Thoracic Ultrasound For The Respiratory System In Critically Ill Patients

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Thoracic Ultrasound For The Respiratory System In Critically Ill Patients

  1. 1. Thoracic Ultrasound for the Respiratory System in Critically Ill Patients Bassel Ericsoussi, MD, PG-Y3 University of Illinois at Chicago Advocate Christ Medical Center
  2. 2. <ul><ul><li>Lung ultrasound performed by physicians in charge of ICUs appears to be one of the most promising techniques for respiratory monitoring and should rapidly expand in the near future </li></ul></ul>
  3. 3. Ultrasound for the Diagnosis of Pneumothorax <ul><li>Easy to learn and apply. </li></ul><ul><li>It can be used quickly to rule out any significant pneumothorax in critically ill patient. </li></ul><ul><li>The entire exam can be completed and interpreted in less than a minute. </li></ul><ul><ul><li>More sensitive than CXR or physical exam. </li></ul></ul><ul><ul><li>Able to detect a very small pneumothorax. </li></ul></ul>Advocate Christ Medical Center
  4. 4. The Technique <ul><li>Locate the parietal pleura: inline the inside of the chest cavity (superficial, easy to find, just beneath the ribs on the chest wall). </li></ul><ul><li>See if the visceral pleura: covering the outer surface of the lung touching the parietal pleura. </li></ul>Advocate Christ Medical Center
  5. 5. Equipment <ul><li>5 mhz curvilinear probe is ideal (low frequency for deeper tissue). </li></ul><ul><li>The high frequency (for superficial, vascular tissue) 6-13 mhz linear probe is not sufficient. </li></ul><ul><li>Decrease the depth setting to 5 cm, so you are scanning only the chest wall and not deeper structures. </li></ul><ul><li>Place the probe on the chest wall longitudinally . </li></ul><ul><li>On the 3 rd or 4 th intercostal space anteriorly, in the midclavicular line, while the patient in the supine position, this location is the best: </li></ul><ul><ul><li>It’s anteriorly, because the pleura surfaces separates anteriorly while the patient in the supine position, in a case of pneumothorax. </li></ul></ul><ul><ul><li>Above the level of the heart on the left side. </li></ul></ul>Advocate Christ Medical Center
  6. 6. What should you see normally? <ul><li>Visceral-Parietal Pleural Interface (VPPI) or Lung-Chest Wall Interface (LCWI) : </li></ul><ul><ul><li>Sliding lung sign: visceral and parietal pleura moving relative to one another with the respiratory cycle. </li></ul></ul><ul><ul><li>+/- lung pulse (pleural surfaces). </li></ul></ul><ul><ul><li>A-lines: </li></ul></ul><ul><ul><ul><li>“ Reverberation” artifacts. </li></ul></ul></ul><ul><ul><ul><li>Parallel to pleural line. </li></ul></ul></ul><ul><ul><ul><li>Distance between A-lines is equal to, or a multiple of, the skin to VPPI distance. </li></ul></ul></ul><ul><ul><li>B-lines (Comet tails): </li></ul></ul><ul><ul><ul><li>Artifacts. </li></ul></ul></ul><ul><ul><ul><li>Usually seen in the lower lung zones, laterally or posteriorly (3-4 lines). </li></ul></ul></ul><ul><ul><ul><li>Originate at the VPPI and usually extend to the bottom of the picture. </li></ul></ul></ul><ul><ul><ul><li>Number correlated with alveolar interstitial pattern on CXR, and indicate either interstitial fibrosis or edema, or maybe ARDS. </li></ul></ul></ul>Advocate Christ Medical Center
  7. 7. Pleural Line (LCWI) B-lines (Comet tails) 3-4 lines A-lines Skin surface to LCWI Multiple (reverberation) Multiple (reverberation) Advocate Christ Medical Center
  8. 8. Rib “shadows” Sliding lung sign: visceral and parietal pleura moving relative to one another with the respiratory cycle B-lines (Comet tails) Advocate Christ Medical Center
  9. 9. Lack of Sliding Sign <ul><li>PNEUMOTHORAX. </li></ul><ul><li>Pleural adhesions. </li></ul><ul><li>Mainstem intubation. </li></ul><ul><li>Pulmonary infiltrates/contusion. </li></ul><ul><li>ARDS. </li></ul><ul><li>Atelectasis. </li></ul><ul><li>Normal sliding lung excludes (100%) </li></ul><ul><li>the presence of significant pneumothorax . </li></ul>Advocate Christ Medical Center
  10. 10. A-lines <ul><ul><ul><li>Normal lung: </li></ul></ul></ul><ul><ul><ul><ul><li>CT. No dense structure is visible against the surface. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ultrasound equivalent. Two or three “Reverberation” artifacts. </li></ul></ul></ul></ul><ul><ul><ul><li>Parallel to pleural line. </li></ul></ul></ul><ul><ul><ul><li>Distance between A-lines is equal to, or a multiple of, the skin to VPPI distance. </li></ul></ul></ul>Advocate Christ Medical Center
