NHS Guidance on use of NIV in adults with coronavirus | INTENSIVE Review

Guidance for the role and use of non-invasive respiratory support in adult patients with coronavirus (confirmed or suspected), March 26, 2020. [Accessed April 1 2020]. Available at URL: https://www.england.nhs.uk/coronavirus/wp-content/uploads/sites/52/2020/03/CLEARED_Specialty-guide_-NIV-respiratory-support-and-coronavirus-v2-26-March-003.pdf

In contrast to ANZICS Guidelines which recommend against the use of non-invasive ventilation (NIV), the National Health Service (England) have released guidance discussing the role and methods to provide NIV to patients with coronavirus disease 2019 (COVID-19). Also, in contrast to the ANZICS guidelines, the NHS guidance recommends against the use of high flow nasal oxygen (HFNO). the use of high flow nasal oxygen (HFNO).

A summary of the NHS recommendations is as follows:

• Treatment escalation plans and limitations to treatment, if any, should be established early in all patients

Indications

• HFNO is not recommended in COVID-19 management
• NIV may be indicated in the following circumstances:
  • As a ceiling of treatment
  • Trial to avoid intubation
  • To facilitate extubation

Settings & targets:

• CPAP for hypoxaemic respiratory failure, commencing at 10 cmH₂O pressure and an FiO₂ of 0.6, with potential to increase to 12-15 cmH₂O and FiO₂ 1.0.
• BiPAP may be used for hypercapnic acute on chronic respiratory failure
• Target SpO2 94-96%, or 88-92% for patients with acute on chronic respiratory failure

Principles of use:

• Ensure steps taken to minimise nosocomial spread (below)
• Consider methods to minimise agitation & distress
• Establish clear escalation plans/criteria for intubation
• Avoid over-ventilation and ‘patient-induced lung injury’ (PILI)
• During breaks off NIV use high flow face mask oxygen (not HFNO) or non-rebreather mask.

Recommendations to minimise nosocomial spread:

• Negative pressure room (>10 cycles/ hour air exchanges)
• Neutral pressure room or a simple side room (if negative pressure room not available)
• Cohorting if outside ICU, with clear plan for intubation if appropriate
• CPAP interface, in order of preference:
  • Full face mask, non-vented, with viral filter on expiratory limb
  • Helmet CPAP (with air cushion, if available) if full face mask not possible
  • Standard mask (least preferred option)
  • Must have ability to entrain oxygen
• Avoid vented masks
• Use HME/viral filter fitted to all exhaust systems
• Ensure staff PPE and methods to inadvertent avoid circuit disconnection

Discussion

The role of NIV and HFNO in COVID-19 remains unclear, with little direct evidence from COVID-19 patients of either efficacy or risk. This uncertainty, plus the purported risks of aerosolization generation and delayed intubation have led to varying recommendations between authorities (World Health Organisation (WHO), ANZICS, NHS and Surviving Sepsis Campaign (SSC) now all provide different advice, Table 1).

Table 1: Summary of recommendations from different groups

	NIV	HFNO
WHO	Yes	Yes
SSC	Yes	Yes
NHS	Yes	No
ANZICS	No	Yes

WHO = World Health Organisation (March 13, 2020); ANIZCS = Australian and New Zealand Intensive Care Society (March 16, 2020); SCCM = Surviving Sepsis Campaign (March 23, 2020); NHS = National Health Service (March 26, 2020).

In general, there is concern about the efficacy and safety of NIV in the management of acute respiratory distress (ARDS). In ARDS cohorts, NIV prior to intubation was associated with high failure, delayed intubation and an increased risk of mortality (LUNG-SAFE observational study and FLORALI RCT). Additionally, there is a suggestion that HFNO may be superior to NIV in these circumstances, particularly in patients with a PaO2:FiO2 ratio of ≤ 200mmHg (FLORALI). In contrast, NIV may be beneficial post-extubation in reducing re-intubation rates in high risk patients, though without improving mortality or ICU length of stay (HIGH-WEAN RCT). There may also be circumstances in which NIV is clearly beneficial, for example, patients with chronic obstructive pulmonary disease (COPD) or cardiogenic pulmonary oedema. The role of NIV in these patients, who may have concurrent confirmed or suspected SARS-CoV-2 is perhaps clearer than for patients with hypoxic respiratory failure due to COVID-19 lung injury.

