NON INVASIVE LIFE SAVERS. Ultrasound in PICU

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3 Table 1. Selected Applications of Point-of-Care Ultrasonography, According to Medical Specialty. Specialty Ultrasound Applications Anesthesia Cardiology Guidance for vascular access, regional anesthesia, intraoperative monitoring of fluid status and cardiac function Echocardiography, intracardiac assessment Critical care medicine Procedural guidance, pulmonary assessment, focused echocardiography Dermatology Assessment of skin lesions and tumors Emergency medicinefast, focused emergency assessment, procedural guidance Endocrinology and endocrine surgery General surgery Gynecology Obstetrics and Assessment of thyroid and parathyroid, procedural guidance Ultrasonography of the breast, procedural guidance, intraoperative assessment Assessment of cervix, uterus, and adnexa; procedural guidance maternal-fetal medicine Assessment of pregnancy, detection of fetal abnormalities, procedural guidance Neonatology Nephrology Neurology Ophthalmology Orthopedic surgery Otolaryngology Pediatrics Cranial and pulmonary assessments Vascular access for dialysis Transcranial Doppler, peripheral-nerve evaluation Corneal and retinal assessment Musculoskeletal applications Assessment of thyroid, parathyroid, and neck masses; procedural guidance Assessment of bladder, procedural guidance Pulmonary medicine Transthoracic pulmonary assessment, endobronchial assessment, procedural guidance Radiology and interventional radiology Ultrasonography taken to the patient with interpretation at the bedside, procedural guidance Rheumatology Trauma surgery Urology Vascular surgery Monitoring of synovitis, procedural guidance FAST, procedural guidance Renal, bladder, and prostate assessment; procedural guidance Carotid, arterial, and venous assessment; procedural assessment VOL 1 NO.1 Jan March

4 Figure 2 Clinical Application of Ultrasound The clinical utility of point of care USG can be broadly divided into Procedural guidance, diagnostic approach and therapeutic intervention. Procedural guidance: Ultrasound guidance may improve success and decrease complications in procedures performed by multiple specialties, including central and peripheral vascular access, thoracentesis, paracentesis, arthrocentesis, regional anesthesia, incision and drainage of abscesses, localization and removal of foreign bodies, lumbar puncture, biopsies, and other procedures. Procedural guidance may be static or dynamic. With VOL 1 NO.1 Jan March

5 static guidance, the structure of interest is identified, and the angle required by the needle is noted, with the point of entry marked on the skin. In dynamic procedures, ultrasonography visualizes the needle in real time. Static guidance may initially be easier to perform, but properly performed dynamic guidance provides more accurate guidance and is generally preferred by experienced users. The use of ultrasound to guide central venous access has been shown to reduce the failure rate, the risk of complications, and the number of attempts, as compared with the landmark technique, particularly in the case of less experienced users or patients with more complex conditions. The evidence for these benefits of ultrasound guidance is greatest for the internal jugular site, with less evidence for the femoral and subclavian sites and in pediatric patients. A needle may be imaged dynamically with the use of either an in-plane or out-of-plane ultra- sound approach (Fig. 2). For vascular access, an in-plane approach corresponds to the long axis of the vessel. An inplane, or long-axis, approach is generally preferred for dynamic vascular access, particularly for central venous access, because the en- tire length of the needle, including the tip, can be visualized throughout the procedure. However, it may be more difficult to keep the needle in view with the use of an in-plane approach, and for smaller vessels, it may be challenging to image the entire vessel in the long axis. An out-of-plane approach is perpendicular to the needle and corresponds to the short axis of the vessel. The advantage of this approach is that the needle can be centered over the middle of the vessel. It is also easier to keep the vessel and the needle in view in the short axis. However, an out-of-plane approach may underestimate the depth of the needle tip if the ultrasound plane cuts across the shaft of the needle, proximal to the tip Diagnostic Approach: The point of care USG utility as diagnostic approach in intensive care has gained importance from lung USG asit allows prompt management based upon reproducible data andgeneratesfewercomputedtomography(ct)examinations,therefore decreasing irradiation, delays, cost, and discomfort to the patient. The learning of lung ultrasound actually comes from understanding artifacts it produces with ultrasound. In a normal lung, the visceral and parietal pleura are closely associated, and ultrasound shows shimmering or sliding at the pleural interface during respiration and as USG does not VOL 1 NO.1 Jan March

