[Is automatic oscillometric measurement of blood pressure reliable in hypotension?]

The reliability of an automatic oscillometric device for measurement of blood pressure (BP) was assessed in a large range of BP values during intraoperative normotension and induced hypotension. Direct BP measurements were carried out with a radial catheter. Data were compared with those obtained with the oscillometric device placed on the opposite arm. Nine patients were studied, undergoing 234 measurements of BP ranging from 55 to 208 mmHg (7.3 to 27.7 kPa) for systolic blood pressure (Pasys), from 32 to 130 mmHg (4.3 to 17.3 kPa) for diastolic blood pressure (Padia) and from 36 to 154 mmHg (4.8 to 20.5 kPa) for mean blood pressure (Pa). Good correlation between the two techniques was found for Pasys measurements recorded during both normotension and hypotension (r = 0.93; p less than 0.01). 92% of the values recorded with the oscillometric device were lower than those measured invasively. In the other cases (8% of the data), the mean difference between the two techniques was 5.5 mmHg (0.7 kPa). When BP values lower than 90 mmHg (12 kPa) for Pasys, 60 mmHg (8 kPa) for Padia and 70 mmHg (9,3 kPa) for Pa were considered individually, the correlation coefficients were 0.83, 0.73 and 0.77 respectively. These findings suggested that the oscillometric method can be considered as relatively suitable for monitoring moderate hypotension induced by vasodilators. The invasive technique must however remain the method of choice during profound hypotension.