscle weakness. Initial investigations excluded pulmonary infection, thromboembolism, and cardiac dysfunction as the underlying cause of her symptoms. She developed deterioration in her level of consciousness due to carbon dioxide narcosis requiring invasive mechanical ventilation. Further workup revealed markedly elevated serum creatine kinase, abnormal electromyography and edema of her thigh muscles on magnetic resonance imaging. Diagnosis of polymyositis was confirmed by muscle biopsy. After receiving pulse steroid, intravenous immunoglobulins, and maintenance immunosuppressive therapy, our patient’s respiratory muscle function improved and she was weaned off mechanical ventilation. Despite good maternal recovery from critical illness, the fetus developed intrauterine growth retardation and distress necessitating emergency cesarian section.

Conclusions

New-onset polymyositis during pregnancy presenting with respiratory failure is rare. Early diagnosis and prompt initiation of therapy is necessary to improve fetal and maternal outcomes.

Defining a Reference Range for Vital Signs in Healthy Term Pregnant Women Undergoing Caesarean Section

Early warning systems (EWS), used to identify deteriorating hospitalised patients, are based on measurement of vital signs. When the patients are pregnant, most EWS still use non-pregnant reference ranges of vital signs to determine trigger thresholds. There are no published reference ranges for all vital signs in pregnancy. We aimed to define vital signs reference ranges for term pregnancy in the preoperative period, and to determine the appropriateness of EWS trigger criteria in pregnancy. We conducted a one-year retrospective study in a tertiary referral obstetric hospital. The study sample was healthy term women undergoing planned caesarean section (CS). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), oxygen saturation (SpO2) and temperature were all measured automatically and data was extracted from the medical record. Two hundred and fifty-eight women met inclusion criteria. Results were (mean ± SD [standard deviation]) SBP 118 ± 11.2 mmHg, DBP 75 ± 10.3 mmHg, HR 84 ± 10.2 /minute, respiratory rate 18 ± 1.5 /minute, SpO2 99% ± 1.0% and temperature 36.4°C ± 0.43°C. The reference ranges (mean ± 2SD) determined were SBP 96–140 mmHg, DBP 54–96 mmHg, HR 64-104 /minute, RR 15–21 /minute, SpO2 97%–100% and temperature 35.5°C–37.3°C. This study defined a reference range for vital signs in healthy term pregnant women undergoing CS. Study findings suggest that currently used criteria for EWS triggers, based on non-pregnant values, may be too extreme for timely detection of deteriorating pregnant patients. Further research examining the modified HR triggers of ≤50 and ≥110 /minute in pregnant women and their relationship to clinical outcomes is required.

Acute respiratory failure and mechanical ventilation in pregnant patient: A narrative review of literature

Physiological changes of pregnancy imposes higher risk of acute respiratory failure (ARF) with even a slight insult and remains an important cause of maternal and fetal morbidity and mortality. Although pregnant women have different respiratory physiology and different causes of ARF, guidelines specific to ventilatory settings, goals of oxygenation and weaning process could not be framed due to lack of large-scale randomized controlled trials. During the 2009 H1N1 pandemic, pregnant women had higher morbidity and mortality compared to nonpregnant women. During this period, alternative strategies of ventilation such as high-frequency oscillatory ventilation, inhalational of nitric oxide, prone positioning, and extra corporeal membrane oxygenation were increasingly used as a desperate measure to rescue pregnant patients with severe hypoxemia who were not improving with conventional mechanical ventilation. This article highlights the causes of ARF and recent advances in invasive, noninvasive and alternative strategies of ventilation used during pregnancy.

Orthostetrics: Management of Orthopedic Conditions in the Pregnant Patient

Managing orthopedic conditions in pregnant patients leads to challenges that must be carefully considered so that the safety of both the mother and the fetus is maintained. Both perioperative and intraoperative considerations must be made based on physiologic changes during pregnancy, risks of radiation, and recommendations for monitoring. Operative timing, imaging, and medication selection are also factors that may vary based on trimester and clinical scenario. Pregnancy introduces unique parameters that can result in undesirable outcomes for both mother and fetus if not handled appropriately. Ultimately, pregnant patients offer a distinct challenge to the orthopedic surgeon in that the well-being of 2 patients must be considered in all aspects of care. In addition, not only does pregnancy affect the management of orthopedic conditions but the pregnant state also causes physiologic changes that may actually induce various pathologies. These pregnancy-related orthopedic conditions can interfere with an otherwise healthy pregnancy and should be recognized as possible complications. Although the management of orthopedic conditions in pregnancy is often conservative, pregnancy does not necessarily preclude safely treating pathologies operatively. When surgery is considered, regional anesthesia provides less overall drug exposure to the fetus and less variability in fetal heart rate. Intraoperative fluoroscopy can be used when appropriate, with 360° fetal shielding if possible. Lateral decubitus positioning is ideal to prevent hypotension associated with compression of the inferior vena cava.

