The effect of positive end-expiratory pressure on pulse pressure variation

  • Francois J Smith University of Pretoria
  • Marlize Geyser University of Pretoria
  • Igne Schreuder University of Pretoria
  • Pieter J Becker Medical Research Council
Keywords: blood volume, monitoring, pulse pressure, blood pressure determination, positive-pressure respiration, positive end-expiratory pressure

Abstract

Objectives: To determine the effect of different levels of positive end-expiratory pressure (PEEP) on pulse pressure variation (PPV). Design: An observational study. Setting: Operating theatres of a tertiary training hospital. Subjects: Ventilated patients who required intra-arterial blood pressure monitoring. Outcome measures: PPV during different levels of PEEP. Method: Patients were anaesthetised by means of a standard technique and ventilated with a tidal volume of 9 ml/kg ideal body mass. The PPV was calculated at PEEP levels of 2, 5, 8 and 10 cmH2O. PPV was compared at the various PEEP levels. Results: PPV at a PEEP of 8 cmH2O and 10 cmH2O was significantly larger than that at 2 cmH2O (p-value < 0.001). PPV at a PEEP of 10 cmH2O was significantly larger than that at 8 cmH2O (p-value < 0.001). PPV at a PEEP of 8 cmH2O was larger than that at 5 cmH2O (p-value = 0.002). PPV at a PEEP of 2 and 5 cmH2O did not differ significantly (p-value = 0.194). Conclusion: We have demonstrated that, in patients with normal lungs, PEEP has a significant influence on PPV. PPV may be overestimated if PEEP ≥ 8 cmH2O is applied in patients who are ventilated with a tidal volume of 9 ml/kg. It is recommended that in patients with healthy lungs PPV should be measured at a standardised PEEP of ≤ 5 cmH2O.

Author Biographies

Francois J Smith, University of Pretoria
BSc, MBChB, MMed, FCA(SA), MD Principal Specialist Department of Anaesthesiology Faculty of Health Sciences University of Pretoria South Africa
Marlize Geyser, University of Pretoria
MBChB, DA(SA), MMed, FCA(SA) Registrar Department of Anaesthesiology Faculty of Health Sciences University of Pretoria South Africa
Igne Schreuder, University of Pretoria
MBChB, DA(SA), MMed Registrar Department of Anaesthesiology Faculty of Health Sciences University of Pretoria South Africa
Pieter J Becker, Medical Research Council
PhD Head Biostatics Unit Medical Research Council
Published
2012-06-19
Section
Original Research