Prone Position and Mechanical Ventilation

Reviewed and revised 19 May 2014

OVERVIEW

Prone positioning can be used in mechanically ventilated patients with severe hypoxic respiratory failure to optimise oxygenation

  • most studied  in patients with acute respiratory distress syndrome (ARDS) where short lived improvements in oxygenation are common (70%) and sometimes dramatic (e.g. Gattinoni et al, 2001). Some patients have no effect and others have a long lasting effect, persisting well after rolling supine again.
  • the PROSEVA trial found a marked mortality benefit in patients with severe ARDS (PF ratio <150)

Refer to Prone Positioning for Hypoxic Respiratory Failure on INTENSIVE for the Alfred ICU guideline, cognitive aid, and checklist for prone ventilation.

INDICATIONS

  • severe ARDS with life threatening, refractory hypoxaemia
  • prone positioning may also be used for patients with posterior wounds, burns and skin flaps

CONTRAINDICATIONS

  • untrained staff
  • increased intracranial pressure
  • increased abdominal pressure
  • abdominal and chest wounds
  • C-spine precautions
  • extreme obesity
  • haemodynamic instability

PROCEDURE

  • assemble sufficient trained staff to coordinate positioning safely
  • provide padding and support for potential pressure areas (face, upper chest, pelvis, knees)
  • turn patient prone
  • abdomen should hang between two pillows/ supports
  • duration varies among protocols (e.g. 6-16 hours a day for up to 10 days)

See this video from the PROSEVA trial paper in NEJM:

PHYSIOLOGICAL EFFECTS

Supine position

  • reduction in VC
  • reduction FRC

Prone position

  • optimisation of V/Q matching (increased blood flow to the dependent lung)
  • increase in FRC
  • reduced atelectasis
  • facilitates secretion drainage
  • less lung deformation in the prone position (increased homogeneity) -> increased ventilation
  • abdomen is less likely to distend when in prone position -> increase in FRC
  • heart sits against sternum (rather than left lung) -> lung is less compressed
  • decreased transpleural pressure gradient between dependent and non-dependent lung in the prone position
  • plateau pressure is more uniformly distributed when prone -> more uniform alveolar ventilation
  • recruitment manoeuvres have been shown to be more effective in the prone position
  • alterations in chest wall mechanics -> allowing lungs to inflate at lower pressures
  • dorsoventral orientation of large airways

COMPLICATIONS

  • decreased enteral nutrition
  • ETT obstruction or dislodgement;
  • chest tube and abdominal drain dislodgement
  • increased intrabdominal pressure
  • increased intracranial pressure
  • difficulty monitoring (e.g. ECG lead placement)
  • labour intensive
  • difficult to perform procedures or reintubate
  • may delay referral to other potentially life-saving measures such as ECMO
  • facial oedema
  • pressure trauma:
    • -> ocular
    • -> blindness, orbital skin necrosis
    • -> bridge of nose
    • -> mentum
    • -> humeral head
    • -> breast implants
    • -> ASIS
    • -> male genitals
    • -> knees

EVIDENCE

Summary

  • there have been multiple conflicting RCTs but the weight of evidence now suggests prone ventilation is beneficial in selected severe ARDS patients
  • Gattinoni et al 2001 was the original study showing improvement in oxygenation of most patients with ALI /ARDS by proning
  • Recent meta-analyses suggest a mortality benefit for patients with severe ARDS (PF ratio <100), with an NNT of 11
  • Subsequent to the above meta-analyses, the PROSEVA trial by Guerin et al 2013 showed a marked mortality benefit (NNT = 6) for prone ventilation in severe ARDS  (28-day mortality 16% prone versus 32.8% supine)
Summaries of key papers

Gattinoni L, et al; Prone-Supine Study Group. Effect of prone positioning on the survival of patients with acute respiratory failure. N Engl J Med. 2001 Aug 23;345(8):568-73. PubMed PMID: 11529210. [fulltext]

  • a prospective RCT with n = 304
    • -> 50-75% of patient have an improvement in oxygenation on turning prone (oxygenation increases in at least 60% of patients, with oxygenation ratios 34% higher)
    • -> response is sustained and results in a decreased requirement for PEEP and FiO2
    • -> proning has been shown to significantly increase oxygenation of ARDS patients
    • -> this did not translate into a significant short or long term benefits
  • Criticisms/ commentary:
    — those randomised to prone ventilation only received 7 hours/day
    — not powered for mortality
    — prone ventilation was not instituted early in course of ALI/ARDS
    — standard ventilation and weaning protocols were not used
    — study only last 10 days
    — numerous breaks in protocol

Sud S, et al. Prone ventilation reduces mortality in patients with acute respiratory failure and severe hypoxemia: systematic review and meta-analysis. Intensive Care Med. 2010 Apr;36(4):585-99. Epub 2010 Feb 4. Review. PubMed PMID: 20130832.

  • meta-analysis of 10 RCTs, n = 1,867
  • prone vs supine position with hypoxic respiratory failure
  • inclusion: adults, children, PF ratio < 300
  • exclusion: neonates
  • primary outcome = hospital mortality with regard to severity of hypoxaemia
  • secondary outcomes = duration of MV, ventilator free days to 28 days, adverse events…
    • -> significant decrease in mortality in those with PF ratio of < 100 (NNT 11)
    • -> increased oxygenation
    • -> reduced VAP
    • -> no effect on duration of mechanical ventilation
    • -> increased adverse effects: ETT obstruction, chest tube dislodgement, pressure ulcers

Abroug F, et al. An updated study-level meta-analysis of randomised controlled trials on proning in ARDS and acute lung injury. Crit Care. 2011;15(1):R6. Epub 2011 Jan 6. PubMed PMID: 21211010; PubMed Central PMCID: PMC3222033.

