Definition of perinatal asphyxia in medical literature: The need of a consensus

Introduction. The pathophysiological definition of perinatal asphyxia (PA) is not operative in clinical practice; by this, several criteria have been propose& abnormalities in electronic fetal monitoring, meconium-stained amniotic fluid, metabolic acidemia, low Apgar score, postasphyctic neurologic and extraneurologic involvement, etc. Aims. 1) To analyze the different definition criteria of PA in international medical literature; 2) to compare the studies in Spain about PA, and to know the epidemiological differences in relation with the definition of PA used Matherial and methods. Bibliographic searching in PubMed database during the period 1994-1999, using the key word perinatal asphyxia'. We review the articles published in these medical journals: Pediatrics, J Pediatrics, Eur J Pediatr, Pediatr Res, Am J Obstet Gynecol, Br Med J, N Engl J Med, An Esp Pediatr and Rev Neurol. Inclusion criteria: original articles with the definition of PA in term-newborns; we excluded other types of articles (letters to editor, review..) and experimental models with animals. In a second part, we review 11 epidemiological studies about PA published in Spain. Results. Twenty-four articles meet the inclusion criteria: 5 in Pediatr Res, 4 in Pediatrics, 4 in J Pediatr, 3 in Eur J Pediatr, 3 in An Esp Pediatr, 3 in Rev Neurol, 1 in Am J Obstet Gynecol and 1 in N Engl J Med. Each study use a different definition: we found differences in the number and combination of criteria, and also in the cutt-of points of quantitative variables (Apgar score and umbilical pH). It is not frequent to classify the severity of asphyctic event. We found important epidemiological differences in the 11 Spanish studies found in the literature about PA: the frequency of PA varies from 1.46 to 14.8% of alive newborns, the frequency of postasphyctic encephalopathy varies from 8.6 to 89%, and the frequency of neurologic sequelae varies from 11.2 to 30.5%. Conclusions. It is necessary to establish a common definition of PA (to differentiate between severe PA, the most important type, and non-severe PA, the most frequent type), wich allow homogeneous comparisons in the epidemiological studies in relation to incidence and morbi-mortality of PA.