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Comparison of central SBP in children estimated from a brachial cuff alone, brachial cuff-calibrated applanation radial tonometry and brachial cuff-calibrated carotid wall-tracking.

OBJECTIVES
We compared the agreement between different techniques to estimate central SBP (cSBP) in children and the relative impact of different methods of measuring peripheral blood pressure (BP).


METHODS
A total of 135 children, aged 12.9 ± 3.0 years including 67 boys, 85 with chronic kidney disease were studied. We measured cSBP using radiofrequency ultrasound carotid wall-tracking (Esaote ART.LAB system, a previously validated reference method), transformation of the radial artery pressure waveform obtained by tonometry (SphygmoCor) and a cuff-based system (cBP301; Centron Diagnostics) during a single visit. Carotid and radial tonometric-derived values were calibrated from mean and diastolic values of brachial BP obtained by aneroid sphygmomanometer. Brachial cuff only values were calibrated from the same aneroid sphygmomanometer values and from oscillometric values obtained from the brachial cuff.


RESULTS
cSBP values estimated from radial tonometry were closely correlated with those obtained from the carotid (r = 0.959, mean difference -0.61 ± 3.5 mmHg). cSBP values estimated by the brachial cuff only method agreed reasonably well with those obtained from the carotid (r = 0.847, mean difference 5 ± 7.4 mmHg) when calibrated by the same method but when calibrated by oscillometric values from the brachial cuff, agreement was less good (r = 0.659, mean difference 8.7 ± 11.4 mmHg).


CONCLUSION
Radial tonometry with a radial-to-central transfer function can be used to estimate cSBP in children with acceptable accuracy when compared with the invasively validated carotid reference method. All methods are subject to errors introduced by calibration from peripheral BP.