Evaluating Oxygen Saturation Monitoring to Detect Pulmonary Edema in Patients with Severe Preeclampsia

ObjectivePulmonary edema is a feature of preeclampsia with severe features (SPEC), but it is unknown whether oxygen saturation (O2 sat) levels can predict pulmonary edema in patients with SPEC. The purpose of this study is to evaluate and compare O2 sat trends in patients with SPEC with and without pulmonary edema. Study DesignThis is a nested case-control study within a retrospective cohort of all patients with SPEC who delivered at a tertiary academic hospital in 2019. Cases were defined as a clinical diagnosis of pulmonary edema (based on imaging findings or clinical concern coupled with empiric treatment with IV diuretic) on postpartum day 0 (PPD0). Controls were patients with SPEC and without pulmonary edema on PPD0. All patients with at least 25 oxygen saturation levels recorded on PPD0 were included. O2 sat trends as well as demographic and clinical features of patients with and without pulmonary edema were compared. Results238 patients in total were included. Five patients (2.1%) were diagnosed with pulmonary edema on PPD0. There were no significant differences in demographic or major obstetric characteristics of patients with and without pulmonary edema. There were also no significant differences between groups in the number of patients with at least one abnormal O2 sat, with a large volume of abnormal O2 sat values in both groups. Significant differences were seen in the minimum oxygen saturation level recorded (92 v. 89, p < 0.04) and the overall percent of abnormal values (7.0% abnormal values without pulmonary edema compared to 46.0% with pulmonary edema, p < 0.01). ConclusionsIndividual O2 sat values are poorly predictive of pulmonary edema in patients at risk, but trends may be more prognostic. Algorithms that employ real-time data trending may position O2 sat as a better surveillance tool for pulmonary edema in patients with SPEC.