6 penetrate bone and air it gives shows bat wing appearance with A lines at regular interval which is normal reverberation artifact as shown in fig 3, 4& 5. Figure 4. In Panel A, a high-frequency linear probe is placed with the indicator toward the patient's head (screen left), in the midclavicular line at approximately the third intercostal space. At the posterior edge of the rib, a hyperechoic (bright) pleural line is seen, which is the interface between the visceral and parietal pleura. In a moving image of a normal lung, shimmering or sliding would be seen at the pleural line, indicating that the visceral pleura is closely associated with the parietal pleura. An A line (a normal reverberation artifact) is also seen. In Panel B, a phased-array sector probe is placed at the same anatomical location on a different patient. This sector image is much deeper, but it shows the same structures, as well as pathological B lines, artifacts that extend to the bottom of the screen ( lung rockets ). This patient had alveolar interstitial syndrome from congestive heart failure. Figure 5. Normal lung pattern. Left: Longitudinal scan of an intercostal space. Only artifacts (rib shadows and air) are visible. Between two ribs (vertical arrows), 0.5 cm lower in the adult, the pleural line is located (upper horizontal arrows). The upper rib, pleural line, and lower rib outline the bat sign. The horizontal lines (lower horizontal arrows) that arise from the pleural line and are displayed at regular intervals, coined A-lines, have clinical applications. Right: Seashore sign (M-mode). The seashore sign demonstrates lung sliding. The lung sliding corresponds to the displacement of the lung along the cranio-caudal axis, synchronized with respiration. The motionless superficial layers generate horizontal lines (wave pattern). The dynamic created by lung sliding generates a sandy pattern, arising from the very pleural line. In the newborn, the same bat pattern is visible in proportion to the size of the infant. Absence of sliding of pleural line can indicate pneumothorax/ pleural effusion (re-appears after appropriate drainage), collapse or endo- bronchial intubation if the lung slide is absent on one side. VOL 1 NO.1 Jan March

7 Interstitial Edema: Other artifacts (arrows) as shown in fig. 6 have seven features: comet-tail artifacts, strictly arising from the pleural line, hyperechoic, well-defined laser-like spreading to the edge of the screen without fading erasing normal A-lines and synchronous with lung sliding. This pattern defines B-lines and distinguishes them from other comet-tail artifacts, such as the Z-lines, which are short do not erase A-lines, and have no Figure 6 Figure 7. Alveolar consolidation. The shred sign: The deep border of the consolidation is in connection with aerated lung tissue; hence, a shredded pattern (arrows). The shred sign distinguishes alveolar consolidation from pleural effusion. significance. Several B-lines in a single view (six here) define lung rockets. Diffuse lung rockets indicate interstitial syndrome. Alveolar Consolidation: Alveolar consolidation is defined as an image arising from the pleural line (or the lung line in the presence of pleural effusion), yielding the tissue-like sign and the shred sign as seen fig 7. VOL 1 NO.1 Jan March

8 Fig 8 showing complete opacification of lung on CXR and shred sign on USG with air bronchogram (long arrow with hypoechogenic pleural line (short arrow). Figure 8 Figure 9. Showing stratosphere pattern on M mode in pneumothorax. Figure 10. Showing Pneumothorax and the lung point. The lung point can be recorded using the M-mode. This image shows a sudden (arrow) replacement of a seashore sign by a stratosphere sign, at the very location where the lung touches the wall on inspiration. Pneumothorax: It can be detected by absent sliding sign, change of sandy shore (fig 9) appearance to stratosphere pattern and lung point detection (fig 10) on M mode with high sensitivity and specifity. Figure 11. VOL 1 NO.1 Jan March

