[Influence of Hypotension on the Short-term Prognosis of Preterm Infants with a Gestational Age of <32 Weeks]

Objectives: To investigate the influence of early-stage hypotension defined as mean arterial pressure (MAP)<gestational age (weeks) or MAP<30 mmHg on the short-term prognosis of preterm infants with a gestational age of <32 weeks.

Methods: A total of 320 preterm infants who were admitted to Maternal and Child Health Hospital of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology from April 2020 to August 2021 and met the inclusion criteria were enrolled in this prospective study. Blood pressure within 72 hours was monitored. The definition of hypotension and grouping were as follows: (1) Of the 320 preterm infants, those with MAP<gestational age in 2 consecutive measurements served as the hypotension group (=104), and the others (=216) served as the control group; (2) Of the 320 preterm infants, those with MAP<30 mmHg in 2 consecutive measurements served as the hypotension group (=114), and the others served as the control group (=206). Perinatal data and clinical data during hospitalization were collected.Poor short-term prognosis was defined as death during hospitalization and/or grade Ⅲ-Ⅳ periventricular-intraventricular hemorrhage identified within 1 week after birth. The multivariate logistic regression analysis was used to investigate the influence of hypotension based on the above two definitions on the short-term prognosis of preterm infants.

Results: Compared with the control group, the hypotension group based on the above two definitions had higher incidence rates of the clinical manifestations of hypoperfusion, poor prognosis, hemodynamically significant patent ductus arteriosus, and pulmonary hemorrhage (<0.05). In addition, compared with the control group, the hypotension group defined by MAP<30 mmHg had higher incidence rates of periventricular-intraventricular hemorrhage and bronchopulmonary dysplasia and mortality rate during hospitalization (<0.05). The incidence of poor short-term prognosis in the hypotension group defined by MAP<30 mmHg was higher than that in the hypotension group defined by MAP<gestational age (18.4% vs 12.5%), but the difference was not statistically significant (>0.05).The univariate analysis showed that the poor short-term prognosis was related to birth of cesarean section, gestational age, an Apgar score of ≤ 5 at 5 minutes, use of vasoactive drugs within 72 hours, mechanical ventilation within 72 hours, and hypotension under the two definitions (<0.05).The multivariate logistic regression showed that hypotension based on either definition was not an independent risk factor for poor prognosis (>0.05).

Conclusions: Hypotension based on either definition is not an independent risk factor for short-term poor prognosis in preterm infants with a gestational age of <32 weeks. Hypotension defined by MAP<30 mmHg might be more sensitive than that defined by MAP<gestational age in predicting short-term adverse outcomes, which needs further analysis by large sample studies.