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

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

In vitro model study.

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

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.

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).

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.

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.