Objective Securing an arterial line to monitor continuous blood pressure (BP) is difficult in infants. We aimed to reveal the extent of discrepancies between oscillometric and direct BP. Study Design Infants who required continuous BP monitoring were prospectively enrolled. Direct and indirect BP were simultaneously recorded. Disposable BP cuffs matching one-half to two-thirds of the upper arm circumference were used. Results A total of 74 infants were studied (gestational age [GA], 24-42 weeks). The correlation coefficients of systolic, diastolic, and mean arterial BP of indirect and direct measurements were 0.87, 0.82, and 0.84, respectively (p < 0.001). The mean differences in systolic, diastolic, and mean arterial BP (indirect minus direct BP) were 2.2 +/- 5.7, - 6.0 +/- 5.8, and - 1.3 +/- 5.7 mm Hg, respectively. Oscillometric measurements significantly underestimated systolic BP in light-for-gestational-age infants and diastolic BP in infants without fentanyl administration. There were no significant correlations between discrepant BP measurements and edema, vasopressor administration, arterial line location, GA, postnatal age, body weight, pulse rate, or hemoglobin level. In 4.1% of infants, systolic BP increased by 10 to 15 mm Hg at the time of cuff expansion. Conclusion We recommend intra-arterial BP measurement when the BP values seriously influence the therapeutic protocol.
