Validation of a new noninvasive method to measure blood pressure and assess baroreflex sensitivity in preterm infants during sleep

Study Objectives: Accuracy and precision of a noninvasive device for continuously measuring blood pressure (BP) (Finometer (TM), FMS, The Netherlands) during sleep was assessed in preterm infants. Design: Absolute BP beat-to-beat values, interbeat changes, measurement precision, and baroreflex sensitivity were compared with BP measurements from intraarterial catheters. Participants: Ten preterm infants (gestational age 27-36 weeks; birth weight 964-2620 gm) were studied in the neonatal intensive care unit. Measurements and Results: The 2 modes of BP measurement were compared in 2-minute epochs (n = 10-12/infant). Mean arterial pressure, systolic arterial pressure, and diastolic arterial pressure were analyzed beat to beat, and baroreflex sensitivity was assessed using spontaneous sequence analysis. Mean differences for absolute BP (mm Hg) were as follows: mean arterial pressure, 3 (limits of agreement, -1 to 8); systolic arterial pressure, -4 (-8 to 1); and diastolic arterial pressure, 7 (4 to 10). Mean differences and limits of agreement for interbeat changes were essentially 0 for mean arterial pressure, systolic arterial pressure, and diastolic arterial pressure. Precision ( 95% confidence intervals, mm Hg) for the Finometer (TM) were mean arterial pressure +/- 7, systolic arterial pressure 8, and diastolic arterial pressure +/- 6. Precision was greater for the arterial catheter (mean arterial pressure 3, systolic arterial pressure 4, and diastolic arterial pressure 4). Baroreflex sensitivity calculated from the Finometer (TM) BP was (mean +/- SEM, ms/mm Hg) 1.74 +/- 0.23 and, from the catheter system, BP was 1.56 +/- 0.21 (p value NS). Conclusions: The Finometer (TM) provides accurate measurements of beat-to-beat BP and baroreflex sensitivity. The ability to continuously measure BP and baroreflex sensitivity during sleep in infants may provide vital clues into pathologic conditions associated with impaired autonomic control during sleep.