Log in | Register

Performance of different continuous positive airway pressure helmets equipped with safety valves during failure of fresh gas supply

Manuela Milan| Alberto Zanella| Stefano Isgrò| Salua Abd El Aziz El Sayed Deab| Federico Magni| Antonio Pesenti| Nicolò Patroniti
Physiological and Technical Notes
Volume 37, Issue 6 / June , 2011

Pages 1031 - 1035



We assessed the performance of different continuous positive airway pressure (CPAP) helmets equipped with a safety valve during discontinuation of fresh gas flow.


This was a physiological study of five healthy volunteers. We delivered CPAP (fresh gas flow 60 l/min, FiO2 60%, PEEP 5 cmH2O) with three different helmets in a random sequence: 4Vent (Rüsch), HelmHAR-cp (Harol) and CaStar CP210 (StarMed). For each helmet we randomly applied, for up to 4 min, three disconnections of fresh gas flow: helmet inlet (Dinlet), flowmeter (Dflowmeter) and gas source (Dsource). We continuously recorded from a nostril: end-tidal CO2 (PetCO2), inspiratory CO2 (PiCO2), fraction of inspired oxygen (FiO2) and respiratory rate (RR).


During every disconnection we observed an increase in PiCO2 and PetCO2 with a drop in FiO2, while RR did not change. FiO2 decreased more quickly in the CaStar, equipped with the largest safety valve, during Dsource and Dflowmeter, while FiO2 decreased more quickly during Dinlet in CaStar and in 4Vent. PiCO2 resulted in a lower increase in CaStar during Dsource and Dflowmeter compared to 4Vent. PetCO2 in CaStar increases more slowly compared to 4Vent during Dsource and more slowly compared to the other two helmets during Dflowmeter. During Dinlet similar degrees of CO2 rebreathing and PetCO2 were recorded among all the helmets.


To minimize CO2 rebreathing during disconnection of the fresh gas supply while performing helmet CPAP, it is desirable to utilize large helmets with a large anti-suffocation valve. Monitoring and alarm systems should be employed for safe application of helmet CPAP.



  1. International Consensus Conferences in Intensive Care Medicine (2001) Noninvasive positive pressure ventilation in acute Respiratory failure. Am J Respir Crit Care Med 163:283–291
  2. Bellani G, Patroniti N, Greco M, Foti G, Pesenti A (2008) The use of helmets to deliver non-invasive continuous positive airway pressure in hypoxemic acute respiratory failure. Minerva Anestesiol 74:651–656
    • View reference on PubMed
  3. Taccone P, Hess D, Caironi P, Bigatello LM (2004) Continuous positive airway pressure delivered with a “helmet”: effects on carbon dioxide rebreathing. Crit Care Med 32:2090–2096
    • View reference on PubMed
    • View reference on publisher's website
  4. Patroniti N, Foti G, Manfio A, Coppo A, Bellani G, Pesenti A (2003) Head helmet versus face mask for non-invasive continuous positive airway pressure: a physiological study. Intensive Care Med 29:1680–1687
  5. Mojoli F, Iotti G, Gerletti M, Lucarini C, Braschi A (2008) Carbon dioxide rebreathing during non-invasive ventilation delivered by helmet: a bench study. Intensive Care Med 34:1454–1460
  6. Antonelli M, Pennisi MA, Montini L (2005) Clinical review: noninvasive ventilation in the clinical setting—experience from the past 10 years. Crit Care 9:98–103
    • View reference on PubMed
    • View reference on publisher's website
  7. Principi T, Pantanetti S, Catani F, Elisei D, Gabbanelli V, Pelaia P, Leoni P (2004) Noninvasive continuous positive airway pressure delivered by helmet in hematological malignancy patients with hypoxemic acute respiratory failure. Intensive Care Med 30:147–150
  8. Mehta S, Hill NS (2001) Noninvasive ventilation. Am J Respir Crit Care Med 163:540–577
    • View reference on PubMed
  9. Tonnelier JM, Prat G, Nowak E, Goetghebeur D, Renault A, Boles JM, L’Her E (2003) Noninvasive continuous positive airway pressure ventilation using a new helmet interface: a case-control prospective pilot study. Intensive Care Med 29:2077–2080
  10. Patroniti N, Saini M, Zanella A, Isgro S, Pesenti A (2007) Danger of helmet continuous positive airway pressure during failure of fresh gas source supply. Intensive Care Med 33:153–157
  11. Lofaso F, Brochard L, Hang T, Lorino H, Harf A, Isabey D (1996) Home versus intensive care pressure support devices. Experimental and clinical comparison. Am J Respir Crit Care Med 153:1591–1599
    • View reference on PubMed

Sign In

Connect with ICM

Top 5 Articles Editors Picks Supplement