Reconnect

Reconnection to mechanical ventilation for 1 h after a successful spontaneous breathing trial reduces reintubation in critically ill patients: a multicenter randomized controlled trial

Fernandez. Intensive Care Medicine 2017. published on-line. DOI 10.1007/s00134-017-4911-0

Clinical Question

  • In critically ill adult patients who pass a spontaneous breathing trial (SBT), does 1-hour rest compared with immediate extubation reduce re-intubation rates at 48 hours?

Background

  • SBTs are used to assess if patients are likely to be successfully liberated from a mechanical ventilator. Post-extubation respiratory failure and the need for re-intubation occurs in 5-30% of patients. These patients have an increased risk of mortality. Respiratory muscles can become fatigued and it is hypothesised that a SBT can lead to fatigue and increase the probability of failure. This trial tried to determine if giving patients a period of rest following a SBT would lead to a higher success rate when liberating patients from a mechanical ventilator.

Design

  • Randomised controlled trial
    • Central randomisation with computerised random-number tables in blocks of 4
    • Stratified by centre and risk of extubation failure before SBT
  • Allocation concealment maintained through numbered opaque envelopes
  • Non-blinded
  • Investigators who collected endpoints excluded from clinical decisions
  • Registered with clinicaltrials.gov
  • Statistical analysis
    • Sample size calculation:
      • 1372 patients required to detect a 5% absolute risk reduction in the intervention group from a 15% baseline, with a false negative rate of 20% and a false positive rate of 5%
    • Intention to treat analysis
    • Categorical variables compared with Cochran-Mantel-Haenszel x2 or Fisher’s exact test
    • Normally distributed continous variables compared with Student’s t test
    • Non-normally distributed continous variables compared with Mann-Whitney U test
    • Multi-variate model assessed with receiver operating characteristic curve and the goodness of fit by Hosmer-Lemeshow test

Setting

  • 17 medical-surgical ICUs, Spain
  • Data collected: October 2013 – January 2015

Population

  • Inclusion: Received invasive mechanical ventilation for ≥12 hours
    • Successfully completed a SBT (screened daily)
  • Exclusion:
    • Age <18 years, tracheostomy, overwhelming respiratory secretions, inability to follow commands, do-not-resuscitate or re-intubate orders, formal indication for non-invasive ventilation after extubation
  • 470 patients randomised
  • Comparing baseline characteristics of control vs. intervention groups
    • Age: 62 vs. 65, p=0.96
    • APACHE II: 18.3 vs. 17.8, p=0.41
    • Co-morbidities >1: 37% vs. 47%, p=0.03
    • Upper airway problems: 22% vs. 29%, p=0.08
    • COPD: 14% vs. 17%, p=0.58
    • > 1 failed SBT: 11% vs. 12%, p=0.75
    • Copious secretions: 15% vs. 9%, p=0.06
    • Duration of mechanical ventilation before SBT: 5.5 vs. 5.7 days, p=0.85
    • SBT technique
      • T-tube: 87% vs. 94%
      • Duration of SBT of 120min: 31.7% vs. 20.7%, p=0.009
    • High risk for requiring re-intubation: 83% vs. 84%
      • Defined as high risk if met any of the following criteria:
        • Age >65
        • Congestive heart failure as reason for intubated
        • COPD
        • APACHE II >12 on extubation day
        • BMI >30
        • Ineffective cough or copious respiratory secretions (>2 suctioning in the 8 hours before extubation)
        • >1 failed SBT
        • >1 co-morbidity
        • Problems related with upper airway (including intubation >7 days)

Intervention

  • Reconnected to ventilator for 1-hour
    • Post-successful completion of SBT
    • At previous ventilatory parameters
    • Then directly extubated
    • 9 (3.7%) patients did not tolerate reconnection to the ventilator, and therefore directly extubated

