High-Flow Oxygen with Capping or Suctioning for Tracheostomy Decannulation

Hernández Martínez et al. N Engl J Med 2020; 383:1009-17. doi:10.1056/NEJMoa2010834]

Clinical Question

• In conscious critically ill patients who have had a tracheostomy inserted as part of their ICU stay and have been weaned from mechanical ventilation, does an assessment of readiness for decannulation that is based on suctioning frequency, when compared to an assessment based on tracheostomy capping, result in a shorter time to successful decannulation?

Background

• Approximately 15% of patients undergoing mechanical ventilation receive a tracheostomy as part of their care
• Evidence for decannulation readiness is limited to expert opinion, survey studies, single-centre experience, unvalidated prediction scores, and randomised trials that have assessed organisational aspects e.g. intensivist-led tracheostomy teams
• Capping trials are commonly used to determine readiness for decannulation. Protocol-based capping trials have led to readiness criteria with a high specificity and positive predictive value for successful decannulation, however this is thought to occur at the cost of delaying decannulation
• An alternative approach to assess readiness for decannulation is to measure the number of times that secretions are suctioned from a patient’s airway over a given period of time, with fewer episodes of suctioning considered to be a positive indicator of potentially successful decannulation

Design

• Multicentre randomised controlled trial
• Randomisation via random number generator, occurring within 8 hours of weaning from mechanical ventilation
• Open label study – treating clinician and patients not blinded
• Sample size
  • Calculated to detect a 3-day difference in the time to decannulation; assuming a mean (+/-SD) time of 13+/-11 days in the control group
  • A sample of 165 patients per group was considered adequate for the trial to have 80% power, with an alpha level of 5% for two-sided tests and with no more than 15% dropout
• Intention-to-treat analysis
• Kaplan-Meier curves were used to assess time to decannulation and compared using log-rank test
• Confidence intervals from time-to-event outcomes were calculated with the use of inference for linear function of medians, and the Newcombe and Wilson hybrid score was used to calculate the interval estimation for the difference between proportions
• Registered on clinicaltrials.gov

Setting

• 5 intensive care units in Spain
• Recruitment occurred between May 2016 and May 2018

Population

• Inclusion: Critically ill patients who had a tracheostomy that was created during an intensive care stay and had been successfully weaned from mechanical ventilation (defined as freedom from mechanical ventilation for 24 consecutive hours)
• Exclusion:
  • Contraindication to decannulation at time of randomisation (unconsciousness, severe swallowing dysfunction, an airway patency problem, neuromuscular disease other than ICU-acquired weakness or tracheostomy for airway control)
  • Age < 18 years
  • Expectation (according to the Sabadell score, which is a measure of risk of death) that death would occur before hospital discharge
• 330 patients were enrolled, out of 799 patients assessed for eligibility
• All patients were followed until hospital discharge or death
• Baseline characteristics were similar in the 2 groups, control vs. intervention
  • Age: 59.3 vs 57.3 yrs
  • Male: 67.1% vs 69.2%
  • APACHE II score: 10.8 vs 11.6
  • Median duration of mechanical ventilation before tracheostomy: 13 vs 13 days
  • Indication for tracheostomy
    • Mechanical ventilation for >21 days: 18.6% vs. 17.2%
    • Prolonged weaning from mechanical ventilation: 39.8% vs. 47.3%
    • Low level of consciousness: 26.7% vs. 21.9%

Intervention

• Continuous high flow oxygen and decannulation based on assessment of suctioning frequency (n=169)
  • Patients underwent decannulation if they received suctioning for pre-specified indications <2 times every 8 hours for a 24-hour period

Control

• Intermittent high flow oxygen therapy and decannulation based on capping trial (n=161)
  • Patients underwent decannulation following a capping trial, in which a cap was placed on the tracheostomy tube for 24 hours
    • Patients were considered to be ready to undergo a capping trial when they had had no more than 1 suction every 4 hours during a 12-hour period according to pre-specified indications
    • Failure of the capping trial was defined as decapping for any reason during the 24-hour period. When a capping trial failed, a new capping trial was not allowed until the following day
    • Patients who repeatedly failed capping trials could undergo decannulation outside the protocol on the basis of suctioning requirements if the attending physicians considered them to be ready

Management common to both groups

• 7mm inner-diameter tracheostomy tube with a fenestrated inner sleeve (TRACHOE twist or medical) was used
  • Unless BMI >45 or anatomical concerns
• Patients were weaned from mechanical ventilation according to the following protocol:
  • Daily screening
  • Drink test:
    • Assessment of aspiration risk: patient swallowed 50mL of water with the cuff deflated
  • Occlusion test:
    • Assessment to rule out tracheal airflow obstruction: tracheostomy tube opening occluded (with the tracheal cuff deflated) for 5 minutes
  • Spontaneous Breathing Trial (SBT):
    • Progressive weaning from mechanical ventilation based on intermittent trials of spontaneous breathing of progressively longer duration through the tracheostomy tube
    • Between trials at least 2 hours of assist-control ventilation
    • SBTs were attempted twice a day
    • If no signs of respiratory distress, the trial was continued for 12 hours
    • When patients were able to sustain spontaneous breathing for >12 hours on 2 consecutive days, they switched to continuous high-flow oxygen therapy through their tracheostomy tube
  • All patients received high-flow oxygen therapy once weaned from mechanical ventilation.
    • Airvo 2 (Fisher and Paykel Healthcare) with a specific interface for tracheostomy tubes
    • Flow of 60L/min, temperature 37^oC, and FiO2 was adjusted to maintain SpO2 92 to 95%
  • Pre-specified criteria for performing suctioning

