विवरण
The ICU is increasingly using echocardiography. It has been demonstrated that TTE improves patient care in 97% of critically sick patients using a condensed focus assessment procedure. When a patient has an endotracheal tube in place, TOE is the first line echocardiographic evaluation and is frequently more helpful in the ICU situation. The safety profile of TOE has been extensively documented, despite the fact that it is categorized as a semi-invasive treatment; the incidence of esophageal perforation is estimated to be 1 in 5000, and the fatality rate to be 1 in 10,000.
सारांश
- Echocardiography is increasingly used by intensivists in the ICU to gain a better understanding of patients' problems, focusing on its usage in shock management rather than for cardiac diagnostics or therapy. The lecture aims to provide a basic understanding of echocardiographic views and their interpretation from an intensive care perspective, emphasizing that it is an introduction to a complex field requiring extensive reading and practice.
- The absence of readily available cardiologists at the bedside in the ICU necessitates intensivist-led echocardiography for repeated scans in critically ill patients, unlike routine cases. Challenges include lighting, patient positioning, ventilation, and hyperinflated lungs, but the advantages of point-of-care ultrasound outweigh these difficulties, offering rapid assessment of cardiac function. Transesophageal echocardiography has proven diagnostic accuracy in a high percentage of patients.
- 2D views provide structural information, while M-mode offers insights into moving structures and timing, particularly useful in IVC assessment. Doppler, including pulse wave and color wave, reveals velocities and directions of fluid flow (Blue Away, Red Towards). The patient's position, preferably left lateral decubitus, aids in obtaining better images, and familiarity with probe handling and machine controls is crucial.
- Basic probe movements include sliding, rocking, rotating, and tilting, each providing unique perspectives on the heart's structures. Sliding involves moving the probe to explore different areas, rocking offers a gentle back-and-forth motion, rotating changes the axis of view, and tilting provides information about structures superior or inferior to the probe. Different orientations and probe placement allows for short-axis versus long-axis views of the heart.
- Key echocardiographic views include parasternal long axis (PLAX), parasternal short axis, apical four-chamber, and subcostal views. The PLAX view is obtained in the third or fourth intercostal space with the notch pointing towards the patient's right shoulder, providing a long-axis view of the heart. The short axis is obtained by rotating the probe 90 degrees from the long axis. The apical four-chamber view is obtained at the point of maximal impulse.
- The subcostal view, obtained below the xiphoid process, is particularly useful in ventilated patients, revealing pericardial effusions, tamponade, and IVC. IVC assessment involves turning the transducer perpendicular to the aorta and tilting to visualize the IVC entering the right atrium, differentiating it from the aorta by its entry point and the presence of the hepatic vein. Measurements like velocity time index, stroke volume, and cardiac output, along with LV and RV functions, are crucial in shock assessment.
- Echocardiography helps determine the type of shock, fluid status, and cardiac function, aiding in management. Assessing intravascular volume involves observing for "kissing ventricles" in hypovolemia and IVC collapsibility or distensibility during respiration. Acute pulmonary embolism is characterized by dilated right-sided chambers and altered RV contraction, while pericardial tamponade presents with fluid around the heart chambers and RV collapse during diastole.
- In septic shock, early phases present with a small LV and collapsing IVC due to vasodilation and fluid extravasation, while later stages may show dilated chambers and myocardial dysfunction. Serial echocardiographic exams are essential for guiding fluid resuscitation and managing septic shock patients, providing dynamic assessments of fluid responsiveness and cardiac function, replacing reliance on CVP measurements. Ultimately, bedside echocardiography is key in optimizing fluid management through dynamic assessment of cardiac function in the critically ill.
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