Influence of prone position on the extent and distribution of lung injury in a high tidal volume oleic acid model of acute respiratory distress syndrome.

Objective: To evaluate the influence of body position on the extent and distribution of experimental lung damage in an oleic acid canine model of acute respiratory distress syndrome, using mechanical ventilation with high tidal volumes and positive end-expiratory pressure (PEEP).

Design: Prospective, randomized study.

Setting: Experimental animal laboratory.

Distal effects of tracheal gas insufflation: changes with catheter position and oleic acid lung injury.

We separated distal (turbulence-related) and proximal (dead space washout-related) effects of tracheal gas insufflation (TGI) by comparing the effects of straight and inverted catheters. We reasoned that the inverted catheter was unlikely to remove CO2 from conducting airways distal to its orifice. In six normal dogs during TGI at 10 l/min, advancing the catheters from 10 to 1 cm above the main carina decreased dead space volume by 29 +/- 12 and 12 +/- 6 ml (P < 0.

Pressure-controlled and volume-cycled mechanical ventilation.

Pressure and volume modes of mechanical ventilation are available as options in the current generation of ventilators, giving clinicians many choices when managing a mechanically ventilated patient. In volume cycled ventilation, tidal volume is set and airway pressures are measured, whereas in pressure-controlled ventilation, pressure is set and volume is measured. This article reviews the characteristics of these two ventilatory modes and discusses in detail conversion from one mode to the other.

Tracheal gas insufflation: catheter effectiveness determined by expiratory flush volume.

Used adjunctively during mechanical ventilation, tracheal gas insufflation (TGI) improves CO2 elimination, principally by decreasing effective anatomic dead space. Continuing lung deflation at end- expiration raises the end-expiratory C02 concentration within the proximal airway, and could theoretically reduce the efficiency of a given catheter flow. To test this possibility, we designed a series of experiments that examined the influence of TGI delivery patterns on the efficiency of CO2 elimination.

Low measured auto-positive end-expiratory pressure during mechanical ventilation of patients with severe asthma: hidden auto-positive end-expiratory pressure.

Objective: To describe the occurrence of low measured auto-end-expiratory pressure (auto-PEEP) during mechanical ventilation of patients severe asthma.

Design: Observational clinical study.

Setting: Medical intensive care unit of a university-affiliated county hospital.