Indian Journal of Critical Care Medicine

Register      Login



Volume / Issue

Online First

Related articles

VOLUME 25 , ISSUE 10 ( October, 2021 ) > List of Articles

Original Article

Helmet NIV in Acute Hypoxemic Respiratory Failure due to COVID-19: Change in PaO2/FiO2 Ratio a Predictor of Success

Onkar K Jha, Sunny Kumar, Saurabh Mehra, Mrinal Sircar, Rajesh Gupta

Keywords : Acute hypoxemic respiratory failure, Acute respiratory distress syndrome, COVID pneumonia, COVID-19, Helmet, Noninvasive mechanical ventilation, PaO2/FiO2 ratio

Citation Information : Jha OK, Kumar S, Mehra S, Sircar M, Gupta R. Helmet NIV in Acute Hypoxemic Respiratory Failure due to COVID-19: Change in PaO2/FiO2 Ratio a Predictor of Success. Indian J Crit Care Med 2021; 25 (10):1137-1146.

DOI: 10.5005/jp-journals-10071-23992

License: CC BY-NC 4.0

Published Online: 21-06-2022

Copyright Statement:  Copyright © 2021; Jaypee Brothers Medical Publishers (P) Ltd.


In acute respiratory failure due to severe coronavirus disease 2019 (COVID-19) pneumonia, mechanical ventilation remains challenging and may result in high mortality. The use of noninvasive ventilation (NIV) may delay required invasive ventilation, increase adverse outcomes, and have a potential aerosol risk to caregivers. Data of 30 patients were collected from patient files and analyzed. Twenty-one (70%) patients were weaned successfully after helmet-NIV support (NIV success group), and invasive mechanical ventilation was required in 9 (30%) patients (NIV failure group) of which 8 (26.7%) patients died. In NIV success vs failure patients, the mean baseline PaO2/FiO2 ratio (PFR) (147.2 ± 57.9 vs 156.8 ± 59.0 mm Hg; p = 0.683) and PFR before initiation of helmet (132.3 ± 46.9 vs 121.6 ± 32.7 mm Hg; p = 0.541) were comparable. The NIV success group demonstrated a progressive improvement in PFR in comparison with the failure group at 2 hours (158.8 ± 56.1 vs 118.7 ± 40.7 mm Hg; p = 0.063) and 24 hours (PFR-24) (204.4 ± 94.3 vs 121.3 ± 32.6; p = 0.016). As predictor variables, PFR-24 and change (delta) in PFR at 24 hours from baseline or helmet initiation (dPFR-24) were significantly associated with NIV success in univariate analysis but similar significance could not be reflected in multivariate analysis perhaps due to a small sample size of the study. The PFR-24 cutoff of 161 mm Hg and dPFR-24 cutoff of −1.44 mm Hg discriminate NIV success and failure groups with the area under curve (confidence interval) of 0.78 (0.62–0.95); p = 0.015 and 0.74 (0.55–0.93); p = 0.039, respectively. Helmet interface NIV may be a safe and effective tool for the management of patients with severe COVID-19 pneumonia with acute respiratory failure. More studies are needed to further evaluate the role of helmet NIV especially in patients with initial PFR <150 mm Hg to define PFR/dPFR cutoff at the earliest time point for prediction of helmet-NIV success.

