Assessment of Doppler ultrasound to measure systolic and diastolic blood pressures in infants and young children.

A recently developed instrument uses the Doppler shift technique to detect vessel wall movement, and it has been suggested that in conjunction with a conventional sphygmomanometer systolic and diastolic blood pressures can be measured. A controlled study was carried out in 20 children recovering from cardiac surgery where direct intra-arterial measurements (one observer) were compared with independent measurements using the Doppler instrument (2 observers). Systolic pressures measured directly and by Doppler technique correlated well and there was no significant difference between intra-arterial and indirect measurements whether the latter were taken by doctors or by nurses. In contrast, direct and indirect diastolic pressure measurements correlated poorly and were significantly overestimated with a mean difference of 6-25 mmHg (range +25 to -10) for doctors, and 4-25 mmHg (range +20 to -10) for nurses. Thus, the instrument adequately measured systolic blood pressure, but in our hands did not give precise measurements for diastolic blood pressure.