Skip to main content
 

Main menu

  • Home
  • Content
    • Current Issue
    • Editor's Commentary
    • Coming Next Month
    • Archives
    • Most-Read Papers of 2021
  • Authors
    • Author Guidelines
    • Submit a Manuscript
  • Reviewers
    • Reviewer Information
    • Create Reviewer Account
    • Reviewer Guidelines: Original Research
    • Reviewer Guidelines: Reviews
    • Appreciation of Reviewers
  • CRCE
    • Through the Journal
    • JournalCasts
    • AARC University
    • PowerPoint Template
  • Open Forum
    • 2022 Call for Abstracts
    • 2021 Abstracts
    • Previous Open Forums
  • Podcast
    • English
    • Español
    • Portugûes
    • 国语
  • Videos
    • Video Abstracts
    • Author Interviews
    • Highlighted Articles
    • The Journal

User menu

  • Subscribe
  • My alerts
  • Log in

Search

  • Advanced search
American Association for Respiratory Care
  • Subscribe
  • My alerts
  • Log in
American Association for Respiratory Care

Advanced Search

  • Home
  • Content
    • Current Issue
    • Editor's Commentary
    • Coming Next Month
    • Archives
    • Most-Read Papers of 2021
  • Authors
    • Author Guidelines
    • Submit a Manuscript
  • Reviewers
    • Reviewer Information
    • Create Reviewer Account
    • Reviewer Guidelines: Original Research
    • Reviewer Guidelines: Reviews
    • Appreciation of Reviewers
  • CRCE
    • Through the Journal
    • JournalCasts
    • AARC University
    • PowerPoint Template
  • Open Forum
    • 2022 Call for Abstracts
    • 2021 Abstracts
    • Previous Open Forums
  • Podcast
    • English
    • Español
    • Portugûes
    • 国语
  • Videos
    • Video Abstracts
    • Author Interviews
    • Highlighted Articles
    • The Journal
  • Twitter
  • Facebook
  • YouTube
EditorialEditorials

Mechanical Ventilation of Patients With and Without ARDS: How Far Have We Come?

Robert P Dickson
Respiratory Care April 2013, 58 (4) 712-714; DOI: https://doi.org/10.4187/respcare.02384
Robert P Dickson
Division of Pulmonary and Critical Care Medicine Department of Internal Medicine University of Michigan Ann Arbor, Michigan
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • For correspondence: [email protected]
  • Article
  • References
  • Info & Metrics
  • PDF
Loading

Nearly 13 years ago, the publication of results from the ARDS Network's ARMA trial revealed an 8.8% absolute mortality reduction in patients with acute lung injury (ALI)/ARDS receiving a low tidal volume ventilation strategy.1 One might have guessed at the time that such unambiguous benefit from a low-cost (strictly speaking, marginally no-cost) intervention, with no need for new equipment, and minimal additional training, would be embraced by clinicians and adopted widely. But such a guess would ignore the well described chasm between evidence-derived best practices and “real world” care as it is delivered.2,3 While much attention is paid to the need for translational research to bridge the gap between the lab bench and the patient's bedside, an equally important gap exists between our best available clinical evidence and our current clinical practice.

Indeed, post-ARMA studies of the adoption of lung-protective ventilation protocols in patients with ALI/ARDS have been discouraging, with estimates of provider adherence ranging from 39% to 57%, even in recent years.4–8 Several studies have explored barriers to implementation of lung-protective ventilation,4,5,9 identifying provider discomfort with low tidal volumes, failure to recognize appropriate contexts for protocol initiation, and provider suspicion of “cookbook medicine,” with a one-size-fits-all protocol for a varied and heterogeneous patient population. Beyond the persistent uncertainties regarding factors influencing clinician management of ARDS, little is known about changes over time in ventilation practices of non-ARDS patients and whether these practices contribute to the pathogenesis of ventilator-induced lung injury and ARDS.

In this issue of Respiratory Care, Chang et al share the results of a study intended to help answer these and other questions regarding “real world” clinical practice in the ventilator management of patients with and without ARDS.10 They performed secondary analysis of an observational study designed to determine early clinical predictors of subsequent ARDS development (the Lung Injury Prevention Study [LIPS]11), with observational data from 829 patients receiving mechanical ventilation at 22 centers. This study's size places it among the largest of its kind, and enabled the authors to analyze practice in various ICU contexts and to consider inter-center variability. It is thus a welcome contribution to our understanding of the state of contemporary ventilator management.

