RESPIRATORY PHYSIOLOGIC CHANGES IN PREGNANCY

Interaction of the pre- and postnatal environment in the maternal immune activation model

Adverse influences during pregnancy are associated with a range of unfavorable outcomes for the developing offspring. Maternal psychosocial stress, exposure to infections and nutritional imbalances are known risk factors for neurodevelopmental derangements and according psychiatric and neurological manifestations later in offspring life. In this context, the maternal immune activation (MIA) model has been extensively used in preclinical research to study how stimulation of the maternal immune system during gestation derails the tightly coordinated sequence of fetal neurodevelopment. The ensuing consequence of MIA for offspring brain structure and function are majorly manifested in behavioral and cognitive abnormalities, phenotypically presenting during the periods of adolescence and adulthood. These observations have been interpreted within the framework of the "double-hit-hypothesis" suggesting that an elevated risk for neurodevelopmental disorders results from an individual being subjected to two adverse environmental influences at distinct periods of life, jointly leading to the emergence of pathology. The early postnatal period, during which the caregiving parent is the major determinant of the newborn´s environment, constitutes a window of vulnerability to external stimuli. Considering that MIA not only affects the developing fetus, but also impinges on the mother´s brain, which is in a state of heightened malleability during pregnancy, the impact of MIA on maternal brain function and behavior postpartum may importantly contribute to the detrimental consequences for her progeny. Here we review current information on the interaction between the prenatal and postnatal maternal environments in the modulation of offspring development and their relevance for the pathophysiology of the MIA model.

Spirometry profiles among pregnant and non-pregnant African women: a cross-sectional study

BACKGROUND

Spirometry is a commonly used lung function test. It assesses respiratory functions by measuring the air volume and the rate at which a person can exhale from lungs filled to their total capacity. The most helpful spirometry parameters are: forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF). Pregnancy derives an altered physiological state due to hormonal and anatomical changes that affect the respiratory system. Despite that, spirometry is less commonly done during pregnancy, and if done, test results are evaluated against non-pregnancy references.

OBJECTIVE

This study aimed to explore spirometry profiles in pregnant and non-pregnant women and describe their differences.

METHODOLOGY

This cross-sectional study involved age-matched pregnant and non-pregnant participants recruited from Mnazi Moja ANC and Muhimbili University (MUHAS). A digital spirometer was used to assess respiratory function. Data were entered and analyzed using SPSS version 23. The mean spirometry values of pregnant participants were compared to those of non-pregnant participants using an independent sample t-test. A p-value of < 0.05 was considered statistically significant.

RESULTS

The study included 92 pregnant and 98 non-pregnant participants subjected to spirometry. Both FVC and FEV1 values were significantly lower in pregnant than in non-pregnant participants (2.7 ± 0.5 L vs. 2.9 ± 0.5 L; p < 0.01 and 2.2 ± 0.4 L vs. 2.5 ± 0.4 L; p < 0.01 respectively). In addition, pregnant participants had significantly lower mean PEF values than their non-pregnant counterparts (303 ± 84 L/min versus 353 ± 64 L/min; p < 0.01).

CONCLUSION

Spirometry test values are lower in pregnancy than in non-pregnant participants.

RECOMMENDATIONS

Interpreting the spirometry test values of pregnant women using references obtained from non-pregnant women may be inappropriate. Future studies should evaluate the appropriateness of predicting spirometry values of pregnant women using reference equations derived from non-pregnant women.

The effectiveness of non-pharmacological healthcare interventions for asthma management during pregnancy: a systematic review

BACKGROUND

While reviews have been published on asthma management in pregnant women, none has examined the effectiveness of non-pharmacological healthcare interventions for optimizing asthma management in pregnant women. This systematic review aims to identify non-pharmacological healthcare interventions for optimizing asthma management during pregnancy and to examine their effects on maternal asthma control and neonatal outcomes.

METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, EMBASE, PsycINFO, CINAHL Plus and International Pharmaceutical Abstracts (IPA) were searched. Two reviewers independently assessed the identified studies against the eligibility criteria and extracted relevant information. The effects of the intervention were assessed qualitatively.

RESULTS

Nine studies were identified, of which six were rejected according to the exclusion criteria. The three studies included in the final review described an education program, progressive muscle relaxation (PMR) and Fraction of exhaled Nitric Oxide (FeNO) guided management of asthma in pregnant women. The PMR and FeNO-guided interventions showed significant improvements in maternal asthma control (lung function and quality of life) and neonatal outcomes (birth weight).

CONCLUSIONS

Further evidence from well-designed studies evaluating non-pharmacological healthcare interventions for optimizing asthma management in pregnant women is required.

Management of asthma during pregnancy

The prevalence of asthma in pregnant women appears to be increasing. Recent evidence demonstrates that pregnant asthmatic women with moderate-to-severe asthma may have an increased risk of adverse perinatal outcomes. The goal of asthma management during pregnancy is to optimize maternal and fetal health.

