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Article Type

Original Study

Abstract

Objective The purpose of this paper was to assess the new mechanical ventilation strategies in acute respiratory distress syndrome (ARDS). Data sources Data sources includes Medline databases (PubMed, Medscape, ScienceDirect, and EMF-Portal) and all materials available on the internet from 2003 to 2016. Study selection The search presented articles that met the inclusion criteria involving the definition, pathophysiology, medical treatment, mechanical ventilation strategies, and prognosis of ARDS. Data extraction If the studies did not fulfill the inclusion criteria, they were excluded. Study quality assessment included whether ethical approval was gained, eligibility criteria specified, appropriate controls, adequate information, and defined assessment measures. Data synthesis Comparisons were made by different lines of treatment and new mechanical ventilation strategies of ARDS. Results The studies show that mechanical ventilation is the hallmark of ARDS treatment and a lifesaving intervention for severe hypoxemia that characterizes it. Despite it being used in this setting for several decades, our knowledge about its benefits and potential harm has evolved widely over time. Early ventilation strategies involved volume-controlled ventilation with tidal volume (Vt) of 10–15 ml/kg to achieve “normal” arterial blood gases. However, ventilation itself can cause lung injury. A landmark trial conducted by the ARDS Network compared conventional Vtof 12 ml/kg with low Vtof 6 ml/kg and permissive hypercapnia. A 9% absolute mortality reduction was found in the low Vtventilation group along with reduced pulmonary and circulating inflammatory cytokines. The aim of positive end-expiratory pressures (PEEP) in ARDS is to recruit (or maintain recruitment) of atelectatic or flooded lung. Initial studies looking at the effects of PEEP described adverse hemodynamic effects at high levels, leading to a reduction in cardiac output and oxygen delivery. Recruitment maneuvers are used to open areas of atelectasis improving lung compliance and oxygenation. The prognosis of ARDS has improved over the past 20 years. Overall, 60–70% of patients survive. Patients with poor prognostic factors include those older than 65 years and those with sepsis as the underlying cause. The adverse effect of age may be related to underlying health status. Conclusion We found that mechanical ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (Vt), and higher PEEPs can improve survival in patients with ARDS, but the relative importance of each of these components is uncertain. The ARDS Network trial showed that a ventilation strategy with a lower tidal volume (4–8 ml/kg of predicted body weight) was associated with lower mortality and shorter length of mechanical ventilation. This trial used a combination of volume and pressure limitation.

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