venous pressure (CVP) and fluid status. The IVC can dilate or collapse depending on intraluminal pressure. In general, a large IVC correlates with higher CVP and a small IVC correlates with a lower CVP. There is usually significant respiratory variation in the size of the IVC because inspiration produces negative intrathoracic pressure and draws blood out of the IVC and into the right atrium, causing the IVC to collapse. The reverse occurs during expiration and the IVC expands. Several investigators have attempted to correlate IVC findings with CVP values, which is difficult since absolute IVC size varies between patients and the IVC can completely collapse with inspiration in a normovolemic patient. Although IVC measurements cannot accurately measure CVP values, they can be used to effectively estimate whether CVP is very low or very high. IVC should be seen below the diaphragm in the sagittal plane. These findings suggested that measurements of IVC may be useful in identifying patients who are in early shock before they develop classic signs of shock. The data also suggested that serial IVC measurements may be useful for monitoring patients with known
or suspected blood loss or any other process that may lead to shock. In general, if the patient’s hemodynamics improves and the IVC changes little on ultrasound, more fluid can be given. When the IVC measurements indicate rapidly increasing fluid pressures, further fluid administration should be limited (see figures 4 and 5).
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GLOBAL CARDIAC SYSTOLIC FUNCTION This assessment relies on overall assessment of endocardial excursion and myocardial thickening, using multiple windows, including the parasternal, subcostal, and apical views. It is important to note that FOCUS is performed to assess global function and differentiates patients into ‘‘normal’’ or minimally impaired function versus ‘‘depressed’’ or significantly impaired
The primary
advantage of FOCUS is in determining whether the shock is cardiogenic
function. This descriptive nomenclature when used by non-echocardiographers has good
correlation with echocardiographer interpretations. The goal of the focused exam is to facilitate clinical decision- making to decide if a patient with acute shortness of breath or chest pain has impaired systolic contractility and thus would benefit from pharmacologic therapies or other interventions. Evaluation of segmental wall motion abnormalities and other causes of shortness of breath (e.g., valvular dysfunction) can be challenging and should be assessed by performing a comprehensive echocardiogram (see figures 6 and 7).
HYPOTENSION/SHOCK The primary advantage of FOCUS is in determining whether the shock is cardiogenic. Shock requires aggressive early intervention to prevent organ dysfunction caused by inadequate tissue perfusion. Therefore, the distinction of cardiogenic shock from shock of other causes is extremely important. The FOCUS exam, as previously stated, should evaluate for the presence of pericardial effusion, global cardiac function, right ventricular size, and IVC size/collapsibility as a marker of central venous pressure. In the right clinical context, this evaluation can direct the clinician at the bedside in important next treatment interventions, optimize diagnostic efficiency, and assess the response to performed interventions. FOCUS can give vital information
regarding the presence, size, and functional relevance of a pericardial effusion as a cause of hemodynamic instability and can expedite pericardiocentesis with fewer complications and a higher success rate. Evaluation of right ventricular size in the peri-arrest patient may lead the clinician to consider thrombolytics if the clinical scenario and the FOCUS findings suggest massive pulmonary embolus. It is worth reiterating that the absence of these findings cannot be used to exclude the presence Of clinically significant pulmonary embolism, although identifying an enlarged RV in an unstable patient can lead to lifesaving therapy. The finding of a hyperdynamic left
ventricle can prompt evaluation for hypovolemia or suggest sepsis or massive
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