Reliability of intrabladder pressure measurement in intensive care.

Background: The reliability of intrabladder pressure measurements obtained in nonsupine patients is unknown.

Objectives: To investigate the reliability of measurements of intrabladder pressure obtained with 30 degrees head-of-bed elevation.

Methods: With patients supine, 30 degrees head-of-bed elevation, and instillation of 0 and 25 mL physiological saline, intrabladder pressure was measured in 10 patients: twice by one nurse to assess intraobserver reliability and once by a different nurse to assess interobserver reliability. Data were analyzed by using paired t tests, Pearson correlation, and Bland-Altman analysis.

Results: For intraobserver reliability, measurements obtained with no instillation (mean difference, -1.8; 95% confidence interval [CI], -4.9 to 1.3; P = .22) and with instillation of 25 mL (mean difference, -0.6; 95% CI, -1.8 to 0.6; P = .28) did not differ significantly. Pearson r values were 0.74 and 0.81, respectively. Estimated Bland-Altman bias and limits of agreements were -1.8 and -10.3 to 6.7 mm Hg and -0.6 and -3.82 to 2.62 mm Hg, respectively. For interobserver reliability, measurements obtained with no instillation (mean difference, 1.0; 95% CI, -2.2 to 4.2; P = .49) and with instillation of 25 mL (mean difference, -0.7; 95% CI, -2.45 to 1.05; P = .39) did not differ significantly. Pearson r values were 0.78 and 0.82, respectively. Estimated Bland-Altman bias and limits of agreement were 1.0 and -7.76 to 9.76 mm Hg and -0.7 and -5.5 to 4.0 mm Hg, respectively.

Conclusions: Reliability of intrabladder pressure measurements obtained with 30 degrees head-of-bed elevation is strong.