Airway management and difficult endotracheal intubation in the pregnant woman require unique considerations that differ from other patient populations. While most pregnant women deliver without the need for airway management, difficulty with endotracheal intubation remains a source of maternal morbidity, maternal mortality and concern for obstetric anaesthesiologists.

Infections of the respiratory tract are a common cause of maternal morbidity. Physiological and immunological changes that occur in pregnancy may contribute to a higher incidence, morbidity and mortality than that observed in the general population. Diagnostic and management strategies for pulmonary infections are broadly similar in pregnant women as in non-pregnant women. Concerns regarding the safety of antimicrobial agents during pregnancy may modify treatment considerations.

Respiratory failure is an uncommon complication of pregnancy, affecting only 0.1% of pregnant women; however, it is one of the main indications for intensive care unit (ICU) admission of pregnant and peri-partum women. Pregnancy is a unique physiologic state in women’s lives, and physicians should be familiar with it. Given the low incidence of respiratory failure during pregnancy, there is limited scientific evidence about the best strategies for this population.

The proportion of the world’s population that is obese has tripled over the last 40 years, according to data from the World Health Organization. Women are more likely to be obese than their age- and country-matched male counterparts; women of reproductive age are no exception. Sleep-disordered breathing (SDB), a spectrum of conditions that range in increasing severity from loud snoring to obstructive sleep apnoea (OSA), is often co-morbid with obesity; in studies, 15–20% of obese pregnant women have OSA and the prevalence of OSA increases with age, BMI and in the presence of other co-morbidities.

Respiratory physiology involves a number of areas, all of which are complex. These areas include the structure and function of the lung, the mechanics of breathing, gas exchange within the lung, oxygen uptake/transport and delivery, control of carbon dioxide and ventilation. Pathologies of the lung itself, as well as other disorders (cardiac disease, neurological disease, haematological disease, musculoskeletal disorders etc.) have varying effects on the different aspects of pulmonary physiology. In addition, advanced respiratory treatments such as mechanical ventilation may also have effects on all of these.

Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that results in a multisystem disease. CF most commonly affects the respiratory, hepatobiliary, digestive and reproductive systems, though the majority of morbidity and mortality results from progressive obstructive lung disease and chronic pulmonary infection. In recent years, the survival of patients with CF has increased significantly with a recently reported median survival of up to 51.8 years of age.

The placenta develops alongside the embryo and fetus and is responsible for fetal gas exchange and nutrition. The placenta also has important immune and endocrine functions and thus undertakes to fulfill the roles played by various somatic organs in the post-natal situation (Figure 5.1). The placental membrane, the chorion, prevents the fetal and maternal blood from mixing, while allowing transport of molecules. The human placenta is haemochorial, which means that maternal blood contacts the chorionic placental membrane (fetal epitheliem).

Pulmonary oedema (PED) is an accumulation of fluid in the lung interstitium and alveoli. PED is typically divided into cardiogenic and non-cardiogenic mechanisms. Cardiogenic PED, or congestive heart failure, occurs when the heart is unable to pump the blood returning from the lungs to the body effectively, either as a result of intrinsic heart dysfunction or external effects such as hypertension causing increased afterload. Non-cardiogenic PED, also known as acute respiratory distress syndrome (ARDS), occurs due to changes in capillary membrane permeability, resulting in the accumulation of fluid in the alveoli and interstitium. PED complicates between 0.08% and 0.5% of pregnancies.

A large range of pulmonary and cardiac diseases may affect pregnant patients. The most common causes include acute viral respiratory infections, chronic pulmonary or cardiac conditions and bacterial pneumonia. Asthma is the most common pulmonary disease to complicate pregnancy, and a third of patients experience worsening of asthma control during pregnancy. In patients with chronic obstructive pulmonary disease, cystic fibrosis (CF), non-CF bronchiectasis or interstitial lung disease, and rarely in patients who have a history of lung transplantation, the physiological and biological conditions of pregnancy will not exacerbate the underlying pulmonary disease as much as reduce pulmonary reserve and disease tolerance. Pregnancy is associated with an increased risk of aspiration pneumonitis, pulmonary embolism, cardiomyopathy, acute myocardial infarction and aortic dissection. Often these occur in patients without other known risk factors.

Despite advances in the treatment of pulmonary hypertension and improvements in obstetric care, pulmonary hypertension (PH) remains a leading cause of cardiac maternal death in the developed world. The last three decades have seen the development of effective therapies for specific forms of PH, improving patients’ symptoms and more than doubling survival in some forms of PH. Consequently there are an increasing number of women of childbearing potential with PH. Women may present for the first time, with PH in pregnancy, in the early post-partum period or patients with PH may consider pregnancy despite counselling regarding the high risks.

Respiratory diseases in pregnancy such as pneumonia or thromboembolic disease are relatively common, and thoracic imaging can be crucial to the diagnosis. Radiologic modalities are subdivided into ionizing or non-ionizing techniques. In pregnancy, ideally, it is preferable to choose non-ionizing modalities to avoid radiation exposure. However, the choice of imaging modality also needs to take into account the modality best likely to obtain the diagnosis. Amongst physicians, the perceived fetal risk from ionizing radiation exposure in pregnancy is generally higher than the actual risk.

common haemoglobinopathy, affecting 283 000 infants born annually. Sickle cell carriers are found throughout sub-Saharan Africa, the Mediterranean, the Middle East and the Indian subcontinent. Estimated frequency for sickle cell trait (HbAS) varies by ethnicity: 1:10 for African-Carribeans, 1:4 for West Africans, 1:100 for Cypriots and 1:100 for Pakistani, Indian. Haemoglobin S is created by the substitution of valine for glutamic acid (CAG → GTG), in the β-globin gene at position 6.