Analysis on the characteristics of postural blood pressure changes recorded with continuous non-invasive arterial pressure monitoring system and the correlative factors in elderly hospitalized patients

Abstract

Objective: To explore the characteristics of postural blood pressure changes in elderly inpatients and the related factors of orthostatic hypotension (OH). Methods: This study was a clinical case control study. Two hundred and sixty-six elderly patients (≥60 years old), who were hospitalized between April 2016 and November 2017 in Geriatric Department of Peking University First Hospital, were included. They were divided into direct standing group and indirect standing group. Direct standing group involved 102 patients, they changed posture from supine directly to standing position, and the blood pressures at the moments of supine, immediately after standing and the first, second, and third minute after standing were recorded by continuous noninvasive arterial pressure (CNAP) system. Indirect standing group involved 164 patients, and they changed posture from supine to sitting for 3 minutes, and then changed to standing position. Blood pressures at the moments of supine, immediately after sitting, the third minute after sitting, immediately after standing and the third minute after standing was recorded by CNAP. Blood pressure changes after different postural changes mode and the rates of OH were compared. The related factors of OH was analyzed by binary logistic regression analysis. Results: The lowest systolic blood pressures (SBP) mostly occurred immediately after postural change: immediately after standing for direct standing group (86.3%(88/102)), and immediately after sitting for indirect standing group (59.1%(97/164)). The lowest diastolic blood pressures (DBP) mostly occurred immediately after standing in the two groups: 87.3%(89/102) for direct standing group and 43.3% (71/164) for indirect standing group. The maximum SBP drop (SBP of supine minus the lowest SBP during postural changes) of direct standing group was significantly higher than indirect standing group (median 20.5(14.0, 29.3) vs. 18.0(11.0, 26.0) mmHg (1 mmHg=0.133 kPa, P<0.05). The rates of OH occurred immediately and within 3 minutes from supine to standing position were significantly higher in direct standing group than in indirect standing group (65.7% (67/102) vs. 43.9% (72/164), and 70.6% (72/102) vs. 49.4% (81/164), both P<0.05). Binary logistic regression analysis showed that brachial-ankle pulse wave velocity was positively associated with OH after a transition from supine to standing position (immediately and within 3 minutes, OR=1.002 (95%CI 1.000-1.004), 1.003 (95%CI 1.001-1.006), P=0.014, 0.006) in direct standing group. Conclusions: OH is common in elderly hospitalized patients. The most obvious blood pressure changes are likely to occur immediately after position changes. Adding a sitting position during the transition of supine to standing position may decrease the amplitude of SBP drop. Brachial-ankle pulse wave velocity is associated with OH after the transition from the supine to standing position in the elderly inpatients.