Critical Care Echocardiography

Critical Care Echocardiography

A 34 year old IV drug abuser was admitted with respiratory failure, bilateral patchy changes on chest X-ray, raised inflammatory markers and septic shock. She was intubated and commenced on antibiotics and noradrenaline. An in-house Focussed Intensive Care Echo was performed to guide fluid resuscitation. This was suggestive of hypovolaemia, but a large mobile mass was also observed in the left ventricular chamber. A departmental echo the next day confirmed the presence of a large vegetation on the anterior mitral valve leaflet with severe mitral regurgitation. She underwent a further period of stabilisation and underwent a mitral valve replacement.

What is the evidence for the development of in-house echocardiography skills within the critical care setting?

Sam Clark

Echocardiography was, perhaps understandably, the preserve of Cardiologists. However, over the last few years, there has been an increasing desire to incorporate the use of echocardiography into Intensive Care units. Many governing bodies and societies associated with intensive care medicine have been involved with developing training programs for the use of echo in critical care. There have been policy statements by the Society of Critical Care medicine(1) and a number of articles in the critical care literature discussing potential programmes(2, 3). The French instigated a training programme for their intensivists as early as 2004. More recently, the Faculty of Intensive care medicine has begun to include trans-thoracic echocardiography (TTE) as an important practical skill for trainee intensivists, and a joint working group set up by the Intensive Care Society and British Society of Echocardiography issued a position statement placing critical echo training firmly on the critical care agenda(4). The outcome of that statement was to lead to the development of the FICE programme (Focused Intensive Care Echo) – a module designed to bring together the best of current methods to produce a high quality programme for the development of practical echo skills rehired on the intensive care.

This drive has coincided with an increasing body of evidence supporting an increasingly important role in the diagnosis and management of critically ill patients (2,7). In their 2004 study, Jenson and colleagues applied a standardized echo protocol to 210 critically ill patients in a single centre adult ICU. They demonstrated that it was possible to get adequate views in 97% of the patients scanned and that Transthoracic echocardiography (TTE) contributed positively to patient outcome in 97% and made a decisive contribution in 24.5% of the trial participants(7). These results are consistent with other studies of a similar nature(8, 9). Manasia et al conducted a study examining the feasibility of developing a focused teaching program in bedside TTE(5). They found that after 10 one-hour tutorials surgical intensivists could successfully TTE in 94% of patients and correctly interpret their findings on 84% of occasions. These focused TTE scans provided new cardiac information and changed management in 37% of patients. TTE added useful information in an additional 47% of patients but did not alter immediate management. Thus demonstrating that even with limited training TTE could improve bedside management of the critically ill.

There are a number of indications for performing echocardiography in critically ill patients including haemodynamic instability (such as hypovolaemia, pulmonary embolism, and cardiac tamponade), infective endocarditis (IE), aortic dissection, and finding the source of embolism(10). Potentially, the most common of these indications is the assessment of haemodynamic instability, which involves an assessment of fluid status, cardiac output and contractility. Drs. Mandeville and Colbourne conducted a review of TTE’s ability to predict fluid responsiveness(11). Out of 3138 potential studies, they found 8 articles that met the inclusion criteria. The results demonstrated that TTE could be highly discriminative test for the prediction of the stroke volume or cardiac output response to volume loading, though there was no significant benefit of one technique over another, with IVC diameter assessment, transaortic stroke volume variability with respiration and stroke volume increment with passive leg raising all providing strong predictive ability for response to a fluid bolus. It appeared to particularly useful in spontaneously breathing patients and those with arrhythmias, which is in contrast to other minimally invasive cardiac output monitors, whose accuracy is diminished by these conditions(12). Other authors have examined the feasibility of assessing LV function and contractility in the context of shock and found that echo consistently provides useful information above and beyond more established cardiac output monitors(13, 14). Though, more recent work has highlighted, the complexity involved in fully interpreting the observed findings(15).

Significant valvular abnormalities can be present in the critically ill patient or can go unrecognised(16). The common indications for bedside echocardiography in such group of patients are aortic and mitral valve disease, excluding native IE as well as prosthetic valve endocarditis. In the critical care setting, TTE can provide valuable information concerning valvular integrity and function, but it may not be optimal and sensitive for detecting vegetations of endocarditis, or evaluating a dysfunctional mitral valve. In the Cardiology literature, TTE has been shown to be accurate diagnose infective endocarditis in 65%-70% of cases to provide a definitive diagnosis, however, evidence a review of over 4000 ICU patients would suggest that those rates drop in the critically ill down to 33%17, secondary to views that are may be acceptable for a standard haemodynamic assessment, but insufficient to categorically diagnose endocarditis. This is especially true of mitral valve lesions due to its anatomical location next to the oesophagus.


References:
(1) Oren-Grinberg A. & Shahul S, Using Echocardiography in critical care. 2010-1 feb.
(2) Vieillard-Baron A, et al. Echocardiography in the intensive care unit: from evolution to revolution? Intensive Care Med. 2008; 34:243–249.
(3) Lau G., & Swanvelder J. Echocardiography in intensive care – where are we
going? editorial Anaesthesia 2011, 66:640-658.
(4) Fox K. A position statement; echocardiography in the critically ill. On behalf of a collaborative working group of the British Society of Echoardiography. JICS 2008;9:197-9
(5) Manasia AR, et al. Feasibility and potential clinical utility of goal-directed transthoracic echocardiography performed by noncardiologist intensivists using a small hand-carried device (SonoHeart) in critically ill patients. J Cardiothorac Vasc Anesth. 2005;19:155-159.
(6) Donovan K., & Colreavy F. Echocardiography in Intensive Care. In Bersten A. & Soni N. Eds. Oh’s Intensive Care Manual 6th ed. P295-312.
(7) Jensen MB, Sloth E, LarsenKM, Schmidt B. Transthoracic echocardiography for cardiopulmonary monitoring in intensive care. Eur J Anaesthesiol 2004;21:700-7.
(8) Orme RM, Oram MP, McKinstry CE: Impact of echocardiography on patient management in the intensive care unit: an audit of district general hospital practice. Br J Anaesth 2009, 102(3):340-344
(9) Vignon P, Mentec H, Terre S, Gastinne H, Gueret P, Lemaire F: Diagnostic accuracy and therapeutic impact of transthoracic and transesophageal echocardiography in mechanically ventilated patients in the ICU. Chest 1994, 106(6):1829-1834.
(10) Beaulieu Y. Bedside echocardiography in the assessment of the critically ill. Crit Care Med. 2007;35:S235–49
(11) Mandeville J., & Colbourne C. Can Transthoracic Echocardiography be used to predict fluid responsiveness in the critically ill patient? A Systematic Review. Critical Care Research and Practice Volume 2012, p1-9.
(12) Michard F., Stroke volume variation: from applied physiology to improved outcomes, Critical Care Medicine, vol. 39, no. 2, pp. 402–403, 2011.
13) Vieillard-Baron A, Caille V, Charron C, et al. Actual incidence of global left ventricular hypokinesia in adult septic shock. Crit Care Med 2008, 36:1701-1706.
(14) Bouferrache K, Amiel JB, Chimot L, et al. Initial resuscitation guided by the Surviving Sepsis Campaign recommendations and early echocardiographic assessment of hemodynamics in intensive care unit septic patients: a pilot study. Crit Care Med 2012, 40:2821-2827.
(15)Represse X., Charron C. & Viellard-Baron. Evaluation of Left ventricular systolic function revisited in septic shock

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