Journal Club

1. Journal Club Naveed Hasan Jan 5, 2011

2. Pleural Ultrasound Compared With Chest Radiographic Detection of Pneumothorax Resolution After Drainage

3. BACKGROUND • NON-INVASIVE AND READILY AVAILABLE (WHEREVER AVAILABLE!!!) • Chest radiographs (CXR) miss 30% to 72% of pneumothoraces because of their anterior location1 • “DEEP SULCUS SIGN” can only detect less than one quarter of the anterior PTXs2 • Pleural Ultrasound (PU) is more sensitive in detection of PTX3,4

4. Hypothesis • PU is more accurate in assessing resolution of PTX after Chest Tube drainage

5. Study Design: • Prospective Observational study • Single center trial • Specialized 4-bed PTX Unit in France

6. Patient Selection • All Patients with PTX were eligible, except - Subcutaneous emphysema - Use of mechanical ventilation

7. End Points: • the number of residual pneumothoraces diagnosed by PU, including those not identified by CXR • The therapeutic impact of PU use • The time to obtain CXR and PU results; and • the residents’ learning curve for using PU

8. Methods • All pneumothoraces were drained using a dedicated device, Pleurocath 8 French • connected to water seal vacuum system regulated to generate a depressurization of 30 cm H2O. • pleural catheter patency check every 4 h by nurses using 5 mL of saline

9. UltrasonographicIdentification of Pneumothorax • Ultrasound diagnosis of pneumothorax relies on three signs: • abolition of lung sliding, • the A-line sign (the presence of A-lines without B-lines, The presence of B-lines rules out pneumothorax diagnosis) • the lung point

10. Technique of PU • performed by a single investigator using a portable SonoSite180 plus and a 7.5-MHz linear probe with the patient erect • probe was placed perpendicular to the intercostal spaces and then moved along the midclavicularline, the midaxillary line, and along the outer edge of the scapula

12. Probe Position

13. Sonographic lung Zones

14. Definition of PTX • Pneumothorax diagnosis by PU was defined as the abolition of lung sliding plus the A-line sign • Presence of lung point was also noted but was not required for pneumothorax to be suspected.

15. What you should see normally • Lung Sliding Sign • A- Lines • B - Lines (comet tail artifacts) • Lung pulse +/-

16. Normal Lung Sliding Sign • Produced by sliding of visceral pleura over parietal pleura • >95% sensitivity for PTX http://www.critcaresono.com/page.php?page=29 Video 9

17. Sea-Shore Sign in Normal Lung • Seen in M-mode • Includes motionless parietal tissues over pleural line and homogenous granular pattern below it.

18. Lack of Sliding Sign • PTX • Pleural Adhesion • Mainstem Intubation • Pulmonary Contusion • ARDS • Atelactesis

19. A- Lines • “Reverberation” Artifact • Parallel to Pleural line • Distance between A-lines is equal to or a multiple of Visceral- Parietal Pleural Interface (VPPI) or Lung Chest Wall Index (LCWI)

20. The B-Lines (Comet-tail Artifacts) • Usually seen in the lower lung zones, laterally or posteriorly • Originate at the VPPI and usually extend down to the bottom of the picture • Usually 3-4 lines in one intercostal space • No of lines correlate with the alveolar interstitial pattern • Presence of B-Lines rule out PTX http://www.critcaresono.com/page.php?page=29 Video 9

21. The B Lines…contd

22. The A-Line Sign • Presence of A-lines in the absence B lines http://www.critcaresono.com/page.php?page=27 Video 11

23. The Lung Point • Denotes the edge of PTX • Most specific sign for diagnosis of PTX (100% specificity)

24. The Lung Point…M-Mode

25. The Lung Point • http://www.critcaresono.com/category/Lung/2

26. The Lung Pulse • excellent sign in the post-pleurodesispatient • rhythmic "pulsations" at the pleural line reflect the cardiac pulsations transmitted to the visceral pleura • Can only be seen when there is NO AIR between the two pleural surfaces and is a good alternative sign to look for when lung sliding cannot be easily detected. • Presence of lung pulse rules out possibility of pneumothorax. http://www.critcaresono.com/page.php?page=27 Video 14

27. CXR and PU Indications • CXR and PU were performed in a double-blind manner at the following times: (1) 24 h after bubbling in the aspiration device had stopped, (2) 6 h after clamping the pleural catheter, and (3) 6 h after removing the pleural catheter. For pneumothorax recurrence, additional CXR and PU were performed at these same time points.