In addition to its large sample size, the study is strengthened by its authors' access to robust clinical data regarding patients' demographics, indications for mechanical ventilation, and subsequent ICU course. The primary limitation of the study is its restriction to “snapshot” ventilator settings at restricted time points: immediately following intubation and (if applicable) following the subsequent development of ALI/ARDS. Thus the data did not permit the authors to fully assess providers' adherence to the lung-protective ventilation protocol, which demands ongoing reassessment and ventilator titration in response to airway pressures and arterial blood gas results. As a proxy, the authors used their own definition of initial tidal volume under 8 mL/kg predicted body weight (PBW) to define patients receiving “low tidal volume ventilation.” While this type of proxy is reasonable (and generally necessary) within the confines of “ecological” observational studies such as this, initial ventilator settings in acute respiratory failure are often set before the first arterial blood gas or chest x-ray are available, limiting bedside assessment of ARDS, and (more importantly) may bear little resemblance to ventilator settings in subsequent days. Moreover, in the ARMA protocol, clinicians were permitted 4 hours after patient randomization before the target tidal volume (6 mL/kg PBW) was to be obtained.1 It is thus impossible to accurately assess whether this study's patients were receiving “low tidal volume ventilation” (as defined in the ARMA trial) based upon initial ventilator settings alone. These limitations may erase meaningful differences in ventilator management between patients, and should be borne in mind before generalizing the authors' findings.

The authors observed that patients initially intubated while meeting the criteria for ALI/ARDS (enrollment was performed prior to the recent publication of the Berlin definition of ARDS, which removed the designation of ALI12) received lower tidal volumes than patients who did not meet the criteria for ALI/ARDS. While this difference is encouraging (and has not always been observed13), the absolute difference in tidal volumes between these 2 groups (7.96 mL/kg PBW vs 8.45 mL/kg PBW) was small. The initial tidal volume of the ALI/ARDS arm is comparable to what has been reported in previous studies,8 and is actually statistically insignificant from the initial tidal volume recommended by the most recent iterations of the ARDS Network protocol (8 mL/kg PBW).14 The small difference in tidal volumes between these groups is in large part driven by the initial tidal volume in the non-ALI/ARDS group, which is low for non-ARDS patients by historical comparison,15,16 and consistent with what has been reported more recently.13 Taken with these other studies, this observation raises 2 possibilities: providers may have been moving in recent years toward the use of lower tidal volumes, even in patients who do not have ARDS; and this trend may obscure or erase differences in ventilator-related outcomes such as those measured in the current study. Recall that the “traditional ventilation” strategy in ARMA utilized an initial tidal volume of 12 mL/kg PBW,1 more than 40% greater than the median tidal volume observed in the current observational study's non-ARDS arm. “Traditional ventilation” is almost certainly a moving target, which makes fair historical comparisons between patients in different studies a challenge, if not impossible.

In their analysis of factors related to initial ventilator settings in patients without ARDS, the authors discovered a remarkable disparity between the likelihood of male and female patients receiving (by their definition) “lower tidal volume ventilation” (81.8% vs 51.1%, respectively). This observation is aligned with those of other recent studies that have demonstrated increased tidal volumes received by female patients, compared to men.4,16 As well, as has also been observed in the same studies, this difference disappears when adjusted for height and body mass index. Chang et al speculate (rightly, in my opinion) that many providers unfortunately still often rely on actual body weight rather than PBW in determining tidal volumes, which would predispose heavy and short patients to inappropriately large tidal volumes. Given that obesity is more common among adult women than men in the United States,17 and given the on-average shorter stature of women than men, clinician reliance on actual body weight may fully explain this potentially important disparity in critical care delivery. Interestingly, the current study found that male sex was a positive risk factor for subsequent development of ARDS among non-ARDS patients; thus, if the sex disparity in initial tidal volumes is adversely affecting female patients, any signal of this is being overwhelmed by other contributing factors.

Finally, while we have known for decades from animal modeling and observational human studies that high tidal volume ventilation can provoke lung inflammation, alveolar damage, and pulmonary edema,18,19 the question of whether low tidal volume ventilation can prevent subsequent development of ARDS among ventilated patients without ARDS has not been definitively answered. In the Chang et al study, increased initial tidal volume among non-ARDS patients was not significantly associated with subsequent development of ARDS. This finding differs from that of a randomized controlled trial20 and several observational series,16,21,22 all of which found significant associations between high tidal volumes and subsequent development of ARDS. As mentioned above, the lack of difference seen in the current study may reflect the relatively low (by historic standards) tidal volumes administered to the non-ARDS patients, and should not be generalized in isolation of this context. The general trend in the above-cited literature supports lower tidal volumes for all patients with risk factors for ARDS (though exactly how low remains undetermined). The lack of significant difference in outcomes in the current study may be evidence only that this message has gotten out.

