Accuracy, precision, and interobserver and intraobserver agreements related to pressure-measurement devices

Abstract

Objective: To evaluate the accuracy, precision, and observer agreement of three pressure measurement devices.

Study design: In vitro model study.

Sample population: Water manometer with built-in gauge (WMg), arterial pressure transducer (APT), and Compass CT (CCT).

Methods: The model was set to five predetermined pressures (4, 8, 13, 17, and 24 cm H₂O) using a water manometer with a ruler (WMr) as the gold standard. Each device was tested at each pressure in a randomized order by three investigators. Bland-Altman plots were used to assess agreement between devices. Intraclass correlation coefficients (ICC) were calculated for interobserver and intraobserver agreements.

Results: The mean differences (cm H₂O) ± SEM in comparison with the set pressure were -0.020 ± 0.010 (WMg), -0.390 ± 0.077 (APT), and -1.267 ± 0.213 (CCT). Pressures measured by WMg did not differ from those measured by WMr. Pressures measured by all devices did not differ from each other (p > .062 for all comparisons). Interobserver agreement was excellent (1.000), and intraobserver agreement was excellent (0.985, 0.990, 0.998 for each observer).

Conclusion: Compared to the WMr, the WMg was the most accurate and precise, followed by the APT; the CCT was the least accurate and precise. Interobserver and intraobserver agreements for all three devices were excellent.

Clinical significance: The largest mean difference of all devices was within 1.3 cm H₂O of the set pressure, indicating possible clinical utility of any of the devices. However, WMr or WMg should be considered first due to their high precision and accuracy.