Midwives will be aware that pregnant women are reflective of the society in which they live. This incudes the prevalence of medical conditions; therefore, it is useful to set the context for asthma as a respiratory condition.
Asthma has been defined as:
‘A heterogeneous disease usually characterised by chronic airway inflammation. It is defined by the history of respiratory symptoms such as, wheeze, shortness of breath, chest tightness and cough that vary over time and in intensity, together with variable expiratory airflow limitation.’
Moderate/severe disease is associated with poor outcomes and is defined as:
‘Patients who have no clinical improvement with initial standard therapy and those whose presenting peak expiratory flow is less than 25%–30% of predicted’
The hypothesis regarding the aetiology of asthma is associated with an immature neonatal immune system, which prompts an exaggerated response to an allergen (Borish, 2016).
Asthma is the most prevalent lung condition in the UK, affecting up to 12% of the population. However, the true extent of the condition is not known, since it may be both over- and under-diagnosed (British Lung Foundation, 2018), due to some people who are symptomatic not seeking assistance (Braido, 2013), and a degree of complacency regarding asthma that means that the disease may be not taken seriously (Hughes et al, 2018). Regardless, someone with asthma is admitted to hospital every 7 minutes in the UK, with deaths are highest in the West Midlands, South East, Scotland and Northern Ireland (Asthma UK, 2018a; 2018b). Severe asthma accounted for most deaths but even moderate disease can result in death, according to the Royal College of Physicians (RCP) (2014). Given that asthma is usually amenable to good management, all mortalities should concern midwives. In an attempt to reduce deaths by identifying potentially avoidable factors, the report Why Asthma Still Kills (RCP, 2014) was published, and found that written, personalised asthma action plans were under-used. Midwives should place the overall findings from this report in the context of pregnancy.
Asthma in pregnancy
Asthma is the most common respiratory condition, affecting 10% of pregnant women (Mehta et al, 2015). Most women with well-controlled asthma are at minimal risk of complications (Vanders and Murphy, 2015); however, poorly controlled asthma is associated with a higher risk of dying (Nair et al, 2016), a risk that is compounded if the woman smokes (Knight and Nelson-Piercy, 2017). Complications may include gestational diabetes, pre-eclampsia and haemorrhage (Murphy et al, 2011; Ali et al, 2016). Asthma also increases the risk of infection; therefore, vaccination against influenza is important (Knight and Nelson-Piercy, 2017).
Midwives should also be aware that complications may be exacerbated by drugs used to manage underlying co-morbidities. This is significant, since cardiac disease and hypertension exist in the pregnant population and account for a significant proportion of morbidity (Nair et al, 2016). Midwives are aware that overall maternal mortality/morbidity is influenced by unemployment, poor socio-economic status, social isolation and relationship breakdown (National Institute for Health and Care Excellence (NICE), 2010; Lindquist et al, 2013). Importantly, these factors were also reported in deaths due to asthma (Jackson et al, 2011). In addition to maternal complications, poorly controlled asthma is associated with sub-optimal neonatal outcomes, including oro-facial clefts, prematurity and low birth weight (Breton et al, 2010; Goldie and Brightling, 2013). However, in contrast to earlier reports linking high-dose steroids with oro-facial anomalies (Schatz et al, 2004), recent data fail to support this (Hviid et al, 2011; Skuladottir et al, 2014). This is important, as it is crucial to manage acute exacerbations of asthma in pregnancy with systemic corticosteroids (McCallister et al, 2011).
As with complex conditions, good control is fundamental in minimising complications (Chamberlain et al, 2014; Nolte et al, 2015); yet predicting which women will experience exacerbations is difficult, as the chances of the disease improving, remaining the same or worsening are equivocal (Blackburn et al, 2014; Murphy, 2015; Pali-SchÖll et al, 2017). Effective drug interventions for controlling asthma also pose a therapeutic challenge (Bain et al, 2014; Mihaltan et al, 2014; Namazy et al, 2014), as hormonal changes in pregnancy alter the maternal response; therefore midwives should be aware of pregnancy and asthma physiology (Tamási et al, 2011).
Physiology of pregnancy and asthma
It is reported that midwives' knowledge of asthma, including the nature of the disease in pregnancy, is variable (McLaughlin et al, 2015; 2018); however, midwives are conversant with the hormonally induced effects of pregnancy on the body systems, and the respiratory system is no exception. This knowledge will therefore aid midwives' understanding of the accompanying pulmonary manifestations of asthma. For example, the hygroscopic effects of oestrogen promote oedema in mucous membranes and the excessive mucus may cause coughing (Hedgewald and Crapo, 2011). Changes are also evident in the chest cavity, as thorax dimensions increase in size in the antero-posterior plane due to the effect of progesterone on rib ligaments, and the fundus upwardly displacing the diaphragm (McCormack and Wise, 2009; LoMauro and Aliverti, 2015). Such changes affect lung capacity, although this depends on whether the woman is inhaling or exhaling. On inspiration, for example, despite diaphragmatic changes, capacity is preserved, whereas on expiration, reserves are generally decreased. In addition, with fetal growth, the total volume of gaseous exchange in the lungs causes increased ventilation in the alveoli and while lung capacity is preserved, respiratory resistance increases. Thus, although ‘hyperventilation’ occurs mainly as a result of changes in serum pH values, chemo-receptor action and metabolic function, the respiratory rate throughout all trimesters, remains the same (LoMauro and Aliverti, 2015). Even the normal dyspnoea of pregnancy can be alarming for women with asthma; a respiratory rate consistently >25 may indicate a worsening clinical condition requiring immediate referral (Nursing and Midwifery Council (NMC), 2015).
