Regional lung volume changes in children with acute respiratory distress syndrome during a derecruitment maneuver.

Objective: Regional differences in lung volume have been described in adults with acute respiratory distress syndrome, but it remains unclear to what extent they occur in children. To quantify regional alveolar collapse that occurred during mechanical ventilation during a standardized suctioning maneuver, we evaluated regional and global relative impedance changes (relative DeltaZ) in children with acute respiratory distress syndrome using electrical impedance tomography.

Design: Prospective observational trial.

Lung volume recruitment after surfactant administration modifies spatial distribution of ventilation.

Rationale: Although surfactant replacement therapy is an established treatment in infant respiratory distress syndrome, the optimum strategy for ventilatory management before, during, and after surfactant instillation remains to be elucidated.

Objectives: To determine the effects of surfactant and lung volume recruitment on the distribution of regional lung ventilation.

Methods: Acute lung injury was induced in 16 newborn piglets by endotracheal lavage.

Comparison of different methods to define regions of interest for evaluation of regional lung ventilation by EIT.

The measurement of regional lung ventilation by electrical impedance tomography (EIT) has been evaluated in many experimental studies. However, EIT is not routinely used in a clinical setting, which is attributable to the fact that a convenient concept for how to quantify the EIT data is missing. The definition of region of interest (ROI) is an essential point in the data analysis.

Breath-to-breath analysis of abdominal and rib cage motion in surfactant-depleted piglets during high-frequency oscillatory ventilation.

Objective: To assess the value of monitoring abdominal and rib cage tidal displacement as an indicator of optimal mean airway pressure (Paw) during high-frequency oscillatory ventilation (HFOV).

Design And Setting: Prospective observational study in a university research laboratory.

Animals: Eight piglets weighing 12.

Static pressure-volume curve characteristics are moderate estimators of optimal airway pressures in a mathematical model of (primary/pulmonary) acute respiratory distress syndrome.

Objective: To study the value of objective pressure-volume characteristics for predicting optimal airway pressures and the development of atelectasis and overstretching during a structured lung volume recruitment procedure with subsequent reduction in airway pressures.

Methods: We used a mathematical model of a lung with adjustable characteristics of acute respiratory distress syndrome (ARDS) characteristics. Simulations were performed in five grades of ARDS in the presence of pure alveolar or combined alveolar-small airway closure as well complete or incomplete lung volume recruitability.

Regional lung volume during high-frequency oscillatory ventilation by electrical impedance tomography.

Objective: To investigate the value of electrical impedance tomography for the assessment of regional lung mechanics during high-frequency oscillatory ventilation (HFOV).

Design: Prospective, interventional animal study.

Setting: University research laboratory.

Estimation of regional lung volume changes by electrical impedance pressures tomography during a pressure-volume maneuver.

Objective: To assess the degree of linearity between lung volume and impedance change by electrical impedance tomography (EIT) in pigs with acute lung injury and to investigate regional impedance changes during a pressure-volume maneuver.

Design And Setting: Experimental animal study in a university research laboratory.

Patients And Participants: Nine pigs with lung injury induced by lung lavage.

Oxygenation index, an indicator of optimal distending pressure during high-frequency oscillatory ventilation?

Objective: To test the hypothesis that, during high-frequency oscillatory ventilation (HFOV) of pigs with acute lung injury, the oxygenation index (OI = Paw*FIO(2)*100/PaO(2)) is minimal at the lowest continuous distending pressure (Paw), where the physiological shunt fraction is below 0.1 (Paw(optimal)).

Design And Setting: Prospective, observational study in a university research laboratory.

Attenuation of pressure swings along the endotracheal tube is indicative of optimal distending pressure during high-frequency oscillatory ventilation in a model of acute lung injury.

We tested the hypothesis that during high-frequency oscillatory ventilation, the oscillatory pressure ratio (OPR) is minimal at the optimal mean airway pressure (Paw). OPR is defined as the ratio of pressure swings at the distal end and the proximal opening of the endotracheal tube. Optimal Paw was assumed to be the lowest Paw at which the physiological shunt fraction was below 0.