Hemodynamic Assessment With Trans-esophageal Doppler (TED) During Prone Ventilation in Patients With Acute Respiratory Distress Syndrome (ARDS)

Introduction and rationale of the study:

Acute respiratory distress syndrome (ARDS) commonly complicates acute illness in intensive care units (ICU). This syndrome is associated with high morbidity and mortality. In management of ARDS patients, lung protective ventilation and prone ventilation are key strategies which have shown survival benefits in recent years and now becomes standard part of care in these patients. Prone positioning has been reported to have hemodynamic disturbances like hypotension and arrhythmias. Prone ventilation can have different cardiovascular effects with a few suggesting increased cardiac output and few decreased cardiac output with unclear literature till date with one recent study suggesting that patients who have preload reserve had increased cardiac output when compared to patients with no preload reserve.

In ICU, hemodynamic monitoring is being done as a part of standard care of management in critically ill patients. There are different modalities of continuous hemodynamic monitoring, which help in timely assessment and appropriate interventions to optimize cardiac output to maintain adequate organ perfusion in these critically ill patients. Cardiac output could be assessed by thermo-dilution technique with pulmonary artery catheter, pulse contour analysis of arterial waveform or echocardiography. In recent years, trans-esophageal Doppler (TED) has become one of the standard hemodynamic assessment tool in ICU due to its minimal invasiveness and easy to use. TED uses Doppler shift principle which is routinely used to measure cardiac output in both trans-thoracic and trans-oesophageal echocardiography. The clinical utility of TED, with the benefit of minimal invasiveness, in assessing hemodynamic perturbations in both operation theatre and ICU has been established by various studies. Doppler measured cardiac output showed high validity and clinical agreement with gold standard pulmonary artery thermo-dilution technique, which is more invasive. Hemodynamic assessment in prone position with TED has been studied intra-operatively with good correlation. In current study, the investigators will evaluate acute hemodynamic effects of prone ventilation with TED in patients of acute respiratory distress syndrome (ARDS).

Work plan methodology:

This will be a prospective, observational study, to be conducted in 12 bedded ICU of department of Critical Care Medicine, Sanjay Gandhi Institute of Postgraduate and Medical Sciences, Lucknow. Patients with ARDS whose hemodynamic monitoring is being done by TED, and planned for prone ventilation by treating physician's decision, will be screened for inclusion in this study.