Impact of Asthma and Obstructive Sleep Apnea on Central Airways Resistance During Pregnancy

Pregnancy is a risk factor for the development of obstructive sleep apnea (OSA) and for worsening of asthma; the interaction between the two disorders is not well described. We aimed to examine airway mechanics in pregnant patients with and without OSA and asthma.

We studied 217 women with BMI above 25 early in the second trimester of pregnancy. Airways resistance was measured using the forced oscillation technique at 5 Hz (R5), 20 Hz (R20), and 35 Hz (R35). All values were expressed as % predicted. level III sleep studies were scored according to the recommended AASM rules; OSA was diagnosed by AHI ≥ 5 events per hour. Asthma was defined by medical history and record review.

Of the 217 women tested, 53 had OSA and 66 had asthma. R20 and R35 were increased in women with both OSA and asthma compared to those with neither asthma nor OSA (adjusted mean difference (aMD) for R20 was 19.7, CI 3.4-36.0, p value = 0.02; aMD for R35 was 36.9 CI 12.4-61.5, p value = 0.003). There was a significant increase in R35 for women with OSA as opposed to those without (aMD 17.6 (CI 1.4-33.8; p value = 0.03).

Pregnant women with both OSA and asthma have higher central airways resistance and upper airway resistance as measured at R20 and R35, respectively, compared to those with neither OSA nor asthma. Further work is needed to understand mechanisms underlying the synergistic effects of OSA and asthma on airways mechanics.