Point-of-Care Ultrasound In Critical Care

Introduction

Treating critically sick patients frequently utilizes point-of-care ultrasonography (POCUS), which allows them to quickly and accurately screen for a variety of diseases, including hemoperitoneum (bleeding in the area between the abdominal and pelvic organs, known as the peritoneal cavity) hydronephrosis (an accumulation of urine inside one or both kidneys), pneumothorax (an accumulation of air outside the lung but inside the pleural cavity. It happens when air is trapped in the chest between the visceral and parietal pleurae), pulmonary edema (a disorder brought on by the lungs' overabundance of fluid), and deep vein thrombosis (a blood clot that commonly forms in the legs in a deep vein).

Diagnostic mistakes are common in medicine and critical care; autopsy reports have revealed significant misdiagnoses. In addition to reducing diagnostic uncertainty, point-of-care ultrasonography (POCUS) has some properties that may help guide prognosis and management. To prevent unintentionally over- or under-diagnosing anomalies, image collection and interpretation must be done carefully and skillfully. Due to inexperience, POCUS misdiagnoses can result in treatment errors that could impair a patient's outcome or even be fatal. This is something that every POCUS practitioner needs to be aware of and, if necessary, follow up or assess using alternatives. The clinical examination, which offers supplementary data for diagnosis and treatment, should still come before any POCUS.

What Is Point-Of-Care Ultrasonography?

Using point-of-care ultrasonography (POCUS) by frontline clinicians caring for critically ill patients has quickly become a diagnostic tool. Sonography of the heart, lungs, abdomen, kidneys, and vascular system is included in this modality. It includes procedural advice as well as diagnostic evaluations. It differs from standard ultrasonography studies in that the images are obtained independently by the frontline doctor caring for a critically ill patient, and they are interpreted in real time to allow for prompt clinical decision-making. Point-of-care ultrasound is the gold standard for procedural guidance and enables the physician to identify a wide range of potentially fatal entities promptly. It also helps in the management of hemodynamically unstable patients.

How Is Ultrasonography Different For Different Body Regions?

Basic Lung Ultrasound: Over the past ten years, lung ultrasound has become incredibly popular and is frequently done at the patient's bedside, particularly in the emergency room and intensive care unit.

• Interstitial Syndrome: B-lines (a particular kind of vertical line) indicate interstitial syndrome. Hyperechoic vertical reverberation artifacts known as B-lines originate from the pleural line, extend to the screen's edge, move dynamically in response to breathing, and obstruct A-lines -horizontal lines. B-lines show thickened interlobular septae, which can be brought on by fibrosis, inflammation, or pulmonary edema. Interstitial syndrome (a collection of illnesses that result in lung tissue scarring over time) is indicated in an interspace by three or more B-lines.

• Pneumothorax: Pneumothoraces happen in fits and starts in the intensive care unit (ICU) and should always be considered a possibility when a patient is acutely decompensating while on mechanical ventilation or while they are having central venous access surgery. Pneumothorax is ruled out in that region with a 100 % negative predictive value when lung sliding is present. The lack of lung sliding is not indicative of pneumothorax because lung sliding can also be lost due to

  • Bullous emphysema happens when the alveolar walls which expand to create sizable air pockets known as bullae are damaged.

  • Pleural adhesion is the pathological ties between the pleura, the chest wall, and the intra-thoracic organs that are typically the outcome of an inflammatory process.

  • Previous pleurodesis is done to treat a persistent pneumothorax or prevent recurring pleural effusion, pleurodesis is a treatment used to obliterate the pleural gap.

• Pleura Effusion: Compared to computed tomography (CT), lung ultrasonography can offer a more thorough image of the fluid properties and is an easy method of detecting pleural effusions. Pleural effusions might appear as a complicated pocket with septations or an anechoic fluid pocket. Research indicates that whereas anechoic effusions might be transudative or exudative, pleural effusions containing echogenic material or septations are invariably exudative.

• Consolidation: Ultrasonography can detect consolidated lungs because no tissue-air interface obstructs imaging. Consolidated lungs are airless. Lung consolidation could indicate a pulmonary infarct, tumor, atelectasis, or pneumonia.

