[New algorithm for oscillometric noninvasive automatic arterial pressure measurement in patients with atrial...

Oscillometric noninvasive arterial pressure monitoring devices frequently fail to measure pressure precisely in patients with arrhythmia, such as atrial fibrillation, because beat-by-beat changes in pulse pressure and mean pressure level distort the relation between cuff pressure and oscillometric wave amplitude. To overcome this problem, we developed a new algorithm for oscillometric measurement in which oscillometric wave amplitude is corrected according to changes in pulse pressure and mean arterial pressure level. In 7 patients with atrial fibrillation, we compared systolic pressure thus estimated with that simultaneously measured invasively in the radial artery and averaged during oscillometric measurement. Correction based on invasively obtained beat-by-beat pulse pressure and mean pressure level decreased the ratio of unmeasurable cases from 11 to 4%. Correction based on plethysmographically estimated pulse pressure decreased unmeasurable cases to 6% (P < 0.01). Standard error of systolic pressure estimates was 6.44 +/- 1.83, 4.10 +/- 0.85, and 4.75 +/- 1.26 mmHg with no, invasive, and plethysmographical correction in this order (P < 0.01). We conclude that oscillometric wave amplitude correction based on beat-by-beat pulse pressure and mean arterial pressure level lessened the number of unmeasurable cases and improved measurement precision in patients with atrial fibrillation.