Ultrasonography (USG) is a fast-advancing imaging modality that is becoming more popular in the ICU due to its proven benefits. A more widespread adoption of this technology by intensivists and ICU specialists requires the incorporation of evidence-based protocols and hands-on training. Multiple organizations have issued guidelines on the use of ultrasonography in various contexts that govern a wide range of applications not limited to the intensive care unit (ICU). In order to assist intensivists who are considering using bedside ultrasound for diagnostic or therapeutic purposes, we crafted an arsenal of evidence-based position statement that review the appropriateness or superiority of bedside ultrasound as a supplementary tool to clinical judgment in the care of critically ill patients. Unless stated otherwise, these recommendations pertain to the adult patient who is critically ill.

Ultrasonography is increasingly being utilized in critical care units. With the advent of portable ultrasound machines and advancements in technology, it has become easier and more fundamental to patient assessment. Echocardiography performed by intensivists, both basic and advanced, has evolved in the diagnosis, monitoring, and management of patients admitted to the intensive care unit (ICU). Critical care echocardiography (CCE) enhances patient safety by providing real-time and dynamic information at the bedside. While transthoracic echocardiography is most commonly used, the importance of transesophageal echocardiography (TEE) has increased, particularly for intubated and ventilated patients. Recent studies indicate that the use of CCE may have a positive impact on outcomes. CCE can be employed in the early evaluation of critically ill patients in the emergency department and during ICU admission and stay. CCE has also proven useful in perioperative settings and in the management of patients on mechanical circulatory support, such as extracorporeal membrane oxygenation (ECMO). Both basic and advanced CCE require extensive training and certification. In recent years, worldwide certification programs in CCE have been established. CCE influences septic shock management, identifying cardiovascular phenotypes and improving early detection and prognosis of septic cardiomyopathy. It is essential for hemodynamic monitoring, evaluating cardiac function, fluid responsiveness, and therapy impacts in critically ill patients. Right ventricular (RV) function is influenced by increased pulmonary vascular resistance (PVR) and pulmonary hypertension, with echocardiographic parameters aiding in assessment with high sensitivity and specificity. CCE aids in identifying weaning difficulties by linking worse diastolic function (E wave, e’ wave, E/e’ ratio) to weaning failure, with no significant correlation to systolic dysfunction. This review article aims to highlight the importance of CCE, outlining its pivotal role in acute care settings.

The use of transesophageal echocardiography (TEE) in critical care units provides a clear view of the heart and great vessels in patients with poor acoustic windows with transthoracic echocardiography (TTE). Importantly, TEE provides good-quality imaging, especially for visualization of posterior structures such as the left atrium (LA) and mitral valve. TEE is useful in the assessment of left/right ventricular (RV) function, valvular lesions, and evaluation of mechanical cardiac support devices in real-time. This review provides a brief outline of the utility of TEE in intensive care units (ICU).

Upper airway is a complex anatomic structure. Anticipating, preparing, and managing a difficult airway is crucial in operating rooms and intensive care units (ICU). Difficult airway management is the most essential skill among anesthesiologists and critical care physicians. Airway ultrasound (AWUS) has become an inherent part of the armamentarium for managing difficult airway. AWUS is utilized for understanding sonoanatomy of the upper airway, anticipating difficult airway prior to intubation, helping in real-time monitoring of the intubation process, screening prior to airway procedures, and preextubation airway assessment. AWUS has added a new bedside dimension to difficult airway management, performing airway procedures with great accuracy in detecting and troubleshooting complications promptly.

Ultrasound examination of the lung has become a widely used tool in recent years in critical care units. It is an easy-to-use, noninvasive, real-time investigative method that aids in the treatment of patients in the intensive care unit. This review discusses the appropriate probe selection for lung ultrasound, sites for scanning the lung, diagnosing causes of acute breathlessness, fluid management of intensive care unit (ICU) patients, and positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome (ARDS) in light of recent evidence. Diaphragmatic functional assessment by lung ultrasound has been used to predict extubation failure in ventilated patients. Ultrasound has proved to be useful in guiding interventional procedures such as pleurocentesis, placement of intercostal drains, and percutaneous tracheostomies.

