Prone position for Acute Respiratory Distress Syndrome

1. Prone position for Acute Respiratory Distress Syndrome Gau-Jun Tang, MD, MHS I-Lan Hospital affiliated with Taipei Veterans General Hospital National Yang-Ming University Taipei, Taiwan

2. Surviving Sepsis CampaignGuidelines for Management of Severe Sepsis and Septic Shock Dellinger RP, Carlet JM, Masur H, et al. Surviving Sepsis Campaign Management Guidelines Committee.Crit Care Med 2004; 32:858-873

3. K. Mechanical Ventilation of Sepsis-Induced ALI/ARDS • Low tidal volume (6 mL/kg) to minimize plateau pressures (Grade B) • Permissive hypercapnia. (Grade C) • High PEEP to prevent lung collapse at end-expiration. (Grade B) • Keep semirecumbent bed position with head up 45˚ unless contraindicated. (Grade D) • Weaning protocol undergo a spontaneous breathing trial. -- low level of PS with CPAP 5 cm H2O -- T-piece. (Grade A)

4. Management of ALI/ARDS • Make the diagnosis • Rx underlying disease • Lung protective ventilation • Low VT, PEEP using ARDSnet protocol • Prone positioning in selected patients • Steroids – no routine use

5. Treatment of ARDS Improving oxygenation Prevent oxygen toxicity Avoid barotrauma Lung rest

6. Improving oxygenation Positive airway pressure PEEP NO ECMO

7. Acute respiratory distress syndrome • improve oxygenation • ventilator-induced lung injury?

8. Improving oxygenation Bryan AC. Comments of devil's advocate Am Rev Respir Dis 1974 Piehl MA. Use of extreme position change in acute respiratory failure. Crit Care Med 1976 Douglas WW. Improved oxygenation in patients with acute respiratory failure: the prone position. Am Rev Respir Dis 1977

9. Plain CXR

10. CT scan

13. Oxygenation

14. Compliance

15. MPAP

16. Clinical experience on 12 ARDS patients • Mean age: 67+18 • Blood gas before prone: PaO2/FiO2: 157+39 • PEEP: 14 + 3 • PC: 33 + 5 • Oxygenation improve in 11 patients • Mean improvement in PaO2 after 4 hr : 52+18

17. Response • Improve in oxygenation 78% • Pa O2 rise 70 mmHg after 4 hr prone • Chatte, AJRCCM, 1997 • Pa O2 rise 58 mmHg after 4 hr prone • Tang (10/12) • non-responder: more severe ARDS

18. Turning Back to Supine • back to supine level • 57% patients improve oxygenation persisted • Chatte, AJRCCM, 1997 • 10 patients oxygenation deteriorate • Cardiac arrest 1 hr after • 1 patient persisted • 1 patient fluctuate and finally stabilize • Mechanism • Difference between opening and closing pressure • Improvement in ALI

19. Effect of Prone on Hemodynamics • No change in BP • Mild increase in CO • Hemodynamic unstable • turn by steps, 45 degree first

20. When turn back • 4-8 hr • Piehl, 1976 • 24-33 Hr • Rappert, 1994 • 2 -3 day • Tang, 1998

21. Mechanism of improve oxygenation • Deloading of abdominal pressure • Douglas, Am Rev Resp D, 1977 • Perfusion to the non-dependent lung • perfusion continue flow to the dorsal lung • Wiener, AJP, 1990

22. Acute lung Injury

23. Supine to Prone PaO2: 76 PaO2: 137

24. Information from CT scan Normal CT densities increase along the gravitational change decrease gas volume and increase tissue volume Supine to prone Anatomical redistribution of CT densities Mechanism decrease in distending (transpulmonary) pressure pleural pressure increase along gravitational change

25. Pleural pressure increase along gravitational change

26. Difference in lung volume along the gravitational line

27. Effect on Survival • Gattinoni L, Tognoni G, Pesenti A, et al. Effect of prone positioning on the survival of patients with acute respiratory failure. N Engl J Med 2001;345

28. Explanation for negative result • prone positioning does not decrease ventilator-induced lung injury. • study may not have had adequate statistical power • more than 300 patients, but this number may have been too small • imprecision in the diagnosis of the ARDS • heterogeneity of the underlying diseases • lack of uniformity among other interventions used, apart from mechanical ventilation.

29. Explanation for negative result • patients were placed in the prone position for an average of only 7.0 hours per day. • patients were exposed to the potentially injurious effects of mechanical ventilation in the supine position for more than 70 percent of each day.

