Bedside assessment of the effects of positive end-expiratory pressure on lung inflation and recruitment by the helium dilution technique and electrical impedance tomography

Tommaso Mauri, Nilde Eronia, Cecilia Turrini, Marta Battistini, Giacomo Grasselli, Roberto Rona, Carlo Alberto Volta, Giacomo Bellani, Antonio Maria Pesenti

Research output: Contribution to journalArticle

Abstract

Purpose: Higher positive end-expiratory pressure might induce lung inflation and recruitment, yielding enhanced regional lung protection. We measured positive end-expiratory pressure-related lung volume changes by electrical impedance tomography and by the helium dilution technique. We also used electrical impedance tomography to assess the effects of positive end-expiratory pressure on regional determinants of ventilator-induced lung injury. Methods: A prospective randomized crossover study was performed on 20 intubated adult patients: 12 with acute hypoxemic respiratory failure and 8 with acute respiratory distress syndrome. Each patient underwent protective controlled ventilation at lower (7 [7, 8] cmH2O) and higher (12 [12, 13] cmH2O) positive end-expiratory pressures. At the end of each phase, we collected ventilation, helium dilution, and electrical impedance tomography data. Results: Positive end-expiratory pressure-induced changes in lung inflation and recruitment measured by electrical impedance tomography and helium dilution showed close correlations (R2 = 0.78, p < 0.001 and R2 = 0.68, p < 0.001, respectively) but with relatively variable limits of agreement. At higher positive end-expiratory pressure, recruitment was evident in all lung regions (p < 0.01) and heterogeneity of tidal ventilation distribution was reduced by increased tidal volume distending the dependent lung (p < 0.001); in the non-dependent lung, on the other hand, compliance decreased (p < 0.001) and tidal hyperinflation significantly increased (p < 0.001). In the subgroup of ARDS patients (but not in the whole study population) tidal hyperinflation in the dependent lung regions decreased at higher positive end-expiratory pressure (p = 0.05), probably indicating higher potential for recruitment. Conclusions: Close correlations exist between bedside assessment of positive end-expiratory pressure-induced changes in lung inflation and recruitment by the helium dilution and electrical impedance tomography techniques. Higher positive end-expiratory pressure exerts mixed effects on the regional determinants of ventilator-induced lung injury; these merit close monitoring.

Original languageEnglish
Pages (from-to)1576-1587
Number of pages12
JournalIntensive Care Medicine
Volume42
Issue number10
DOIs
Publication statusPublished - Oct 1 2016

Keywords

  • Acute respiratory distress syndrome
  • Electrical impedance
  • Lung volume measurements
  • Mechanical ventilation
  • Positive end-expiratory pressure
  • Ventilator-induced lung injury

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine

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