Thoracostomy tubes: A comprehensive review of complications and related topics

Tube thoracostomy (TT) placement belongs among the most commonly performed procedures. Despite many benefits of TT drainage, potential for significant morbidity and mortality exists. Abdominal or thoracic injury, fistula formation and vascular trauma are among the most serious, but more common complications such as recurrent pneumothorax, insertion site infection and nonfunctioning or malpositioned TT also represent a significant source of morbidity and treatment cost. Awareness of potential complications and familiarity with associated preventive, diagnostic and treatment strategies are fundamental to satisfactory patient outcomes. This review focuses on chest tube complications and related topics, with emphasis on prevention and problem-oriented approaches to diagnosis and treatment. The authors hope that this manuscript will serve as a valuable foundation for those who wish to become adept at the management of chest tubes.

Alterations in physiology and anatomy during pregnancy

Pregnant women undergo profound anatomical and physiological changes so that they can cope with the increased physical and metabolic demands of their pregnancies. The cardiovascular, respiratory, haematological, renal, gastrointestinal and endocrine systems all undergo important physiological alterations and adaptations needed to allow development of the fetus and to allow the mother and fetus to survive the demands of childbirth. Such alterations in anatomy and physiology may cause difficulties in interpreting signs, symptoms, and biochemical investigations, making the clinical assessment of a pregnant woman inevitably confusing but challenging. Understanding these changes is important for every practicing obstetrician, as the pathological deviations from the normal physiological alterations may not be clear-cut until an adverse outcome has resulted. Only with a sound knowledge of the physiology and anatomy changes can the care of an obstetric parturient be safely optimized for a better maternal and fetal outcome.

Influenza infection during pregnancy: virology, pathogenesis and clinical challenges

Seasonal influenza infections are an important cause of morbidity and mortality worldwide. Pregnant and postpartum women are at increased risk of complications from influenza infection, partly due to the altered physiologic and immunologic parameters of pregnancy. While most influenza infections in pregnant women will take a mild, self-limited course, a minority of susceptible pregnant women suffer a severe life-threatening respiratory illness. The morbidity of influenza infection during pregnancy is compounded by the potential for adverse obstetric outcomes as well as the potential for detrimental fetal and neonatal effects. Suspected or confirmed influenza infection in a pregnant woman warrants treatment with antiviral medications. Influenza vaccination is the most effective way to prevent influenza infection during pregnancy and is recommended for women who are or will be pregnant during influenza season.

Maternal valvular heart disease in pregnancy

Valvular heart disease is common in pregnancy. Maternal physiology changes significantly during gestation with substantial increases in cardiac output and blood volume; this can cause unmasking or worsening of cardiac disease. Acquired valvular lesions most frequently arise from rheumatic fever, especially in patients who have emigrated from developing nations. Congenital lesions are also encountered. The most common conditions seen, mitral stenosis and regurgitation and aortic stenosis and regurgitation, each require a specific evaluation and management and are associated with their own set of possible complications. Patients with prosthetic valves require anticoagulation, and maternal and fetal risks and benefits must be carefully weighed. Patients with heart disease should be meticulously managed preconceptionally up to the postpartum period by maternal-fetal medicine specialists, obstetricians, cardiologists, and anesthesiologists using a multi-disciplinary approach to their cardiac conditions.

TARGET AUDIENCE

Obstetricians & Gynecologists and Family Physicians.

LEARNING OBJECTIVES

After the completing the CME activity, physicians should be better able to examine the epidemiology of valvular heart disease in pregnancy, categorize key physiologic parameters that change in the cardiovascular system during pregnancy, classify the pathophysiology of valvular lesions, and evaluate the general principles of maternal and fetal management for cardiac disease.

Ibuprofen-related renal tubular acidosis in pregnancy

Ibuprofen-related renal tubular acidosis (RTA) has not been previously described in pregnancy but its occurrence outside of pregnancy is being increasingly described. In this case, a 34-year-old woman presented in the third trimester of pregnancy with Type 1 or distal RTA related to ibuprofen and codeine abuse. It was complicated by acute on chronic renal dysfunction and hypokalemia. Delivery at 37 weeks gestation due to concerns of evolving preeclampsia resulted in the birth of a healthy neonate. RTA and hypokalemia were remediated and ibuprofen and codeine abuse ceased. Some renal dysfunction however continued. Thorough and repeated history taking as well as vigilance for this condition is suggested.

