How to Ventilate Patients with ALI/ARDS: a Search for Consensus

Overview

The article deals with conclusions the American-European consensus Conferences on ALI/ARDS and VALI and their impacton current protocol of mechanical ventilation. Re-targeting of goals of mechanical ventilation, which give priority toavoidance of lung damage with inappropriate ventilation pattern leads to introduction of lung protective ventilatory strategy.It is based on Lachmann’s concept of „open the lung and keep it open“. Barotrauma, volotrauma and atelectrauma arerecognized as main determinants for lung damage. The causative relation between lung damage due to mechanicalventilation and its deleterious effect on extrapulmonary organs leading to multiple organ dysfunction was determined.Several prospective randomized trials (Amato, NIH) proved a decrease of mortality from ARDS to 38 %., and 31 %respectively. Although there is a consensus now about use of lower tidal volumes than in the past (6–8ml/kg ideal b.w),keeping plateau pressures less than 30cmH2O, setting of PEEP remains controversial.Various methods ofPEEP adjustmentwas proposed based on analysis of PV curves and lower inflection point. However, their practical utilisation at the bedsideremains controversial. There is a consensus about the need to tolerate a certain level of hypercapnia, even its therapeuticpotential was proposed. Prone position has become increasingly used worldwide as a part of rescue procedures in earlyARDS. Besides its traditionally accepted pivotal role in improvement of arterial oxygenation, it seems to play an importantrole in the improvement of CO2 elimination. Another promising strategies requiring future research include varioustechniques of recruitment and non-invasive ventilation. A search for subgroup of candidates who would profit fromnon-invasive ventilation is needed. HFO appears to be another promising technique of the lung protective ventilationstrategy. Finally, some new experimental interventions (pharmacological and adjunctive ventilatory measures) are discussed.Some of them (iNO, almitrine), although failed as a isolated intervention in terms of improving outcome, might proveto play positive role when used in combination with prone position.

Key words:
mechanical ventilation – ARDS– protective lung ventilation strategy – ventilator associated lung injury – positiveend expiratory pressure – prone position – recruitment manoeuvres