Footnotes

  • Correspondence: Robert P Dickson MD, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan, 3916 Taubman Center, Ann Arbor MI 48109. E-mail: robertpdickson{at}gmail.com.
  • The author has disclosed no conflicts of interest.

  • See the Original Study on Page 578

  • Copyright © 2013 by Daedalus Enterprises

References

  1. 1.↵
    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(18),1301-1308.
    OpenUrlCrossRefPubMed
  2. 2.↵
    1. Mcglynn EA,
    2. Asch SM,
    3. Adams J,
    4. Keesey J,
    5. Hicks J,
    6. DeCristofaro A,
    7. Kerr EA
    . The quality of health care delivered to adults in the United States. N Engl J Med 2003;348(26):2635-2645.
    OpenUrlCrossRefPubMed
  3. 3.↵
    1. Liang L
    . The gap between evidence and practice. Health Aff (Millwood) 2007;26(2):w119-w121.
    OpenUrlAbstract/FREE Full Text
  4. 4.↵
    1. Han S,
    2. Martin GS,
    3. Maloney JP,
    4. Shanholtz C,
    5. Barnes KC,
    6. Murray S,
    7. Sevransky JE
    . Short women with severe sepsis-related acute lung injury receive lung protective ventilation less frequently: an observational cohort study. Crit Care 2011;15(6):R262.
    OpenUrlPubMed
  5. 5.↵
    1. Kalhan R,
    2. Mikkelsen M,
    3. Dedhiya P,
    4. Christie J,
    5. Gaughan C,
    6. Lanken PN,
    7. et al
    . Underuse of lung protective ventilation: analysis of potential factors to explain physician behavior. Crit Care Med 2006;34(2):300-306.
    OpenUrlCrossRefPubMed
  6. 6.
    1. Weinert CR,
    2. Gross CR,
    3. Marinelli WA
    . Impact of randomized trial results on acute lung injury ventilator therapy in teaching hospitals. Am J Respir Crit Care Med 2003;167(10):1304-1309.
    OpenUrlCrossRefPubMed
  7. 7.
    1. Young MP,
    2. Manning HL,
    3. Wilson DL,
    4. Mette SA,
    5. Riker RR,
    6. Leiter JC,
    7. et al
    . Ventilation of patients with acute lung injury and acute respiratory distress syndrome: has new evidence changed clinical practice? Crit Care Med 2004;32(6):1260-1265.
    OpenUrlCrossRefPubMed
  8. 8.↵
    1. Checkley W,
    2. Brower R,
    3. Korpak A,
    4. Thompson BT
    . Effects of a clinical trial on mechanical ventilation practices in patients with acute lung injury. Am J Respir Crit Care Med 2008;177(11):1215-1222.
    OpenUrlCrossRefPubMed
  9. 9.↵
    1. Rubenfeld GD,
    2. Cooper C,
    3. Carter G,
    4. Thompson BT,
    5. Hudson LD
    . Barriers to providing lung-protective ventilation to patients with acute lung injury. Crit Care Med 2004;32(6):1289-1293.
    OpenUrlCrossRefPubMed
  10. 10.↵
    1. Chang SY,
    2. Dabbagh O,
    3. Gajic O,
    4. Patrawalla A,
    5. Elie MC,
    6. Talmor D,
    7. et al
    . Contemporary ventilator management in patients with and at risk of ALI/ARDS. Respir Care 2013;58(4):578-588.
    OpenUrlAbstract/FREE Full Text
  11. 11.↵
    1. Gajic O,
    2. Dabbagh O,
    3. Park PK,
    4. et al
    . Early identification of patients at risk of acute lung injury: evaluation of lung injury prediction score in a multicenter cohort study. Am J Respir Crit Care Med 2011;183(4):462-470.
    OpenUrlCrossRefPubMed
  12. 12.↵
    1. Ranieri VM,
    2. Rubenfeld GD,
    3. Thompson BT,
    4. Ferguson ND,
    5. Caldwell E,
    6. Fan E,
    7. et al
    ARDS Definition Taskforce; Ranieri VM, Rubenfeld GD, Thompson BT, Ferguson ND, Caldwell E, Fan E, et al. Acute respiratory distress syndrome: the Berlin Definition. JAMA 2012;307(23):2526-2533.
    OpenUrlCrossRefPubMed
  13. 13.↵
    1. Linko R,
    2. Okkonen M,
    3. Pettilä V,
    4. Perttilä J,
    5. Parviainen I,
    6. Ruokonen E,
    7. et al
    . Acute respiratory failure in intensive care units. FINNALI: a prospective cohort study. Intensive Care Med 2009;35(8):1352-1361.
    OpenUrlCrossRefPubMed
  14. 14.↵
    National Institutes of Health; National Heart, Lung and Blood Institute; Acute Respiratory Distress Syndrome Network. NIH NHLBI ARDS clinical network mechanical ventilation protocol summary. http://www.ardsnet.org/system/files/6mlcardsmall_2008update_final_JULY2008.pdf. Accessed January 31, 2013.
  15. 15.↵
    1. Esteban A,
    2. Anzueto A,
    3. Alía I,
    4. Gordo F,
    5. Apezteguía C,
    6. Pálizas F,
    7. et al
    . How is mechanical ventilation employed in the intensive care unit? An international utilization review. Am J Respir Crit Care Med 2000;161(5):1450-1458.
    OpenUrlPubMed
  16. 16.↵
    1. Gajic O,
    2. Dara SI,
    3. Mendez JL,
    4. Adesanya AO,
    5. Festic E,
    6. Caples SM,
    7. et al
    . Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation. Crit Care Med 2004;32(9):1817-1824.
    OpenUrlCrossRefPubMed
  17. 17.↵
    1. Flegal KM,
    2. Carroll MD,
    3. Ogden CL,
    4. Curtin LR
    . Prevalence and trends in obesity among US adults, 1999–2008. JAMA 2010;303(3):235-241.
    OpenUrlCrossRefPubMed
  18. 18.↵
    1. Greenfield LJ,
    2. Ebert PA,
    3. Benson DW
    . Effect of positive pressure ventiation on surface tension properties of lung extracts. Anesthesiology 1964;25:312-316.
    OpenUrlPubMed
  19. 19.↵
    1. Dreyfuss D,
    2. Saumon G
    . Ventilator-induced lung injury lessons from experimental studies. Am J Respir Crit Care Med 1998;157(1):294-323.
    OpenUrlCrossRefPubMed
  20. 20.↵
    1. Determann RM,
    2. Royakkers A,
    3. Wolthuis EK,
    4. Vlaar AP,
    5. Choi G,
    6. Paulus F,
    7. et al
    . Ventilation with lower tidal volumes as compared with conventional tidal volumes for patients without acute lung injury: a preventive randomized controlled trial. Crit Care 2010;14(1):R1.
    OpenUrlCrossRefPubMed
  21. 21.↵
    1. Gajic O,
    2. Frutos-Vivar F,
    3. Esteban A,
    4. Hubmayr RD,
    5. Anzueto A
    . Ventilator settings as a risk factor for acute respiratory distress syndrome in mechanically ventilated patients. Intensive Care Med 2005;31(7):922-926.
    OpenUrlCrossRefPubMed
  22. 22.↵
    1. Jia X,
    2. Malhotra A,
    3. Saeed M,
    4. Mark RG,
    5. Talmor D
    . Risk factors for ARDS in patients receiving mechanical ventilation for > 48 h. Chest 2008;133(4):853-861.
    OpenUrlCrossRefPubMed
PreviousNext
Back to top

