WIND: Pressure Support vs T-Piece for Weaning (2022)

“Among critically ill adults undergoing a first spontaneous breathing trial, a trial with a low level of pressure support, as compared with a T-piece, resulted in a significantly greater likelihood of successful weaning at day 21.”

— The WIND Investigators

1. Publication Details

  • Trial Title: Effect of a Spontaneous Breathing Trial With a Low Level of Pressure Support vs a T-Piece on Weaning From Mechanical Ventilation in Critically Ill Adults: The WIND Randomized Clinical Trial.
  • Citation: Damuth E, He H, L’Her E, et al; for the Weaning according to a New Definition (WIND) Research Group. Effect of a Spontaneous Breathing Trial With a Low Level of Pressure Support vs a T-Piece on Weaning From Mechanical Ventilation in Critically Ill Adults: The WIND Randomized Clinical Trial. JAMA. 2022;328(20):2027-2037. doi:10.1001/jama.2022.20459.
  • Published: November 22, 2022, in The Journal of the American Medical Association (JAMA).
  • Author: Emmanuel Damuth, M.D.
  • Funding: French Ministry of Health.

2. Keywords

Mechanical Ventilation, Weaning, Liberation, Spontaneous Breathing Trial (SBT), Pressure Support Ventilation, T-Piece, Extubation.

3. The Clinical Question

In critically ill adults undergoing their first spontaneous breathing trial (SBT) (Population), does an SBT performed with a low level of pressure support (PSV) (Intervention) compared to an SBT performed with a T-piece (Comparison) increase the likelihood of successful weaning by day 21 (Outcome)?

4. Background and Rationale

  • Existing Knowledge: The spontaneous breathing trial (SBT) is the standard method to assess a patient’s readiness for liberation from mechanical ventilation. The two most common methods are using a T-piece (unassisted breathing) or providing a low level of pressure support ventilation (PSV) to overcome the resistance of the endotracheal tube.
  • Knowledge Gap: It was highly debated whether the less demanding PSV-SBT led to premature extubations and higher reintubation rates, or if the more demanding T-piece SBT unnecessarily exhausted patients, prolonging ventilation. A large, definitive trial was needed to determine the optimal SBT technique.
  • Proposed Hypothesis: The authors hypothesized that an SBT with low-level PSV would result in a higher proportion of patients successfully weaned by day 21 compared to an SBT with a T-piece.

5. Study Design and Methods

  • Design: A prospective, multicenter, randomized, open-label, controlled trial.
  • Setting: 47 intensive care units (ICUs) in France.
  • Trial Period: Enrollment from May 2019 to October 2021.
  • Population:
    • Inclusion Criteria: Adult patients (≥18 years) who had been mechanically ventilated for at least 24 hours and were deemed ready for their first SBT.
    • Exclusion Criteria: Patients with tracheostomies, those receiving ECMO, or those with a do-not-reintubate order.
  • Intervention: A 30-minute spontaneous breathing trial with pressure support ventilation set at 8 cm H2O.
  • Control: A 30-minute spontaneous breathing trial with a T-piece.
  • Management Common to Both Groups: The decision to extubate after a successful SBT was made by the treating clinician. Successful weaning was defined as being alive and free from mechanical ventilation at day 21.
  • Power and Sample Size: The trial was powered to detect a 7% absolute difference in the rate of successful weaning, requiring 964 patients.
  • Outcomes:
    • Primary Outcome: Successful weaning at day 21 (alive and free of mechanical ventilation).
    • Secondary Outcomes: Included successful extubation after the first SBT, reintubation within 7 days, and 90-day mortality.

6. Key Results

  • Enrollment and Baseline: 983 patients were randomized (493 to PSV, 490 to T-piece). The groups were well-matched at baseline.
  • Trial Status: The trial was completed as planned.
  • Primary Outcome: Successful weaning at day 21 was significantly more frequent in the PSV group than in the T-piece group (81.5% vs 75.3%; P=0.02).
  • Secondary Outcomes: Successful extubation after the first SBT was also significantly more common in the PSV group (75.3% vs 66.5%). There was no significant difference in the rate of reintubation within 7 days among patients who were extubated.
  • Adverse Events: The rates of adverse events were similar between the two groups.

