uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Positive end-expiratory pressure optimization with forced oscillation technique reduces ventilator induced lung injury: a controlled experimental study in pigs with saline lavage lung injury
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
Show others and affiliations
2011 (English)In: Critical Care, ISSN 1364-8535, E-ISSN 1466-609X, Vol. 15, no 3, R126- p.Article in journal (Refereed) Published
Abstract [en]

Introduction: Protocols using high levels of positive end-expiratory pressure (PEEP) in combination with low tidal volumes have been shown to reduce mortality in patients with severe acute respiratory distress syndrome (ARDS). However, the optimal method for setting PEEP is yet to be defined. It has been shown that respiratory system reactance (Xrs), measured by the forced oscillation technique (FOT) at 5 Hz, may be used to identify the minimal PEEP level required to maintain lung recruitment. The aim of the present study was to evaluate if using Xrs for setting PEEP would improve lung mechanics and reduce lung injury compared to an oxygenation-based approach.

Methods: 17 pigs, in which acute lung injury (ALI) was induced by saline lavage, were studied. Animals were randomized into two groups: in the first PEEP was titrated according to Xrs (FOT group), in the control group PEEP was set according to the ARDSNet protocol (ARDSNet group). The duration of the trial was 12 hours. In both groups recruitment maneuvers (RM) were performed every 2 hours, increasing PEEP to 20 cmH(2)O. In the FOT group PEEP was titrated by monitoring Xrs while PEEP was reduced from 20 cmH(2)O in steps of 2 cmH(2)O. PEEP was considered optimal at the step before which Xrs started to decrease. Ventilatory parameters, lung mechanics, blood gases and hemodynamic parameters were recorded hourly. Lung injury was evaluated by histopathological analysis.

Results: The PEEP levels set in the FOT group were significantly higher compared to those set in the ARDSNet group during the whole trial. These higher values of PEEP resulted in improved lung mechanics, reduced driving pressure, improved oxygenation, with a trend for higher PaCO(2) and lower systemic and pulmonary pressure. After 12 hours of ventilation, histopathological analysis showed a significantly lower score of lung injury in the FOT group compared to the ARDSNet group.

Conclusions: In a lavage model of lung injury a PEEP optimization strategy based on maximizing Xrs attenuated the signs of ventilator induced lung injury. The respiratory system reactance measured by FOT could thus be an important component in a strategy for delivering protective ventilation to patients with ARDS/acute lung injury.

Place, publisher, year, edition, pages
2011. Vol. 15, no 3, R126- p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-162094DOI: 10.1186/cc10236ISI: 000295799700008OAI: oai:DiVA.org:uu-162094DiVA: diva2:458858
Available from: 2011-11-24 Created: 2011-11-24 Last updated: 2015-07-07Bibliographically approved
In thesis
1. New methods for optimization of mechanical ventilation
Open this publication in new window or tab >>New methods for optimization of mechanical ventilation
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Mechanical ventilation saves lives, but it is an intervention fraught with the potential for serious complications. Prevention of these complications has become the focus of research and critical care in the last twenty years. This thesis presents the first use, or the application under new conditions, of three technologies that could contribute to optimization of mechanical ventilation.

Optoelectronic plethysmography was used in Papers I and II for continuous assessment of changes in chest wall volume, configuration, and motion in the perioperative period. A forced oscillation technique (FOT) was used in Paper III to evaluate a novel positive end-expiratory pressure (PEEP) optimization strategy. Finally, in Paper IV, FOT in conjunction with an optical sensor based on a self-mixing laser interferometer (LIR) was used to study the oscillatory mechanics of the respiratory system and to measure the chest wall displacement.

In Paper I, propofol anesthesia decreased end-expiratory chest wall volume (VeeCW) during induction, with a more pronounced effect on the abdominal compartment than on the rib cage. The main novel findings were an increased relative contribution of the rib cage to ventilation after induction of anesthesia, and the fact that the rib cage initiates post-apneic ventilation. In Paper II, a combination of recruitment maneuvers, PEEP, and reduced fraction of inspired oxygen, was found to preserve lung volume during and after anesthesia. Furthermore, the decrease in VeeCW during emergence from anesthesia, associated with activation of the expiratory muscles, suggested that active expiration may contribute to decreased functional residual capacity, during emergence from anesthesia.

In the lavage model of lung injury studied in Paper III, a PEEP optimization strategy based on maximizing oscillatory reactance measured by FOT resulted in improved lung mechanics, increased oxygenation, and reduced histopathologic evidence of ventilator-induced lung injury.

Paper IV showed that it is possible to apply both FOT and LIR simultaneously in various conditions ranging from awake quiet breathing to general anesthesia with controlled mechanical ventilation. In the case of LIR, an impedance map representing different regions of the chest wall showed reproducible changes during the different stages that suggested a high sensitivity of the LIR-based measurements.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 62 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1102
mechanical ventilation, optoelectronic plethysmography, forced oscillation technique, laser interferometry
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology and Intensive Care
urn:nbn:se:uu:diva-249172 (URN)978-91-554-9238-0 (ISBN)
Public defence
2015-06-03, Enghoffsalen, Entrance 50, Akademiska sjukhuset, Uppsala, 09:15 (Swedish)
Available from: 2015-05-13 Created: 2015-04-11 Last updated: 2015-07-07

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Kostic, PeterHedenstierna, GöranLarsson, AndersFrykholm, Peter
By organisation
Anaesthesiology and Intensive CareClinical Physiology
In the same journal
Critical Care
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 203 hits
ReferencesLink to record
Permanent link

Direct link