  11. 11. B-lines (Comet tails) <ul><ul><ul><li>Artifacts. </li></ul></ul></ul><ul><ul><ul><li>Usually seen in the lower lung zones, laterally or posteriorly (3-4 lines). </li></ul></ul></ul><ul><ul><ul><li>Originate at the VPPI and usually extend to the bottom of the picture. </li></ul></ul></ul><ul><ul><ul><li>Number correlated with alveolar interstitial pattern on CXR, and indicate either interstitial fibrosis or edema, or maybe ARDS. </li></ul></ul></ul>Advocate Christ Medical Center
  12. 12. Explanation Of The Formation Of The B-lines (Comet-tail Artifact). <ul><li>When the US beam meets the thickened interstitial area, it reflects resulting in an artifact composed of all the micro-reflections. </li></ul><ul><li>Each reflection of the beam is displayed on the screen behind the previous reflection. </li></ul><ul><li>A distance of about 1 mm separates each reflection. </li></ul>Advocate Christ Medical Center
  13. 13. Normal lung. <ul><li>CT section at the level of the hepatic dome. Note visible sub-pleural interlobular septa in this area . </li></ul><ul><li>Ultrasound equivalent: Three comet-tail artifacts are visible arising from the lung surface. </li></ul><ul><li>Some lower lung zone interstitial markings are normal. </li></ul><ul><li>Hence, a few Comet Tails in this area are also normal. </li></ul>Advocate Christ Medical Center
  14. 14. Diffuse interstitial fibrosis <ul><li>CT. Thickened interlobular septa. </li></ul><ul><li>Ultrasound equivalent. These four comet-tail artifacts are separated from each other by a distance of 7 mm. </li></ul>Advocate Christ Medical Center
  15. 15. Acute pulmonary edema <ul><li>CT. At this level, ground-glass areas can be observed in the left lung. Note posterior consolidations. </li></ul><ul><li>Ultrasound equivalent. Closely spaced comet-tail artifacts are visible. </li></ul>Advocate Christ Medical Center
  16. 16. <ul><li>More than the usual number (>3-4 lines), or presence in the upper lung zones (usually lower zones), indicate pulmonary edema or interstitial disease. </li></ul><ul><ul><li>In interstitial disease, lines are about 7mm apart. </li></ul></ul><ul><ul><li>In ground glass processes, lines are usually closer together. </li></ul></ul>Diffuse Interstitial Fibrosis vs. Acute Pulmonary Edema Advocate Christ Medical Center
  17. 17. lung consolidation and a pleural effusion (a) Transversal view of consolidated left lower lobe; lung consolidation is seen as a tissular structure (C). In this consolidation, hyperechoic punctiform images (indicated by asterisk) can be seen; these correspond to air bronchograms (air-filled bronchi). Pleural effusion is anechoic (Pl). (b) Cephalocaudal view of consolidated left lower lobe: lung consolidation with air bronchograms. Ao, descending aorta; D, diaphragm; Pl, pleural effusion. Advocate Christ Medical Center
  18. 18. Evaluation for Pneumothorax <ul><li>Occurs frequently. </li></ul><ul><li>Radiography is imperfect (lacks sensitivity and specificity). </li></ul><ul><li>CT is most sensitive, but costly/cumbersome. </li></ul><ul><li>Several signs have been described which help evaluate for pneumothorax with ultrasound: </li></ul><ul><ul><li>Absence of lung sliding. </li></ul></ul><ul><ul><li>Barcode sign (M-mode). </li></ul></ul><ul><ul><li>A-line sign. </li></ul></ul><ul><ul><li>Lung Point. </li></ul></ul>Advocate Christ Medical Center
  19. 19. Lung Sliding and Seashore Sign in Normal Lungs <ul><li>The pleural line (black bold arrow) between upper and lower ribs (white arrow), and B-lines “Comet-tail artifacts “ (blue bold arrows). </li></ul><ul><li>Lung-sliding is a forward-and-back movement of visceral pleura against parietal pleura. </li></ul><ul><li>Seashore Sign: In time-motion mode (M-mode), it includes motionless parietal tissues over the pleural line and a homogenous granular pattern below it, which indicates normal lung motion during respiration (right image). </li></ul>Advocate Christ Medical Center
  20. 20. Absence of Lung Sliding and Barcode Sign in Pneumothorax <ul><li>In pneumothorax and due to the trapped air between the visceral and parietal pleura, the lung sliding disappear. </li></ul><ul><li>No B-lines. </li></ul><ul><li>Barcode Sign: In time-motion mode (M-mode), and due to the pneumothorax, the granular pattern disappear. The seashore sign turn to barcode sign (right image). </li></ul>Advocate Christ Medical Center
  21. 21. A-line Sign in Pneumothorax <ul><li>Reverberation artifacts. </li></ul><ul><li>Parallel to pleural line </li></ul><ul><li>Distance between A-lines is equal to, or a multiple of, the skin to pleural line distance. </li></ul><ul><li>In PTX, A-lines are common: Known as the “A-line sign”. </li></ul><ul><li>No B-lines. </li></ul>Advocate Christ Medical Center