‘Midwives have a professional duty to promote the safety and wellbeing of women in their care and should minimise the risk of drug interactions by careful assessment of the woman's medical history and the medicines administration chart in hospital’
Key recommendations and safe drug administration
Antepartum care is focused on good control of asthma, which should be managed by appropriate experts. All women should be advised to use long-acting asthma preventers rather than relying on short-acting relievers, as it was recently reported that compared with short-acting medication, long-acting medication increased conception rates (Grzeskowiak et al, 2018). Since exacerbations of symptoms, including cough, dyspnoea, chest tightness and wheezing, may challenge the oxygen-carrying capacity of the woman (Blackburn et al, 2014), those displaying worsening symptoms should receive prescribed medication (Murphy, 2015).
Acute exacerbations of asthma can arise at any time, but are more prevalent towards the end of the second trimester, with key triggers being infection (Murphy, 2015) and lack of medication compliance (Enriquez et al, 2006; Powell et al, 2012). All women on medication require objective review with peak flow assessments to ensure adequate steroid doses (McCallister, 2013) and prescribed medication should comply with national guidelines (British Thoracic Society (BTS) and Scottish Intercollegiate Guidelines Network (SIGN), 2016) shown in Table 1. Acute exacerbations are rare in labour, and therefore national guidelines (BTS and SIGN, 2016) have recommended that:
| Medications for asthma in pregnancy | Use as normal in pregnancy |
|---|---|
| Short acting B2 agonists | Yes |
| Long acting B2 agonists | Yes |
| Inhaled corticosteroids | Yes |
| Oral and intravenous theophyllines | Yes |
| Oral corticosteroids | Yes (for severe asthma) |
| Leukotriene receptor antagonists | Caution: If required to achieve adequate control of asthma, they should not be withheld during pregnancy |
Source: British Thoracic Society and Scottish Intercollegiate Guidelines Network (2016)
The role of the midwife
Midwives have a duty to promote the safety and wellbeing of women in their care (NMC, 2015) and should minimise the risk of drug interactions by careful assessment of the woman's medical history and the medicines administration chart in hospital (NMC, 2007). Midwives should carefully assess all prescriptions and alert the doctor of any concerns before drug administration (NMC, 2007), as verifying whether a medical ID band is in situ and alerting for underlying medical conditions may minimise adverse reactions (NHS England, 2013). The midwife must stay with the woman in the immediate period following administration of medication and observe for signs of an adverse reaction.
Compliance with medication regimens should be promoted, since it is reported that a resurgence of asthma symptoms is a cause of anxieties in pregnant women (Chamberlain et al, 2014). Women may understandably be concerned about taking corticosteroids, fearing increased risks of congenital anomalies (Vasilakis-Scaramozza et al, 2013) and reduced birth weight (Eltonsy and Blaise, 2016); however, as with all risk assessments, the benefit-to-harm ratio must be balanced in favour of minimising severe, uncontrolled asthma that increases the risk of mortality/morbidity (BTS and SIGN, 2016). All women with asthma should have a written, personalised asthma action plan (RCP, 2014), and a traffic light system can help to escalate care (Asthma UK, 2016). Where severe exacerbations arise, midwives need to be aware of the main priorities for care.
Management priorities in an acute asthma attack
It is important for midwives to appreciate that acute, severe attacks are potentially life-threatening to the woman, with hypoxia posing significant risk to the fetus. This may be compounded by pregnant women not accessing early assistance and not receiving adequate corticosteroids when admitted to hospital (Schatz and Dombrowski, 2009). All attacks should therefore be treated as an emergency and the midwife should offer first aid while summoning medical assistance (NMC, 2015). It is crucial for midwives to realise that attacks can be both unpredictable and unstable (Hodder et al, 2010); hence, medical aid should never be delayed (BTS and SIGN, 2016).
During a severe, acute attack, key principles include:
Conclusion
Pregnancy and asthma can affect each other, and it is therefore crucial for midwives to be conversant with guidelines on asthma management in pregnancy. Sub-optimal risk management of moderate/severe asthma has contributed to deaths in the general population, while poorly controlled asthma is also problematic in pregnancy and may pose challenges for the multi-disciplinary team. However, key priorities of care for managing a potentially life-threatening asthma attack in pregnancy do not differ from the general population. Midwives can help to minimise risks to women by undertaking a thorough medical history, advocating expert referral for the implementation of a personalised asthma action plan, and encouraging compliance with optimal medication, which can positively influence the control of asthma.