The main criticism of the NHS guideline is that it doesn’t provide a review of the evidence/rationale behind the recommendations. The NHS authors propose that lung compliance of COVID-19 patients is generally preserved hence the rationale for CPAP, however this may not always be the case. Positive pressure ventilated, spontaneous breathing patients may develop what the authors refer to as ‘patient-induced lung injury’, due to generation of excess tidal volume or elevated transpulmonary pressure, the potential mechanism of which is described by Brochard et al. 2016. The NHS authors warn clinicians to be vigilant against harmfully high tidal volumes, but do not provide specific criteria against which to titrate CPAP pressure (in contrast to the FLORALI RCT protocol, for example).

Both NIV with vented and non-vented masks have the potential to generate dispersal jets containing droplet or aerosolised viral particles with a risk of infection to health care workers (HCW) and other patients. During SARS in 2002/2003, non-invasive ventilation was associated with increased risk of HCW infection. Under simulated conditions; vented masks may generate large dispersal plumes up to 65cm in length. With well fitting, non-vented NIV masks, leakage plumes appear to remain limited to around patient’s head and face, although evidence is poor, and will depend on fit. Importantly, HCW intervention is still required to apply and remove the mask, with potential for droplet or aerosolization while in close proximity. A poor fitting mask may both increase leakage and the frequency of HCW interventions. Distress or agitation may lead to a poor fitting mask, frequent removal, or disconnection of the circuit. Patients on NIV may therefore require closer supervision, increasing risk of HCW exposure. Finally, NIV may delay early intervention for patients who are deteriorating, resulting in intubation under more urgent conditions, where a risk of PPE breach may be higher.

While endorsing CPAP, the NHS authors recommend against the use of HFNO, citing a ‘lack of efficacy, oxygen use and infection spread.’ Like NIV, HFNO may generate dispersal plumes of exhaled air however droplet deposition from HFNO under simulated conditions appears to be limited to within 30 cm of the face. Furthermore, co-operative patients may be able to adjust HFNO cannulae themselves without HCW being in close proximity, and wear a mask to reduce forward droplet spread. Like NIV, the potential for aerosolization remains unclear.

Summary

Whether and when patients with COVID-19 should be offered NIV or HFNO remains contentious. For patients who have limitations to treatment, for patients with acute on chronic respiratory failure, for facilitating extubation (for example, obese patients) NIV may offer a viable alternative. In these circumstances, the NHS guidelines provide clear advice on how to use NIV and minimise the risk of nosocomial spread. The main criticism of this guideline is that it doesn’t provide a review of the evidence/rationale behind the recommendations.

Further in vivo evidence regarding the safety and potential role for NIV or HFNO is desperately needed, as health systems face having to rationalise treatment to patients due to a lack of resources. For clinicians who choose to offer NIV to patients with COVID-19, the NHS guidance otherwise offers clear and detailed advice on how to provide this in a way that reduces (as much as possible) risk to patients and staff, however additional guidance on how to titrate therapy to avoid ‘patient-induced lung injury’ may be necessary to avoid adverse outcomes from the therapy.

Note: This review does not imply an endorsement of any particular guideline, and the opinions offered are the author’s own, with best available evidence at the time of writing. Clinicians should adhere to local guidelines where possible.

