Impact of atrial fibrillation on the accuracy of oscillometric blood pressure monitoring.

The introduction of automated oscillometric blood pressure monitors was the basis for today's widespread use of blood pressure self-measurement. However, in atrial fibrillation, there is a controversial debate on the use of oscillometry because there is a high variability of heart rate and stroke volume. To date, the accuracy of oscillometric blood pressure monitoring in atrial fibrillation has only been investigated using auscultatory sphygmomanometry as reference method, which may be biased by arrhythmia as well. We performed a cross-sectional study in 102 patients (52 sinus rhythm, 50 atrial fibrillation) assessing the accuracy of an automated and validated oscillometric upper arm (M5 Professional, Omron) and wrist device (R5 Professional, Omron) to invasively assessed arterial pressure. Blood pressure values were calculated as the mean of 3 consecutive measurements. Systolic and diastolic blood pressure did not significantly differ in patients with sinus rhythm and atrial fibrillation, independent of the method of measurement (P>0.05 each). The within-subject variability of the oscillometric measurements was higher in patients with atrial fibrillation compared with sinus rhythm (P<0.01 each). The biases of systolic and diastolic blood pressure, however, did not significantly differ in presence or absence of atrial fibrillation in Bland-Altmann analysis (P>0.05 each). In conclusion, atrial fibrillation did not significantly affect the accuracy of oscillometric measurements, if 3 repeated measurements were performed.

Volumetric hemodynamic parameters to guide fluid removal on hemodialysis in the intensive care unit.

Estimation of removable excess body fluid is difficult in critically ill patients with renal failure. Volumetric hemodynamic parameters are increasingly being used to guide fluid therapy in the intensive care unit, but their suitability to monitor fluid removal with hemodialysis in critically ill patients is not known. Changes in the extravascular lung water index (EVLWI) and intrathoracic blood volume index (ITBVI) measured with transpulmonary thermodilution immediately before and after hemodialysis were analyzed from 39 hemodialysis sessions of 9 patients consecutively treated in the medical intensive care unit of a German University Hospital. Additional hemodynamic, ventilation, and oxygenation-related parameters were recorded at the same time. Online relative blood volume (RBV) monitoring was performed in 29 sessions. Comparisons of pre and postdialysis values showed a significant reduction of the EVLWI with fluid removal (p=0.009), with only a slight nonsignificant decrease in the ITBVI. The cardiac index (CI) also decreased significantly (p=0.010), whereas blood pressure remained stable. Oxygenation improved significantly (p=0.005), and the hematocrit increased significantly with dialysis (p=0.039). There was no correlation between hematocrit changes and RBV measurements. Significant correlations existed between ITBVI and CI changes (p<0.001), but not to EVLWI reduction. The removal of excess body fluid on hemodialysis is reflected by the EVLWI reduction, whereas the preservation of cardiac preload is shown by ITBVI stability. Volumetric hemodynamic parameters could be useful to guide fluid removal with hemodialysis in the intensive care unit.