28. Confirmation of Pneumothorax Identified by PU But Not CXR • aspiration with a syringe of >10 mL of air through the pleural catheter if it has previously been clamped, or • by CT scan in other cases

29. Statistics • The positive predictive value (PPV) of PU for pneumothorax diagnosis was calculated using the standard formula.

30. Results • 51 patients screened over 18 months, 7 were excluded. • All had unilateral PTX • Cause of PTX as follows - Primary Spontaneous (70%) - Traumatic (15.9%) - Secondary to emphysema (9%) - Iatrogenic (4.5%) • Mean stay in ICU was 3.9 +/- 1.5 days • 84 % patients were treated successfully, 16% required surgical intervention

31. Results…contd

32. Results…contd *5 confirmed by CT scan and 8 confirmed by aspiration of air

33. Therapeutic Intervention • Aspiration switched on or maintained longer than predicted, n = 8 • Unblocking the pleural catheter, n = 3 • Introduction of second pleural catheter, n =1 • Surgical intervention, n = 1

34. Results…contd • PPV of PU was 100% for diagnosing residual PTX after drainage of primary spontaneous PTX with or without the presence of lung point. • PPV of PU was 90% for diagnosing residual PTX after drainage of non-primary spontaneous PTX without lung point and 100% in the presence of lung point.

35. PU Learning Curve • Six ICU residents took part in the study • Each received 2h of training with no previous USG experience • Mean no. of exams performed by each resident was 27+/- 12 • There was no significant difference between the results of resident and primary investigator

36. Critical Analysis • Use of small size catheter for PTX drainage - Large-bore Chest tube vs 8 F catheter • Confirmation of PTX by non-standard method (aspiration of air) • Impact on patient outcome - clinical significance of detecting occult PTX • Generalizability - Majority of study population had primary spontaneous PTX

37. CHEST TUBE vs PleureX J THORAC CARDIOVAS SURG 2011;141:683-7 • Retrospective study on non-trauma patients • 12 F catheter was used • 399 catheters were placed for PTX • 75% were primary PTX • Success rate was 93 % • Failure mostly secondary to dislodgment

38. Confirmation of Residual/Occult PTX • Gold standard is CT scan • Does 10 ml of air aspiration corresponds to residual/occult PTX on CT scan???

39. Clinical Significance of Occult PTX Injury, Int. J. Care Injured 40 (2009)928-931 • Retrospective review of 1881 Blunt trauma patients • 307 PTXs were found, 68 were occult • 35/68 received Tube thoracostomy, 33/68 were observed • No Tension PTXs seen in each group • Mortality was similar • LOS was significantly shorter in observation group

40. Conclusions: • PU is more sensitive in diagnosing Pneumothoraces, Primary spontaneous and post-procedural • The clinical significance of diagnosing these small PTXs missed by CXRs remains to be determined

41. Thank You

42. References: • 1. Soldati G , Testa A , Pignataro G , et al . The ultrasonographicdeep sulcus sign in traumatic pneumothorax . Ultrasound Med Biol . 2006 ; 32 ( 8 ): 1157 – 1163 • 2. Ball CG , Kirkpatrick AW , Fox DL , et al. Are occult pneumothoraces truly occult or simply missed? J Trauma . 2006 ; 60(2):294-298. • 3. Lichtenstein DA , Mezière G , Lascols N , et al . Ultrasound diagnosis of occult pneumothorax . Crit Care Med . 2005 ; 33 ( 6 ): 1231 - 1238 .