In this issue

Respiratory Care: 58 (4)
Respiratory Care
Vol. 58, Issue 4
1 Apr 2013
  • Table of Contents
  • Table of Contents (PDF)
  • Cover (PDF)
  • Index by author
  • Monthly Podcasts

 

Print
Download PDF
Article Alerts
Sign In to Email Alerts with your Email Address
Email Article

Thank you for your interest in spreading the word on American Association for Respiratory Care.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Mechanical Ventilation of Patients With and Without ARDS: How Far Have We Come?
(Your Name) has sent you a message from American Association for Respiratory Care
(Your Name) thought you would like to see the American Association for Respiratory Care web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
Mechanical Ventilation of Patients With and Without ARDS: How Far Have We Come?
Robert P Dickson
Respiratory Care Apr 2013, 58 (4) 712-714; DOI: 10.4187/respcare.02384

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero

Share
Mechanical Ventilation of Patients With and Without ARDS: How Far Have We Come?
Robert P Dickson
Respiratory Care Apr 2013, 58 (4) 712-714; DOI: 10.4187/respcare.02384
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
    • Footnotes
    • References
  • Info & Metrics
  • References
  • PDF

Related Articles

Cited By...

Info For

  • Subscribers
  • Institutions
  • Advertisers

About Us

  • About the Journal
  • Editorial Board
  • Reprints/Permissions

AARC

  • Membership
  • Meetings
  • Clinical Practice Guidelines

More

  • Contact Us
  • RSS
American Association for Respiratory Care

Print ISSN: 0020-1324        Online ISSN: 1943-3654

© Daedalus Enterprises, Inc.

Powered by HighWire