  1. Alhazzani W, Moller MH, Arabi YM, Loeb M, Gong MN, Fan E, et al. Surviving sepsis campaign: guidelines on the management of critically ill adults with Coronavirus Disease 2019 (COVID-19). Intensive Care Med 2020;46(5):854–887. DOI: 10.1007/s00134-020-06022-5.
  2. Gattinoni L, Chiumello D, Caironi P, Busana M, Romitti F, Brazzi L, et al. COVID-19 pneumonia: different respiratory treatments for different phenotypes? Intensive Care Med 2020;46(6):1099–1102. DOI: 10.1007/s00134-020-06033-2.
  3. Demoule A, Hill N, Navalesi P. Can we prevent intubation in patients with ARDS? Intensive Care Med 2016;42(5):768–771. DOI: 10.1007/s00134-016-4323-6.
  4. Cortegiani A, Madotto F, Gregoretti C, Bellani G, Laffey JG, Pham T, et al. Immunocompromised patients with acute respiratory distress syndrome: secondary analysis of the LUNG SAFE database. Crit Care 2018;22(1):157-018-2079-9. DOI: 10.1186/s13054-018-2079-9.
  5. Brochard L, Slutsky A, Pesenti A. Mechanical ventilation to minimize progression of lung injury in acute respiratory failure. Am J Respir Crit Care Med 2017;195(4):438–442. DOI: 10.1164/rccm.201605-1081CP.
  6. Schwartz AR, Kacmarek RM, Hess DR. Factors affecting oxygen delivery with bi-level positive airway pressure. Respir Care 2004;49(3):270–275. PMID:14982645.
  7. Squadrone V, Coha M, Cerutti E, Schellino MM, Biolino P, Occella P, et al. Continuous positive airway pressure for treatment of postoperative hypoxemia: a randomized controlled trial. JAMA 2005;293(5):589–595. DOI: 10.1001/jama.293.5.589.
  8. Patel BK, Wolfe KS, Pohlman AS, Hall JB, Kress JP. Effect of noninvasive ventilation delivered by helmet vs face mask on the rate of endotracheal intubation in patients with acute respiratory distress syndrome: a randomized clinical trial. JAMA 2016;315(22):2435–2441. DOI: 10.1001/jama.2016.6338.
  9. Duan J, Han X, Bai L, Zhou L, Huang S. Assessment of heart rate, acidosis, consciousness, oxygenation, and respiratory rate to predict noninvasive ventilation failure in hypoxemic patients. Intensive Care Med 2017;43(2):192–199. DOI: 10.1007/s00134-016-4601-3.
  10. Bellani G, Laffey JG, Pham T, Madotto F, Fan E, Brochard L, et al. Noninvasive ventilation of patients with acute respiratory distress syndrome. Insights from the LUNG SAFE study. Am J Respir Crit Care Med 2017;195(1):67–77. DOI: 10.1164/rccm.201606-1306OC.
  11. Antonelli M, Conti G, Esquinas A, Montini L, Maggiore SM, Bello G, et al. A multiple-center survey on the use in clinical practice of noninvasive ventilation as a first-line intervention for acute respiratory distress syndrome. Crit Care Med 2007;35(1):18–25. DOI: 10.1097/01.CCM.0000251821.44259.F3.
  12. Cheung TM, Yam LY, So LK, Lau AC, Poon E, Kong BM, et al. Effectiveness of noninvasive positive pressure ventilation in the treatment of acute respiratory failure in severe acute respiratory syndrome. Chest 2004;126(3):845–850. DOI: 10.1378/chest.126.3.845.
  13. Alraddadi BM, Qushmaq I, Al-Hameed FM, Mandourah Y, Almekhlafi GA, Jose J, et al. Noninvasive ventilation in critically ill patients with the Middle East respiratory syndrome. Influenza Other Respir Viruses 2019;13(4):382–390. DOI: 10.1111/irv.12635.
  14. Rello J, Rodriguez A, Ibanez P, Socias L, Cebrian J, Marques A, et al. Intensive care adult patients with severe respiratory failure caused by Influenza A (H1N1)v in Spain. Crit Care 2009;13(5):R148. DOI: 10.1186/cc8044.
  15. Australian and New Zealand Intensive Care Society. Melbourne: ANZICS. The Australian and New Zealand Intensive Care Society (ANZICS) COVID-19 Guidelines Version 1. 2020; Available at:
  16. Ackermann M, Verleden SE, Kuehnel M, Haverich A, Welte T, Laenger F, et al. Pulmonary vascular endothelialitis, thrombosis, and angiogenesis in Covid-19. N Engl J Med 2020;383(2):120–128. DOI: 10.1056/NEJMoa2015432.
