To determine the utility of using total peripheral systemic vascular resistance assessed using non-invasive cardiac monitor for individualizing the duration of postpartum magnesium sulfate in individuals with preeclampsia with severe features.

Single center pilot randomized controlled trial in which singleton pregnant individuals with preeclampsia with severe features were randomized to 24 h of postpartum magnesium sulfate per standard of care (control group) or individualized duration of postpartum magnesium sulfate based on reduction in post-delivery systemic vascular resistance (intervention group). Systemic vascular resistance was assessed with non-invasive cardiac monitoring using the Cheetah® system. A 30 % reduction (maintained for 1 h) from baseline post-delivery systemic vascular resistance was used as a cutoff for discontinuation of postpartum magnesium sulfate. Our primary outcome was duration of postpartum magnesium sulfate use in hours. Secondary outcomes included a composite of maternal morbidities associated with preeclampsia.

Of 53 individuals enrolled, we excluded 6 from this analysis due to insufficient data to assess primary outcome. Baseline characteristics of the control (n = 26) and intervention (n = 21) groups were similar. Six (28.6 %) individuals in intervention group met the systemic vascular resistance criteria and had their postpartum magnesium sulfate discontinued before 24 h. The duration of postpartum magnesium sulfate infusion was shorter in the intervention group (21.6 ± 4.7 h; range: 7–24 h) compared with control group (24 h, p = 0.02). There was no difference in secondary outcomes between the two groups. There was no difference in adverse outcomes in individuals that had magnesium discontinued earlier than 24 h.

Non-invasive monitoring of systemic vascular resistance can be a valuable tool to individualize the duration of postpartum magnesium sulfate for preeclampsia with severe features. These findings should be conformed in a larger trial.