Accuracy of oscillometric blood pressure measurement according to the relation between cuff size and upper-arm circumference in critically ill patients

Objective: To evaluate the accuracy of oscillometric blood pressure measure ment according to the relation between cuff size and upper-arm circumferenc e in critically ill patients. Design: Prospective data collection. Setting: Emergency department in a 2,000-bed inner city hospital, Patients: Thirty-eight patients categorized into three groups according to their upper-arm circumference (group 1: 18-25 cm; group 11: 25.1-33 cm; and group ill: 33.1-47.5 cm) were enrolled in the study protocol, Interventions: In each patient, all three cuff sizes (Hewlett-Packard Cuff 40401 B, C, and D) were used to perform an oscillometric blood pressure mea surement at least within 3 mins until ten to 20 measurements for each cuff size were achieved. Invasive mean arterial blood pressure measurement was d one by cannulation of the contralateral radial artery with direct transduct ion of the systemic arterial pressure waveform, The corresponding invasive blood pressure value was obtained at the end of each oscillometric measurem ent. Measurement and Main Results: Overall, 1,494 pairs of simultaneous oscillom etric and invasive blood pressure measurements were collected in 38 patient s (group I, n = 5; group II, n = 23; and group III, n = 10) over a total ti me of 72.3 hrs, Mean arterial blood pressure ranged from 35 to 165 mm Hg, T he overall discrepancy between oscillometric and invasive blood pressure me asurement was -6.7 +/- 9.7 mm Hg (p < ,0001), if the recommended cuff size according to the upper-arm circumference was used (539 measurements), Of al l the blood pressure measurements, 26.4% (n = 395) had a discrepancy of gre ater than or equal to 10 mm Hg and 34.2% (n = 512) exhibited a discrepancy of greater than or equal to 20 mm Hg. No differences between invasive and n oninvasive blood pressure measurements were noted in patients either with o r without inotropic support (-6,6 + 7.2 vs, -8.6 + 6.8 mm Hg; not significa nt). Conclusion: The oscillometric blood pressure measurement significantly unde restimates arterial blood pressure and exhibits a high number of measuremen ts out of the clinically acceptable range, The relation between cuff size a nd upper-arm circumference contributes substantially to the inaccuracy of t he oscillometric blood pressure measurement, Therefore, oscillometric blood pressure measurement does not achieve adequate accuracy in critically ill patients.