Comparison of noninvasive and central arterial blood pressure measurements in ELBW infants

Objective: The objective of this study was to evaluate the difference between noninvasive and central arterial blood pressure measurements in extremely low-birth-weight (ELBW) infants. Study Design: We conducted a retrospective cohort study of infants with birth weight ≤ 1000 g and who were admitted to a single center in 2005. Paired noninvasive and umbilical arterial blood pressure measurements obtained in the first 72 h were compared. The primary outcome was the differential between the paired measurements. Noninvasive blood pressure (NBP) measurements were defined as clinically acceptable if the differential between the pairs was 15% or lower. Result: We obtained 146 pairs of measurements from 38 infants. The median absolute differences between noninvasive and arterial systolic, mean and diastolic blood pressure measurements were + 18.5, + 12 and + 10 mm Hg, respectively (percentage differential of 43, 39 and 41%, respectively). In total 75% of the noninvasive measurements of mean blood pressure were clinically unacceptable. No patient or measurement characteristic was significantly associated with clinically unacceptable noninvasive measurements. Conclusion: In ELBW infants, NBP measurements substantially overestimate systolic, mean and diastolic blood pressures compared with central arterial measurements.