The management of the critically ill obstetric patient

Hypertensive disorders, postpartum hemorrhage, and sepsis are the most common indications for intensive care unit admission among obstetric patients. In general, ICU mortality is low, and better than would be predicted using available mortality prediction tools. Provision of care to this special population requires an intimate understanding of physiologic changes that occur during pregnancy. Clinicians must be aware of the way various diagnostic and treatment choices can affect the mother and fetus. Most clinically necessary radiographic tests can be safely performed and fall under the maternal radiation exposure limit of less than 0.05 Gray (Gy). Careful attention must be paid to acid-base status, oxygenation, and ventilation when faced with respiratory failure necessitating intubation. Cesarean delivery can be justified after 4 minutes of cardiac arrest and may improve fetal and maternal outcomes. The treatment of obstetric patients in the ICU introduces complexities and challenges that may be unfamiliar to many critical care physicians; teamwork and communication with obstetricians is crucial.

Pulmonary complications in pregnancy: considerations for care

Anatomic and physiologic changes of pregnancy predispose the mother to increased morbidity and mortality whereas increasing risks of a less than optimal outcome for the fetus. The frequency and significance of acute and chronic respiratory conditions in pregnant women have increased in recent years. Clinicians must have an understanding of cardiopulmonary physiology to promptly recognize and treat pregnant women with respiratory conditions ranging from asthma to adult respiratory distress syndrome. Hospitals must establish systems to assure timely assessment, multidisciplinary care, and possibly a plan for transfer to a higher level of care to provide highest quality care to the perinatal patient presenting with a severe respiratory condition to promote optimal outcomes for the woman and the fetus.

Respiratory failure in pregnant women infected by Swine-Origin influenza A (H1N1)

Two pregnant women developed acute respiratory distress syndrome from Swine-Origin influenza A (H1H1) virus. They were put on mechanical ventilation. We discussed the issues that face obstetricians and intensive care physicians in such situations.

The 2010 Canadian Cardiovascular Society guidelines for the diagnosis and management of heart failure update: Heart failure in ethnic minority populations, heart failure and pregnancy, disease management, and quality improvement/assurance programs

Since 2006, the Canadian Cardiovascular Society heart failure (HF) guidelines have published annual focused updates for cardiovascular care providers. The 2010 Canadian Cardiovascular Society HF guidelines update focuses on an increasing issue in the western world - HF in ethnic minorities - and in an uncommon but important setting - the pregnant patient. Additionally, due to increasing attention recently given to the assessment of how care is delivered and measured, two critically important topics - disease management programs in HF and quality assurance - have been included. Both of these topics were written from a clinical perspective. It is hoped that the present update will become a useful tool for health care providers and planners in the ongoing evolution of care for HF patients in Canada.

Sleep disorders in pregnancy

Sleep complaints are a common occurrence in pregnancy that are in part due to pregnancy-associated anatomic and physiological changes but may also be due to pathological causes. In the non-pregnant population, sleep deprivation has been associated with physical and cognitive issues; poor sleep may even be associated with adverse maternal outcomes. Maternal obesity, one of the most prevalent risk factors in obstetric practices, together with physiologic changes of pregnancy predispose to the development of sleep disordered breathing. Symptoms of sleep disordered breathing have also been associated with poor maternal outcomes. Management options of restless legs syndrome and narcolepsy pose a challenge in pregnancy; benefits of therapy need to be weighed against the potential harm to the fetus. This article briefly reviews the normal changes in pregnancy affecting sleep, gives an overview of certain sleep disorders occurring in pregnancy, and suggests management options specific for this population.

Pre-oxygenation and apnoea in pregnancy: changes during labour and with obstetric morbidity in a computational simulation

Using the Nottingham Physiology Simulator, we investigated the effects on pre-oxygenation and apnoea during rapid sequence induction of labour, obesity, sepsis, pre-eclampsia, maternal haemorrhage and multiple pregnancy in term pregnancy. Pre-oxygenation with 100% oxygen was followed by simulated rapid sequence induction when end-tidal nitrogen tension was less than 1 kPa, and apnoea. Labour, morbid obesity and sepsis accelerated pre-oxygenation and de-oxygenation during apnoea. Fastest pre-oxygenation was in labour, with 95% of the maximum change in expired oxygen tension occurring in 47 s, compared to 97 s in a standard pregnant subject. The labouring subject with a body mass index of 50 kg x m(-2) demonstrated the fastest desaturation, the time taken to fall to an arterial saturation < 90% being 98 s, compared to 292 s in a standard pregnant subject. Pre-eclampsia prolonged pre-oxygenation and tolerance to apnoea. Maternal haemorrhage and multiple pregnancy had minor effects. Our results inform the risk-benefit comparison of the anaesthetic options for Caesarean section.