  22. 22. Lung Point in Pneumothorax <ul><li>The lung point sign will appear at the precise line where the lung reaches the wall (yellow arrow). </li></ul><ul><li>Lung sliding with B lines in one area (the part of the lung the reaches the wall), then absence of the lung sliding with A line sign in the adjacent area ( the part of the lung that is separated from the wall). </li></ul><ul><li>On M-mode: lung point sign will appear at the precise line where the seashore sign switch to barcode sign. </li></ul><ul><li>It is a very specific sign for pneumothorax, will be able to detect minimal (millimeter-scale) pneumothorax, that often will be missed on the CXR. </li></ul>
  23. 23. Ultrasound for the Diagnosis of Pneumothorax Chan SSW et al Acad Emerg Med Jan 2003 Vol.10 1. Ultrasound Feature Patient Population Sensitivity Specificity No Lung Sliding 328 Surgical And Trauma 95.5% 100% No Lung Sliding 111 Medical ICU 95.3% 91.1% No B Lines “ Comet Tails” 114 Med-surgical Unit 100% 60% Combined 617 100% 96.5% Lung Point 233 Med-surgical Unit 66% 100%
  24. 24. Other Utilities of Ultrasound <ul><li>• Laryngeal U/S: </li></ul><ul><ul><li>To identify patients at high risk for reintubation due to stridor (more studies needed). </li></ul></ul><ul><ul><li>The high frequency (for superficial, vascular tissue) 6-13 mhz linear probe is sufficient. </li></ul></ul><ul><ul><li>The cuff-leak test: was widely used but its application is limited due to controversial results. </li></ul></ul><ul><ul><li>The air-column width during cuff deflation is a potential predictor of post-extubation stridor. </li></ul></ul>Advocate Christ Medical Center
  25. 25. Air-column during balloon-cuff inflation (hyper-echoic ). True cords are over both sides of the air-column (hypo-echoic). Cartilages are behind the true vocal cords and beside the air-column (Hyper-echoic). <ul><li>Air-column during balloon-cuff deflation (air-column width increased). </li></ul><ul><li>This patient didn’t developed post-extubation stridor. </li></ul><ul><ul><li>The air-column width during cuff deflation is a potential predictor of post-extubation stridor. </li></ul></ul>From Ding LW, Wang HC, Wu HD, et al. Laryngeal ultrasound: a useful method in predicting post-extubation stridor. A pilot study. Eur resp J 2006; 27-384-389
  26. 26. Other Utilities of Ultrasound <ul><li>ETT position assessment with ultrasound: </li></ul><ul><ul><li>Proximal ETT malposition: </li></ul></ul><ul><ul><ul><li>Esophageal. </li></ul></ul></ul><ul><ul><ul><li>ETT too high (can measure distance from vocal cord to tip of tube; in most, tube should not be visible above sternal notch). </li></ul></ul></ul><ul><ul><li>Distal ETT malposition: </li></ul></ul><ul><ul><ul><li>Bilateral lung sliding indicates normal ETT position. </li></ul></ul></ul><ul><ul><ul><li>Unilateral pleural sliding may indicate mainstem intubation. </li></ul></ul></ul><ul><ul><li>Combination of both may eliminate need for chest x-ray (study underway). </li></ul></ul>Advocate Christ Medical Center
  27. 27. Transverse view showing ETT
  28. 28. Longitudinal view showing ETT
  29. 29. ETT Position Tube position OK Confirm with auscultation, ETCO2 Translaryngeal Ultrasound Tip visible Intratracheal Remove and reintubate May be too high, measure distance below VC Pleural Ultrasound Bilateral sliding pleura Unilateral sliding pleura Mainstem intubation Pull tube back 1-2 cm Yes Yes No No
  30. 30. Limitations of lung ultrasound <ul><li>Require formal training aimed at acquiring the necessary knowledge and skills. </li></ul><ul><li>Obese patients are frequently difficult to examine. </li></ul><ul><li>The presence of subcutaneous emphysema or large thoracic dressings. </li></ul><ul><li>Lung ultrasound cannot detect lung over-inflation resulting from an increase in intrathoracic pressures. </li></ul>Advocate Christ Medical Center
  31. 31. Conclusion <ul><li>Easy to learn and apply. </li></ul><ul><li>It can be used quickly to rule out any significant pneumothorax in critically ill patient. </li></ul><ul><li>The entire exam can be completed and interpreted in less than a minute. </li></ul><ul><li>Thoracic ultrasound to rule out pneumothorax should be part of the FAST exam. </li></ul><ul><ul><li>Able to detect a very small pneumothorax. </li></ul></ul><ul><ul><li>Normal sliding lung excludes (100%) the presence of significant pneumothorax. </li></ul></ul><ul><ul><li>More sensitive than CXR or physical exam. </li></ul></ul><ul><ul><li>The routine use of lung ultrasound appears as an attractive alternative to bedside chest radiography. </li></ul></ul>Advocate Christ Medical Center
  32. 32. It isn't tough.....

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