Background: During pregnancy, upper airway resistance is increased, predisposing vulnerable women to pregnancy-related OSA. Elevation of the upper body increases upper airway cross-sectional area (CSA) and improves severity of OSA in a subgroup of nonpregnant patients (positional-dependent sleep apnea). We tested the hypothesis that elevated position of the upper body improves OSA early after delivery.
Methods: Following institutional review board approval, we conducted a randomized, crossover study on two postpartum units of Massachusetts General Hospital. Women during the first 48 h after delivery were included. Polysomnography was performed in nonelevated and 45° elevated upper body position. Upper airway CSA was measured by acoustic pharyngometry in nonelevated, 45° elevated, and sitting body position.
Results: Fifty-five patients were enrolled, and measurements of airway CSA obtained. Thirty patients completed polysomnography in both body positions. Elevation of the upper body significantly reduced apnea-hypopnea index (AHI) from 7.7 ± 2.2/h in nonelevated to 4.5 ± 1.4/h in 45° elevated upper body position (P = .031) during sleep. Moderate to severe OSA (AHI > 15/h) was diagnosed in 20% of postpartum patients and successfully treated by elevated body position in one-half of them. Total sleep time and sleep architecture were not affected by upper body elevation. Change from nonelevated to sitting position increased inspiratory upper airway CSA from 1.35 ± 0.1 cm2 to 1.54 ± 0.1 cm2 during wakefulness. Position-dependent increase in CSA and decrease in AHI were correlated (r = 0.42, P = .022).
Conclusions: Among early postpartum women, 45° upper body elevation increased upper airway CSA and mitigated sleep apnea. Elevated body position might improve respiratory safety in women early after delivery.
Trial registry: ClinicalTrials.gov; No.: NCT01719224; URL: www.clinicaltrials.gov.