The assessment of agreement between non-invasive, near continuous radial blood pressure measurement and conventional ambulatory blood pressure monitoring during night time sleep

The objective of this study was to compare the blood pressure (BP) measurements during night time sleep of a non-invasive, near-continuous, radial BP instrument to a conventional ambulatory blood pressure monitoring (ABPM) device in a field study setting, in which individuals were not controlled for moving. In order to assess the validity of the radial BP meter in a field setting, we carried out a study in which subjects slept with both instruments: the ambulatory BP monitoring device (Numed’s Mobil-O-Graph®) and the non-invasive, near continuous radial meter (Medwave’s APM205A Vasotrac®). They were positioned on 7 healthy subjects, 2 males and 5 females, aged from 14 to 83, who volunteered to take part in the study. It was found that under the normal field conditions the agreement of the Vasotrac® monitor to the ambulatory Mobil-O-Graph® was relatively small. The range of the observed correlations was from 0.09 to 0.50 for systolic BP and -0.11 to 0.65 for diastolic BP. The mean difference between Vasotrac® and Mobil-O-Graph® ranged from -1.0 to 23.0 mmHg for systolic BP and -11.0 to 8.4 for diastolic BP. In conclusion, the poor agreement of the near continuous radial BP meter to the established ABPM method in the field sleep study setting shows that the first is probably not a suitable BP monitoring device in such conditions.