NDT Advance Access originally published online on June 7, 2007
Nephrology Dialysis Transplantation 2007 22(10):2950-2961; doi:10.1093/ndt/gfm288
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In vitro and in vivo evaluation of an oscillometric device for monitoring blood pressure in dialysis patients
1R&D, Gambro Dasco S.p.A, Medolla (MO), Italy, 2Department of Nephrology, Toronto General Hospital, Toronto, Canada and 3Lean S.r.l., Medolla (MO), Italy
Correspondence and offprint requests to: Carlo Alberto Lodi, R&D, Gambro Dasco S.p.A., Via Modenese, 66, I – 41036 Medolla, (MO), Italy. Email: carlo.lodi{at}gambro.com
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Abstract |
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Background. Nowadays, an increasing number of dialysis machines lodge a blood pressure (BP) measuring device, whose accuracy has a clear implication for the patients’ clinical management.
Methods. An automated oscillometric sphygmomanometer (HD-BPMTM by Gambro Dasco) used during haemodialysis was submitted to both in vitro and in vivo tests, in order to evaluate some modifications aimed at improving measurement accuracy and consistency. The results were compared with those obtained by another oscillometric monitor (BX-100TM by Colin).
Three steps of evaluation were followed. First, the maintenance of the overall accuracy requirements prescribed by ANSI/AAMI SP-10 standard was verified. Then, an in vitro validation was carried out by using a test simulator. Finally, during a multi-centre field trial, 392 BP measurement sessions on 53 dialysis patients were collected. Every session consisted of two consecutive intra-dialysis measurements by the oscillometric monitors, each one performed simultaneously to an auscultatory measurement. A comparison with the intra-arterial method was performed as well.
Results. When compared with an in vivo data set previously collected, the HD-BPM accuracy complied with required limits. Second, the internal repeatability with respect to the simulator was satisfactory (SD of the differences between device and simulator readings: HD-BPM: systolic = 5.7, diastolic = 4.2; BX-100: systolic = 4.2, diastolic = 5.5 mmHg). Moreover, the comparison between oscillometric and auscultatory methods during in vivo trial gave similar results for the two monitors, even if systolic pressure SD exceeds the limit recommended by ANSI/AAMI SP-10 (mean value of the differences ± SD: HD-BPM: systolic = 0.5 ± 9.0, diastolic = 1.5 ± 6.9; BX-100: systolic = 3.1 ± 8.2, diastolic = –2.0 ± 7.6 mmHg).
Conclusions. These data underline the importance of performing accuracy evaluations for BP monitors in the conditions where they normally work, by using well-accepted protocols.
Keywords: arrhythmias; blood pressure; dialysis patients; mercury sphygmomanometer; oscillometric device; validation
Received for publication: 22. 8.06
Accepted in revised form: 17. 4.07