Discussion Forum


Journal Club: Helmet trials: resolving the puzzle 

By: Marcelo Alcantara, Médico - 03/17/2023 11:23

👉In a clever editorial at Intensive Care Med March 2023, Yaseen M. Arabi from Saudi Arabia, Bhakti K. Patel from the USA,  & Massimo Antonelli from Italy made a very in-depth analysis of the most relevant papers that assessed the performance of Helmet based ventilation for patients with ARDS (non-COVID and COVID-19) in randomized controlled trials.

👉The three studies' main characteristics are shown in the figure below.

👉Main thoughts on the papers are brilliantly addressed by enumerating and explaining nine points of view that can explain the differences in the design, methodology, and results of the three studies.

😎 The authors' conclusions:

  • Until further evidence becomes available, the three trials collectively suggest that helmet noninvasive ventilation is at least as effective as mask NIV and HFNO, mainly when used in centers with experience with this approach.
  • Better outcomes with helmet noninvasive ventilation are probably more likely with early use and allowing the alternate use of helmet noninvasive ventilation, mask noninvasive ventilation, and HFNO to increase tolerance and apply stringently. 

😓 Future directions in their opinion:

  • Future trials should consider the early timing of the intervention to prevent undue influence of pre-randomization respiratory support practices.
  • Randomization may need to be stratified based on physiological parameters of the severity of hypoxemia or inspiratory effort to identify essential sub-phenotypes that may benefit from helmet NIV. 
  • Postintervention respiratory support may need standardization to minimize variation in post-randomization usual respiratory care clinical practices that could affect patient outcomes.

🧐 Our opinion:

Excellent editorial, but it misses crucial points:

👉What about the HELMET-CPAP comparison with HELMET-NIV or with other types of ventilatory support? In our view, this type of comparison deserves future trials.

👉HELMET-CPAP may have some advantages and drawbacks in comparison with HELMET-NIV.

  • HELMET-CPAP advantages: a stable CPAP typically powered by a continuous free-flow system and a PEEP valve. During CPAP, the patient is free to inhale or exhale while the pressure within the helmet remains more stable, and there is no interaction with a ventilator. Therefore, no patient-ventilator asynchrony! Actually, it does need a ventilator! This makes HELMET-CPAP a very attractive type of respiratory support to be applied early on the course of hypoxemic respiratory failure, even outside the ICU, as we evaluated in a feasibility study.
  • ELMO, a new helmet interface for CPAP to treat COVID-19-related acute hypoxemic respiratory failure outside the ICU: a feasibility study
  • HELMET-CPAP's main drawbacks are the impossibility of measuring the VT and no differential inspiratory support. The latter is a disadvantage in a patient with high work of breathing but, maybe, also a potential advantage as the VT may be lower than those obtained during HELMET-NIV, which can potentially aggravate the P-SILI (patient self-inflicted lung injury) mechanisms in ARDS.

👉Click on the link below to assess the editorial: 

Arabi, Y.M., Patel, B.K. & Antonelli, M. Helmet trials: resolving the puzzle. Intensive Care Med (2023). https://doi.org/10.1007/s00134-023-07004-z


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