Differences in response of hemodynamic parameters between pregnant and non-pregnant women during a cardiopulmonary exercise test.

Normal pregnancy is characterized by a rise in cardiac output (CO) and a drop
in heart rate (HR) and systemic vascular resistance (SVR) already in the first
trimester of pregnancy, in order to cope with the increased demands of oxygen
and nutrient to allow appropriate growth of a fetus. This cardiac adaptation to
pregnancy can be compared to a nine month lasting moderate exercise. It is
thought that in women who develop placenta-related pregnancy complications
(PPC) an increased risk for cardiovascular disease is unmasked by the stressed
state of pregnancy. To study differences in the cardiovascular adaptation to
pregnancy between women who will or will not develop PPC it is necessary to
gather insight in normal values of hemodynamic parameters in pregnant and
non-pregnant women. A cardiopulmonary exercise test (CPET) is a reliable test
to study the responses of the cardiovascular and respiratory system during
physical stress. Impedance cardiography (ICG) allows continuous, non-invasive
monitoring of several hemodynamic parameters, including cardiac output, stroke
volume and SVR. Physioflow is a device that can be used for ICG and is equipped
with high signal stability. It is therefore very suitable to be used during a
CPET. However the differences in patterns of hemodynamic parameters measured
with ICG during CPET between pregnant women and non-pregnant women have not yet
been investigated.

We aim to examine the differences in response of hemodynamic and ventilatory
parameters between women in their first trimester of pregnancy and non-pregnant
women during a CPET.

A prospective comparative study, conducted at Erasmus University Medical Centre
Rotterdam. There will be no randomisation or blinding.

Burden associated with participation exists of one investigation for an
estimated time of 30 minutes. Participants will exercise on a cycle ergometer,
according to a Rapid AccuMulation protocol (RAMP), until their heart rate rises
up to 70% of their maximum heart rate. During the CPET measurements take place,
using ICG, pulse oximeter, blood pressure meter and a breath-by-breath mask.
Before and after the CPET a blood lactate will be assessed, using a single
finger prick. The exercise test will not take place when the participant has
high blood pressure (>140mmHg systolic and/or >90mmHg diastolic) or low oxygen
saturation (<94%) during baseline measurements. The tests and measurements are
validated and are considered safe for pregnant women, their fetus and
non-pregnant women. There is no individual benefit for participants. In case of
any adverse finding women will be referred to specialized care (i.e.
cardiologist, gynaecologist).