BLOOD-PRESSURE RANGES IN PREMATURE-INFANTS .2. THE FIRST WEEK OF LIFE

Objective. To examine the arterial blood pressure in the first week of life in a healthy premature population. Design. Population-based coho rt study. Setting. Three intensive care nurseries in central New Jerse y. Patients. Premature infants with birth weights less than 2000 g. Ma in Outcome Measures. We documented daily maximum and minimum systolic and maximum and minimum diastolic blood pressures during the first 7 d ays of life. To examine the effects on these ranges of blood pressure of specific risk factors likely to affect blood pressure, we identifie d four groups of infants: (1) healthy infants without any of the major risk factors (n = 193); (2) infants who were mechanically ventilated but free of any of the other conditions (n = 225); (3) infants with hi stories of maternal hypertension or preeclampsia (n = 38); and (4) inf ants with low Apgar scores (less than 3 at 1 minute and less than 6 at 5 minutes) regardless of the presence of other conditions (n = 86). R esults. Blood pressure increased steadily in the first week of life in all four groups. There was no relationship between any of the four bl ood pressure variables, or trends in blood pressure over time, with bi rth weight, gender, or race. Regression equations (based on all infant s with available data) for blood pressure ranges by day of life reveal ed that the maximum systolic blood pressure increased by 2.6 mm Hg/d, the minimum systolic blood pressure increased by 1.8 mm Hg/d, the maxi mum diastolic blood pressure increased by 2.0 mm Hg/d, and the minimum diastolic blood pressure increased by 1.3 mm Hg/d. Conclusions. Infan ts with birth asphyxia and ventilated infants had significantly lower systolic and diastolic blood pressures than healthy infants.