 Data from the critical care and trauma literature further support the use of pulse pressure as a marker of hypovolemia. Conventional static indicators of cardiac preload, such as central venous pressure CVP or pulmonary capillary wedge pressure PCWP, are poor predictors of volume responsiveness, which is the cardiovascular response i.e. changes in preload to intravascular volume expansion with IV fluid. However, dynamic parameters such as variation in pulse pressure or stroke volume, are highly predictive of volume responsiveness 16, 17. While data on pulse pressure variation are primarily derived from non-pregnant, mechanically ventilated individuals, a small case series demonstrated that pulse pressure variation accurately reflects volume responsiveness in pregnant women undergoing cesarean delivery under regional anesthesia 18. Additionally, data from the trauma literature have also demonstrated pulse pressure to represent an accurate surrogate of stroke volume and marker of central hypovolemia 19, 20. Covertino et al. reported a direct relationship between pulse pressure and central volume reductions without any difference in mean arterial pressure 19. As such, pulse pressure may serve as a better maker of central hypovolemia than blood pressure alone. Therefore, pulse pressure may better predict low maternal intravascular volume and serve as a marker for post-epidural FHR changes. 