Quality of care of asthma during pregnancy

The goal of asthma management during pregnancy is to keep the mother symptom free and to prevent complications in the fetus. Asthma is a common chronic condition in pregnancy that, if inadequately treated, has the potential to cause adverse effects for both mother and fetus. Aggressive treatment during pregnancy can decrease costs associated with asthma now and additional costs later if the fetus has a poor outcome due to maternal asthma. A stepwise approach to the management of asthma during pregnancy has been developed and is not unlike the management of the nonpregnant patient. Although there are no double-blind, placebo-controlled studies on asthma medications in pregnant women, large cohort studies have shown the efficacy of aggressive management. With adequate control of asthma from the preconception time through delivery, studies have shown similar outcomes in asthmatic patients compared with nonasthmatics, thus obtaining the goal of a symptom-free mother and a healthy baby.

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.

Respiratory physiologic changes in pregnancy

In summary, the major physiologic changes that occur in pregnancy are the increased minute ventilation, which is caused by increased respiratory center sensitivity and drive; a compensated respiratory alkalosis; and a low expiratory reserve volume. The vital capacity and measures of forced expiration are well preserved. Patients who have many lung diseases tolerate pregnancy well, with the exception of those who have pulmonary hypertension or chronic respiratory insufficiency from parenchymal or neuromuscular disease.

The effects of rhinitis, asthma, and acute respiratory distress syndrome as acute or chronic pulmonary conditions during pregnancy

Pulmonary complications from both obstetrical and non-obstetrical causes contribute to a mortality rate as high as 80% in the pregnant population. The effect of numerous mechanical and biochemical physiologic alterations during pregnancy can influence the maternal and fetal outcomes in a woman with a pulmonary complication. Progesterone, the primary hormone of pregnancy, is a respiratory stimulant that enhances carbon dioxide release and alters the maternal pH in favor of releasing oxygen to the fetus. During systemic compromise, which may be experienced as an acute asthmatic attack or respiratory distress syndrome, desaturation and carbon dioxide retention ensue. Under these conditions, the fetus is at risk for perinatal hypoxemia. Although prompt recognition and treatment are important to minimize maternal, fetal, and neonatal morbidity and mortality, evidence-based literature regarding critical care techniques that promote optimal obstetrical outcomes is limited. Therefore, a collaborative approach to the care of these women is warranted. In addition to critical care, emergency medicine, and obstetrical nurses, the medical team may include an obstetrician, a perinatologist, a neonatologist, a pulmonologist, an intensivist, and an immunologist.

Acute pulmonary edema in pregnancy

Pulmonary edema is a secondary disease process characterized by an excess accumulation of fluid in the pulmonary interstitial and alveolar spaces, preventing adequate diffusion of both oxygen and carbon dioxide. The excess fluid accumulation interferes with maternal oxygenation and, if not identified and corrected, can lead to maternal and fetal hypoxemia. The purpose of this article is to review principles of oxygen transport and the pathophysiology, diagnosis, management, and nursing implications of acute pulmonary edema in pregnancy.

Managing asthma during pregnancy. The whys and hows of aggressive control

Asthma occurs in about 4% of pregnancies and can worsen during pregnancy. Aggressive treatment is needed because failure to control asthma during pregnancy can lead to poor outcomes for both mother and child. At the same time, the risk-benefit profile of various asthma medications should be considered to avoid any adverse effects. In this article, Dr Blaiss discusses the foundations for management of asthma during pregnancy: environmental control, pharmacotherapy, and allergen immunotherapy.

Management of rhinitis and asthma in pregnancy

OBJECTIVES

To objectively critique recent available data on the proper management of allergy and asthma during pregnancy, with an emphasis on understanding the risk and benefit of medications used during pregnancy for these disorders.

DATA SOURCES

Data for this article were obtained from a MEDLINE search of literature from 1975 until the present published in English.

STUDY SELECTION

It was the expert opinion of the author to select and synthesize recently published articles and reviews on this broad subject.

RESULTS

Asthma is estimated to affect up to 4% of pregnancies, whereas rhinitis complicates up to 20%. The cornerstones of management are environmental avoidance procedures, pharmacologic treatment, and allergen immunotherapy. Pharmaceutical treatment for allergic rhinitis should start with the first-generation antihistamines, chlorpheniramine and tripelennamine. In pregnant women, who cannot tolerate first-generation antihistamines, use of a second-generation agent, either loratadine or cetirizine, should be considered. Though data are lacking, intranasal corticosteroids appear to be safe during pregnancy. For pregnant women with persistent asthma, the use of inhaled cromolyn should be the first-line therapy, followed by inhaled budesonide if symptoms worsen. Other agents such as salmeterol, leukotriene modifiers, and newer inhaled corticosteroids may be considered in women who exhibited a good response to these agents before pregnancy. Immunotherapy is the only disease-modifying treatment for allergic rhinitis and asthma. It can be continued during pregnancy.

CONCLUSIONS

Understanding the important differences in treatment for the pregnant patient is vital for all physicians caring for these patients. Proper medical management needs to take into consideration possible adverse effects of different agents used in asthma and rhinitis.