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Anesth Analg 2007;104:466-468
© 2007 International Anesthesia Research Society
doi: 10.1213/01.ane.0000253691.32957.8b

LETTER TO THE EDITOR

Section Editor:
Lawrence Saidman

Prone Position in Early and Severe Acute Respiratory Distress Syndrome: A Design for a Definitive Randomized Controlled Trial

Spyros D. Mentzelopoulos, MD, PhD, Charis Roussos, MD, PhD, and Spyros G. Zakynthinos, MD, PhD

Department of Intensive Care Medicine; University of Athens Medical School; Evaggelismos Hospital; Athens, Greece; sdm{at}hol.gr

To the Editor:

The physiological rationale for placing patients with either acute respiratory failure (ARF) or acute respiratory distress syndrome (ARDS) in a prone position, rather than in some other position, includes better lung mechanics, better gas exchange, better alveolar ventilation, better lung volumes, homogeneity of lung aeration, increased effectiveness of recruitment maneuvers (i.e., sighs), and avoidance of ventilator-induced lung injury (1–14). Potential outcome benefits for the prone position may be most evident in patients with severe oxygenation failure (PAo2/inspired O2 fraction <88 mm Hg), simplified acute physiology score ≥50, and diffuse ARDS (11,12). However, the potential lung-protective effects of the prone position seem more pronounced in lobar ARDS (7).

Four randomized controlled trials (RCTs) concerning the effects of systematic prone positioning on patients with ARF or ARDS failed to definitively demonstrate improvement in survival (11–14). Methodological limitations of these studies include insufficient duration of prone position, study enrollment late in the patient’s ARDS course, absence of ventilation guidelines, use of higher tidal volumes in the prone position group, lack of homogeneity with respect to ARF etiology, and insufficient statistical power (11). Consequently, we propose a new, sufficiently powered, multicenter RCT on prone positioning of an ARDS subgroup. The major methodological points are presented in Table 1. Detection of a 15% decrease (i.e., effect size = 0.15) in severe ARDS mortality (11) by "group x event cross-tabulation" and {alpha} and ß values of 0.05 and 0.80, respectively, would require enrollment of 350 patients in a new RCT (G*Power, Duesseldorf University, Germany). I invite investigators interested in participating in this study to contact me directly.


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  		Table 1. Summary of the Proposed Multicenter Protocol

 

REFERENCES

  1. Pelosi P, Tubiolo D, Mascheroni D, et al. Effects of the prone position on respiratory mechanics and gas exchange during acute lung injury. Am J Respir Crit Care Med 1998;157:387–93.
  2. Friedrich P, Krafft P, Hochleuthner H, Mauritz W. The effects of long-term prone positioning in patients with trauma-induced adult respiratory distress syndrome. Anesth Analg 1996;83:1206–11.[Abstract]
  3. Gattinoni L, Vagginelli F, Carlesso E, et al. Decrease in PaCO2 with prone position is predictive of improved outcome in acute respiratory distress syndrome. Crit Care Med 2003;31:2727–33.[ISI][Medline]
  4. Vieillard-Baron A, Rabiller A, Chergui K, et al. Prone position improves mechanics and alveolar ventilation in acute respiratory distress syndrome. Intensive Care Med 2005;31:220–6.[ISI][Medline]
  5. Mentzelopoulos SD, Roussos C, Zakynthinos SG. Static pressure volume curves and body posture in acute respiratory failure. Intensive Care Med 2005; 31:1683–92.[ISI][Medline]
  6. Richter T, Bellani G, Scott Harris R, et al. Effect of prone position on regional shunt, aeration, and perfusion in experimental acute lung injury. Am J Respir Crit Care Med 2005;172:480–7.[Abstract/Free Full Text]
  7. Galiatsou E, Kostanti E, Svarna E, et al. Prone position augments recruitment and prevents alveolar overinflation in acute lung injury. Am J Respir Crit Care Med 2006;174:187–97.[Abstract/Free Full Text]
  8. Pelosi P, Bottino N, Chiumello D, et al. Sigh in supine and prone position during acute respiratory distress syndrome. Am J Respir Crit Care Med 2003;167:521–7.[Abstract/Free Full Text]
  9. Mentzelopoulos SD, Roussos C, Zakynthinos SG. Prone position reduces lung stress and strain in severe acute respiratory distress syndrome. Eur Respir J 2005;25:534–44.[Abstract/Free Full Text]
  10. Valenza F, Guglielmi M, Maffioletti M, et al. Prone position delays the progression of ventilator-induced lung injury in rats: does strain distribution play a role? Crit Care Med 2005;33:361–7.[ISI][Medline]
  11. Mancebo J, Fernández R, Blanch L, et al. A multicenter trial of prolonged prone ventilation in severe acute respiratory distress syndrome. Am J Respir Crit Care Med 2006;173:1233–9.[Abstract/Free Full Text]
  12. Gattinoni L, Tognoni G, Pesenti A, et al. Effect of prone positioning on the survival of patients with acute respiratory distress syndrome. N Engl J Med 2001;345:568–73.[Abstract/Free Full Text]
  13. Guérin C, Gaillard S, Lemasson S, et al. Effects of systematic prone positioning in hypoxemic acute respiratory failure: a randomized controlled trial. JAMA 2004; 292:2379–87.[Abstract/Free Full Text]
  14. Curley MA, Hibberd PL, Fineman LD, et al. Effect of prone positioning on clinical outcomes in children with acute lung injury: a randomized controlled trial. JAMA 2005;294:229–37.[Abstract/Free Full Text]
  15. The Acute Respiratory Distress Syndrome Network. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med 2000;342:1301–8.[Abstract/Free Full Text]
  16. Dellinger RP, Carlet JM, Masur H, et al. Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock. Crit Care Med 2004;32:858–73.[ISI][Medline]
  17. Nuckton TJ, Alonso JA, Kallet RH, et al. Pulmonary dead-space fraction as a risk factor for death in the acute respiratory distress syndrome. N Engl J Med 2002; 346:1281–6.[Abstract/Free Full Text]



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S. Sud MD, M. Sud BSc, J. O. Friedrich MD DPhil, and N. K.J. Adhikari MDCM MSc
Effect of mechanical ventilation in the prone position on clinical outcomes in patients with acute hypoxemic respiratory failure: a systematic review and meta-analysis
Can. Med. Assoc. J., April 22, 2008; 178(9): 1153 - 1161.
[Abstract] [Full Text] [PDF]

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Lippincott, Williams & Wilkins Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999 HighWire Press