9 Pleural effusion (E): A pleural effusion is limited by four regular borders forming a quad (the quad sign): the pleural line, the upper and lower shadows of the ribs, and the deep border, which is always regular. This border, the lung line, shows the visceral pleura (arrows). Fig 11. Figure 12. Pleural effusion and the sinusoid sign. This M-mode image highlights the sinusoid sign, a basic dynamic sign specific to fluid pleural effusion, also indicating low viscosity. The sinusoid sign shows the centrifugal inspiratory shifting of the lung line toward the pleural line with a decrease in the interpleural distance. As the lung expands its volume toward a core-surface axis, the pattern, in M-mode, is sinusoidal along the respiratory cycle. I, inspiration; E, expiration; black arrows, pleural line; white arrows, lung line. Hemodynamic Monitoring by USG is another important aspect of point of care USG and has been discussed in the article on Echocardiography(page 48). FAST Examination FAST is an integrated, goal-directed, bedside examination to detect fluid, which is likely to be hemorrhagic in cases of trauma. The extended FAST (e-fast) also includes examination of the chest for pneumothorax. The e-fast examination combines five focused examinations for the detection of: free intraperitoneal fluid, free fluid in the pelvis, pericardial fluid, pleural effusion, and pneumothorax. Peritoneal fluid is detected using views of the hepatorenal space (Morrison's pouch), splenorenal space, and retrovesicular spaces. The thorax is evaluated for fluid at the flanks and for pneumothorax anteriorly. The pericardium may be evaluated for effusion, particularly in cases of peneterating trauma. A FAST examination may be completed in less than 5 minutes and has been shown to have a sensitivity of 73 to 99%, a specificity of 94 to 98%, and an overall accuracy of 90 to 98% for clinically significant intra -abdominal injury in trauma. The use of the FAST examination has been shown to reduce the need for CT or diagnostic peritoneal lavage and to reduce the time to appropriate intervention, resulting in a shorter hospital stay, lower costs, and lower overall mortality, although more rigorous study of patientcentered outcomes is recommended. A complete or partial FAST examination may also be helpful in evaluating patients who do not have trauma for ascites, intra-peritoneal hemorrhage, pleural effusion, pneumothorax, or pericardial effusion. ICP monitoring: Optic nerve sheath diameter has been used to predict raised ICP with good sensitivity and VOL 1 NO.1 Jan March

10 specificity. USG can also detect pupillary size and their reaction in patient with closed eyes because of trauma. Therapeutic uses: Real time use of USG in draining fluid from any cavity or spaces has been very well documented and now the standard of care in most of the western ICU. It reduces complication and also check need of unnecessary shifting the patient to operation theatre. Conclusion USG is an excellent tool to compliment clinical examination to asses any organ system. It is free of any complication and side effects, can be done rapidly at the bedside. It has shown to be very useful in trauma, to check volume responsiveness, ICP measurement and diagnosis and management of lung pathologies. Its major limitation is operator dependence. This is a skill all intensivist must learn. Conflict of Interest: None Source of Funding: None Suggested Readings 1. Moore C, CopelJ.Point-of-Care Ultrasonography.N Engl J Med 2011;364: Koeze J et all. Bedside lung ultrasound in the critically ill patient with pulmonary pathology: different diagnoses with comparable chest X-ray opacification. Critical Ultrasound Journal :1 3. Khilnani P. The pediatric BUS has arrived: Is bedside ultrasound in the pediatric intensive care unit a feasible option? PediatrCritCareMed 2011;12(6): Lambert RL, Boker JR, MaffeiFA. National survey of bedside ultrasound use in pediatric critical care. Pediatr CritCareMed 2011; 12: Froehlich C, Stockwell J, Rigby M. Ultra- sound guided central venous access in children. PCCM 2006; 7: Shiloh AL, Savel RH, Paulin LM, et al: Ultra- sound guided catheterization of the radial artery: A systematic review and meta analysis of randomized controlled trials. Chest 2011; 139: Khilnani P. Bedside ultrasound and echocardiography by the pediatric intensivist: An evolving tool and a feasible option in a pediatric ICU. IndianJCritCareMed 2013;17: VOL 1 NO.1 Jan March