Gender differences in airway behaviour and in the clinical manifestations of airway disease occur throughout the human life span and are related to biological as well as sociocultural factors.1-11 Though they have not escaped recognition, they have received less attention than gender differences in the rates of, for instance, cardiovascular disease, both in terms of research and their implications for clinical practice.4 5 10-12Physiologists have in general paid more attention than clinicians to gender differences in airway behaviour, even though gender differences are an important determinant of the clinical manifestations of airway disease. Similarly, in population based (epidemiological) studies of airway disease, gender is invariably considered a standardising variable rather than a determinant worthy of investigation in its own right.4 However, there have been some notable historical exceptions.

In 1846 John Hutchison,1 a London surgeon, presented a report to the Royal Medical and Chirurgical Society entitled On the capacity of the lungs and the respiratory functions with a view of establishing a precise and easy method of detecting disease by the spirometer . He had developed the spirometer specifically for this research and his study is one of the first, if not the first, population based (epidemiological) study in respiratory health. One of the outcome measurements he used in his research was the “vital capacity” (VC), a term he coined to describe “the greatest voluntary expiration following the deepest inspiration”. His study population comprised over 2000 men drawn from various professions and occupations (including soldiers, sailors, guardsmen, policemen, gentlemen, giants, and dwarfs) and 26 young girls, and he identified height, weight, and age as the important determinants of VC. His epitome (as he called his summary) does not include a comment on whether there were gender differences, probably wisely given the limited number of women …

https://thorax.bmj.com/content/thoraxjnl/54/12/1119.full.pdf

Gender differences in airway behaviour over the human life span

Asthma is becoming increasingly prevalent worldwide. Numerous historical and prospective cohort studies have investigated the effects of maternal asthma on pregnancy outcome; however, the data has been conflicting and many studies have not used standard classifications for asthma severity. Overall, the literature suggests that asthmatic females are more at risk of low birth weight neonates, pre-term delivery and complications such as pre-eclampsia, especially in the absence of actively managed asthma treated with inhaled corticosteroids. Pregnancy with a female foetus may particularly increase the risk of these outcomes. In addition, pregnancy has an effect on the course of asthma. The risk of an exacerbation requiring medical intervention may be as high as 50% in females with severe asthma and this may further increase the risk of poor outcomes, particularly low birth weight and pre-term delivery. The mechanisms responsible for changes in asthma with pregnancy, or alterations in pregnancy outcomes due to asthma have not been thoroughly explored. Maternal inflammatory pathways may contribute to reduced foetal growth through alterations in placental function. Asthma treatment, by reducing maternal inflammation and preventing exacerbations, is safe for use in pregnant females and contributes to improved outcomes for both mother and foetus.

https://erj.ersjournals.com/content/erj/25/4/731.full.pdf

Asthma during pregnancy: mechanisms and treatment implications

Asthma, asthma medications and their effects on maternal/fetal outcomes during pregnancy

Objectives To provide an overview on the interrelationship between asthma and pregnancy, focusing on management of pregnant women presenting with an acute severe exacerbation. Design A review of the current English-language published clinical trials was performed based on MEDLINE search using the Medical Subject Headings pregnancy and asthma. Current reviews on the topic and practice guidelines were also reviewed. Results Asthma is the most common medical condition to complicate pregnancy, and episodes of acute asthma requiring emergency department visits or hospitalization have been reported in 9-11% of pregnant women managed by asthma specialists. Pregnancy can affect the course of asthma, and the risk of asthma exacerbations requiring intervention in pregnant women is higher than in nonpregnant women. Similarly, asthma can affect pregnancy outcomes. Maternal inflammatory pathways may contribute to the poor pregnancy outcomes, especially in women with uncontrolled asthma. Although data on the effects of maternal asthma on pregnancy have been conflicting, mainly because many published studies have not corrected for asthma severity, it has generally been observed that poorly managed asthma during pregnancy is associated with a higher risk of preterm delivery, low birth weight, and complications such as preeclampsia. Optimal therapy of asthma has been shown to contribute to improved maternal and fetal outcomes. Conclusions Asthma can complicate the course of pregnancy, and pregnancy can worsen asthma control in some women. Optimal management of asthma during pregnancy is key in ensuring the safety of the mother and the fetus.

Acute asthma in pregnancy.

https://www.criticalcare.theclinics.com/article/S0749-0704(04)00061-2/pdf

A 19-year-old woman was admitted with acute severe asthma in her eleventh week of pregnancy. Despite vigorous therapy, severe hypoventilation and hypoxemia persisted with mechanical ventilation. Termination of pregnancy resulted in dramatic improvement in airflow. Her course was complicated by pneumonia, barotrauma, and atelectasis accompanying her moribund state. Although she immediately improved following abortion (within 2 hr, peak airway pressure fell from > 70 to 38 cmH2O, without change in plateau pressure), superimposed morbidities improved more slowly, and the patient made a complete recovery. The mechanism accounting for this observation is unknown but the rapid improvement following abortion suggests that increased bronchomotor tone predominated inflammatory changes in causing flow limitation.

Peter T

Papers

Reversal of Intractable Acute Severe Asthma by First-Trimester Termination of Pregnancy