Physiologic changes in pregnancy

Pregnancy is associated with physiologic changes that affect virtually every organ system in the mother. These physiologic changes allow the parturient to support the growing uterus and fetus and to withstand labor and the postpartum course. Because the gravida may require surgery while pregnant, it is important to have an appreciation of these physiologic changes. These maternal adaptive responses have significant implications for anesthetic, operative, and perioperative management.

Chemical and mechanical adaptations of the respiratory system at rest and during exercise in human pregnancy

Human pregnancy is characterized by significant increases in ventilatory drive both at rest and during exercise. The increased ventilation and attendant hypocapnia of pregnancy has been attributed primarily to the stimulatory effects of female sex hormones (progesterone and estrogen) on central and peripheral chemoreflex drives to breathe. However, recent research from our laboratory suggests that hormone-mediated increases in neural (or non-chemoreflex) drives to breathe may contribute importantly to the hyperventilation of pregnancy. This review challenges traditional views of ventilatory control, and outlines an alternative hypothesis of the control of breathing during human pregnancy that is currently being tested in our laboratory. Conventional wisdom suggests that pregnancy-induced increases in central respiratory motor output command in combination with progressive thoraco–abdominal distortion may compromise the normal mechanical response of the respiratory system to exercise, increase the perception of exertional breathlessness, and curtail aerobic exercise performance in otherwise healthy pregnant women. The majority of available evidence suggests, however, that neither pregnancy nor advancing gestation are associated with reduced aerobic working capacity or increased breathlessness at any given work rate or ventilation during exhaustive weight-supported exercise.

Effects of human pregnancy and advancing gestation on respiratory discomfort during exercise

This study examined the effects of human pregnancy and advancing gestation on the intensity of respiratory discomfort (dyspnea) during cycle exercise. Fourteen pregnant women (PG) performed a progressive cycle ergometer exercise test involving 20 W/min increases in work rate to symptom limitation and/or a heart rate of 170-175 beats/min at 19.7+/-1.2 weeks (ENTRY), 28.2+/-0.3 weeks (TM2) and 36.3+/-0.3 weeks (TM3) gestation. Eight, age-matched, sedentary non-pregnant women (CG) were also studied for comparison purposes. Measurements included dyspnea intensity (Borg scale), minute ventilation (VE), breathing pattern and other cardiorespiratory parameters. At peak exercise, neither pregnancy nor advancing gestation had an effect on dyspnea, VE, breathing pattern, oxygen uptake or work rate (p>0.05). VE was significantly greater (by 11 L/min at 100 W) in the PG at TM3 versus CG (p<0.05) at all submaximal work rates. VE also increased progressively from ENTRY to TM2 and TM3 during submaximal exercise. Dyspnea was not significantly different at any submaximal work rate in the PG at TM3 versus CG or with advancing gestation in the PG. In addition, dyspnea at a standardized exercise VE of 40 L/min was not different at TM3 versus ENTRY or in the PG at TM3 versus CG. Neither pregnancy nor advancing gestation were associated with increased respiratory discomfort during strenuous non-weight bearing cycle ergometer exercise, despite substantial increases in VE and progressive mechanical adaptations of the respiratory system to accommodate the increasing size of the gravid uterus.

Pneumonia during pregnancy

BACKGROUND

We determined the incidence, clinical course, risk factors, and outcomes of community-acquired pneumonia complicating pregnancy.

METHODS

A prospective study was performed of pregnant and nonpregnant patients in the same age range who presented to any of 6 hospitals in Edmonton, Alberta, with signs and symptoms of pneumonia together with an acute infiltrate evident on chest radiography compatible with pneumonia.

RESULTS

There were 28 patients with pneumonia during pregnancy, for an incidence of 1.1 per 1000 deliveries, whereas there were 333 nonpregnant females in the 20- to 40-year age group with pneumonia, for an incidence of 1.3 per 1000. No significant differences in signs and symptoms were present between the two groups. Asthma requiring treatment was present in 46.4% of the pregnant patients, compared with 17.1% of the nonpregnant patients. No maternal or fetal deaths were noted except an abortion at 10 weeks of gestation. No anomaly was detected among newborns. Two patients had preterm deliveries.

