Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT03920189 |
| Other study ID # |
ARDS-ECHO |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
September 1, 2018 |
| Est. completion date |
September 1, 2021 |
Study information
| Verified date |
June 2022 |
| Source |
University of Milan |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
The purpose of this study is to assess the left diastolic function at different levels of in
patients affected by the acute respiratory distress syndrome (ARDS)
Description:
Introduction Left ventricular diastolic dysfunction (DD) is a clinical entity that remains
poorly understood and identified in the intensive care unit (ICU) setting. In general, it is
a syndrome defined by the presence of symptoms of congestive heart failure without sign of
reduced left ventricle systolic dysfunction. Distinguishing diastolic heart failure from
systolic heart failure is important because of differences in treatment and prognosis, even
if often the two entities coexist, and some authors have proposed the hypothesis that
diastolic LV dysfunction is essentially a precursor of systolic failure. At the base on DD
there are multiple causes and multiple disorders. Among these, the impaired relaxation
(common in ischemia and during systemic inflammatory states), an impaired peak left
ventricular (LV) filling rate (with inadequate trans-mitral pressure gradient due to raised
LV pressure or inability to generate negative LV pressure), the stiffness of LV (fibrosis and
hypertrophy), and constriction (pericardial or compression from dilated right ventricle).
Diastolic LV dysfunction is common in the ICU but often unrecognized. Its knowledge and
determination of its severity may be useful to optimize circulatory support in critically ill
patients. From this point of view, echocardiography is one of the most powerful diagnostic
and monitoring tools available, providing the means to diagnose cardiac systolic or diastolic
dysfunction, its underlying cause, and suggest therapeutic interventions. The aim of this
study is to describe the presence and the grade of the eventually left diastolic dysfunction
in ARDS patients and its possible correlation with the severity of illness and outcome.
Definitions and pathophysiology Diastolic heart failure is defined as a condition caused by
increased resistance to the filling of one or both ventricles; this leads to symptoms of
congestion from the inappropriate upward shift of the diastolic pressure-volume relation.
Although this definition describes the principal pathophysiologic mechanism of diastolic
heart failure, it is not clinically applicable. In a more practical definition diastolic
heart failure is a condition that includes classic congestive heart failure findings with
normal systolic function at rest, but with alteration in diastolic function. During DD the
combination of active relaxation and passive myocardial compliance that normally maintain an
adequate cardiac output are altered and left atrial pressure should be increased to maintain
a satisfactory cardiac output. Different parameters have been used over the past two decades
to describe the DD, so it is difficult to define its real incidence in critically ill
patients. It seems to occur in about 30% of cases, and the majority of the studies tend to
relate it with concomitant syndrome such as sepsis or clinical conditions such as respiratory
weaning failure.
Left Diastolic dysfunction in ICU Most of the literature available investigated left DD in
septic patient, and even if in the majority of these studies the patients were mechanically
ventilated, only few information are available about the role of mechanical ventilation (MV)
or the acute phase of lung injury.
With The advent of tissue Doppler imaging (TDI) has simplified echocardiographic estimation
of ventricular relaxation and ventricular filling pressures, and the increasing number of
studies in the field have showed that diastolic dysfunction is common in critically ill
patients. The significance of diastolic dysfunction was recently highlighted by studies that
demonstrated that TDI parameters might be prognostically useful in ICU population. More
recent observations may help to clarify the scenario in these terms. An alteration in the
E/e' ratio has been described in patients with septic shock and, although one study found
that the E/e' ratio is an independent predictor of mortality [20], another investigation
failed to find this association.
Left diastolic dysfunction in mechanical ventilated and ARDS patients It is well known that
mechanical ventilation can induce hemodynamic compromise and that myocardial dysfunction and
its consequences are not properly reflected by conventional hemodynamic parameters.
Myocardial function can be assessed at the bedside using transthoracic echocardiography
(TTE); however, the 2D echocardiographic measurements have been used to investigate
predominantly the effects on systolic rather than diastolic ventricular function. Recently,
TDI has provided more load-independent parameters to assess cardiac function, but its use is
not widespread in ICU. For these reasons and probably because DD is greatly underestimated,
there are few paper focused on mechanical ventilation and DD, most of them during weaning
period, and almost none during the acute phase. What we know is that positive pressure
ventilation can affect preload, afterload and ventricular compliance. The net effect in most
situations is a decrease in cardiac output. However, the effect may be beneficial in the
context of decompensated heart failure, where the decreased preload and afterload result in a
return to a more productive part of the Starling curve.
More it is known in patients with prolonged weaning time. In this scenario, isolated
diastolic dysfunction is present in about 22% up to 39% of patients. The increase in preload
and afterload during MV may impair the LV compliance and determine a pulmonary edema. The
fall in LV pressure during relaxation phase is a key determinant of diastolic function, and
depends on intrinsic (contractility, LV stiffness) and extrinsic (preload, afterload)
factors. Recently, has been suggested how the LV relaxation impairment with increased filling
pressures may be a key mechanism of failed prolonged weaning trials. To summarize all these
evidence, we could state that the elimination of positive ventilation increases LV preload
and afterload and may induce some physiologic changes that can determine tachycardia and
hypertension. Those are coincidentally two major determinants of diastolic dysfunction, as
higher heart frequency reduces diastolic filling time and/or decreases coronary perfusion,
and hypertension can exacerbate heart failure in patients with preserved ejection fraction.
These findings suggest that echocardiography could be an excellent tool to guide the weaning
process, helping to decide the best therapy to accomplish it.
Methods Consecutive mechanically ventilated patients will be enrolled within 48 hours after
ICU admission with the diagnosis of ARDS. Demographic characteristics and respiratory
mechanics variables (including esophageal pressure) will be recorded at two levels of
positive end-expiratory pressure (PEEP); all patients will be study by a CT analysis at two
levels of PEEP (5-45 cmh20) for the evaluation of recruitment potential, together with the
computation of functional residual capacity (FRC). A well-trained cardiologist will perform a
completed transthoracic echocardiography with the aim to describe the presence and the grade
of left ventricular diastolic dysfunction (LVDD) applying a simplified definition of left DD,
based on septal e', which is considered to be an index of myocardial relaxation, and the
ratio of early diastolic velocity of mitral inflow to mitral annular velocity (E/e'), which
has a strong association with left atrial pressure.
