Establishing normal ranges for maternal haemodynamic parameters using the Vicorder® device: experience from a single centre

Objective. To establish normal reference ranges for haemo­dynamic parameters assessed with the Vicorder® device in a cohort of healthy pregnant women between 30 and 39 weeks gestational age.
Materials and Methods. We performed a prospective observa­tional study of healthy women with singleton, non-anomalous pregnancies between 30+0 and 39+0 weeks gestational age re­cruited during routine antenatal appointments at a single inner city maternity unit. Participants with significant comorbidities at time of inclusion including cardiovascular disease, chronic or gestational hypertension, diabetes or estimated foetal weight < 10th centile were excluded. Haemodynamic assessments were conducted in standardised conditions with Vicorder® (Skid­more Medical Ltd). Data regarding cardiac output (CO), stroke volume (SV), heart rate (HR), mean arterial pressure (MAP), augmentation index (AIx), pulse wave velocity (PWV) and total peripheral resistance (TPR) were collected.
Results. 246 haemodynamic assessments performed in 176 participants were included in the analysis. HR does not change significantly with gestational age. The central hae­modynamic parameters CO and SV significantly decrease with gestation between 30 and 39 weeks (p < 0.01) with a me­dian decrease respectively of 0.09 L/min and 1.32 ml for each increase in gestational week. Conversely MAP (p < 0.001), TPR (p < 0.001) and arterial function parameters PWV and AIx increase significantly with gestation (p < 0.0001 and p < 0.05 respectively).
For each haemodynamic parameter of interest stratified by gestational week we developed the centile curve reflective of the model with the best fit and the crude median ± inter­quartile ranges.
Conclusions. CO, SV, MAP, SVR, PWV and AIx assessed with the Vicorder® haemodynamic device demonstrate significant change with gestation in uncomplicated pregnancies between 30 and 39 gestational weeks. Thus, normalization for gesta­tional age and the use of Vicorder® specific reference ranges is recommended in future research utilising this maternal hae­modynamic assessment machine.