Non-invasive blood pressure monitoring with an oscillometric brachial cuff: impact of arrhythmia

Arrhythmia-induced beat-to-beat variability of blood pressure (BP) is deemed to hinder the reliability of non-invasive oscillometric measurements (NIBP) but few data support this belief. We assessed the impact of arrhythmia on a NIBP device never tested for this purpose. We compared, in intensive care unit patients with and without arrhythmia, the agreement between three pairs of NIBP (Infinity (TM) Delta monitor, Drager medical systems) and invasive readings. For systolic, diastolic and mean BP, the mean bias between NIBP and invasive measurements was not higher, in 89 patients with arrhythmia, than that observed in 127 patients with regular rhythm (p = 0.93 for mean BP). Averaging three measurements overcame the higher within-subject variability of NIBP measurements during arrhythmia, and yielded similar agreement between the two techniques in patients with arrhythmia and with regular rhythm. The international organization for standardization criteria (mean bias < 5 and SD < 8 mmHg) were satisfied neither during arrhythmia nor during regular rhythm: for mean BP, mean bias of - 8.0 +/- 6.5 and - 7.5 +/- 6.1 mmHg, respectively. The detection of hypotension (systolic invasive BP < 90 mmHg or mean invasive BP < 65 mmHg) or hypertension (systolic invasive BP > 140 mmHg) by NIBP was similar during arrhythmia and regular rhythm [areas under the receiver operating characteristic curves (AUC(ROC)) of 0.88-0.92, p > 0.13]. The detection of a 10% increase in mean invasive BP after cardiovascular intervention was also associated with similar AUC(ROC)s between the two groups. Provided that triplicates are averaged, the agreement between NIBP measured with the tested device and invasive measurements was not worse during arrhythmia than during regular rhythm.