Tracing best PEEP by applying PEEP as a RAMP

Byline: C. D. Punt (1), J. J. Schreuder (2), J. R. C. Jansen (3), S. A. A. P. Hoeksel (2), A. Versprille (3) Keywords: Key words (Best) PEEP; Haemodynamics; Oxygen transport; Pulmonary edema Abstract: Objective: The aim of this study was to show the feasibility of a slow, continuously increasing level of positive end-expiratory pressure (PEEP) (ramp manoeuvre) in selecting best PEEP and to evaluate whether best PEEP, as definded by maximal oxygen transport, coincides with best systemic arterial oxygenation or best compliance. Design: In 11 anaesthetized piglets, PEEP was increased between 0 cm[H.sub.2]O (zero end-expiratory pressure ZEEP) and 15 cm[H.sub.2]O (PEEP.sub.15) with a constant rate of 0.67 cm[H.sub.2]O * min.sup.-1. This ramp manoeuvre was performed both under normal conditions and after induction of an experimental lung oedema. During the ramp manoeuvre, haemodynamic and pulmonary variables were monitored almost continuously. Results: During the rise in PEEP, cardiac output declined in a non-linear way. In the series with normal conditions, best PEEP was always found at ZEEP. In the series with experimental lung oedema, best PEEP, as defined by maximum oxygen transport, was found at PEEP.sub.1--6, as defined by maximal compliance, at PEEP.sub.7.5 and by maximal arterial oxygen tension (PaO.sub.2) at PEEP.sub.10--14. Conclusions: Best PEEP according to oxygen transport is lower than best PEEP according to compliance and PaO.sub.2 the use of PEEP as a ramp might prevent unnecessarily high levels of PEEP. Author Affiliation: (1) Atrium Medisch Centrum, Department of Anaesthesiology, P. O. Box 4446, 6401 CX Heerlen, The Netherlands Tel.: + 31 (45) 5 76 70 10 Fax: + 31 (45) 5 76 60 55, NL (2) Department of Anaesthesiology, Cardiovascular Research Institute, University Hospital Maastricht, The Netherlands, NL (3) Pathophysiological Laboratory of the Department of Pulmonary Diseases, Erasmus University Rotterdam, The Netherlands, NL Article note: Received: 16 June 1997 Accepted: 24 April 1998