Sleep disordered breathing in pregnancy: the maternal and fetal implications.
STUDY OBJECTIVES Recent studies suggest a specific association between intrauterine growth restriction that commonly occurs in preeclampsia and decreased maternal cardiac output. Sleep is associated with marked hypertension in preeclampsia. We therefore aimed to determine how sleep influences other hemodynamic parameters in preeclampsia, specifically to determine if sleep-induced exacerbation of hypertension was associated with reductions in cardiac output. STUDY DESIGN Randomized controlled trial of nasal continuous positive airway pressure. SETTING King George V, Royal Prince Alfred Hospital. PATIENTS Twenty-four women with severe preeclampsia and 15 control nulliparous subjects. INTERVENTION Full polysomnography including beat-to-beat blood-pressure recording. Stroke volume, heart rate, cardiac output, total peripheral resistance, and ejection duration were derived from the blood pressure waveform. Half of the 24 preeclamptic subjects were randomly assigned to receive treatment with nasal continuous positive airway pressure and the other half to receive no treatment. MEASUREMENTS AND RESULTS Heart rate, stroke volume, and cardiac output were similar in controls and patients with preeclampsia during wakefulness, while total peripheral resistance was significantly elevated. Sleep induced marked decrements in heart rate, stroke volume, and cardiac output in preeclamptic subjects and resulted in further increments in total peripheral resistance. Cardiac output during sleep was correlated with fetal birth weight (r2 = 0.64, P < .001). When preeclamptic subjects were treated with continuous positive airway pressure, reductions in cardiac output were minimized, while increments in total peripheral resistance were also reduced. CONCLUSIONS These data indicate that sleep is associated with adverse hemodynamic changes in women with preeclampsia. These changes are minimized with the use of continuous positive airway pressure. Reduced cardiac output during sleep may have an adverse effect on fetal development.