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J Clin Monit Comput · Feb 2016
Transient stop-flow arm arterial-venous equilibrium pressure measurement: determination of precision of the technique.
- Hollmann D Aya, Andrew Rhodes, Nick Fletcher, R Michael Grounds, and Maurizio Cecconi.
- Intensive Care Directorate, St George's University Hospitals NHS Foundation Trust and St George's University of London, Blackshaw road, Tooting, London, SW17 0QT, UK. hollmann.aya@nhs.net.
- J Clin Monit Comput. 2016 Feb 1; 30 (1): 55-61.
AbstractTransient stop-flow arm arterial-venous equilibrium pressure (Pmsf-arm) is a validated technique for measuring the mean systemic filling pressure (Pmsf). Pmsf is a functional measure of the effective intravascular volume status. This study aims to assess the precision of the Pmsf-arm measurement. Pmsf-arm was measured by inflating a pneumatic tourniquet around the upper arm 50 mmHg above systolic pressure for 60 s, four times consecutively, with an interval of 5 min. Arterial (Pa) and venous pressure (Pv) were recorded every 10 s. Pa-Pv difference was calculated to determine the stop-flow time. The coefficient error (CE) was determined and used to derive the least significant change (LSC) in Pmsf-arm that this technique could reliably detect. The rANOVA test was used to compare repeated measurements of the four determinations of Pmsf-arm. 80 measurements of Pmsf-arm were studied in 20 patients. Pa and Pv equalised after 60 s of inflation (Pa-Pv difference 0 ± 0.01 mmHg). There were no significant differences of Pmsf-arm values among determinations. For a single measurement, the CE was 5 % (±2 %) and the LSC was 14 % (±5 %). Averaging two, three and four measurements the CE improves to 4 % (±1 %), 3 % (±1 %) and 3 % (±1 %) respectively, and the LSC was reduced to 10 % (±4 %), 8 % (±3 %) and 7 % (±3 %) respectively. One measurement of Pmsf-arm can reliably detect changes on Pmsf-arm of 14 %. The precision of Pmsf-arm technique improves when averaging two or three measurements.
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