Method specificity of non‐invasive blood pressure measurement: oscillometry and finger pulse pressure vs acoustic methods

1. The agreement of blood pressure measurements by stethoscope auscultation (SBPa, DBPa‐IV and DBPa‐V), oscillometry (Dinamap; SBPo, and DBPo) and digital photoplethysmography (Finapres; SBPf, and DBPf) with the graphical analysis of the analogue microphone signals of vascular wall motion sound (SBPg and DBPg) was evaluated in eight healthy subjects in the presence of responses to the intravenous infusion of 1 microgram min‐1 isoprenaline. 2. In general, there was good agreement between the SBP/DBP‐measurements based on auscultatory Korotkoff‐I‐ and IV‐criteria and the reference method; the average method difference in estimating the isoprenaline responses for SBPa‐ SBPg was: ‐1.1, 95% CI: ‐5.4 to 3.1 mm Hg with a within‐subject between‐ method repeatability coefficient (REP) of 11.6 mm Hg and for DBPa‐IV‐ DBPg: 3.5, 95% CI: ‐0.5 to 6.5 mm Hg, REP: 11.5 mm Hg. The ausculatation of Korotkoff‐V substantially overestimated the isoprenaline induced reduction of DBP: method difference DBPa‐V‐DBPg: ‐ 11.3, 95% CI: ‐17.8 to ‐4.7 mm Hg, REP: 31.8 mm Hg. 3. Oscillometry yielded good approximations for the SBP response to isoprenaline (average method difference SBPo‐SBPg: ‐2.9, 95% CI: ‐9.0 to 3.3 mm Hg, REP: 17.6 mm Hg) but was poorly sensitive with regard to the DBP responses: method difference DBPo‐DBPg: 6.5, 95% CI: ‐1.3 to 14.3 mm Hg, REP: 25.7 mm Hg. 4. Whilst the finger pulse pressure agreed well with regard to DBP (method difference for the DBP responses to isoprenaline: DBPf‐DBPg: 1.8, 95% CI: ‐5.1 to 8.6 mm Hg, REP: 18.5 mm Hg) it was rather unsatisfactory with regard to SBP (method difference SBPf‐SBPg: ‐14.1, 95% CI: ‐28.2 to ‐0.1 mm Hg, REP: 49.9 mm Hg).