CONCLUSIONS

Pneumonia is well tolerated during pregnancy. Asthma may be a predisposing factor for pneumonia in this group of patients.

Clinical heart failure during pregnancy and delivery in a cohort of female childhood cancer survivors treated with anthracyclines

The cumulative incidence of peripartum anthracycline-induced clinical heart failure (A-CHF) was evaluated in a cohort of 53 childhood cancer survivors who had delivered one or more children. None of them developed peripartum A-CHF (cumulative incidence 0%; 95% confidence interval (CI) 0-5.7%). The mean follow-up time after the first administration of anthracycline therapy was 20.3 years. They received a mean cumulative anthracycline dose of 267 mg/m2. It is worth noticing that even 2 patients with A-CHF before pregnancy did not develop peripartum A-CHF. Since there were no cases of peripartum A-CHF in our cohort, it was not possible to evaluate associated risk factors. In conclusion, this study demonstrates a low risk of developing peripartum A-CHF in childhood cancer survivors. However, more cohort studies with adequate power and long-term follow-up are needed to reliably evaluate the cumulative incidence of peripartum anthracycline-induced cardiotoxicity (both clinical and asymptomatic) and associated risk factors.

Smallpox during pregnancy and maternal outcomes

A historical study evaluated maternal outcomes in pregnancy complicated by smallpox. The overall case fatality was estimated to be 34.3% (95% confidence interval [CI] 31.4–37.1), and the proportion of miscarriage or premature birth was estimated to be 39.9% (95% CI 36.5–43.2). Vaccination before pregnancy reduced the risk for death.

Caring for pregnant and postnatal women in intensive care: what do we know?

Critically ill pregnant and postnatal women admitted to intensive care units (ICUs) require highly specialised care, components of which many critical care nurses are unfamiliar with. There are no specialist critical care obstetric centres in Australia, with critically ill obstetric patients admitted to general ICUs. There are no published guidelines and little research that assist critical care nurses to care for such women. Furthermore, the admission of pregnant or postnatal women to ICUs is likely to increase with emerging childbearing patterns in Australia. It is therefore timely to review what we know about caring for critically ill pregnant and postnatal women. This paper analyses the literature on intensive care utilisation by obstetric patients and provides an overview regarding which pregnant and postpartum women require intensive care. The key areas of providing mechanical ventilation to pregnant women and assessment of fetal wellbeing are explored in detail. The most frequent conditions and their treatment, preeclampsia and obstetric haemorrhage, are also reviewed. The establishment of lactation is also considered as the critical carenurse is commonly involved in supporting the woman's endeavour to breastfeed.

Maternal physiology and complications of multiple pregnancy

Approximately 1% to 3% of all pregnancies in the United States are multiple gestations. The vast majority (97-98%) are twin pregnancies. Multiple pregnancies constitute significant risk to both mother and fetuses. Antepartum complications-including preterm labor, preterm premature rupture of the membranes, intrauterine growth restriction, intrauterine fetal demise, gestational diabetes, and preeclampsia-develop in over 80% of multiple pregnancies as compared with approximately 25% of singleton gestations. This article reviews in detail the maternal physiologic adaptations required to support a multiple pregnancy and the maternal complications that develop when these systems fail or are overwhelmed.

Effects of human pregnancy and aerobic conditioning on alveolar gas exchange during exercise

This study examined the effects of aerobic conditioning during the second and third trimesters of human pregnancy on ventilatory responses to graded cycling. Previously sedentary pregnant women were assigned randomly to an exercise group (n = 14) or a nonexercising control group (n = 14). Data were collected at 15–17 weeks, 25–27 weeks and 34–36 weeks of pregnancy. Testing involved 20 W·min–1 increases in work rate to a heart rate of 170 beats·min–1 and (or) volitional fatigue. Breath-by-breath ventilatory and alveolar gas exchange measurements were compared at rest, a standard submaximal [Formula: see text]O2 and peak exercise. Within both groups, resting [Formula: see text]E, [Formula: see text]A, and VT/TI increased significantly with advancing gestation. Peak work rate, O2 pulse [Formula: see text]O2/HR, [Formula: see text]E, [Formula: see text]A respiratory rate, VT/TI, [Formula: see text]O2, [Formula: see text]CO2, and the ventilatory threshold (Tvent) were increased after physical conditioning. Chronic maternal exercise has no significant effect on pregnancy-induced changes in ventilation and (or) alveolar gas exchange at rest or during standard submaximal exercise. Training-induced increases in Tvent and peak oxygen pulse support the efficacy of prenatal fitness programs to improve maternal work capacity. Key words: human gestation, respiration, chronic exercise.