Little is known about the accuracy of non-invasive central blood pressure by an oscillometric automated device (Mobil-O-Graph) to the invasive blood pressure measurement by arterial cannulation conducted on the same population in hypertensive pregnant women.
Key findings of our study are as follows: (1) there was no difference between non-invasive BP readings by oscillometric automated devices (Mobil-O-Graph) and invasive BP readings, and (2) hypertension in pregnancy was associated with an increase in arterial stiffness, left ventricular diastolic dysfunction, and complications.
Regarding the main aim of the study, to assess the accuracy of non-invasive central BP measurements in comparison to invasive BP measurement, results showed no statistically significant difference between SBP and DBP measurements by the two methods between the different studied groups indicating that central blood pressure measured non-invasively by the oscillometric automated device (Mobil-O-Graph) is accurate as of the invasive assessment of blood pressure, and the strong positive correlation between non-invasive central blood pressure measurements and invasively measured both systolic BP and diastolic BP confirm this conclusion.
In agreement with our results, Gotzmann and colleagues [14] conducted a cross-sectional study of non-invasive central BP measurement by an oscillometric automated device (Mobil-O-Graph). It showed that the automated oscillometric monitors could assess central BP with acceptable accuracy. Their study was performed on 502 patients (228 women, 274 men) with a mean age of 67.9 ± 11.6 years undergoing elective coronary angiography. Their results revealed a highly significant positive correlation between invasively measured systolic (r = 0.763, p < 0.001) and diastolic (r = 0.618, p < 0.001) central blood pressures and non-invasive BP readings.
In the same context, another study, by Sanchez and colleagues [15], in 20 subjects (10 males (68 ± 12 years) and ten females (77 ± 8 years)), submitted for invasive coronary evaluations, showed a highly significant positive correlation between Mobil-O-Graph central BP, and the invasive BP values were found in men (r = 0.89) and women (r = 0.917).
Another study, by Weber and colleagues [16], included 30 patients undergoing elective coronary angiography for suspected coronary artery disease, mean age was 59 ± 11 years, non-invasive assessment of central SBP was performed by the same oscillometric automated device (Mobil-O-Graph) and invasive assessment during elective coronary angiography, and results revealed a high positive correlation to invasively measured systolic (r= 0.899, p < 0.001) central blood pressure in agreement with our results.
Of note, central hemodynamics recorded by the oscillometric device (Mobil-O-Graph) uses in the current study showed that AIx and PWV were higher in the pre-existing hypertension group with a significant difference when compared to non-hypertensive control.
Concordant to our results, Franz and colleagues [11] conducted a case-control study over 35 healthy pregnant women and 21 patients with pre-eclampsia; AIx and PWV were measured by an oscillometric device TensioClinic TL1 Arteriograph and TensioClinic software (TensioMed Ltd.) and found that the patients with pre-eclampsia had significantly elevated AIx values with p value 0.001, and the PWV values were higher in the preeclamptic groups but with a non-significant difference.
Furthermore, in Elvan-Tasšpinar and colleagues’ [17] study of 122 pregnant women divided into a normotensive group (51 women), hypertensive group (19 with chronic HTN, 19 with gestational HTN ), and preeclamptic group (31 women), PWV and AIx were measured non-invasively in all groups and results showed that the AIx and PWV were significantly higher in the hypertensive and preeclamptic group with p value < 0.05.
Despite being used routinely, sphygmomanometer BP has many limitations, as it does not represent real-life BP, in addition to the discrepancy between brachial BP and central BP with its predictive value for cardiovascular events [4]. Central BP was one of the explanations of the increased stroke risk in the atenolol arm in the landmark LIFE trial [5]. BP measurement via a catheter introduced into the artery (mostly radial or femoral artery) is called invasive or direct blood pressure measurement and is considered to be the most accurate method of blood pressure measurement [6].
In our study, we found a significant difference between sphygmomanometer and central methods in both SBP and DBP readings in patients with HDP, including pre-eclampsia. This was in concordance with Langenegger et al. who found discordance between readings collected by direct intra-arterial monitoring and peripheral methods by both manual and automated devices, and they concluded that invasive central BP monitoring is mandatory in patients with severe pre-eclampsia [18].
Regarding diastolic dysfunction, we found that diastolic dysfunction was more frequent in patients with HDP, including pre-eclampsia. In concordance with these results, Guirguis et al. found more frequent diastolic dysfunction in patients with pre-eclampsia. Furthermore, we demonstrated that other variants of HDP were also associated with diastolic dysfunction [19].