• Lower Extremity Deep Vein Thrombosis: About 12 % of ICU patients develop deep vein thromboses (DVTs) despite pharmacologic thromboprophylaxis. It is only sometimes possible to have a fast diagnostic study when something is suspected. Moreover, individuals with hemodynamic instability frequently have an acute pulmonary embolism (PE) on the differential, and the co-existence of a big right ventricle (RV) and a lower extremity DVT deep vein thrombosis may indicate the presence of an acute pulmonary embolism PE.

• Retroperitoneal and Abdominal Ultrasonography: For several reasons, abdominal and retroperitoneal ultrasonography is frequently indicated for a critically unwell patient. Abdominal ultrasound aspects have been examined within integrated protocols, but basic heart and lung ultrasound features have generally been well characterized independently. Scanning the abdomen, heart, pericardium, and pleural spaces is part of the Focused Assessment with Sonography for Trauma (FAST) protocol with trauma patients. This included the extended FAST (E-FAST) as a basic thoracic injury evaluation tool. Abdominal sonography in FAST centers on finding free fluid in the abdominal cavity, a symptom of hemoperitoneum connected to severe abdominal injuries. The four sonographic images used in the FAST assessment are the pericardial, perihepatic, perisplenic, and pelvic regions. FAST's shortcomings include its poor accuracy in the initial post-injury period and its inability to identify retroperitoneal hemorrhage.

• Acute (AKI) Kidney Injury: In 15 to 38 % of critically ill patients, acute renal damage occurs; prompt assessment helps manage this condition. A normal kidney's sonographic appearance in POCUS can easily detect bilateral hydronephrosis due to obstructive uropathy in some individuals. When both sides exhibit hydronephrosis, the bladder must be examined for distension, which most likely indicates bladder outlet blockage. Hydronephrosis and a noticeably enlarged bladder. CT imaging is typically necessary to investigate the cause of unilateral hydronephrosis further. However, a trained sonographer may detect an obstructive and infected ureteral stone that needs to be removed right away.

Ultrasound In Trauma:

Over the past 30 years, there has been a great deal of discussion and development on the use of POCUS for trauma patients. In the 1990s, the use of ultrasonography as a diagnostic tool for traumatic abdominal and thoracic injuries moved from Europe to North America. These days, the main uses of ultrasonography in trauma include

1. Hemothorax (an illness where blood builds up in the pleural space)

2. Pneumothorax (an illness where air builds up in the pleural space),

3. Pericardial tamponade (a state in which the pericardial sac fills with enough fluid to squeeze the heart, lowering cardiac output and causing shock), and

4. Intraperitoneal hemorrhage (Ruptures of the liver and spleen) identification.

A typical term for this group of applications is "extended focused assessment with sonography for trauma" (FAST). The most basic six-view trauma ultrasound exam includes the hepatorenal space ("Morrison's pouch"), peri splenic space, subcostal space, pelvis, and views of each hemithorax.

Cardiology Ultrasound:

• Pain in the Chest: The initial evaluation of chest pain in the (ED) erectile dysfunction (a person with erectile dysfunction cannot maintain or achieve an erection strong enough for fulfilling sexual activity), includes other diagnoses such as aortic dissection, pulmonary embolism, pericardial effusion, and several main pulmonary processes, even though acute coronary syndrome is a "must not miss" diagnosis. In such circumstances, POCUS can be utilized to increase diagnostic specificity.

• Dyspnea: When a patient appears with dyspnea, the first concern for the emergency physician is to determine if the cause is largely cardiac or pulmonary. POCUS is a fantastic tool for making this distinction. Pulmonary results on POCUS can range from the following:

  • A-line (horizontal) or B-line (vertical) alignments help to determine the pathology of lungs by expertise.

  • Consolidation: The hepatization of lung tissue as a result of reduced oxygenation as the lung tissue begins to collapse.

  • Anomalies of the Pleural Line: A thick, uneven pleural line (inflammatory and/or infectious process) in contrast to a thin, homogenous pleural line (normal or hydrostatic pressure).

Conclusion

Ultrasound techniques for the heart, lungs, and abdomen should be possessed by physicians who are caring for critically ill patients. Due to its operator dependence, POCUS's ability to identify or rule out abnormalities may be impacted by the operator's level of experience. Clinician experience also plays a role in how POCUS findings affect treatment. Although various protocols incorporating various POCUS modalities have been reported, further research is still needed to determine these protocols' applicability in various contexts. An increasing corpus of research is detailing the accuracy of POCUS applications, and as one gains more expertise and experience, one hopes that the accuracy will increase.