Venous thromboembolism (VTE) is one of the important causes of mortality in critically ill patients. Critically ill patients have unique risk factors for the development of deep venous thrombosis (DVT) namely immobilization, presence of venous catheters/extracorporeal devices, sepsis, endothelial injury, and hypercoagulability. Undiagnosed DVT can lead to the development of acute pulmonary thromboembolism. Pharmacological prophylaxis is initiated in the majority of patients. However, due to coagulopathy, pharmacological prophylaxis cannot be initiated in some of the patients. Ultrasound is one modality that helps in the early and real-time evaluation of critically ill patients and is one of the screening techniques in the diagnosis of DVT. Understanding the anatomy of the venous system helps in learning venous ultrasound. Ultrasound involves two-point, three-point, or whole leg ultrasound for lower limb DVT. Upper limb ultrasound is also necessary to rule out DVT.

Transcranial Doppler (TCD) is an excellent bedside tool for assessing the stroke, monitoring complications of subarachnoid hemorrhage (SAH), and detect brain dead patients in ICU.

Ultrasonography (USG) as a part of point-of-care ultrasound (POCUS) is helpful in providing a comprehensive overview of intraabdominal organs. USG is useful in bedside evaluation of the stomach, liver, gallbladder, common bile duct (CBD), kidneys, and abdominal aorta. USG can also help in the placement of feeding tubes, urinary catheters, and for paracentesis. Gastric ultrasound provides a good noninvasive measurement of gastric residual volume (GRV). This can be helpful in the intensive care units (ICU) to prevent aspiration prior to performing procedures. In hepatobiliary disorders, USG can assist in grading fatty liver disease and measuring the damping index (with the help of Doppler ultrasound). Gallstones are characteristically identified as hyperechoic shadows with gravitational dependence. USG is also of great importance in diagnosing the etiology of acute kidney injury (AKI). Renal resistive index (RRI) is a novel index measured with the help of Doppler ultrasound. Normal values range between 0.5 and 0.7. Higher values are indicative of AKI. USG can also aid in performing ICU procedures like paracentesis (marking the site), urinary catheterization, and feeding tube placement.

The purpose of the article is to discuss the use of ultrasound in critical care settings for vascular cannulation and its associated complications. Ultrasound has become indispensable in critical care units for bedside procedures, especially in vascular cannulations. Despite having a higher success rate with fewer complications, the adoption of ultrasound for vascular cannulations in the intensive care unit (ICU) is not uniform. The article will provide a greater understanding of various techniques for the use of ultrasound-guided vascular catheterization, supporting evidence, and ways of dealing with complications. There is enough supporting evidence showing that ultrasound should be made the standard of care for vascular catheterization in critical care settings.

Optic nerve sheath diameter (ONSD) is a noninvasive, bedside tool for estimating intracranial pressure (ICP) in conditions such as traumatic brain injury, intracranial hypertension, and optic neuritis. It is risk free compared to conventional methods, avoiding radiation and infection risks. ONSD also aids in evaluating intraventricular shunts, lumbar puncture feasibility, and conditions like idiopathic intracranial hypertension, intracranial hypotension, and stroke progression. Using ultrasound, ONSD correlates significantly with ICP. Measurement involves imaging 3 mm posterior to the globe with a high-frequency linear probe, avoiding oblique views and artifacts. Both transverse and sagittal views are assessed, with color Doppler assisting in accuracy. Compared to computed tomography (CT), ultrasound is cost-effective, safer, and suitable for serial ICP monitoring. However, caution is needed in cases of globe rupture, requiring prior ophthalmology evaluation. ONSD is a reliable and accessible tool in neurocritical care.

Fluid therapy in critically ill patients has its own complication in terms of fluid overload. The conventional strategies to monitor vascular congestion often fail to identify this accurately. The use of point-of-care ultrasound (POCUS) is presently being considered as a cornerstone for the management of critically ill patients. Venous excess ultrasound score (VExUS) is now becoming an integral part of the management of such patients to rule out venous congestion and its association with outcome.