Controlled trial of a non-invasive continuous blood pressure monitor: Cortronic AMP 770

The performances of a Cortronic AMP 770 monitor, a new apparatus for non invasive continuous blood pressure monitoring was assessed. Its working principle is derived from oscillometry. The blood pressure cuff is kept at a low pressure (about 20 mmHg), and the oscillations induced by the arterial pulse are converted into blood pressure. Systolic, mean and diastolic blood pressure was measured in 9 healthy volunteers, under physiological conditions, using both the AMP 770 and a traditional oscillometer (Physiogard SM 785 NI, Odam). A group of 124 paired measurements was obtained, with values ranging from 87 to 150 mmHg for systolic pressure, from 48 to 97 mmHg for diastolic pressure, and from 63 to 114 mmHg for mean pressure. The mean differences (APM 770-Physiogard) were -1.2 +/- 10 mmHg for systolic pressure, 3.2 +/- 8 mmHg for diastolic pressure, and -3.8 +/- 8 mmHg for mean pressure. There was no correlation between blood pressure levels and discrepancy in the measurements obtained with the two methods. The Cortronic AMP 770 was reliable under normal circumstances, when compared with a traditional oscillometer. However further studies are required to assess its reliability under pathological circumstances (severe hypotension or hypertension, arrhythmias and sudden changes in blood pressure).