Which pressure to believe? A comparison of direct arterial with indirect blood pressure measurement techniques in the pediatric intensive care unit.

OBJECTIVE

To determine the accuracy of arterial blood pressure monitoring using 1) direct arterial; 2) automated oscillometric; and 3) sphygmomanometer/Doppler ultrasound measurements in pediatric intensive care patients comparing methods 1) and 2) with 3), the gold standard used to define normal blood pressure.

DESIGN

Prospective observational study.

SETTING

Pediatric intensive care unit of a tertiary care pediatric teaching hospital.

PATIENTS: Forty children (birth to 17 yrs) admitted to the pediatric intensive care unit with various clinical conditions requiring a radial arterial catheter for continuous arterial blood pressure monitoring.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN

RESULTS

Each subject had measurements taken every 6 hrs over a 24-hr period. Each set of measurements were: direct arterial blood pressure, indirect blood pressure using the Phillips automated oscillometric device, and indirect blood pressure using the sphygmomanometer and Doppler ultrasound. Analysis used the Bland-Altman plot followed by paired t testing to compare the three different methods. One hundred sixty triads of measurements were analyzed. There were no significant differences between the methods of blood pressure measurement when groups were analyzed based on age. When analyzed by age-specific normo-, hypo-, and hypertensive criteria, arterial blood pressure measurements agree closely with Doppler ultrasound readings, whereas systolic arterial blood pressure measurements were lower than indirect blood pressure using the Phillips automated oscillometric device readings in the hypotensive group (p < .001). In the hypertensive group, the systolic arterial blood pressure values were higher and indirect blood pressure using the Phillips automated oscillometric device readings lower (p < .001) than Doppler ultrasound (p = .03). There was no clinically significant difference between methods in the normotensive group. Diastolic blood pressure measurements were higher by arterial blood pressure in normotensive and hypertensive groups but no different in the hypotensive group.

CONCLUSION

Outside the normotensive range, the automated readings were higher during hypotension and lower during hypertension compared with the arterial and Doppler ultrasound methods. The arterial blood pressure was closer to the gold standard Doppler ultrasound blood pressure in all three blood pressure groups.