1 Dept of Pediatric Cardiology, The Children's Hospital, Ladywood, Birmingham B16 8ET, England
To the Editor.
We enjoyed this recent paper from Walther et al1 assessing pressure gradient across the arterial duct in neonates with respiratory distress syndrome. However, the initial statement that there have been no previous studies relating severity of respiratory distress syndrome to pulmonary artery pressure is incorrect. The conclusions of this study need to be related to the three earlier studies of Halliday et al,2 Evans and Archer,3 and Skinner et al,4 all of which studied the relationship of pulmonary artery pressure to disease severity.