Echocardiography in Acute Respiratory Distress Syndrome: A Promising Clinical Tool

Abstract

Submit Manuscript | http://medcraveonline.com Briefly, in the era of protective ventilation, ACP occurs in the 2025% of ARDS patients and its development seems to be especially related to plateau pressure, driving pressure and pCO2 [4]. The presence of ACP may cause or precipitate circulatory failure and it seems to have an impact on prognosis since it resulted an independent risk factor for 28-day mortality in moderate-tosevere ARDS patients [7]. Based on the echocardiographic findings on ACP in ARDS patients and its clinical meaning, it has been proposed an approach to protect the right ventricle by setting/ adapting the ventilatory strategy in presence of echocardiographic finding of RV overload [4,7-15]. Though this “protective RV approach” has to be validated in a randomized controlled trial, it has an indubitable clinical relevance since it aims to protect both the lung and the ventricle by a single-patient tailored strategy. In presence of ACP the adaptation of the ventilatory settings to RV function may consist in decreasing the plateau pressure (below 27 to 28 cm of H2O), limiting the PEEP, avoiding intrinsic PEEP, and controlling hypercapnia. In this setting in ARDS patients, it is now recommended to perform at least one echocardiographic examination per day during the first 3 days to evaluate RV function and to adapt the ventilator. New lines of evidence strongly suggest a potential clinical role of echocardiography in ARDS patients since the early phase of the disease [16]. Three elements, which can be all investigated by echocardiography, characterize the pulmonary vascular alterations and its effects on the right ventricle and systemic circulation in ARDS: a) pulmonary systolic arterial hypertension (sPAP); b) RV dimension and function; c) septal dyskinesis. The clinical significance (that is prognostic impact and/or potential therapeutic target) of each of these three elements has not yet been elucidated. Boissier et al. [7] observed that moderate RV dilation (defined as RV/LD end diastolic area ratio >0.6 and < 1) was detectable in the 49% of patients without ACP, thus suggesting that RV dilation may precede ACP development and a progressive increase in mortality was observed with increase in pulmonary dysfunction severity. In a small subset of 21 patients with refractory ARDS treated with Veno-Venous Extracorporeal Membrane Oxygenation [17,18], the prevalence of acute cor pulmonale was low (9.5%) but a lower incidence of RV dysfunction (as indicated by Tricuspid Anular Plane Excursion), lower peak systolic pulmonary arterial pressures and higher values of left ventricle ejection fraction were found in survivors in comparison with dead patients. In moderate-to-severe ARDS [19], serial troponin I assessment together with echocardiography evaluation helped to identify a subgroup at higher risk for in-ICU death since systolic pulmonary arterial pressure (together with troponin I and pCO2) were independent predictors of early mortality.