Pregnant Women With Asthma, Obstructive Sleep Apnea Have Increased Airways Resistance
May 23, 2023

Pregnant Women With Asthma, Obstructive Sleep Apnea Have Increased Airways Resistance

Key takeaways:

  • Pregnant women with asthma and obstructive sleep apnea had greater central airway resistance than those without asthma or OSA.
  • These women are more susceptible to dyspnea and respiratory complications.

Pregnant women who have both asthma and obstructive sleep apnea have increased central airways resistance, but not increased peripheral airways resistance, according to a presentation.

These patients are more susceptible to developing dyspnea and respiratory complications, Christopher D. Theroux, MD, pulmonary/critical care fellow, Brown University/Lifespan Hospitals, and colleagues wrote in the study, which was presented at the American Thoracic Society International Conference.

Pregnancy is a risk factor for developing OSA, while asthma symptoms worsen during pregnancy for a third of women, researchers said.

“Sleep-disordered breathing in this population is quite common, yet not well recognized and certainly under-diagnosed. Both sleep-disordered breathing and asthma can carry significant risks to the mother and neonate,” Theroux told Healio.

These disorders are known to overlap in the general population, with obesity common to both, Theroux continued, but data about these disorders are lacking in pregnancy.

“The aim of this study was to understand the impact of each disorder on airway resistance in women with obesity and overweight and to investigate the cumulative effect of the disorders on airway mechanics,” he said.

Study design, results

The study measured the airway resistance at 5 Hz (R5, total airways resistance) and 20 Hz (R20, central airways resistance) of 217 patients who were pregnant and in their first trimester. Patients were measured in the seated position, and none of them were experiencing any acute symptoms of asthma at the time of testing.

“We used oscillometry, a noninvasive, safe, and readily available office-based tool that can provide significant information on respiratory mechanics,” Theroux said.

Forced oscillometry assesses airway caliber and examines bronchial reactivity and reversible small and large airway obstruction in asthma accurately, the researchers said.

Patients included 115 who did not have asthma or OSA, 49 who only had asthma, 36 who only had OSA and 17 who had both asthma and OSA.

There was no statistically significant difference in R5 between the four groups, the researchers said, nor was there any difference in R5-R20 between them.

However, R20 totals included 172.5 for pregnant women with asthma and OSA and 156.9 for pregnant women who did not have asthma or OSA (adjusted mean difference, 18.3; 95% CI, 2.8-33.8).

The researchers also noted a trend for increased R20 among pregnant women with asthma or OSA alone compared with pregnant women who did not have asthma or OSA (adjusted mean difference, 15.6; 95% CI, –1.8 to 33.1).

Conclusions, next steps

Theroux noted that 25% of women with overweight and obesity who have asthma also have sleep apnea in early pregnancy.

“Our study showed that pregnant women who are overweight or obese with both asthma and OSA have a significant increase in central airways resistance,” he said.

“Central airway resistance was higher in women with both disorders compared to women with neither disorder and compared to women with asthma alone, suggesting that sleep apnea has an additive effect on central airway resistance,” he continued.

Sleep apnea appears to complicate the physiology associated with asthma, Theroux said, so physicians should maintain a high degree of suspicion for sleep apnea.

“Future investigation into whether treatment of OSA improves asthma biology/control is needed. Though most women who are pregnant and have OSA have mild disease, the disorder is associated with significant perinatal outcomes,” he said.

Further, Theroux called early recognition of both sleep-disordered breathing and poor asthma control during pregnancy extremely important with implications for the health of the mother and fetus alike.

When women experience this heightened resistive load as well as the added elastic load related to pregnancy weight gain and central weight distribution, the work of breathing increases and makes these women more susceptible to developing dyspnea and respiratory complications, the researchers said.

“Hence, collaboration between OBGYNs and medical specialists such as pulmonologists and sleep physicians is crucial, especially given the rising maternal mortality in the U.S.,” Theroux said.

Ghada Bourjeily, MD, professor of medicine at Brown University and coauthor of this study, also was the cochair of a consensus guideline on screening, diagnosis and management of sleep apnea in pregnancy that has been accepted for publication in a major obstetric journal, Theroux said.

“This should help efforts to identify women with sleep apnea better,” he said.

Next, the researchers plan to examine results from later stages of pregnancy where sleep apnea is more common and pregnancy body composition differs.

“It would be important to examine whether screening for OSA in women with asthma and obesity improves patient outcomes and better understand the impact of OSA treatment on asthma care,” Theroux said.

Authored by: Christopher D. Theroux, MD