Echocardiography for cardiopulmonary optimization in the intensive care unit: should we expand its use?

TAKING care of the hemodynamically unstable patient in the intensive care unit (ICU) has always been a challenge. Choosing the correct therapeutic approach assumes both relevant and sufficient patient-specific information but also a fair amount of basic physiologic understanding. Although these facts should be obvious, they are quite often disregarded in the daily clinical practice. The hypotensive and hypovolemic patient being treated with inotropic drugs without any objective signs of impaired myocardial contractility is a common example well known to all of us. Hemodynamic optimization is a complex task and monitoring armamentarium is therefore impressive. Monitoring various arterial and venous pressures, blood flow, oxygen content, acid-base balance and urine output is mandatory in almost every ICU patient nowadays. However, all these parameters more precisely reflect the overall circulatory state, and the basic physiologic determinants, preload, afterload and contractility are only indirectly and poorly described (1). When considering factors like ventricular compliance and relaxation (diastolic determinants), which are extremely important in, for example, conditions characterized by ventricular hypertrophy, almost no information is provided. Likewise no specific indication of more significant pathology such as pericardial and pleural effusion, pulmonary embolism or valvulopathy is provided by these ‘conventional’ monitoring techniques. Insufficient knowledge about these hemodynamic determinants may lead to unfavorable or even harmful assumptions, decisions and therapy. Both preload and afterload imply knowledge about cardiac dimensions, and these therefore require imaging of the heart (2). Contractility is an inherent characteristic of the change in myocardial fiber length causing a reduction in ventricular dimension during systole. This ability is described by means of the ejection fraction (EF), a practical clinical notion. Imaging is therefore an important prerequisite for optimal assessment of preload, afterload and myocardial contractility. Echocardiography is at present the only method that can provide bedside real-time imaging of the heart — either from the esophagus (TOE) or from the transthoracic (TTE) approach. This not only allows us to assess ventricular contractility and loading conditions but also supplies us with information about, for example, ventricular interdependency and significant pathology. By means of Doppler ultrasound, insight into the diastolic function is possible (3). These are all important features to consider in relation to circulatory instability and are readily obtainable by a combination of the different Doppler ultrasound modalities. In this light, the application of echocardiography in ICU patients is surprisingly limited. Practice guidelines, education and certification of anesthesiologists and ICU physicians have been developed almost exclusively for transesophageal imaging. Very often however, at least a repeated insertion of an esophageal probe is not practical or safe for lightly sedated ICU patients and institution of heavy sedation or anesthesia may significantly confound hemodynamic findings. We have experienced that TTE represents a powerful tool and can be of tremendous help in problem solving and hemodynamic optimization. After more than 10 years’ experience with TOE and TTE, we now use a rapid and systematic TTE protocol for cardio-pulmonary screening and monitoring, known as focus assessed transthoracic echo (FATE). A FATEexamination is carried out without the skills required to fulfil a thorough and much more time-consuming diagnostic procedure as performed by the cardiologists. In the FATE-protocol, the heart and pleura should be imaged in the most favorable sequence from one or more positions (1, subcostal; 2, apical; 3, Acta Anaesthesiol Scand 2004; 48: 1069—1070 Copyright # Acta Anaesthesiol Scand 2004 Printed in Denmark. All rights reserved ACTA ANAESTHESIOLOGICA SCANDINAVICA