A computerized system for continuous physiologic data collection and analysis: initial report on mean arterial blood pressure in very low-birth-weight infants.

A system for continuous measurement and analysis of mean arterial blood pressure (MABP) by microcomputer is presented. The system allows prolonged recording and maintenance of fine detail by sequential evaluation and storage of up to 3,600 data points per hour. Fifteen preterm appropriate-for-gestational-age (AGA) infants weighing less than or equal to 1,500 g (very low birth weight) who were free of pulmonary and neurologic disease were monitored continuously from birth to 5 days of age. MABP was recorded via an umbilical arterial catheter with a pressure transducer and module interfaced with the microcomputer. Software was developed to analyze this stored data rapidly. MABP was found to correlate significantly with gestational age from 3 to 15 hours of age (P less than .05). Significant correlation was rare after 20 hours of age. MABP increased as a function of postnatal age in 11 infants. This increase was greater (0.31 to 0.54 mm Hg/h) for the least mature infants (27 to 29 weeks of gestation). The increase for the most mature infants (31 to 32 weeks of gestation) was low (0 to 0.24 mm Hg/h), and in three infants a small negative slope was seen. The steep rise in MABP during the first 40 hours of life in the least mature infants may be due to the perfusion requirements of extrauterine life. These pressures may be at or near the threshold for rupture of immature vascular beds such as are found in the subependymal germinal matrix and thus predispose to intraventricular hemorrhage.