Blood pressure exerts more influence on cerebral blood flow velocity than arterial carbon dioxide tension in piglets less than 24 hours old : J.M. Renniea, P.J. Morrisa, D.H. Evansb, M.I. Levenea and M. Thoresen, dAddenbrooke's Hospital, Cambridge, bDept. of Medical Physics, Leicester Royal Infirmary, cDept. of Paediatrics, University of Leeds, U.K. and Dept. of Paediatrics, Ulleval Sykehus, Oslo, Norway