30. Explanation for negative result • limited the use of the prone position to 10 days • too short a period for any significant long-term benefit to occur • The authors reported a trend toward a decrease in mortality at 10 days in the prone group; this effect was not apparent by the time of discharge from the intensive care unit. • future trials should examine the efficacy of maintaining the prone position for longer periods. • The Acute Respiratory Distress Syndrome, Mechanical Ventilation, and the Prone Position, [Editorial], Slutsky, NEJM, 2001

31. Clinical practice • Reluctance • Despite the numerous studies demonstrating a significant improvement in oxygenation, prone positioning is still underused • (Gosheron et al 1998, Webster 1997). • logistical difficulties in turning critically ill patients onto their stomachs • (O'Connor et al 1998), • unpredictability of the prone position.

32. Indications • Mechanically ventilated and well-sedated patients should be placed in the prone position if oxygenation is inadequate • Greater than 50 per cent FiO2, • PEEP levels higher than 10cmH2O, • Pulmonary artery pressure (PAP) is <18mmHg (or there is no clinical sign of left ventricular failure), • Bilateral infiltrates are present on the anterior-posterior chest X-ray • (Dirkes and Dickinson 1998, Voggenreiter et al 1999).

33. Frequency of turning • no consensus regarding the length of time a patient should be placed in the prone position. • Predict how a patient will react to being turned • Haemodynamic stability and maintaining an adequate gas exchange. • If oxygenation improves during the pronation period, the patient can be keeped in the prone position for up to 20 hours a day • (Fridrich et al 1996).

34. Frequency of turning • The frequency of turning will ultimately depend on the patient's response. • If a patient is returned to the supine position too early, • respiratory decompensation can occur, • oxygenation may return to pre-pronation levels • (Curley et al 2000, Dirkes and Dickinson 1998, Mure et al 1997, Vollman 1997).

35. Contraindications • spinal instability, • increased intracranial pressure • (Gentilello et al 1988) • abdominal compartment syndrome, • shock, • multiple trauma, • massive resuscitation, • pregnancy, • abdominal surgery • extreme obesity (Balas 2000).

36. Complications • possibility of self-extubation, loss of intravenous access • (Fridrich et al 1996), • difficulties in monitoring patients and in performing cardiopulmonary resuscitation • (Vollman 1997). • The positioning of ventilator tubing • risk of aggravating cardiovascular instability • (Thomas 1997). Hess et al (1992)

37. Ongoing management • Keep haemodynamic status continually during and after turning (Vollman 1997). • Significant drop in blood pressure, • fluid replacement may be required or it may be necessary to increase the level of inotropic support. • The patient should be returned to the supine position if the oxygen saturation level drops significantly and does not improve after several minutes of increased FiO2. • Arterial blood gases should be performed once the patient has been undisturbed in the prone position for at least 30 minutes.

38. Ongoing management • The position of the head should be altered every two to three hours to prevent pressure ulcers forming on the cheeks, ears and neck, and the arm positions should also be altered at this time • positioning of the breasts and the male genitalia • high inotropic support, making the pressure areas even more vulnerable. • A small pillow can be placed under the iliac crest to avert pressure on the penis and scrotum, or under the upper chest to avoid compression of the breasts.

39. 'unrestricted abdomen' • allow the passive movement of the diaphragm and the downward displacement of the abdominal contents. • high inspiratory pressures due to reduced lung compliance • addition of abdominal pressure could potentially cause a further rise in inspiratory pressure and barotrauma. • Chatte et al 1997, Douglas et al 1977

40. Kinetic therapy • If a patient cannot be placed in the prone position because of contraindications, • special beds. • facilitating gas exchange using rotation movements • prevent 'pooling' of secretions. • initiated before prone positioning is considered.

42. Contraindications Shock Acute bleeding Multiple trauma Spinal instability Pregnancy Raised intracranial pressure Recent abdominal surgery ?

43. Complications Airway security Dislodging access lines Facial edema Nerve compression Venous stasis Pressure sore Diaphragmatic limitation

44. Facial edema

45. Prone for Acute Lung Injury the biologic rationale for using the prone position is strong major complications,appear to be limited; the costs are minimal; and there is evidence, albeit weak at present, that mortality is decreased in the subgroup of patients who are most severely ill. Oxygenation improve in 70% patients Early implement to prevent ventilator induced lung injury Team approach