[Risk factors for presence of complications of the mechanical ventilatory assistance in the newborn].

Background: The mechanical ventilatory assistance (MVA) is a procedure that is used very often in the neonatal intensive care units but its use its linked to a lot of complications. The objective of this study was to determine the risk factors for the presence of complications of the MVA in the newborns infants.

Material And Methods: One hundred thirty five medical records from January 98 to June 2000 of newborns that had been discharged by amelioration or death were reviewed retrospectively. All of them had been received MVA; twenty medical record were excluded. They were divided in two groups: group A, neonates that had presented complications during MVA, composed of 40 patients (cases) and B, neonates with MVA, but that had not presented complications due to the procedure of 75 patients (controls). In group A there were 39 preterm neonates and in B, 58 preterm neonates, the rest were term neonates. It was used descriptive and inferential statistics. Odds ratio (OR) and multivariate analysis were used to study risk factors with confidence interval (CI) of 95%. Statistical significance was considered at p < 0.05.

Results: There was significative difference in birth weight. Gestational age and Apgar score between the two groups in favor of group B. There was significative difference too in inspiratory oxygen fraction (IOF), the peak inspiratory pressure (PIP) and cycles in favor of group A (before complications occur). The significative risk factors in the bivariate analysis for the presence complications were: birth weight of 1,500 g or less, 36 weeks of gestational age or less, total time of ventilation of seven days or more , IOF of 1 (100%), cycles of 60 per minute or more and peak inspiratory pressure (PIP) of 30 cm of water or more in the first days of life (all with p < 0.05). The combination of prematurity plus respiratory distress syndrome (RDS) as admission diagnosis reached significance for the presence of complications with an OR of 7.34 and CI of 95% from 1.91 to 23.05, p = 0.001 and the multivariate analysis reached significance for the presence of complications: low birth weight, total time of ventilation of seven days or more, IOF of 1 (100%), cycles of 60 per minute or more, and the combination of prematurity plus RDS as admission diagnosis all with p < 0.05. The mortality was associated significatively to the complications with p < 0.009. The more frequent complications were pneumonia, pulmonary interstitial emphysema and bronchopulmonary dysplasia.

Conclusions: We concluded that newborn patients critically ill, with low birth weight, low gestational age, with RDS, who need more ventilatory support will be more liable to have complications and, as consequence, the mortality will be increased. For this reason it is essential a close monitoring of this group of patients for not over supporting them in IOF, PIP and cycles, thus avoiding as far as possible, the complications of the MVA.