Intraobserver variation in Doppler ultrasound assessment of pulmonary artery pressure.

Intraobserver variation associated with the non-invasive assessment of pulmonary artery pressure (PAP), using measurement of pulmonary artery Doppler derived systolic time intervals, was investigated. Forty pairs of independent ultrasound examinations of the pulmonary artery were performed by a single observer in 20 preterm infants, median gestation 27 weeks (range 24-31 weeks). Median age at study was 17 days (range 1-47 days). paired measurements of acceleration time (AT), ratio between acceleration time and right ventricular ejection time (AT:RVET), corrected AT, and corrected AT:RVET were compared to assess intraobserver agreement. For the corrected AT:RVET ratio, the mean percentage difference between observations was -0.9% (95% confidence intervals -5.0 to 3.1%). The limits of agreement for the two measurements were -26.3 to 24.5%. The coefficient of repeatability was 25.4%. Variation for other indices was similar. Non-invasive assessment of PAP using Doppler derived systolic time intervals is associated with considerable intraobserver variation.