Control

  • Immediate extubation
    • Post successful competion of SBT

Management common to both groups

  • Patients screened daily for SBT
  • Criteria for assessing weanability by SBT:
    • Subjective: resolution of the acute phase of disease for which patient was intubated, adequate cough, absence of tracheobronchial secretions
    • Objective: HR <140, sBP 90-160 with no or minimal vasopressors, temp <38C, adequate level of consciousness, SpO2 >90% at FiO2 ≤0.4 and PEEP <8, RR<35, minute volume <10L/min and f/VT <105 breaths/min/L
  • Technique for SBT (T-tube, low-level pressure support, continuous positive pressure airway pressure (CPAP) and duration (30, 60 or 120 min) at discretion of treating physician
  • Successful SBT defined as:
    • Correct gas exchange (SpO2 ≥85-90%, PaO2 ≥50-60mmHg, FiO2 ≤0.4 pH ≥7.32, increase in PaCO2 <10mmHg),
    • Haemodynamic stability (HR <140, systolic BP <180-200mmHg and >90mmHg without vasopressors)
    • Stable ventilatory pattern (RR <30-35 and <150% from basal)
  • The protocol at each participating hospital determined the treatment of post-extubation respiratory failure. Re-intubation and the use of non-invasive ventilation at discretion of attending physicians. High flow nasal cannula were not used.
  • Comparing type and length of SBT between groups (control vs intervention groups)
    • CPAP
      • 30min: 1.2% vs. 1.3%
      • 60min: 1.2% vs. 1.3%
    • Pressure support
      • 30min: 4.9% vs. 2.6%
      • 60min: 4.9% vs. 0.4%, p<0.05
    • T-tube
      • 30min: 30.9% vs. 37.9%
      • 60min: 26.7% vs. 36.1%, p<0.05
      • 120min: 30% vs. 20.3%, p<0.05

Outcome

  • Primary outcome: Re-intubation within 48 hours – significantly more common in control group
    • 14% vs. 5%, OR 0.33, 95% C.I. 0.16-0.65, p<0.001
    • Number Needed to Treat: 11
    • Fragility index: 8
  • Reason for re-intubation, comparing control (n=35) vs. intervention (n=12) groups:
    • Inability to manage secretions: 63% vs. 50%, p=0.43
    • Level of consciousness: 11% vs. 50%, p=0.005
    • Gasping: 11% vs. 0%, p=0.56
    • Cardiac arrest: 8% vs. 8%, p=0.98
    • Surgery: 3% vs 17%, p=0.16
    • Others: 15% vs. 17%, p=0.87
  • Secondary outcomes
    • Post-extubation respiratory failure within 48 hours (need for re-intubation or ventilatory support with NIV due to predefined criteria) – significantly more common in control group
      • 24% vs. 10%, OR 0.35 (0.21-0.61), p<0.001
      • In both groups a similar proportion underwent rescue NIV and direct re-intubation
    • Causes of respiratory failure, comparing control (n=58) vs. intervention (n=24) groups
      • SpO2 <90%: 43% vs. 50%, p=0.57
      • Tachypnoea: 62% vs. 50%, p=0.31
      • Muscle fatigue: 58% vs. 41%, p=0.16
      • Respiratory acidosis: 17% vs. 12%, p=0.75
      • Low level of consciousness: 10% vs. 21%, p=0.2
    • No difference in length of ICU or hospital stay or mortality
  • Sub-group analysis, comparing control vs. intervention groups
    • Re-intubation within 48 hours
      • High risk patients: 16% vs. 6%, p=0.001
      • Low-risk patients: 7% vs. 3%, p=0.36
      • Duration of mechanical ventilation
        • <1 day: 6% vs. 0% (2/42 vs. 0/37)
        • <8 days: 9% vs. 4%, OR 0.42 (0.15-1.11)
        • >8 days: 24% vs. 8% OR 0.27 (0.10-0.72)

Authors’ Conclusions

  • Allowing patients to rest for 1 hour following a successful SBT reduced re-intubation and post-extubation respiratory failure

Strengths

  • Randomised controlled trial
  • Multi-centre
  • Intention to treat analysis
  • Registered with clinicaltrials.gov
  • Exclusion of clinicians who collected endpoints from clinical decisions

Weaknesses

  • Subjectivity of some of the outcomes including the definition of respiratory failure. When the study is non-blinded there is a concern that this could result in bias.
  • There were some differences in the baseline characteristics of the 2 groups.
  • Patients in the different groups were treated differently with those in the control group more likely to have a longer duration of SBT compared with the intervention group.
  • Only after concluding the study did the authors realise that they had miscalculated the sample size. They only recruited 470 patients where as they should have recruited 1372 patients.

The Bottom Line

  • In critically ill patients who pass a spontaneous breathing trial, reconnection to a ventilator for 1-hour compared with immediate extubation, significantly reduced the rate of re-intubation within 48 hours.

External Links

Metadata

Summary author: David Slessor
Summary date: 9th October 2017
Peer-review editor: Adrian Wong

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