Further reading

• Australian and New Zealand Intensive Care Society (2020). ANZICS COVID-19 Guidelines Version 1. Melbourne: ANZICS. https://www.anzics.com.au/wp-content/uploads/2020/03/ANZICS-COVID-19-Guidelines-Version-1.pdf [accessed 2020 Mar 16]
• Bellani G, Laffey JG, Pham T, 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
• Berbenetz N, Wang Y, Brown J, et al. Non-invasive positive pressure ventilation (CPAP or bilevel NPPV) for cardiogenic pulmonary oedema. Cochrane Database Syst Rev. 2019;4(4):CD005351. Published 2019 Apr 5. doi:10.1002/14651858.CD005351.pub4
• 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
• Frat JP, Thille AW, Mercat A, et al. High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med. 2015;372(23):2185–2196. doi:10.1056/NEJMoa1503326
• Hui DS, Chow BK, Lo T, et al. Exhaled air dispersion during high-flow nasal cannula therapy versus CPAP via different masks. Eur Respir J. 2019;53(4):1802339. Published 2019 Apr 11. doi:10.1183/13993003.02339-2018
• Hui DS, Chow BK, Ng SS, et al. Exhaled air dispersion distances during noninvasive ventilation via different Respironics face masks. Chest. 2009;136(4):998–1005. doi:10.1378/chest.09-0434
• Hui DS, Hall SD, Chan MT, et al. Noninvasive positive-pressure ventilation: An experimental model to assess air and particle dispersion. Chest. 2006;130(3):730–740. doi:10.1378/chest.130.3.730
• Kotoda M, Hishiyama S, Mitsui K, et al. Assessment of the potential for pathogen dispersal during high-flow nasal therapy. J Hosp Infect. 2019;S0195-6701(19)30479-7. doi:10.1016/j.jhin.2019.11.01
• Loh NW, Tan Y, Taculod J, et al. The impact of high-flow nasal cannula (HFNC) on coughing distance: implications on its use during the novel coronavirus disease outbreak [published online ahead of print, 2020 Mar 18]. Can J Anaesth. 2020;10.1007/s12630-020-01634-3. doi:10.1007/s12630-020-01634-3
• NHS (2020). Guidance for the role and use of non-invasive respiratory support in adult patients with coronavirus (confirmed or suspected). 2020 March 26. https://www.england.nhs.uk/coronavirus/wp-content/uploads/sites/52/2020/03/CLEARED_Specialty-guide_-NIV-respiratory-support-and-coronavirus-v2-26-March-003.pdf [accessed 2020 March 29].
• Osadnik CR, Tee VS, Carson-Chahhoud KV, Picot J, Wedzicha JA, Smith BJ. Non-invasive ventilation for the management of acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2017;7(7):CD004104. Published 2017 Jul 13. doi:10.1002/14651858.CD004104.pub4
• Pan C, Chen L, Lu C, et al. Lung Recruitability in SARS-CoV-2 Associated Acute Respiratory Distress Syndrome: A Single-center, Observational Study [published online ahead of print, 2020 Mar 23]. Am J Respir Crit Care Med. 2020;10.1164/rccm.202003-0527LE. doi:10.1164/rccm.202003-0527LE
• Raboud J, Shigayeva A, McGeer A, et al. Risk factors for SARS transmission from patients requiring intubation: a multicentre investigation in Toronto, Canada. PLoS One. 2010;5(5):e10717. Published 2010 May 19. doi:10.1371/journal.pone.0010717
• Thille AW, Muller G, Gacouin A, et al. Effect of Postextubation High-Flow Nasal Oxygen With Noninvasive Ventilation vs High-Flow Nasal Oxygen Alone on Reintubation Among Patients at High Risk of Extubation Failure: A Randomized Clinical Trial. JAMA. 2019;322(15):1465–1475. doi:10.1001/jama.2019.14901
• World Health Organisation. Clinical management of severe acute respiratory infection (SARI) when COVID-19 disease is suspected: Interim Guidance v1.2. 2020 March 13. Ref: WHO/2019-nCoV/clinical/2020.4. https://www.who.int/publications-detail/clinical-management-of-severe-acute-respiratory-infection-when-novel-coronavirus-(ncov)-infection-is-suspected