  • meta-analysis of 7 RCTs, n= 1,675
  • prone versus supine position in patients with ALI/ARDS
  • overall did not reduce ICU mortality (OR = 0.91, 95% CI = 0.75 to 1.2; P = 0.39)
  • but did significantly reduced the ICU mortality in the 4 recent studies that enrolled only patients with ARDS (OR = 0.71; 95% CI = 0.5 to 0.99; P = 0.048; NNT = 11)

Guérin C, et al; PROSEVA Study Group. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013 Jun 6;368(23):2159-68. doi: 10.1056/NEJMoa1214103. Epub 2013 May 20. PubMed PMID: 23688302. [Free Full Text]

  • MCRCT n =466
  • patients with severe ARDS (PaO2/Fi02 ratio <150 mm Hg, with FiO2 of at least 0.6, PEEP  at least 5 cmH2), and VT 6 ml/kg of IBW)
  • prone-positioning sessions of at least 16 hours duration (n=237) with the supine position (n=229)
  • primary outcome: 28-day mortality lower in the prone group (16% versus 32.8%; P<0.001; hazard ratio for death 0.39, 95% CI 0.25 to 0.63)
  • secondary outcomes:
    — Unadjusted 90-day mortality lower with prone positioning (23.6% versus 41.0%; P<0.001; hazard ratio 0.44, 95% CI 0.29 to 0.67), NNT=6
    — incidence of cardiac arrests higher in the supine group
    — no difference in ICU LOS or other complications such as pneumothorax
    — better oxygenation, lower oxygen requirements, and more ventilation-free days in prone group
  • commentary:
    — highly select group: <15% of all patients with ARDS and <1/3 of screened patients with ARDS underwent randomization,  almost 60% ineligible on the basis of exclusion criteria
    — benefit may be because of long duration proning
    — mortality among controls (32.8%) was similar to the mortality of 25 to 40% observed in various trials

Beitler JR, Shaefi S, Montesi SB, Devlin A, Loring SH, Talmor D, Malhotra A. Prone positioning reduces mortality from acute respiratory distress syndrome in the low tidal volume era: a meta-analysis. Intensive Care Med. 2014 Mar;40(3):332-41. doi: 10.1007/s00134-013-3194-3. Epub 2014 Jan 17. PubMed PMID: 24435203; PubMed Central PMCID: PMC3976426.

  • Meta-analysis, 7 trials, n > 2100 in whom 1088 were proned
  • Results
    • Overall prone positioning was not associated with RR of death, but significant heterogeneity amongst studies
    • When stratified by low or high tidal volume, proning was associated with significant decreased risk of death in low Vt (< 8ml/kg) group only
    • Tidal volume accounted for over half of the heterogeneity in proning studies
    • High vs low PEEP strategies were not explored

AN APPROACH

  • Use proning for severe ARDS if refractory to other treatments, trained staff are available and ECMO is not otherwise required

References and Links

Journal articles and textbooks

  • Abroug F, Ouanes-Besbes L, Dachraoui F, Ouanes I, Brochard L. An updated study-level meta-analysis of randomised controlled trials on proning in ARDS and acute lung injury. Crit Care. 2011;15(1):R6. PMC3222033.
  • Fessler HE, Talmor DS. Should prone positioning be routinely used for lung protection during mechanical ventilation? Respir Care. 2010 Jan;55(1):88-99. PMID: 20040127.
  • Gattinoni L, Tognoni G, Pesenti A, Taccone P, Mascheroni D, Labarta V, Malacrida R, Di Giulio P, Fumagalli R, Pelosi P, Brazzi L, Latini R; Prone-Supine Study Group. Effect of prone positioning on the survival of patients with acute respiratory failure. N Engl J Med. 2001 Aug 23;345(8):568-73. PMID: 11529210.
  • Gattinoni L, Carlesso E, Taccone P, Polli F, Guérin C, Mancebo J. Prone positioning improves survival in severe ARDS: a pathophysiologic review and individual patient meta-analysis. Minerva Anestesiol. 2010 Jun;76(6):448-54. PMID: 20473258.
  • Guérin C, et al; PROSEVA Study Group. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med. 2013 Jun 6;368(23):2159-68. PMID: 23688302.
  • Soo Hoo. In Prone Ventilation, One Good Turn Deserves Another. New Engl J Med 2013; epublished May 20th
  • Messerole E, Peine P, Wittkopp S, Marini JJ, Albert RK. The pragmatics of prone positioning. Am J Respir Crit Care Med. 2002 May 15;165(10):1359-63. PMID: 12016096.
  • Pelosi P, Brazzi L, Gattinoni L. Prone position in acute respiratory distress syndrome. Eur Respir J. 2002 Oct;20(4):1017-28. PMID: 12412699.
  • Sud S, Friedrich JO, Taccone P, Polli F, Adhikari NK, Latini R, Pesenti A, Guérin C, Mancebo J, Curley MA, Fernandez R, Chan MC, Beuret P, Voggenreiter G, Sud M, Tognoni G, Gattinoni L. Prone ventilation reduces mortality in patients with acute respiratory failure and severe hypoxemia: systematic review and meta-analysis. Intensive Care Med. 2010 Apr;36(4):585-99. PMID: 20130832.

Social media and web resources


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Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

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