Outcome

• Primary outcome: Median time to tracheostomy decannulation – significantly greater in the control vs. the intervention group
  • Defined as time from the completion of weaning from MV (24 consecutive hours disconnected from the ventilator) to actual decannulation
  • Control 13 days (IQR 12 to 14) vs. Intervention 6 days (IQR 5 to 7); absolute difference 7 days (95% CI 5 to 9)
• Secondary outcomes: (comparing control vs. intervention groups)
  • Regardless of the method used, 95% of all enrolled patients underwent decannulation successfully, and there was no significant difference between the groups in terms of recannulation
    • 5.6%  vs. 2.4%, Difference 3.2% (95% C.I. -1.2 to 8.1)
  • Infection – increased in control group
    • Pneumonia
      • 9.9% vs. 4.1%
      • Difference 5.8% (95% C.I. 0.2 to 11.8)
    • Tracheobronchitis
      • 29.9% vs. 18.9%
      • Difference 10.3% (95% C.I. 1.0 to 19.3)
  • Length of stay (median)
    • In the ICU – no difference
      • 35 vs. 32 days
      • Difference 3 days (95% C.I. -1 to 11)
    • In the hospital – increased in control group
      • 62 vs. 48 days
      • Difference 14 days (95% C.I. 9-33)
  • ICU mortality
    • 0% vs. 0%
• Post-hoc analysis
  • Weaning failure (defined as re-initiation of mechanical ventilation within 7 days) – greater in control group
    • 16.8% vs. 6.5%, (Difference 10.3%, 95% C.I. 3.4 to 17.4)
  • In the control group
    • 73% of patients had at least 1 failure on the capping trial; the majority (81%) of these were to remove accumulated pulmonary secretions
    • 7% patients had repeated failures on capping trials, however successfully underwent decannulation out of protocol
  • Decannulation before ICU discharge – reduced in control group
    • 64.6% vs. 82.2%
    • Difference -17.7% (95% C.I. -26.8 to -8.1%)

Authors’ Conclusions

• In conscious, critically ill adult patients with a tracheostomy tube, time to decannulation was shorter in those with decannulation based on suctioning frequency plus the use of continuous high-flow oxygen therapy than in those who received the standard of care with capping trials plus the use of intermittent high-flow oxygen therapy, with no significant difference in the incidence of recannulation
• The reasoning for this is hypothesized to be that capping trials require patients to overcome an excessively demanding ventilatory workload

Strengths

• Multicentre, randomised control trial
• Intention-to-treat analysis
• Important question with relevant patient-centred outcomes
• Protocolised approach to weaning
• Registered on clinicaltrials.gov

Weaknesses

• Unblinded to clinicians and patients; unclear if blinded to investigators
• Protocol had a relatively conservative approach to:
  • weaning from mechanical ventilation
  • the initiation of capping trials
  • length of time required to be achieved for capping trials (24 hours)
• The use of high-flow oxygen therapy is a confounder
  • The intervention group received continuous high-flow and the control group received intermittent high-flow oxygen therapy (when not undergoing capping)
• Industry supported
  • Fisher and Paykel Healthcare paid for writing assistance with the manuscript, and travel support for two authors

The Bottom Line

• This was really a trial of decannulation based on suction frequency with continuous high-flow oxygen therapy versus decannulation based on conservative capping with intermittent high-flow oxygen therapy
• Many aspects of this trial differ from my usual practice, including tracheostomy selection, the method of weaning from mechanical ventilation, and the routine use of high-flow oxygen therapy
• However, overall, this trial supports what has already been assumed by many, that in conscious patients with no concerns about upper airway patency, 24 hour capping trials are an unnecessary burden
• We should avoid routine tracheostomy capping and instead base a decannulation readiness assessment on suction frequency, armed with the knowledge that this should result in a shorter time to decannulation without an increased risk of tracheostomy reinsertion or patient harm

External Links

• N Engl J Med High-Flow Oxygen with Capping or Suctioning for Tracheostomy Decannulation
• N Engl J Med Editorial Building an Evidence Base for Survivors of Critical Illness
• Further reading Ward mortality after ICU discharge: a multicenter validation of the Sabadell score

Metadata

Summary author: Kate Triplett @TriplettKate
Summary date: 16/09/2020
Peer-review editor: Luke Collett @luke_col