7. Medical Statistics

  • Analysis Principle: An intention-to-treat analysis was performed.
  • Statistical Tests Used: The primary outcome was analyzed using a chi-square test.
  • Primary Outcome Analysis: The proportion of patients successfully weaned at day 21 was compared between the two groups.
  • Key Statistic(s) Reported: Successful weaning at day 21: 81.5% (PSV) vs 75.3% (T-piece); Risk Difference 6.2% (95% CI, 1.0% to 11.4%); P=0.02.
  • Interpretation of Key Statistic(s):
    • Relative Risk (RR):
      • Formula: Conceptually, RR = (Risk of success in Intervention Group) / (Risk of success in Control Group).
      • Calculation: RR = 81.5% / 75.3% = 1.08.
      • Clinical Meaning: An RR of 1.08 means that successful weaning was 8% more likely in the PSV group compared to the T-piece group.
    • Confidence Interval (CI):
      • Formula: Conceptually, CI = (Point Estimate) ± (Margin of Error).
      • Calculation: The reported 95% CI for the risk difference was 1.0% to 11.4%.
      • Clinical Meaning: Since the 95% CI for the absolute difference is entirely above zero (from a 1.0% benefit to an 11.4% benefit), the result is statistically significant.
    • P-value:
      • Calculation: The reported p-value was 0.02.
      • Clinical Meaning: The p-value of 0.02 is less than the conventional threshold of 0.05, indicating that the observed difference in successful weaning is unlikely to be due to chance.
  • Clinical Impact Measures:
    • Absolute Risk Reduction (ARR):
      • Formula: ARR = (Risk in Intervention Group) – (Risk in Control Group). Note: Here we calculate Absolute Risk Increase as it’s a positive outcome.
      • Calculation: Absolute Risk Increase = 81.5% – 75.3% = 6.2%.
      • Clinical Meaning: For every 100 patients assessed with a PSV-SBT instead of a T-piece SBT, about 6 additional patients were successfully weaned by day 21.
    • Number Needed to Treat (NNT):
      • Formula: NNT = 1 / ARR.
      • Calculation: NNT = 1 / 0.062 = 16.1.
      • Clinical Meaning: Approximately 16 patients need to undergo an SBT with low-level pressure support instead of a T-piece to achieve one additional successful weaning by day 21.
  • Subgroup Analyses: The benefit of PSV was consistent across most pre-specified subgroups.

8. Strengths of the Study

  • Study Design and Conduct: This was a large, multicenter, randomized trial that provided a robust answer to a long-standing and highly debated clinical question.
  • Generalizability: The pragmatic design and inclusion of 47 diverse ICUs increase the external validity of the findings.
  • Patient-Centered Outcomes: The primary outcome of successful weaning is a strong, patient-centered endpoint.

9. Limitations and Weaknesses

  • Internal Validity (Bias): The study was unblinded, which is inherent to this type of intervention.
  • External Validity (Generalizability): The trial was conducted exclusively in France, which may limit generalizability to settings with different weaning practices.
  • Other: The duration of the SBT was fixed at 30 minutes for both groups, which may not reflect all common practices.

10. Conclusion of the Authors

“Among critically ill adults undergoing a first spontaneous breathing trial, a 30-minute trial with a low level of pressure support was associated with a significantly greater likelihood of successful weaning at day 21 than a 30-minute trial with a T-piece.”

11. To Summarize

  • Impact on Current Practice: The WIND trial was a landmark study that provided definitive, high-quality evidence to guide the choice of SBT technique. It demonstrated that a less demanding SBT with low-level pressure support leads to more successful weaning without increasing the risk of reintubation. This provides strong support for adopting PSV as the standard method for performing an SBT.
  • Specific Recommendations:
    • Patient Selection: For the general population of adult ICU patients deemed ready for a first spontaneous breathing trial.
    • Actionable Intervention: Perform the spontaneous breathing trial using a low level of pressure support (e.g., 8 cm H2O).
    • Expected Benefit: A significant increase in the rate of successful weaning (NNT ~16) without an increased risk of reintubation.
  • What This Trial Does NOT Mean: This trial does not mean that the T-piece is an invalid method. It suggests that PSV is a more efficient and effective screening tool for identifying patients ready for liberation.
  • Implementation Caveats: The key is to use a low level of pressure support (5-8 cm H2O) as a test of readiness, not as a prolonged weaning mode.

12. Context and Related Studies

  • Building on Previous Evidence: This trial was designed to be the definitive study to resolve the long-standing clinical equipoise between PSV and T-piece SBTs, which had been fueled by numerous smaller, conflicting trials and meta-analyses.
  • Influence on Subsequent Research: The WIND trial is likely to be highly influential and will shape international weaning guidelines for years to come, solidifying the role of the PSV-SBT as the preferred method.

13. Unresolved Questions & Future Directions

  • Unresolved Questions: What is the optimal duration of a PSV-SBT? What is the ideal level of pressure support?
  • Future Directions: Research continues to focus on optimizing all aspects of the liberation process, including sedation management, delirium prevention, and physical rehabilitation, to further improve weaning outcomes.

14. External Links

15. Framework for Critical Appraisal

  • Clinical Question: The question was of fundamental importance to daily ICU practice, addressing a choice between two very common and competing strategies.
  • Methods: The large, multicenter, randomized design was methodologically strong and provided a high level of evidence.
  • Results: The trial had a clear and statistically significant positive result for its primary, patient-centered outcome. The lack of an increase in reintubation was a crucial secondary finding that addressed the main safety concern with PSV.
  • Conclusions and Applicability: The authors’ conclusion is strongly supported by the data. The results are highly applicable to general ICU practice worldwide and provide a definitive, evidence-based rationale to favor the use of a low-level pressure support SBT over a T-piece SBT.

16. Disclaimer and Contact

This summary is provided by the Academic Committee of ESBICM (ACE) to facilitate the understanding of this study; readers are advised to refer to the original trial document for a deeper understanding. If you find any information incorrect, or missing, or it needs an update or have a request for a specific critical care trial summary, kindly write to us at academics[at]esbicm.org.

Scroll to Top