  17. Gattinoni L, Coppola S, Cressoni M, Busana M, Rossi S, Chiumello D. COVID-19 does not lead to a “typical” acute respiratory distress syndrome. Am J Respir Crit Care Med 2020;201(10):1299–1300. DOI: 10.1164/rccm.202003-0817LE.
  18. Avdeev SN. Non-invasive ventilation in patients with novel coronavirus infection COVID-19. Pulmonologiya 2020;30(5):679–687. DOI: 10.18093/0869-0189-2020-30-5-679-687.
  19. Cabrini L, Landoni G, Oriani A, Plumari VP, Nobile L, Greco M, et al. Noninvasive ventilation and survival in acute care settings: a comprehensive systematic review and metaanalysis of randomized controlled trials. Crit Care Med 2015;43(4):880–888. DOI: 10.1097/CCM.0000000000000819.
  20. Crimi C, Noto A, Princi P, Esquinas A, Nava S. A European survey of noninvasive ventilation practices. Eur Respir J 2010;36(2):362–369. DOI: 10.1183/09031936.00123509.
  21. Liu Q, Gao Y, Chen R, Cheng Z. Noninvasive ventilation with helmet versus control strategy in patients with acute respiratory failure: a systematic review and meta-analysis of controlled studies. Crit Care 2016;20(1):265. DOI: 10.1186/s13054-016-1449-4.
  22. Franco C, Facciolongo N, Tonelli R, Dongilli R, Vianello A, Pisani L, et al. Feasibility and clinical impact of out-of-ICU noninvasive respiratory support in patients with COVID-19-related pneumonia. Eur Respir J 2020;56(5):2002130. DOI: 10.1183/13993003.02130-2020.
  23. Hua J, Qian C, Luo Z, Li Q, Wang F. Invasive mechanical ventilation in COVID-19 patient management: the experience with 469 patients in Wuhan. Crit Care 2020;24(1):348. DOI: 10.1186/s13054-020-03044-9.
  24. Hui DS, Chow BK, Lo T, Ng SS, Ko FW, Gin T, et al. Exhaled air dispersion during noninvasive ventilation via helmets and a total facemask. Chest 2015;147(5):1336–1343. DOI: 10.1378/chest.14-1934.
  25. Duca A, Memaj I, Zanardi F, Preti C, Alesi A, Della Bella L, et al. Severity of respiratory failure and outcome of patients needing a ventilatory support in the Emergency Department during Italian novel coronavirus SARS-CoV2 outbreak: preliminary data on the role of helmet CPAP and non-invasive positive pressure ventilation. EClinical Medicine 2020;24:100419. DOI: 10.1016/j.eclinm.2020.100419.
  26. Du K. Noninvasive ventilation in patients with acute respiratory distress syndrome. Crit Care 2019;23(1):358. DOI: 10.1186/s13054-019-2666-4.
  27. Dobler CC, Murad MH, Wilson ME. Non-invasive positive pressure ventilation in patients with COVID-19. Mayo Clin Proc 2020;95(12):2594–2601. DOI: 10.1016/j.mayocp.2020.10.001.
  28. Frat JP, Ragot S, Coudroy R, Constantin JM, Girault C, Prat G, et al. Predictors of intubation in patients with acute hypoxemic respiratory failure treated with a noninvasive oxygenation strategy. Crit Care Med 2018;46(2):208–215. DOI: 10.1097/CCM.0000000000002818.
  29. Hager DN, Krishnan JA, Hayden DL, Brower RG, ARDS Clinical Trials Network. Tidal volume reduction in patients with acute lung injury when plateau pressures are not high. Am J Respir Crit Care Med 2005;172(10):1241–1245. DOI: 10.1164/rccm.200501-048CP.
  30. Protti A, Cressoni M, Santini A, Langer T, Mietto C, Febres D, et al. Lung stress and strain during mechanical ventilation: any safe threshold? Am J Respir Crit Care Med 2011;183(10):1354–1362. DOI: 10.1164/rccm.201010-1757OC.
  31. Cruces P, Retamal J, Hurtado DE, Erranz B, Iturrieta P, Gonzalez C, et al. A physiological approach to understand the role of respiratory effort in the progression of lung injury in SARS-CoV-2 infection. Crit Care 2020;24(1):494. DOI: 10.1186/s13054-020-03197-7.
  32. Telias I, Katira BH, Brochard L. Is the prone position helpful during spontaneous breathing in patients with COVID-19? JAMA 2020;323(22):2265–2267. DOI: 10.1001/jama.2020.8539.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.