The monitoring of acute cor pulmonale is still necessary in "Berlin" ARDS patients

Ventilator-Associated Lung Injury

Ventilatory support, while life saving, can also cause or aggravate lung injury through several mechanisms which are encompassed within ventilator-associated lung injury (VALI). The important realizationin the acute respiratory distress syndrome that the “baby” lung resided in non-dependent areas led to the conceptualization of “lung rest” to reduce stress and strain to exposed alveolar units. We discuss concepts and mechanisms within VALI that ultimately induce maladaptive lung responses, as well as, current and future management strategies to detect and mitigate VALI at the bedside.

Usefulness of ultrasound in the management of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening disease. Different imaging techniques have been used to diagnose and guide the ventilatory management of patients with ARDS. Chest ultrasound is a reliable tool to identify interstitial syndrome, lung consolidation, lung collapse, and pleural effusion. In addition, echocardiography is essential in the diagnosis of diastolic left ventricle dysfunction and the estimation of elevated ventricle filling pressures, which is necessary before diagnosing ARDS. Therefore, combining chest and heart ultrasound assessment is useful to diagnose ARDS and guide the ventilatory management of the disease. Available data in the literature suggest that protocol-based approaches should be implemented for the purposes of diagnosis and management.

Pulmonary vascular dysfunction in refractory acute respiratory distress syndrome before veno-venous extracorporeal membrane oxygenation

BACKGROUND

Pulmonary vascular dysfunction has been described in patients with acute respiratory distress syndrome (ARDS). Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a well-established treatment for these patients. We hypothesized that severe pulmonary vascular dysfunction and cor pulmonale identified by echocardiography before cannulation in these patients were associated with worse survival.

METHODS

Echocardiography was used to identify pulmonary hypertension in 21 patients with refractory ARDS just before ECMO implantation. Survival was compared for those with and without cor pulmonale.

RESULTS

In our series, the overall mortality rate was 57.1% (12/21). Echocardiographic exams were transthoracic in 5 patients (23.8%), transesophageal in 4 patients (19%), and both (transthoracic and transesophageal) in the remaining 12 patients (57.1%). In our series, six patients (28.5%) showed LV dysfunction. Acute cor pulmonale was detectable in 2 patients (9.5%), while the remaining 19 patients showed moderate pulmonary dysfunction. Survivors had a higher pre-cannulation LV ejection fraction (EF) (P = 0.02) and tricuspid annular plane excursion (P = 0.04), and lower peak systolic pulmonary artery pressures (P = 0.02).

CONCLUSIONS

In patients with refractory ARDS immediately before ECMO implantation, the prevalence of acute cor pulmonale is low (9.5%). Survival is associated with higher LVEF and lower systolic pulmonary arterial pressure. These findings support the idea that echocardiographic assessment of pulmonary artery pressure in patients with refractory ARDS before VV-ECMO implantation may have value for risk-stratification.

The potential role and limitations of echocardiography in acute respiratory distress syndrome

Bedside use of Doppler echocardiography is being featured as a promising, clinically useful tool in assessing the pulmonary circulation in patients with acute respiratory distress syndrome (ARDS). The present review is aimed at summarizing the available evidence obtained with echocardiography on right ventricle (RV) function and pulmonary circulation in ARDS and to highlight the potential of this technique in clinical practice (only articles in English language were considered). According to the available evidence on echocardiographic findings, the following conclusions can be drawn: (a) echocardiography (transthoracic and transesophageal) has a growing role in the management ARDS patients mainly because of the strict interactions between the lung (and ventilation) and the RV and pulmonary circulation; (b) there may be a continuum of alterations in RV size and function and pulmonary circulation which may end in the development of acute cor pulmonale, probably paralleling ARDS disease severity; and (c) the detection of acute cor pulmonale should prompt intensivists to tailor their ventilatory strategy to the individual patient depending on the echocardiography findings. Bearing in mind the clinical role and growing importance of echocardiography in ARDS and the available evidence on this topic, we present a flow chart including the parameters to be measured and the timing of echo exams in ARDS patients. Despite the important progress that echocardiography has gained in the evaluation of patients with ARDS, several open questions remain and echocardiography still appears to be underused in these patients. A more systematic use of echocardiography (mainly through shared protocols) in ARDS could help intensivists to tailor the optimal treatment in individual patients as well as highlighting the limits and potential of this methodology in patients with ALI.

Hemodynamics of Acute Right Heart Failure in Mechanically Ventilated Patients with Acute Respiratory Distress Syndrome

In critically ill patients with circulatory shock, the role of the left ventricle has long been appreciated and the object of measurement and therapeutic targeting. The right ventricle is often under appreciated and dysfunction may be overlooked. Generally, the right ventricle operates passively to support the ejection of the left ventricular diastolic volume. A loss of right ventricular wall compliance secondary to pulmonary pressures may result in an alteration in the normal pressure-volume relationship, ultimately affecting the stroke volume and cardiac output. Traditional right heart filling indices may increase because of decreasing compliance, further complicating the picture. The pathophysiology of pulmonary vascular dysfunction in acute respiratory distress syndrome combined with the effects of a mean airway pressure strategy may create an acute cor pulmonale.