Patel

helmet vs facemaske

Effect of Noninvasive Ventilation Delivered by Helmet vs Face Mask on the Rate of Endotracheal Intubation in Patients With Acute Respiratory Distress Syndrome

Patel. JAMA 2016; 315(22): 2435-41. doi:10.1001/jama.2016.6338

Clinical Question

  • In patients with acute respiratory distress syndrome (ARDS), does the use of non-invasive ventilation (NIV) delivered by helmet compared to NIV delivered by face mask reduce the need for intubation?

Design

  • Randomised controlled trial
    • Sealed envelope-based randomisation
    • Computer-generated, permuted block randomisation
  • Clinicians and patients non-blinded
  • Decision to intubate made by primary care team based on predetermined criteria
  • Consecutive patients
  • Intention to treat analysis
  • Standardised NIV and invasive ventilation protocols
  • Planned for enrolment of 206 patients (80% power to detect a 20% absolute reduction in the rate of intubation with a 2-sided α level of 0.05), but stopped for efficacy at first interim analysis

Setting

  • Single Medical Intensive Care Unit in a University Hospital, USA
  • Sep 2012 – Sep 2015

Population

  • Inclusion criteria:
    • Adult patients
    • ARDS as defined by the Berlin criteria
    • Requiring NIV for at least 8 hours
  • Exclusion criteria:
    • Impending cardiac arrest
    • Glasgow coma score <8
    • Absence of airway protective reflexes
    • Elevated intracranial pressure
    • Tracheostomy or upper airway obstruction
    • Pregnant
    • Had refused endotracheal intubation
  • 83 patients randomised

Comparing baseline characteristics of intervention  vs. control group

  • Age (median): 58 vs. 61
  • BMI (median): 27 vs. 28
  • Solid cancer: 11% vs. 26%
  • Stem cell transplant: 11% vs. 3%
  • Pneumonia: 86% vs. 72%
  • PaO2:Fio2 ratio: 118 vs. 144
  • On vasopressors: 2% vs. 10%

Intervention

  • NIV delivered by helmet
    • Latex-free helmet (Sea Long)
    • NIV via ICU ventilator (Engström Carestation, GE Healthcare)
    • Ventilator inspiratory flow rate maintained at >100 l/min to prevent CO2 rebreathing

Control

  • NIV delivered by face mask
    • NIV via non-invasive ventilator (Phillips Respironics V60)

In both intervention and control groups:

  • PEEP titrated to achieve SpO2 >90% with FiO2 ≤0.6
  • Inspiratory pressure titrated to respiratory rate <25/min and loss of accessory muscle use

Outcome

  • Primary outcome: Proportion of patients requiring intubation – significantly lower in helmet group
    • 18.2% vs. 61.5%, p<0.001
      • Number needed to treat 3
      • Fragility index of 10 patients
      • Absolute difference 43.3% (95% C.I. -62.4 to -24.3)
  • Secondary outcomes:
    • 28-day invasive ventilator-free days – significantly higher in helmet group
      • 28 vs. 12.5 days, p<0.001
      • Absolute difference 8.4% (95% C.I. 13.4 to 3.4)
    • ICU length of stay – significantly shorter in helmet group
      • 4.7 vs. 7.8 days, p=0.04
      • Absolute difference -2.76 days (95% C.I. -6.07 to 0.54)
    • Hospital length of stay – no significant difference
      • 10.1 vs. 15.2 days, p=0.16
      • Absolute difference −2.92 days (95% C.I. −8.47 to 2.63)
    • Hospital mortality – significantly lower in helmet group
      • 27.3% vs. 48.7%, p=0.04
      • Absolute difference −21.4% (95% C.I.−41.9 to −1.0)
    • 90-day mortality – significantly lower in helmet group
      • 34.1% vs. 56.4%, p=0.02
      • Absolute difference −22.3% (95% C.I. −43.3 to −1.4)
    • Mask related skin-ulceration – no significant difference
      • 7.6% vs. 6.8%

Authors’ Conclusions

  • In this single-center, randomised clinical trial, NIV delivered by helmet significantly reduced the intubation rate amongst patients with ARDS compared with the patients receiving NIV by face mask. The helmet was also associated with improved ventilator-free days and significantly reduced ICU length of stay as well as 90-day mortality.

Strengths

  • Randomised trial
  • No crossover between groups
  • No patients lost to follow-up

Weaknesses

  • Single-centre study
  • Non-blinded
  • Criteria for starting NIV not standardised
  • Probably a cohort with relatively mild ARDS
    • Requirement for 8 hours of NIV prior to enrollment likely to have excluded more hypoxic patients
    • Median duration of NIV after randomisation 19.8 vs. 26.4 hours
  • Multiple protocol changes to broaden inclusion criteria to include all causes of respiratory failure
  • Early termination of the trial likely to overestimate the treatment effect

The Bottom Line

  • Helmet NIV shows promise as a tool to reduce the need for intubation in patients with rapidly reversible hypoxaemic respiratory failure. However, larger trials are needed to determine if these results are generalisable outside of this small single-centre study

External Links

Metadata

Summary author: @tompratt
Summary date: 9th October 2016
Peer-review editor: @davidslessor

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